High Performance Concrete 1990
3100
ACI Committee 363
"STATE-OF-THE-ART REPORT ON HIGH-STRENGTH CONCRETE"
ACI Manual of Concrete Practice, 1990, Part 1, 48 pp.Currently available information about high-strength concrete is summarized. Topics discussed include selection of materials, concrete mix proportioning, batching, mixing, transporting, placing, control procedures, concrete properties, structural design, economics, and applications. A bibliography is included.
3101
Adelman, D. and Cousins, T. E.
"EVALUATION OF THE USE OF HIGH STRENGTH CONCRETE BRIDGE GIRDERS IN LOUISIANA"
PCI Journal, Sep-Oct 1990, Vol. 35, No. 5, pp 70-78.The strength of concrete used in routine bridge construction has increased gradually over the past 20 years. The use of high strength concrete is especially promising in the precast concrete industry, where quality control is more easily monitored. The purpose of the research described herein was to develop a high strength concrete mix design, investigate its material properties, and evaluate the cost effectiveness of its use in prestressed, pretensioned bridge girder design. A mix design yielding 11,460 psi (79 MPa) compressive strength at 28 days is presented. The material properties of this mix, including 18-hour compressive strength, modulus of elasticity, and modulus of rupture, are described. Span increases, made possible by the use of high strength concrete, are shown for several AASHTO girder shapes. A cost comparison, performed for span lengths ranging from 40 to 140 ft (12 to 43 m), shows that as much as $66/ft ($216/m) of bridge length could be saved with the use of high strength concrete girders in place of normal strength concrete girders.
3102
"AIRPORT OPEN TO AIR TRAFFIC HOURS AFTER REPAIR"
Public Works, Jan 1990, Vol. 121, No. 1, p 96.Yeager Airport in Charleston, West Virginia, is refurbishing its 6,300-ft concrete main runway with a new cement that allows jets to roll over fresh pavement just several hours after the concrete is placed. Nearly 250 cu yd of cement concrete made with Pyrament (registered trademark - Lone Star Industries, Inc., Greenwich, Connecticut), covering more than 1,100 sq yd of surface, are being placed on the runway during nighttime construction. There have been no construction-related air traffic delays.
3103
Aitcin, P-C. and Laplante, P.
"LONG-TERM COMPRESSIVE STRENGTH OF SILICA-FUME CONCRETE"
Journal of Materials in Civil Engineering, Aug 1990, Vol. 2, No. 3, pp 164-170.The long-term compressive strength of silica-fume concrete has been recently questioned by some researchers. This paper reports the results of compressive strength data on 4- to 6-year-old cores obtained from well-documented field experiments where both silica-fume and nonsilica-fume concrete mixtures were used. All concretes were exposed to freeze/thaw and thawing cycles and heavy deicing salt applications. The 1988 core results clearly show that the silica-fume field concretes have not experienced any strength loss, compared to the nonsilica-fume concretes. Moreover, the compressive strength results obtained on concrete cores taken after a 4-year period from an experimental column built with a very high-strength concrete also confirmed that there was no tendency for strength loss in silica-fume concretes.
3104
Aitcin, P-C. and Mehta, P. K.
"EFFECT OF COARSE-AGGREGATE CHARACTERISTICS ON MECHANICAL PROPERTIES OF HIGH-STRENGTH CONCRETE"
ACI Materials Journal, Mar-Apr 1990, Vol. 87, No. 2, pp 103-107.An experimental study investigated the influence of four coarse aggregate types available in Northern California on the compressive strength and elastic behavior of a very high-strength concrete mixture. Using identical materials and similar mix proportions, it was found that using diabase and limestone aggregates produced concretes with significantly higher strength and elastic modulus than those using granite and river gravel. The mineralogical differences in the aggregate types are considered to be responsible for this behavior.
3105
Aitcin, P-C., Sarkar, S. L., and Laplante, P.
"LONG-TERM CHARACTERISTICS OF A VERY HIGH STRENGTH CONCRETE"
Concrete International: Design and Construction, Jan 1990, Vol. 12, No. 1, pp 40-44.This article describes testing on cores taken two and four years after construction of an experimental high-strength concrete column. Core compressive strength equalled that of cube specimens cured in lime-saturated water at room temperature for 28 days, and after four years the concrete had retained a very dense microstructure without network microcracking. Recorded strains show very few volumetric changes in the concrete in the time since placement.
3106
Akers, D. J. and Miller, R. "LONG-TERM STRENGTH GAIN OF HIGH STRENGTH CONCRETE AS MONITORED BY DRILLED CORES"
Serviceability and Durability of Construction Materials, Proceedings of the First Materials Engineering Congress, held Aug 13-15, 1990, Denver, CO; Ed. by Bruce A. Suprenant; ASCE, New York, 1990, Vol. 1, pp 204-211.An evaluation was made of the relationship between standard cylinders, four-inch by eight-inch cylinders, and drilled cores. The evaluation results showed that the strengths obtained from drilled cores are highly dependent upon three factors: their tested orientation relative to that in the structure; the elevation of the core in the structure; and, the type of pre-test conditioning. A comparison of the core and cylinder compressive strengths indicates that the acceptance criteria of ACI 318, Section 4.7 may have limited applicability at the higher strength levels. Thus, it becomes very important that prior to core testing high strength concrete, the testing, conditioning, and acceptance criteria be agreed upon in advance and be rigorously followed.
3107
Artigues, J. C., Curado, J., and Iglesias, E.
"IMPERMEABILITY AND RESISTANCE TO CARBONATION OF CONCRETE WITH MICRO-SILICA AND WATER-REDUCING AGENTS"
Admixtures for Concrete: Improvement of Properties, Proceedings of the International Symposium held by RILEM, May 14-17, 1990, Barcelona, Spain; Ed. by E. Vazquez; Chapman and Hall, London, 1990, pp 229-240.The use of microsilica in concrete is under development, owing to the excellent properties it confers to the concrete on a durability level. This paper shows that to attain optimization of the properties of concrete filled with microsilica, the use of water-reducing admixtures with a high effectiveness is required, and, with these admixtures, different behaviours have been observed depending on their chemical nature. This study discusses the combined effects of the microsilica and water-reducing admixtures in two fundamental properties of the concrete in relation to its durability: its waterproofness and its carbonation resistance. The different types of admixtures used have shown differing behaviour, not only in their effectiveness as far as reducing the water/cement ratio is concerned, but also in the durability and compressive strength of the concrete, depending on their chemical constitution. Modified lignosulphonate and carboxylic polymer-based admixtures show greater effectiveness than these based on naphthalene sulphonate-formaldehyde condensate and sulphonated melamina-formaldehyde condensate.
3108
Babaei, K. and Hawkins, N. M.
"PERFORMANCE OF BRIDGE DECK CONCRETE OVERLAYS. EXTENDING THE LIFE OF BRIDGES"
ASTM Special Technical Publication, 1990, No. 1100, pp 95-108.This paper documents the performance of twelve concrete bridge decks in Washington State that were rehabilitated and/or protected with latex-modified concrete and low-slump dense concrete overlays in order to prevent further deicing salt penetration and concrete deterioration caused by reinforcing steel corrosion. An evaluation is made of the factors that have affected the serviceability of those overlaid bridge decks, and recommendations are made based on that evaluation for the design and construction of concrete overlays in order to improve bridge deck performance and to extend bridge deck service life. The factors evaluated are overlay freeze-thaw scaling, surface wear and skid resistance, surface cracking, bond with the underlying deck, chloride and water intrusion, and finally the concrete overlay's ability to retard continued reinforcing steel corrosion and corresponding concrete deterioration. The results of the evaluation indicate that, regardless of concrete deterioration caused by reinforcing steel corrosion, concrete overlaid bridge decks will require resurfacing after about 25 years of service. That maintenance will be needed as a result of traffic action and weathering. Typical forms of distress are freeze-thaw scaling, extensive wear in wheel lines, lack of skid resistance, and the loss of overlay bond. Concrete overlays are resistant but not impermeable to chloride infiltration. Further contamination of the underlying deck occurs in time depending on the rate of salt application. There are indications that the continued corrosion of reinforcing steel in the salt-contaminated underlying deck is less extensive in the absence of overlay surface cracking. There are numerous reasons for concrete overlays cracking during construction and service, and those reasons and their relation to the performance of bridge decks are discussed.
3109
Bahnasawy, H. H. and El-Refai, F. E.
"HIGH STRENGTH CONCRETE USING DOLOMITE AS COARSE AGGREGATE"
Protection of Concrete, Proceedings of the International Conference held Sep 11-13, 1990 at the University of Dundee, Scotland, UK; Ed. by Ravindra K. Dhir and Jeffrey W. Green; E. & F. N. Spon, London, 1990, pp 1037-1047.High strength concrete has become of special significance to be used in special structures, precast concrete and prestressed concrete. In this work about 12 concrete mixes have been investigated using crushed dolomite as coarse aggregate, for comparison with control mixes. Various cement contents, water/cement ratios, coarse/fine aggregate ratio and different curing methods have been studied to evaluate the potentiality of using this type of coarse aggregate to produce high strength concrete to be used for some special structures erected in Suez Canal area. Plasticizer and early strength admixture with different dosages are used in order to reduce the amount of mixing water to compensate the relatively high water absorption of the crushed dolomite. Fresh and hardened concrete properties are studied and compared with control mixes having gravel as coarse aggregates. The increase in concrete strength when using crushed dolomite as coarse aggregate is tangible. Analysis, discussions and conclusions for test results of the basic properties and their control in both fresh and hardened stages are presented.
3110
Bakhsh, A. H., Wafa, F. F., and Akhtaruzzaman, A. A.
"TORSIONAL BEHAVIOR OF PLAIN HIGH-STRENGTH CONCRETE BEAMS"
ACI Structural Journal, Sep-Oct 1990, Vol. 87, No. 5, pp 583-588.Test results of 13 rectangular plain high-strength concrete beams subjected to pure torsion are presented. The variable was the concrete strength, with the nominal concrete strength ranging from 40 to 90 MPa (5,800 to 13,000 psi). Coarse aggregate with high crushing strength and sand having a high fineness modulus were used along with a Type I portland cement. The plain high-strength concrete beams under torsion failed suddenly and violently along a smooth surface. The skew-bending theory is found suitable for predicting the torsional capacity of plain high-strength concrete beams, provided that the splitting tensile strength is taken to represent the concrete tensile strength.
3111
Baronio, G., Mantegazza, G., and Carminati, G.
"MECHANICAL PROPERTIES AND DURABILITY OF SUPERPLASTICIZED SILICA FUME MORTARS"
Admixtures for Concrete: Improvement of Properties, Proceedings of the International Symposium held by RILEM, May 14-17, 1990, Barcelona, Spain; Ed. by E. Vazquez; Chapman and Hall, London, 1990, pp 241-250.The purpose of this paper is to describe the preparation of a mortar with good workability and durability, low permeability and sufficient strength at early curing stages. It studies the influence of increasing the amounts of silica fume and superplasticizers on the strength, workability, permeability, and carbonation of the mortars. It also investigated whether the calcium hydrate present in the cement paste was fixed mainly by the pozzolanic action of the silica fume or by carbon dioxide. Portland cement type 425 and Durasil silica fume were used. The superplasticizer was Fluiment 40, and the aggregate was sand with a particle size distribution in the 0.075 to 2.0 mm. Four mix designs were tested. All the samples were stored for 24 hours in an environment of 20 degrees centigrade and 90% relative humidity, and then cured in water at 20 degrees centigrade for 28 days. Permeability tests were carried out according to DIN 1048. Compression and flexural strength tests were carried out according to the Italian code at 1, 3, 7 and 28 days. Accelerated carbonation tests were carried out after 28 days. Reference samples were sealed in plastic bags to avoid carbon dioxide penetration and therefore carbonation. The results show that the addition of 5, 10, 15 and 20% silica fume increases the mechanical strength of the mortar, and reduces both permeability and workability. Carbonation is reduced to about 35% of that of the control. Adding superplasticizer improves workability and permits the use of a lower water cement ratio. If silica fume percentage is greater than 15% and that of the superplasticizer is greater than 1.5%, the pozzolan action reduces carbonation by 70% after a month.
3112
Berke, N. S. and Rosenberg, A.
"CALCIUM NITRITE CORROSION INHIBITOR IN CONCRETE"
Admixtures for Concrete: Improvement of Properties, Proceedings of the International Symposium held by RILEM, May 14-17, 1990, Barcelona, Spain; Ed. by E. Vazquez; Chapman and Hall, London, 1990, pp 251-268.Extensive testing shows that calcium nitrite is an effective corrosion inhibitor for steel in concrete. Furthermore, in most cases, calcium nitrite improves the compressive strength of the concrete mix, and with proper air entrainment is freeze-thaw durable. In this paper data is presented documenting the effectiveness of calcium nitrite, and it shows how corrosion performance can be further improved with the use of the proper concrete mix designs and concrete cover.
3113
Berntsson, L., Chandra, S., and Kutti, T.
"PRINCIPLES AND FACTORS INFLUENCING HIGH-STRENGTH CONCRETE PRODUCTION"
Concrete International, Dec 1990, Vol. 12, No. 12, pp 59-62.Factors that control concrete strength, aggregates, cement, and superplasticizers are discussed. Ways of achieving low porosity in cement paste are noted, and laboratory tests are described that have applied the principles to obtain the maximum possible strength with normal packing on a vibrating table. The results show that it is possible to make mortar and concrete with exceptionally high strength using traditional procedures and the principles discussed. Cement type, amount of silica fume, gap grading of aggregates, size and quality of aggregates, and water-to-binder ratio are major factors that determine concrete strength. Using portland cement, silica fume, high dosages of superplasticizer, normal aggregates, and steel fibers, mortars with a compressive strength of more than 200 MPa were achieved.
3114
Bosco, C., Carpinteri, A., and Debernardi, P. G.
"MINIMUM REINFORCEMENT IN HIGH-STRENGTH CONCRETE"
Journal of Structural Engineering, Feb 1990, Vol. 116, No. 2, pp 427-437.A dimensional analysis criterion is proposed to compute the minimum amount of reinforcement for high-strength concrete members in flexure. Such an amount is assumed to be provided by the condition of simultaneous first cracking and steel yielding. The fracture mechanics model utilized defines a brittleness number NP, which is revealed to be a measure of the experimental brittleness or ductility of the test. NP is a function of steel-yield strength fy, concrete fracture toughness KIC, steel percentage As/A, and beam depth. The brittleness of the structural member increases by increasing the size and/or decreasing the steel content. On the other hand, a physically similar behavior is revealed in the cases where the brittleness number NP is the same. The experimental investigation carried out by the writers shows that the failure mechanism changes completely when the beam depth is varied, the steel percentage being the same. Only when the steel percentage is inversely proportional to the square root of the beam depth is the mechanical behavior reproduced.
3115
Brook, J. W., Berkey, R. A., and Farzam, H.
"A NON-CHLORIDE ACCELERATING ADMIXTURE FOR CLASS CF FLY ASH"
Concrete International, Oct. 1990, Vol. 12, No. 10, pp. 51-54.A new nonchloride admixture has been developed that accelerates the setting time and early strength development of concrete containing Class CF, Class F, or Class C fly ash. This admixture allows the economical production of high-strength concrete using fly ash, while maintaining the shortened construction cycles normally obtained with concrete containing only cement.
3116
Brown, J. H.
"FACTORS AFFECTING REAL LIFE PERFORMANCE OF CONCRETE IN BRIDGE SUB-STRUCTURES IN THE UK"
The United States Strategic Highway Research Program: Sharing the Benefits, Proceedings of the Conference Organized by the Institution of Civil Engineers in Cooperation with U.S. Strategic Highway Research Program, Oct 29-31, 1990, London; Ed. by J. Porter; T. Telford, London, 1990, pp 77-86.From 17 bridges, 50 small areas of concrete were selected for detailed investigation to find what particular difference of concrete quality had resulted in some having failed to protect the reinforcement from corrosion while others had proved adequate. The age range was 11 to 68 years. Site measurements included carbonation depth, cover and chloride profiles together with resistivity and half-cell potentials. Concrete quality was assessed from core samples and included gas permeability, absorption, porosity and cement content. The results showed some correlation between the different parameters and with durability, but also showed great field results and suggests that fundamental laboratory studies may well be a more effective way to investigate durability.
3117
Bungey, J. H.
"MEASUREMENT OF QUALITY"
Protection of Concrete, Proceedings of the International Conference held Sep 11-13, 1990 at the University of Dundee, Scotland, UK; Ed. by Ravindra K. Dhir and Jeffrey W. Green; E. & F. N. Spon, London, 1990, pp 831-845.Quality of concrete may be defined in a variety of ways, and these are considered in relation to specifications and performance requirements. Current procedures are outlined, and the range of available quality testing approaches briefly reviewed. Particular attention is concentrated on methods of insitu assessment of hardened concrete including strength, composition, permeability, surface zone parameters, internal uniformity and integrity, causes and extent of deterioration, and structural performance. Consideration is given to test planning, execution and interpretation with emphasis upon limitations including environmental influences. Possibilities for changes in testing practice are identified, with reference to developments in other countries, especially in terms of specification compliance procedures relating to durability performance.
3118
Burg, R. G.
"HEAT DEVELOPMENT AND IN-SITU STRENGTH OF LARGE DIAMETER CAISSONS MADE WITH HIGH-STRENGTH CONCRETE"
in Serviceability and Durability of Construction Materials, Proceedings of the First Materials Engineering Congress, held Aug 13-15, 1990, Denver, CO; Ed. by Bruce A. Suprenant; ASCE, New York, 1990, Vol. 1, pp 212-215.The test program essentially consisted of casting two prototype caissons using two different high-strength concretes, measuring internal caisson and adjacent soil temperatures, extracting concrete core samples at various test ages, and performing standard concrete control tests. Of particular interest was the relationship between the in-situ concrete strength as measured by cores and the concrete strength measured by standard 6 multiplied by 12-inch control specimens. Because the test program is currently underway all test results are not available, only the specifics of the test program are described.
3119
Burg, R. G., Cichanski, W. J., and Hoff, G. C.
"SELECTED PROPERTIES OF THREE HIGH-STRENGTH LIGHTWEIGHT CONCRETES DEVELOPED FOR ARCTIC OFFSHORE STRUCTURES"
Proceedings of the 9th International Conference on Offshore Mechanics and Arctic Engineering, Feb 18-23, 1990, Houston, TX; ASME, New York, Vol. 3, Part A, pp 85-92.Three high-strength, lightweight concretes intended for severe, marine exposure were developed for the unique set of environmental and operating conditions encountered by arctic offshore structures. Two of the concretes had a design compressive strength of 7000 psi; one with fly ash as a mineral admixture, and one with silica fume. The third concrete had a design compressive strength of 9000 psi and used silica fume as a mineral admixture. This paper presents the results of the mix design development for all three concretes. Salient properties of fresh concrete are detailed, including slump, unit weight, and fresh air content. Properties discussed for the hardened concrete include compressive strength, modulus of elasticity, Poisson's ratio, splitting tensile strength, modulus of rupture, and chloride permeability. Where possible, measured data are compared with theoretical values based on compressive strength. As appropriate, modified relationships which compare measured compressive strength values and other mechanical properties are suggested.
3120
Castillo, C. and Durrani, A. J.
"EFFECT OF TRANSIENT HIGH TEMPERATURE ON HIGH-STRENGTH CONCRETE"
ACI Materials Journal, Jan-Feb 1990, Vol. 87, No. 1, pp 47-53.The effect of transient high temperature on strength and load-deformation behavior of high-strength concrete was investigated. The concrete strength varied between 4500 to 12,900 psi (31.1 to 89 MPa) and the temperature exposure was in the range of 23 to 800 C (73 to 1472 F). The presence of loads in real structures was simulated by preloading the test specimens before exposure to elevated temperature. Exposure to temperatures in the range of 100 to 300 C (212 to 572 F) was observed to decrease the compressive strength of high-strength concrete by 15 to 20 percent. At temperatures in the range of 400 to 800 C (752 to 1472 F), the compressive strength of concrete decreased to about 30 percent of its strength at room temperature. The exposure to high temperature also decreased the modulus of elasticity of concrete.
3121
Charif, H., Jaccoud, J-P., and Alou, F.
"REDUCTION OF DEFORMATIONS WITH THE USE OF CONCRETE ADMIXTURES"
Admixtures for Concrete: Improvement of Properties, Proceedings of the International Symposium held by RILEM, May 14-17, 1990, Barcelona, Spain; Ed. by E. Vazquez; Chapman and Hall, London, 1990, pp 402-428.As part of a vast research programme concerning the calculation and the reduction of concrete slabs deformations, an experimental study on high strength concrete, (HSC), and its use in the case of slabs was undertaken. Concrete characterized by a good tensile strength, and by a weak deformability, i.e. where the elastic modulus is as high as possible, and the time-dependent deformations are as small as possible were investigated. The aim was also to make concretes with good workability. In order to obtain the "optimum" high performances of these concretes, the following parameters were varied: the cement dosage, the dosage of a superplasticizer used as a water reducing agent, the eventual addition of silica fume, the maximum diameter and the shape of the aggregates. The experimental study, which lasted for two years (April 87 - April 89), was divided into three phases. The first two phases consisted of different time duration (short or long) tests on cylinders. The final results indicate that the following improved performances are provided by the high strength concretes in comparison to ordinary concretes: (a) The compressive strength can be increased by 100 to 150%; (b) The elastic modulus can be increased by 20 to 30%; (c) The tensile strength can be increased by 40 to 60%; (d) The shrinkage deformations are more important at an early age, but attain the same values after one year; and (e) The creep deformations can be reduced by 30 to 60%.
3122
Chen, G. and Nielsen, M. P.
"SHEAR STRENGTH OF BEAMS OF HIGH STRENGTH CONCRETE"
Danmarks Tekniske Hojskole, Afdelingen for Baerende Konstruktioner, 1990, Serie R, No. 258, 23 pp.Several groups of shear tests of beams with high strength concrete, which are found so far in the literature, have been compared with the theoretical solutions of beam shear. The agreement between tests and theory has been found to be satisfactory.
3123
Collepardi, M., Moriconi, G., Pauri, M., Biagini, S., and Alvera, I., "SUPERPLASTICIZED SILICA FUME HIGH-STRENGTH CONCRETES"
Admixtures for Concrete: Improvement of Properties, Proceedings of the International Symposium held by RILEM, May 14-17 1990, Barcelona, Spain; Ed. by E. Vazquez; Chapman and Hall, London, 1990, pp 175-182.The effect of combined additions of silica fume and superplasticizer on concrete compressive strength has been studied by taking into account the following parameters: (a) type and dosage rate of superplasticizer; (b) type and content of portland cement; (c) way of silica fume utilization (as additional component or as cement replacement). In the presence of silica fume, for both type I and type III portland cement, the melamine sulphonated polymer superplasticizer performs better than the naphthalene sulphonated polymer, particularly when a high dosage such as 4% is used. A change from 2 to 4% superplasticizer dosage rate in general does not modify or reduce compressive strength in the absence of silica fume, whereas significantly increases compressive strength in the presence of silica fume.
3124
Cormack, G.
"ADVANCES IN CONCRETE CONSTRUCTION - MATERIALS AND TECHNIQUES"
New Zealand Engineering, 1990, Vol. 45, No. 7, pp 8-9.The concrete mix design has changed rapidly with high strengths being used in the search for improved durability. High strength overlays have been used on roads to improve freeze-thaw characteristics and resistance to steel studded snow tires. Silica fume is being used to reduce rebound and dust for shotcrete applications. Rollcrete, with crack inducers, has been used on the construction of an arch dam. Cracks appearing at predetermined locations are grouted. Many bridges are being built and they are generally precast concrete short to medium spans with unbonded external cables or longer spans of cantilever construction cast in situ with cable stays. Some Belgian cable stayed bridges have been constructed alongside a river and then rotated through 90 degrees. Externally prestressed bridges are less costly and can be quickly constructed. A floating bridge is planned for Norway where the first underwater bridge was constructed. Bi-prestressing has been used when structural depth is limited. Glass fibre composite materials are being used where light cables or electromagnetic neutrality are required. Prototype bridges are now being built with the capability for regularly transmitting readings of crack widths, stress changes and durability back to the client's or designer's office.
3125
Cortez, E. R. and Eaton, R. A.
"FREEZE-THAW TESTS OF FULL-SCALE ROLLER-COMPACTED CONCRETE TEST SECTIONS"
Special Report, Cold Regions Research and Engineering Laboratory, Hanover, NH, 1990, 19 pp. (CRREL-SR-90-25; AD-A228577)Roller-compacted concrete (RCC) is a new construction material that is being studied to determine its freeze-thaw performance and failure criteria. The ingredients are basically the same as portland cement concrete (PCC), but RCC is placed like asphalt concrete. RCC has rapidly gained widespread acceptance. Some concern still exists, however, about its ability to withstand cycles of freezing and thawing. Preliminary tests run on samples from early projects showed little resistance to freeze and thaw damage. Attempts to air-entrain RCC were not successful. However, new equipment and quality control methods have substantially improved the quality in recent projects. This report describes a research program that included the construction and freeze-thaw testing of eight full-scale pavement test sections. The overall performance demonstrated that the freeze-thaw durability of RCC is comparable with that of air-entrained PCC.
3126
Cortez, E. R. and Gerlach, J. A.
"ROLLER-COMPACTED CONCRETE PAVEMENT CONSTRUCTION AT FORT DRUM, NEW YORK"
Transportation Research Record, 1990, No. 1282, pp 8-17.During the 1988 and 1989 construction seasons, 335,000 sq m (83 acres) of roller-compacted concrete (RCC) pavement 0.254 m (10 in.) thick was built for the U.S. Army, 10th Mountain Division (Light Infantry) at Fort Drum, New York. The design, construction, quality control practice, and durability of the RCC under the seasonal frost environmental conditions at this location were studied.
3127
Cox, B. E.
"THE UNITED STATES STRATEGIC HIGHWAY RESEARCH PROGRAM"
Proceedings of the Institution of Civil Engineers, Part 1: Design and Construction, Oct 1990, Vol. 88, pp 815-837.A general overview is given of the history, funding, management, and technical research areas of the United States Strategic Highway Research Program (SHRP), a five-year, $150 million research effort targeted to achieve rapid progress in specific areas of highway technology. Relationships between the SHRP and research in the UK are discussed, including cooperation between the SHRP and the Transport and Road Research Laboratory, the role of the UK SHRP coordinator, involvement in research contracts, and the funding by the Science and Engineering Research Council of UK academic research complementary to specific SHRP contracts. There follows a detailed discussion of the impact of the SHRP on future highway engineering technology, including performance-oriented specifications for bituminous materials, pavement design and pavement management systems, the cost-effectiveness of highway maintenance, high performance concrete, assessment of the physical conditions, and the repair and replacement of concrete bridge components.
3128
de Larrard, F.
"A METHOD FOR PROPORTIONING HIGH-STRENGTH CONCRETE MIXTURES"
Cement, Concrete and Aggregates, Summer 1990, Vol. 12, No. 1, pp 47-52.This paper describes two semi-empirical mix-design tools. The strength of the concrete is predicted by Feret's formula from a limited number of mix-design parameters. The workability is assumed to be closely related to the viscosity of the mix, which can be computed using the Farris model, a rheological model dealing with viscosity of a polydispersed suspension. The theoretical model and the empirical formula that are presented allows determination of the composition of a concrete mixture having a given strength and workability with a minimal number of trial concrete batches.
3129
de Larrard, F., Gorse, J-F., and Puch, C.
"COMPARATIVE EFFECTIVENESS OF VARIOUS SILICA FUMES AS ADDITIVES IN HIGH-PERFORMANCE CONCRETE"
Bulletin de Liaison des Laboratoires des Ponts et Chaussees, Jul-Aug 1990, No. 168, pp 97-106.This paper deals with marginal variations in the properties of very high performance mortars and concretes as affected by the property of the silica fume used. Twenty silica fumes were tested in the presence of two cement/superplasticizer combinations. The overall results were analyzed in terms of principal components and regressions. The influence of carbon on the workability of the mixes was verified. Finally, to the closest approximation to the dispersion of the results, it was possible to validate an empirical law based on previous results, showing the influence of the alkali content of the silica fume on its pozzolanic action. In French.
3130
Dhir, R. K., Jones, M. R., and Green, J. W.
"PROTECTION OF STRUCTURAL CONCRETE"
Protection of Concrete, Proceedings of the International Conference held Sep 11-13, 1990 at the University of Dundee, Scotland, UK; Ed. by Ravindra K. Dhir and Jeffrey W. Green; E. & F. N. Spon, London, 1990, pp 331-346.An overview is provided of the current practice of concrete construction and how concrete can be protected from premature deterioration. The characteristics of environments to which concrete are exposed are examined together with their effects on concrete materials and reinforcement. The influence of method specifications for concrete are considered in terms of their approach to durability. It is suggested that a move towards performance specifications will help provide better protection for concrete. It is argued that tests for this purpose should concentrate on the cover concrete. The concept of design life and whole life costs are introduced. Options for providing durable concrete are discussed. The role of education and training is raised.
3131
Dilly, R. L., Olsen, M. P. J., and Berger, W. J. "MATURITY AND PULLOUT FOR HIGH-STRENGTH CONCRETE"
Serviceability and Durability of Construction Materials, Proceedings of the First Materials Engineering Congress, held Aug 13-15, 1990, Denver, CO; Ed. by Bruce A. Suprenant; ASCE, New York, 1990, Vol. 1, pp 233-243.As with other types of concrete mixtures, construction with high-strength concrete requires assurance that sufficient levels of in-place strength are reached at specific times. An experimental investigation of concrete with compressive strengths in excess of 6,000 psi was undertaken to investigate the application of combining the maturity and the pullout test methods for evaluation of greater in-place concrete strengths than previously reported. Relationships are reported between pullout test and compressive strength results for several mixtures. Also reported are the relations between the logarithm of maturity and the pullout test results for a mixture cured in two different environments.
3132
Feng, N-Q., Li, G-Z., and Zang, X-W.
"HIGH-STRENGTH AND FLOWING CONCRETE WITH A ZEOLITIC MINERAL ADMIXTURE"
Cement, Concrete and Aggregates, Winter 1990, Vol. 12, No. 2, pp 61-69.This is an experimental study of the zeolitic mineral admixture (ZMA), natural zeolite ground with a bit of triethanolamine. The principal mineral composition of this admixture is clinaptilolite or mordenite whose content is about 60%. The details of the experiment are given, and the test results are discussed. The strengthening mechanism of ZMA on cement concrete is described. It was found that a partial replacement of cement by ZMA can more effectively make high-strength concrete. The strengthening effect of ZMA on concrete is determined by its chemical activity and mineral compositions. It was also found that ZMA not only can decrease the orientation of Ca(OH)2 in the interface transition zone between the cement paste and the aggregate, but also reduce its orientation range.
3133
Fjeld, S. and Rosendahl, F.
"APPLICATION OF CONCRETE FOR FLOATING OFFSHORE STRUCTURES"
Proceedings of the Ninth International Conference on Offshore Mechanics and Arctic Engineering, held Feb 18-23, 1990, Houston, TX; ASME, New York, 1990, Vol. 3, Pt. A, pp 105-114.The properties and feasibility of reinforced concrete as construction material for floating platforms for exploitation of offshore oil and gas is described. Recent development in the field of high quality concrete mix design and constituent materials are discussed. The strength, water tightness and durability of the concrete are discussed on the basis of production testing, theoretical investigations and in service experience. Possibilities for construction of concrete hulls in shallow water areas such as the Gulf of Mexico is briefly described. The conclusion is that present high quality structural concrete is feasible for application in permanently floating structures. Significant merits in terms of strength, robustness and durability are demonstrated.
3134
Gagne, R., Pigeon, M., and Aitcin, P-C.
"FROST RESISTANCE DURABILITY OF HIGH-STRENGTH CONCRETES"
Materials and Structures, Mar 1990, Vol. 23, No. 134, pp 103-109.This text presents the main results of research carried out towards a better understanding of the behaviour of high-strength concrete subjected to freeze-thaw cycles. High-strength concrete is a new material and it is not yet possible to assess its in situ capacity to resist attack by frost and de-icing salts. The durability of 80-100 MPa high-strength concrete was analyzed at the University Laval, subjecting it to quick laboratory freeze-thaw tests in water (ASTM C 666) and daily freeze-thaw cycles in de-icing salt solution (C672). None of the test pieces made was destroyed by the freeze-thaw cycles. It is the use of fine-grain high-strength cement with 6% silica fumes and of relatively low water to cement ratios ( less than 0.30) which ensures the durability of these concretes. In French.
3135
Gerwick, B. C., Jr.
"INTERNATIONAL EXPERIENCE IN THE PERFORMANCE OF MARINE CONCRETE"
Concrete International: Design and Construction, May 1990, Vol. 12, No. 5, pp 47-53.Selected examples are described of marine structures that have been successful as well as those that have failed. Performance criteria for concrete structures are discussed. The importance of structural design and the evaluation of all probable load combinations are noted, and the existence of guides for designs and analyses are noted. Durability enhancing measures, including the importance of impermeability to chloride ions is discussed. The specific projects discussed include the following: North Sea offshore platforms; the Ooosterschelde storm surge barrier in the Netherlands; seawater cooling canal, eastern Saudi Arabia; Ju'Aymah LPG trestle; King Faud Causeway; Rodney Terminal, St. John, New Brunswick; Tarsiut Caisson-Retained Drilling Island, Beaufort Sea; Baltic Sea lighthouse structures; and Global Marine Development's Arctic Offshore Drilling Platform. Undersea tunnels and prestressed concrete structures are also discussed.
3136
Gettu, R., Bazant, Z. P., and Karr, M. E.
"BRITTLENESS OF HIGH STRENGTH CONCRETE"
Serviceability and Durability of Construction Materials, Proceedings of the First Materials Engineering Congress, held Aug 13-15, 1990, Denver, CO; Ed. by Bruce A. Suprenant; ASCE, New York, 1990, Vol. 2, pp 976-985.Fracture mechanics approaches are needed to determine material parameters which are related to the brittleness of concrete and its structural response. The size effect method is used to determine these fracture parameters for typical high strength silica fume concrete. The method requires only the peak loads of geometrically similar fracture specimens that are significantly different in size. Three-point bending tests of notched specimens are used. Comparison with data of normal strength concrete shows that for an increase in compressive strength of about 160%, the fracture energy and fracture toughness increase by only 12% and 25%, respectively. The brittleness more than doubles, and the effective fracture process zone length decreases by about 60%.
3137
Gettu, R., Bazant, Z. P., and Karr, M. E.
"FRACTURE PROPERTIES AND BRITTLENESS OF HIGH-STRENGTH CONCRETE"
ACI Materials Journal, Nov-Dec 1990, Vol. 87, No. 6, pp 608-618.The size-effect method for determining material fracture characteristics, as previously proposed by Bazant and extensively verified for normal strength concrete, is applied to typical high-strength concrete. Geometrically similar three-point bending specimens are tested and the measured peak load values are used to obtain the fracture energy, the fracture toughness, the effective length of the fracture process zone, and the effective critical crack-tip opening displacement. The brittleness of the material is shown to be objectively quantified through the size-effect method. By comparing the material fracture properties obtained with those of normal strength concrete, it is shown that an increase of 160 percent in compressive strength causes: (1) an increase of fracture toughness by only about 25 percent, (2) a decrease of effective fracture process zone length by about 60 percent, and (3) more than doubling of the brittleness number, which may be an adverse feature that will need to be dealt with in design. The brittleness number, however, is still not high enough to permit the use of linear elastic fracture mechanics. The R-curves are demonstrated to derive according to the size-effect law exclusively from the maximum loads of specimens of various sizes and yield remarkably good predictions of the load-deflection curves.
3138
Gjorv, O. E., Baerland, T., and Ronning, H. R.
"ABRASION RESISTANCE OF HIGH-STRENGTH CONCRETE PAVEMENTS"
Concrete International: Design and Construction, Jan 1990, Vol. 12, No. 1, pp 45-48.Experimental work on the abrasion resistance of highway concrete pavements subjected to heavy traffic from studded tires has been carried out. Increasing the concrete strength from 50 to 100 MPa (7,100 to 14,300 psi) reduced the abrasion of the concrete by roughly 50%. At 150 MPa (21,400 psi) the abrasion of the concrete was comparable to that of high quality massive granite. Compared to an Ab 16t asphalt highway pavement, this represents an increase in the service life of the pavement by a factor of approximately ten.
3139
Gjorv, O. E., Monteiro, P. J. M., and Mehta, P. K.
"EFFECT OF CONDENSED SILICA FUME ON THE STEEL-CONCRETE BOND"
ACI Materials Journal, Nov-Dec 1990, Vol. 87, No. 6, pp 573-580.This paper reports a study of the effect of condensed silica fume (CSF) on the mechanical behavior of the steel-concrete bond, and on the microstructure of the steel-cement paste transition zone. The mechanical behavior of the steel-cement was studied by using the pullout test on concrete of varying compressive strength, and varying contents of CSF. Increased additions of CSF up to 16 % by weight of cement showed an improving effect on the pullout strength, especially in the high compressive strength range of the concrete. The presence of CSF affected the morphology and microstructure of the steel-cement paste transition zone. Thus, both porosity and thickness of the transition zone were reduced. The observed effect of CSF may be explained by several mechanisms: reduced accumulation of free water at the interface during casing of the specimens; reduced preferential orientation of the CH crystals at the steel-paste transition zone; and densification of the transition zone due to pozzolanic reaction between CH and CSF.
3140
Gudmestad, O. T. and Stead, B.
"DEVELOPMENT OF SMALL CONCRETE STRUCTURES FOR SAFE, ECONOMICAL PRODUCTION"
Proceedings of the European Petroleum Conference - EUROPEC 90, Oct 21-24, 1990, Hague, Neth.; European Offshore Petroleum Conference, London, 1990, Vol. 2, pp 515-522.The interest in concrete structures is presently gaining much attention. This interest is caused by the designers offering optimized structures answering the need to stimulate marginal field developments. Furthermore, the use of high strength concrete, the low installation costs for concrete structures and the need for competition in the platform construction market have enhanced the interest in concrete structures. Small concrete structures are being studied for several applications both as wellhead platforms and small wellhead/process platforms often combined with storage facilities. The paper describes recent development towards optimized small concrete structures for safe, economical production. The following items are in particular highlighted: The design process, concrete material aspects and the importance of the fabrication and installation procedures. Furthermore, the safety of the structures in the fabrication and installation phases are discussed in view of the need to secure the investments. Requirements to secure competitive structures and safe operations are furthermore being reviewed and examples of interesting small concrete solutions are shown. This paper can be seen as a guidance note related to design of safe economical small concrete structures.
3141
Hammons, M. I. and Smith, D. M.
"EARLY-TIME STRENGTH AND ELASTIC MODULUS OF CONCRETE WITH HIGH PROPORTIONS OF FLY ASH"
in Serviceability and Durability of Construction Materials, Proceedings of the First Materials Engineering Congress, held Aug 13-15, 1990, Denver, CO; Ed. by Bruce A. Suprenant; ASCE, New York, 1990, Vol. 2, pp 844-853.Compressive strength and elastic modulus data are presented for four concrete mixtures with ratios (by volume) of Class C fly ash to total cementitious materials (portland cement plus fly ash) varying from 0.25 to 0.50. Data were collected at times ranging from one and one-half hours after final set to 14 days. These data are plotted versus the logarithm of time and in the modulus of elasticity-square root of compressive strength plane.
3142
Hatanaka, S., Hattori, H., Yoshida, N., and Tanigawa, Y.
"COMPRESSIVE DEFORMATION CAPACITY OF HIGH STRENGTH CONCRETE UNDER LOW LATERAL CONFINING PRESSURE"
Transactions of the Japan Concrete Institute, 1990, Vol. 12, pp 151-158.A series of triaxial compressive tests of high strength concrete were conducted, and the effect of various factors on the plastic deformation capacity of high strength concrete was discussed. Based on the test data, a stress-strain model was modified to be applicable to a wide strength range of concrete including the high strength concrete. Numerical analysis was carried out for the prediction of the stress-strain relation of confined concrete by using the proposed model.
3143
Hayward, D.
"RIDER OF THE STORMS"
New Civil Engineer, 1990, Vol. 905, pp 28-30.A number of precautions are being taken to ensure the durability of the new Dornie bridge across Loch Long. The 260 m long bridge is on the busy A87 tourist route 18 km before the Kyle of Lochalsh and will replace the existing 50 year old bridge which is suffering from chloride attack. The bridge has to accommodate a 5 m tidal range, seven knot currents, 130 km/h winds and high rainfall. The largely prestressed concrete deck consists of 26 m spans above in situ reinforced concrete piers founded on steel H-piles and formed within nine separate cofferdams. The bridge is being built from a temporary bridge alongside, built to take NCK Eiger 110-ton crawler cranes and allowing access to all 10 spans. The design of the permanent bridge aims to eliminate expansion joints, and a novel in situ crosshead on the same level as the deck head and integral with it has been developed. Reinforcements are a vivid green, being coated with a fusion bonded sprayed epoxy coating to help counteract carbonation. Tight control is kept over the high strength air entrained concrete at a nearby quality control centre set up by the contractor. Exposed surfaces of the bridge will be treated with the water repellent silane.
3144
"HIGH-STRENGTH CONCRETE"
Papers from the Second International Symposium on Utilization of High Strength Concrete, held May 1990, Berkeley, CA; Ed. by Weston T. Hester; American Concrete Institute, Detroit, MI, 1990, viii, 786 pp. (ACI SP-121)This volume is a collection of thirty-eight papers presented at the Second International Symposium on Utilization of High Strength Concrete held in Berkeley, California, May, 1990. The papers are arranged according to the following topics: Design; Material Selection and Proportioning; Material Performance; Lightweight Concrete; and Applications. The participants were surveyed to identify areas of consensus and areas where additional research is needed. There is a clear consensus that high strength concrete is exceptionally durable and readily obtainable in commercial practice. Use of silica fume, blast furnace slag cement, and other mineral and chemical admixtures can be particularly helpful in achieving the desired properties for the concrete. But, appropriate test methods need to be developed and there is a need for better understanding of in situ mechanical properties and overall structural ductility.
3145
"HIGH STRENGTH CONCRETE; STATE OF THE ART REPORT"
by the Joint Working Group of the Federation Internationale de la Precontrainte/Comite Euro-International du Beton; Federation Internationale de la Precontrainte, London, Aug 1990, FIP SR 90/1, 61 pp. (Also issued as CEB Bulletin d'Information, No. 197)High strength concrete, in its various forms, has been under development and used for some years in different countries. The objective of the joint FIP/CEB working group on high strength concrete (HSC) is to extend further applications and develop national and international standards and design methodologies of high strength concrete. The research requirements on HSC, the formation of CEB/FIP model code MC90, and the current rules and regulations are also discussed.
3146
"HIGH-STRENGTH CONCRETE PASSES BIG CAISSON TEST"
ENR, Nov 26, 1990, Vol. 225, No. 21, pp 29-30.In an effort to lay to rest reservations about using high-strength concrete in unenclosed or thinly-cased caissons, the Portland Cement Association announced that a nearly-concluded experiment indicates that heat generated by the concrete while it cures in the ground does not seem to affect the material's long-term strength. Details of the tests are briefly described.
3147
Holm, T. A. and Bremner, T. W.
"70 YEAR PERFORMANCE RECORD FOR HIGH STRENGTH STRUCTURAL LIGHTWEIGHT CONCRETE"
Serviceability and Durability of Construction Materials, Proceedings of the First Materials Engineering Congress, held Aug 13-15, 1990, Denver, CO; Ed. by Bruce A. Suprenant; ASCE, New York, 1990, Vol. 2, pp 884-893.The paper briefly discusses the first ship, the USS Selma, built using expanded aggregates manufactured in a rotary kiln. It then goes on to discuss achieving high strength concrete with low density expanded aggregate, characteristics of high strength lightweight concrete that influence long term performance, rehabilitation of bridges and parking decks with high strength lightweight concrete, offshore structures, and precast structures.
3148
Hwee, Y. S. and Rangan, B. V.
"STUDIES ON COMMERCIAL HIGH-STRENGTH CONCRETES"
ACI Materials Journal, Sep-Oct 1990, Vol. 87, No. 5, pp 440-445.The results of an experimental investigation conducted on a commercially available high-strength concrete are reported. The study tested 12 reinforced concrete columns in concentric compression and measured creep and shrinkage properties of the concrete. For columns, the main test variables were area of longitudinal steel and tie spacing. The experimental results are compared with other test data and present code recommendations. The results confirm previous findings and raise concern regarding the absence of ductility of tied columns made of high-strength concrete.
3149
Idorn, G. M.
"CONCRETE MICROSTRUCTURE RESEARCH AND ITS APPLICATIONS IN HIGHWAY CONSTRUCTIONS"
VTI Rapport, 1990, No. 352A, pp 83-114.This paper surveys the concrete technology issues of the SHRP C-201 project: Microstructure of Concrete. The purpose of this research is to generate knowledge which will enable improvement in the quality of highway concrete by controlling the development of the microstructure. This study emphasizes those features which will aid in the management of processing of fresh concrete and early curing of concrete in highway construction work. The specific program of the research in progress in an outgrowth of experience which has shown that the homogeneity and the workability of fresh concrete, and the conditions to which the concrete is exposed during its early curing, have a profound influence on the homogeneity and associated characteristics of the microstructure of the hardened concrete, and thereby on the durability of concrete structures. This research is therefore concentrating initially on an exploration of the principles of mixture proportioning of the concrete components which determine the packing characteristics of the concrete components as mixed, and also on the chemical reactions in the fresh cement paste, which influence its rheological characteristics. This knowledge is indispensable for the development of design methods, which can result in practical monitoring for optimum quality of the fresh concrete, forming the basis for the design of the corresponding monitoring methods. Other emphases of the research include the adaptation of methods for monitoring the early curing of concrete. This is important because thermal stresses originating during early curing may cause severe microcracking, and available systems for monitoring the curing appear to be adaptable for application to highway construction work. Finally, diagnostic methods for evaluation of the microstructure and associated properties are the focus of much of the current effort.
3150
Japan Society of Civil Engieers, Subcommittee on Durability Design for Concrete Structures
"PROPOSED RECOMMENDATION[S] ON DURABILITY DESIGN FOR CONCRETE STRUCTURES"
Tokyo, Concrete Library of JSCE, Mar 1990, No. 14, pp35-71. (Translated from the Concrete Library, Aug 1989, No. 65).The Concrete Committee of the Japan Society of Civil Engineers (JSCE) organized the Subcommittee on Durability Design for Concrete Structures in 1988 to provide some recommendations for the design of concrete structures for durability. The proposed recommendations were drawn up in 1989 by the subcommittee based on the research results and consensus of the committee members.
3151
Kabeyasawa, T., Li, K-N., and Huang, K.
"EXPERIMENTAL STUDY ON STRENGTH AND DEFORMABILITY OF ULTRA HIGH STRENGTH REINFORCED CONCRETE COLUMNS"
Transactions of the Japan Concrete Institute, 1990, Vol. 12, pp 315-322.This paper presents an experimental investigation on the strength and deformability of ultra high strength reinforced concrete columns under high axial load and lateral load reversals. Three columns of one-third scale were tested, for which concrete of 800 kgf/cm2 grade and reinforcing bars of 8.88 tonf/cm2 and 13.60 tonf/cm2 grades were used. Axial load level and longitudinal reinforcement ratio were varied. Approximate design equation overestimated the ultimate flexural strength of the specimens. Axial load level had a significant effect on the deformability of the columns.
3152
Kikukawa, H.
"RHEOLOGICAL STUDIES ON FRESH CONCRETE USING ADMIXTURES"
Admixtures for Concrete: Improvement of Properties, Proceedings of the International Symposium held by RILEM, May 14-17 1990, Barcelona, Spain; Ed. by E. Vazquez; Chapman and Hall, London, 1990, pp 34-50.Since admixtures for concrete are known to improve the properties of fresh concrete and increase strength and durability of hardened concrete they are now widely used all over the world. However, rheological studies made on the influences of admixtures on fresh concrete have been comparatively scarce up till the present. This paper describes rheological analyses of the properties of fresh concretes containing admixtures. Particularly, it describes the improvement in finish of fresh concrete containing admixtures, when used to produce concrete slabs or pavements. It also presents a method of estimating plastic viscosity of fresh concrete containing a superplasticizer. A simplified method for estimating yield values is also discussed.
3153
Kudlapur, S. T. and Nawy, E. G.
"SHEAR INTERACTION OF HIGH-STRENGTH TWO-LAYERED CONCRETES AT EARLY AGES PLACED IN SUBFREEZING TEMPERATURES"
Transportation Research Record, 1990, No. 1284, pp 37-52.There are few studies on the early-age performance of high-strength cold weather concretes and their shear strength interaction in cold weather. Shear strength characteristics of high-strength cold weather concrete in subfreezing temperatures is the topic of this paper. Tests were conducted on cylinders and L-shaped push-off specimens to determine the early-age shear interlock and shear frictional resistance between high-strength regular portland cement concrete and cold weather high-strength concretes in the rehabilitation of bridge decks and other infrastructure systems. Results validate previous findings on polymer-modified concretes: the American Concrete Institute code limits on the shear-friction strength are too conservative even at early ages of high-strength cold weather concretes and need to be modified.
3154
Kulash, D. J.
"SHRP'S CONCRETE AND STRUCTURE RESEARCH: GOALS AND RECENT DEVELOPMENT"
VTI Rapport, 1990, No. 352A, pp 69-82.SHRP's program on Concrete and Structures has two major goals: increasing the durability of portland cement concrete in highway applications, and rehabilitation and protection of existing steel-reinforced concrete bridges subject to corrosion. In both cases, the research has been planned to result in tangible products that can be applied in the field immediately and have the potential to result in substantial savings in the construction and operation budgets of highway agencies. Many professionals involved in the design and rehabilitation of concrete pavements have identified the gaps in current knowledge and practice and have planned the research needed to fill them. Research contractors are executing those plans now. Through SHRP they will develop a number of products, including better techniques for preventing and repairing problems such as alkali-silica reactivity, freeze-thaw damage, and D-cracking; an improved quality control/quality assurance system, with emphasis on quicker, more reliable non-destructive tests; and better design guidance for use of admixtures and aggregates. In the area of concrete bridge components SHRP will develop diagnostic techniques for assessment of the physical condition of concrete bridge components. Techniques for repair and protection are to be developed. Three different types of approaches are being refined: (1) electrochemical repair and protection techniques, (2) chemical corrosion inhibitors, and (3) improvement of conventional physical repair methods.
3155
Leming, M. L. "COMPARISON OF MECHANICAL PROPERTIES OF HIGH-STRENGTH CONCRETE MADE WITH DIFFERENT RAW MATERIALS," Transportation Research Record, 1990, No. 1284, pp 23-30.Properties of high-strength concrete can vary significantly depending on the specific raw materials used and the strength levels attained. Data on these characteristics are needed by agencies such as departments of transportation that must consider construction alternatives with various materials and develop plans on the basis of economics as well as engineering properties. Results are presented of a study to determine the properties of high-strength concrete produced with several sets of materials. These materials represent those used in structures built under North Carolina Department of Transportation control. Data obtained included compressive strength, creep, shrinkage, elastic modulus, modulus of rupture, and splitting tensile strength of high-strength concrete produced from a variety of sources and types of materials. Rudimentary cost comparisons were also made.
3156
Leming, M. L., Ahmad, S. H., Zia, P., Schemmel, J. J., Elliott, R. P., and Naaman, A. E., "HIGH PERFORMANCE CONCRETES: AN ANNOTATED BIBLIOGRAPHY 1974-1989"
Strategic Highway Research Program, National Research Council, Washington, D. C., 1990, 402 pp. (SHRP-C/WP-90-001)This bibliography is the first product of the research conducted under the SHRP contract C-205 and is the result of an extensive literature search. It covers a period of 15 years beginning in 1974. The bibliography is divided into two sections: (I) plain concrete and (II) fiber reinforced concrete. An author index and a subject index are included at the end of each section.
3157
Luciano, J. J. and Bobrowski, G. S.
"USING STATISTICAL METHODS TO OPTIMIZE HIGH-STRENGTH CONCRETE PERFORMANCE"
Transportation Research Record, 1990, No. 1284, pp 60-69.Sound experimental design principles, rather than three-point curves, can be employed to determine high-strength concrete mixture proportions that maximize performance while minimizing cost. Important issues on experimental design and empirical modeling are discussed. Graphical methods illustrate how high compressive strengths can be obtained for a wide range of costs--and how to get the most for your money. An example is given using a classical experimental design. It greatly reduces the number of concrete mixes that otherwise would have been necessary to obtain information on five variables that change simultaneously. This experiment illuminates the effect of the silica fume addition percentage and the high-range water reducer dosage on 28-day compressive strength and raw material cost. Contour plots are provided to demonstrate the usefulness of a statistical approach.
3158
Luther, M. D.
"HIGH-PERFORMANCE SILICA FUME (MICROSILICA)--MODIFIED CEMENTITIOUS REPAIR MATERIALS"
Transportation Research Record, 1990, No. 1284, pp 88-94.Basic information about silica fume (microsilica), portland cement-based materials containing silica fume, and the use of these materials in the repair of structures is reviewed in this paper. Information is presented about high-performance (strength in excess of 20,000 psi) repair materials containing silica fume. Various applications are discussed, including those involving grout, underwater concrete, shotcrete, and concrete repairs.
3159
Mak, S. L. and Sanjayan, G.
"MIX PROPORTIONS FOR VERY HIGH STRENGTH CONCRETES"
Second National Structural Engineering Conference, Oct 3-5 1990, Adelaide, Australia; National Conference Publication - Institution of Engineers, Barton, Australia, No. 90, Pt. 10, pp 127-130.A series of experiments were carried out to study the mix proportions for very high strength concretes of compressive strengths between 90 to 140 MPa, produced at low water/binder ratios and with the use of pozzolanic additives and superplasticisers. In the light of the results obtained, this paper discusses the influence of water/binder ratio, aggregate size, type and grading and the use of condensed silica fume on the compressive strength of very high strength concretes.
3160
Malhotra, V. M.
"DURABILITY OF CONCRETE INCORPORATING HIGH-VOLUME OF LOW-CALCIUM (ASTM CLASS F) FLY ASH"
Cement and Concrete Composites, 1990, Vol. 12, No. 4, pp 271-277.Research on structural concrete incorporating high volumes of low-calcium (ASTM Class F) fly ash has been in progress at CANMET since 1985. In this type of concrete, the cement content is kept at about 150 kg/m3. The water-to-cementitious materials ratio is of the order of 0.30, and fly ash varies from 54 to 58% of the total cementitious material. A large dosage of a superplasticizer is used to achieve high workability. This paper presents data on the durability of this new type of concrete. The durability aspects considered are: freezing and thawing cycling; resistance to chloride ion permeability; and the expansion of concrete specimens when highly reactive aggregates are used in the concrete. The investigations performed at CANMET indicate that concrete incorporating high volumes of low-calcium fly ash has excellent durability with regard to frost action, has very low permeability to chloride ions and shows no adverse expansion when highly reactive aggregates are incorporated into the concrete.
3161
Malier, Y. and Pliskin, L.
"BRIDGE AT JOIGNY: HIGH-STRENGTH-CONCRETE EXPERIMENTAL BRIDGE"
Transportation Research Record, 1990, No. 1275, pp 19-22.An experimental bridge constructed of high-strength concrete was built at Joigny, France. The project is part of a national research program bringing together the French Ministry of Public Works and Ministry of Research, the cement industry, university and state laboratories, and professional associations and institutions. The bridge is instrumented to verify its long-term behavior and its durability in comparison with that of ordinary concrete bridges.
3162
Mana, F.
"USE OF SUPERPLASTICIZERS FOR CONCRETE IN UNDERGROUND CONSTRUCTION WORK"
Admixtures for Concrete: Improvement of Properties, Proceedings of the International Symposium held by RILEM, May 14-17, 1990, Barcelona, Spain; Ed. by E. Vazquez; Chapman and Hall, London, 1990, pp 524-532.The proliferation of underground construction work in big cities and the durability requirement of concealed concrete construction (screens, piles etc) require this material to respond to rigorous impermeability demands. Comparative tests were carried out between fluid concretes and plastic concretes with added superplasticizers with ample operating time. The pouring procedure for both concretes was the same. It was shown that the impermeability achieved with the latter, in the circumstances studied, was at least 2.6 times greater than that of the fluid concretes.
3163
Maruyama, T., Tsuchida, S., and Kohno, K.
"EXPERIMENTAL RESEARCH ON THE VARIOUS PROPERTIES OF SILICA FUME CONCRETE"
Transactions of the Japan Concrete Institute, 1990, Vol. 12, pp 9-16.Silica fume, an industrial by-product having an extremely small average particle size of 0.1 m, fills the fine voids of concrete and produces the required pozzolanic reaction when used as a concrete admixture, making it an extremely promising material in the development of ultra high strength concrete. In previous works, the authors have succeeded in obtaining ultra high strength concrete with a maximum strength of 1870 kgf/cm2. In this study, ultra high strength concrete using silica fume was developed. Comparison and review of various properties of three different kinds of high strength concrete mix proportions show that use of silica fume results in same performance and, in some cases, improved performance and durability characteristics.
3164
Marzouk, H.
"DURABILITY OF HIGH-STRENGTH CONCRETE CONTAINING FLY-ASH AND SILICA FUME"
Serviceability and Durability of Construction Materials, Proceedings of the First Materials Engineering Congress, held Aug 13-15, 1990, Denver, CO; Ed. by Bruce A. Suprenant; ASCE, New York, 1990, Vol. 2, pp 1026-1038.The durability of high-strength concrete made with local materials was tested with regard to the freezing and thawing resistance of concrete in accordance with ASTM C666 procedure A. The changes in weight, length, pulse velocity, resonant frequency, compressive strength, freezing and thawing were recorded for 458 cycles. At various intervals the specimens were removed from the apparatus at the thawed phase of the cycles. The specimens were then weighed and nondestructive methods of testing were performed by using V-meter and sonometer. The dynamic modulus of elasticity of each specimen was determined and used as a reference for the condition of each concrete after certain cycles. Study results are discussed.
3165
Marzouk, H. M. and Hussein, A.
"PROPERTIES OF HIGH-STRENGTH CONCRETE AT LOW TEMPERATURES"
ACI Materials Journal, Mar-Apr 1990, Vol. 87, No. 2, pp 167-171.This investigation deals with the effect of cold ocean water on the mechanical properties of green high strength concrete containing silica fume and fly ash. Tests were performed on cylinders exposed for periods of over 3 months, in cold ocean water, to temperatures varying from -10 to 20 C. The test specimens were exposed after 24 hr of normal curing. Preliminary results of the investigation indicated that low temperature affects both strength and elasticity of concrete. For the specimens exposed to cold ocean water, the gain in strength at 28 and 91 days was 40 and 54 % of the 3-day strength at room temperature. However, for the specimens exposed to temperatures of -10 C, the strength at 28 and 91 days was 97 and 91 % of the 3-day strength at room temperature, respectively. This low rate of maturity may be attributed to the fact low temperature slows down the main hydration process. Thus the rate of evolution of calcium hydroxide will be decreased, and the secondary pozzolanic reaction will be ceased.
3166
McCarter, W. J. and Ezirim, H.
"SORPTIVITY OF CONCRETE"
in Developments in Structural Engineering, Proceedings of the Forth Rail Bridge Centenary Conference, Aug 21-23, 1990, Heriot-Watt University, Edinburgh, Scotland; Ed. by B. H. V. Topping; E. & F. N. Spon, London, 1990, Vol 2, pp 817-824.The movement of water and aggressive agents into concrete, which has been subjected to drying action, is largely dictated by the capillary suction forces at or near the exposed surface. This paper presents experimental data on the movement of water into concrete. Sorptivity results are obtained from depth of penetration tests. A high and a low strength concrete were tested to investigate the movement of a water front into concrete. Ordinary portland cement was used throughout and specimens were cast in 300 x 150 mm cylinders. The high strength concrete had mix proportions of 1:1:2 (cement: fine aggregate: coarse aggregate by weight) and a water cement ratio of 0.35. The low strength concrete had a mix design of 1:1:3 and a water cement ratio of 0.6. On demolding, after 24 hours, the sides of the cylinders were sealed with a latex based paint, and left to cure at 21 degrees C, +55% or -5% relative humidity. After curing the samples were placed in plastic containers on stainless steel rods and filled such that the water was 10 mm above the exposed (cut) surface. Samples were removed after 1, 4, 9, 25 and 169 hours and split longitudinally. The depth of water penetration was detected by dusting the fractured surface with a moisture sensitive dye. The results were plotted on a depth of penetration versus root-time graph for the complete test period, and an equation obtained for calculating the depth of penetration of water.
3167
Mehta, P. K. and Aitcin, P-C.
"PRINCIPLES UNDERLYING PRODUCTION OF HIGH-PERFORMANCE CONCRETE"
Cement, Concrete and Aggregates, Winter 1990, Vol. 12, No. 2, pp 70-78.Durability rather than high strength appears to be the principal characteristic for high-performance concrete mixtures being developed for use in hostile environments such as seafloor tunnels, offshore and coastal marine structures, and confinement for solid and liquid wastes containing hazardous materials. Strength, dimensional stability, impermeability, and high workability are usually the principal characteristics required of high-performance concrete. In this paper an overview of the composition of concrete and its effect on the properties desired for high performance is given. This overview can be used as a basis for selection of component materials and mix proportioning. A new step-by-step procedure for mix proportioning is described. The calculated mix proportions from this procedure appear to be consistent with the state-of-the-art laboratory and field practice. Also, a brief review is given of concrete production and construction practices essential for making a high-performance end product.
3168
Moreno, J.
"225 W. WACKER DRIVE"
Concrete International: Design and Construction, Jan 1990, Vol. 12, No. 1, pp 35-39.The development of high-strength concrete began in Chicago in 1962 with 6000 psi (41 MPa) concrete, culminating in 1989 with the delivery of silica fume mixtures of 14,000 psi (96 MPa) for six stories of columns and one 17,000 psi (117 MPa) experimental column to the 225 W. Wacker project. The experimental column has provided information on structural properties of this new concrete strength. This project is representative of the state of the art of high-strength concrete in terms of strength, concrete quality, testing, construction techniques, and structural design.
3169
Murota, T., Hiraishi, H., Kaminosono, T., Teshigawara, M., and Shiohara, H., "DEVELOPMENT OF ADVANCED REINFORCED CONCRETE BUILDINGS USING HIGH-STRENGTH CONCRETE AND REINFORCEMENT"
NIST Special Publication, Sep 1990, No. 796, pp 388-399.This paper lists research subjects conducted in 1989 in the Ministry of Constructions's five-year research project on reinforced concrete buildings using high strength and high-quality concrete and reinforcing steel. This project is simply referred to as 'New RC'. The paper also describes the outlines of some important research subjects related to structural performance.
3170
Naik, T. R.
"EVALUATION OF FACTORS AFFECTING HIGH-STRENGTH CONCRETE CORES"
Serviceability and Durability of Construction Materials, Proceedings of the First Materials Engineering Congress, held Aug 13-15, 1990, Denver, CO; Ed. by Bruce A. Suprenant; ASCE, New York, 1990, Vol. 1, pp 216-222.A number of factors are discussed to explain different effects they have on core strength. These factors should be considered when evaluating cores tested to determine 'true' in-situ compressive strength. Subjects covered include nondestructive testing, factors affecting cylinder strength, test specimen dimensional effects, lightweight concrete, wall concrete cores, and others.
3171
Naik, T. R. and Ramme, B. W.
"HIGH EARLY STRENGTH CONCRETE CONTAINING LARGE QUANTITIES OF FLY ASH"
Serviceability and Durability of Construction Materials, Proceedings of the First Materials Engineering Congress, held Aug 13-15, 1990, Denver, CO; Ed. by Bruce A. Suprenant; ASCE, New York, 1990, Vol. 2, pp 1039-1050.This paper presents results of research performed at a precast/prestressed concrete plant to identify optimum mix proportions for production of high early strength concrete with high fly ash contents. Compressive strength, workability and water demand results are presented.
3172
Naik, T. R. and Ramme, B. W.
"HIGH EARLY STRENGTH FLY ASH CONCRETE FOR PRECAST/PRESTRESSED PRODUCTS"
PCI Journal, Nov-Dec 1990, Vol. 35, No. 6, pp 72-78.This paper presents field applied research to report the advantages of using a high quality ASTM C-618 Class C fly ash on water demand, workability and compressive strength of concrete. The research was performed at two precast/prestressed concrete plants to identify optimum mixture proportions for production of high early strength concrete with high fly ash contents. Tests were carried out on nominal 5000 psi (34 MPa) concrete utilizing fly ash produced at Wisconsin Electric Power Company's Pleasant Prairie Power Plant. Fly ash replacement improved workability, decreased water demand, and increased strength while maintaining the high early strength requirements of precast/prestressed concrete operations.
3173
Naik, T. R. and Salameh, Z.
"EVALUATION OF HIGH STRENGTH CONCRETE BY THE BREAK-OFF METHOD"
Serviceability and Durability of Construction Materials, Proceedings of the First Materials Engineering Congress, held Aug 13-15, 1990, Denver, CO; Ed. by Bruce A. Suprenant; ASCE, New York, 1990, Vol. 2, pp 1233-1245.The reliability of the Break-Off method to test inplace high-strength concrete was investigated. A total of 188 Break-Off tests and 30 standard cylinder tests were carried out for this project. Analysis of the results show that Break-Off test readings have a higher variability than the standard cylinder test readings. The accuracy of the Break-Off test method is not affected by the aggregate shape, the slab thickness nor the type of specimen. Also, the aggregate shape and the slab thickness do not affect the Break-Off test reading. However, the specimen type (sleeve or drilled) does affect the Break-Off reading. This study confirms that the Break-Off test method is accurate for testing in-situ strength of concrete as reported by other researchers.
2174
Ohama, Y., Demura, K., Satoh, Y., Tachibana, K., Endoh, T., and Miyazaki, Y., "PROPERTIES OF SUPER-DURABLE MORTARS WITH ADMIXTURES"
in Admixtures for Concrete: Improvement of Properties, Proceedings of the International Symposium held by RILEM, May 14-17 1990, Barcelona, Spain; Ed. by E. Vazquez; Chapman and Hall, London, 1990, pp 317-324.This paper repots a study conducted to develop effective admixtures for improving the durability of reinforced concrete structures by using a good combination of an amino alcohol derivative, an alkyl alkoxy silane and a calcium nitrite. Experimental admixtures were prepared with various formulations of the chemical compounds. Mortars were prepared with the experimental admixtures, and tested for strength, water absorption, chloride ion penetration and carbonation. It is concluded from the test results that the simultaneous use of the amino alcohol derivative, alkyl alkoxy silane and calcium nitrite is effective for producing super-durable mortar with excellent resistance to water absorption, chloride ion penetration and carbonation.
3175
Olsen, N. H.
"DESIGN PROPOSAL FOR HIGH STRENGTH CONCRETE SECTIONS SUBJECTED TO FLEXURAL AND AXIAL LOADS"
Danmarks Tekniske Hojskole, Afdelingen for Baerende Konstruktioner, 1990, Serie R, No. 233, 118 pp.This report covers design proposal for high strength concrete sections subjected to flexural and axial loads which is one of the four investigations dealt with in the author's thesis. The thesis consists of four separate reports. A short summary is given in each report.
3176
Olsen, N. H. "HEAT-INDUCED EXPLOSION IN HIGH STRENGTH CONCRETE," Danmarks Tekniske Hojskole, Afdelingen for Baerende Konstruktioner, 1990, Serie R, No. 231, 41 pp.This report contains the result and description of a series of tests which were conducted to evaluate the explosion risk of heat induced high strength concrete as compared to normal strength concrete. The tests were carried out with concrete test specimens shaped as 100 x 200 mm cylinders with a compressive strength in the range from 30 MPa to 90 MPa. The cylinders were cured in two different ways: (a) Seven days in water followed by 21 days in laboratory atmosphere (20 degree C and 60% RH). (b) Seven days in water followed by 21 days sealed with plastic aluminum foil. A total of 36 concrete cylinders were heated in an electrical oven at a heating rate of 2.5 degree C per min. until reaching a temperature of 600 degree C. After 2 hours at this temperature the cylinders were cooled at a rate of up to 1 degree C per min. The tests show that the explosion risk depends on the curing conditions and that the explosion risk in the case of high strength concrete is not higher than for normal strength concrete especially for concrete cured under condition a.
3177
Olsen, N. H.
"STRENGTH OF OVERLAPPED DEFORMED TENSILE REINFORCEMENT SPLICES IN HIGH STRENGTH CONCRETE"
Danmarks Tekniske Hojskole, Afdelingen for Baerende Konstruktioner, 1990, Serie R, No. 234, 193 pp.This report covers strength of overlapped deformed tensile reinforcement splices in high strength concrete which is one of the four investigations dealt with in the author's thesis. The thesis consists of four separate reports. A short summary is given in each report.
3178
Olsen, N. H.
"UNIAXIAL STRESS-STRAIN CURVES OF HIGH STRENGTH CONCRETE"
Danmarks Tekniske Hojskole, Afdelingen for Baerende Konstruktioner, 1990, Serie R, No. 232, 68 pp.This report covers uniaxial stress-strain curves of high strength concrete which is one of the four investigations dealt with in the author's thesis. The thesis consists of four separate reports. A short summary is given in each report.
3179
Ozawa, K., Maekawa, K., and Okamura, H.
"HIGH PERFORMANCE CONCRETE WITH HIGH FILLING CAPACITY"
Admixtures for Concrete: Improvement of Properties, Proceedings of the International Symposium held by RILEM, May 14-17 1990, Barcelona, Spain; Ed. by E. Vazquez; Chapman and Hall, London, 1990, pp 51-62.This paper describes a mix of high performance concrete, which is defined as a concrete with high filling capacity. It can be filled into all the corners of formwork without using any vibrators. The objective of this study was to investigate the role of chemical admixtures such as superplasticizer and viscosity agents on the deformational and segregational behavior of fresh concrete. The study is important for developing the concrete with high filling capacity. The optimum mix proportion of superplasticizer and viscosity agent was clarified for the concrete with high filling capacity. It was found that there exists the suitable viscosity of paste for improving not only the deformability but also the segregation resistance, which is highly dependent on the volume of free water in fresh concrete.
3180
Page, K. M.
"PUMPING HIGH-STRENGTH CONCRETE ON WORLD'S TALLEST CONCRETE BUILDING"
Concrete International: Design and Construction, Jan 1990, Vol. 12, No. 1, pp 26-28.The article describes how a single concrete pump and separate placing boom placed almost all of the concrete for the 79-story South Wacker Tower in Chicago. Concrete mixes, containing high-range water reducers and silica fume to develop ultra high strengths, were combined with a post-tensioned floor design to speed the construction. Details of the pumping are briefly described, and other highlights of the construction are noted.
3181
Park, R. and Li, B.
"APPLICATION OF THE NEW ZEALAND CONCRETE DESIGN CODE NZS 3101 TO HIGH STRENGTH CONCRETE"
New Zealand Concrete Construction, 1990, No. 34, 5 pp.High strength concrete reduces the mass of concrete needed permitting smaller beam and column cross sections. Its high elastic modulus also reduces deflection and it has low creep deformation. The paper deals with provisions, in the New Zealand concrete design code NZS 3101, which need to be revised before being applicable to high strength concrete of compressive strength greater than 55 MPa. The revision can be partly based on results from past investigations, but further testing is required to determine properties peculiar to New Zealand made concrete, and seismic design needs to be studied. Details are given of the requirements for material properties in terms of the modulus of elasticity and modulus of rupture. Design criteria for flexure and axial load are discussed. Minimum beam reinforcement, flexural strength and confined columns are dealt with. High strength concrete has very brittle failure in compression if not confined by adequate transverse reinforcement. Shear resisting mechanisms involving aggregate interlock may not be so effective because the faces of the cracks are often smoother than in normal strength concrete due to possible fracture of the aggregate. Smaller cover thickness would reduce the width of surface cracks and lessen the effect of the loss of cover due to severe seismic loading.
3182
Parrott, L. J.
"A REVIEW OF METHODS TO DETERMINE THE MOISTURE CONDITIONS IN CONCRETE"
British Cement Association, Slough, 1990, 28 pp.A wide range of methods for the laboratory and in situ measurement of moisture conditions in concrete and related materials are reviewed in terms of their purpose, principles and practicalities. The effects of sampling volume, sample geometry, pore fluid composition and moisture gradients are considered. Methods based upon destructive sampling, relative humidity, resistivity, dielectric properties, thermal properties, infrared adsorption and neutron scattering are reviewed. Destructive sampling and relative humidity measurements can provide reliable data relevant to a wide range of concrete properties, including durability and permeation. Microwave and neutron scattering methods seem to warrant further development for moisture measurements in concrete.
3183
"PAUL KLIEGER SYMPOSIUM ON PERFORMANCE OF CONCRETE"
held in Nov. 1989 at the ACI Fall Meeting in San Diego, CA; Ed. by David Whiting; American Concrete Institute, Detroit, MI, 1990, 499 pp. (ACI SP-122)The Paul Klieger International Symposium on Performance of Concrete cosponsored by Committees 201 on Durability of Concrete and Committee 222 on Corrosion of Metals in Concrete, was held at the ACI Fall Meeting in San Diego, California in November 1989. This publication contains 24 papers presented at four sessions of the symposium. The papers cover topics ranging from fundamental aspects and laboratory studies of concrete durability and field studies where concrete is exposed to natural conditions, to case histories of the performance and rehabilitation of concrete structures in severe service environments.
3184
Philipose, K. E., Feldman, R. F., and Beaudoin, J. J.
"QUALIFYING CONCRETE FOR A LOW-LEVEL WASTE REPOSITORY"
Atomic Energy of Canada Limited, Chalk River, Ontario, Chalk River Nuclear Labs., Jun 1990, 17 pp. (AECL No. 10176; DE92607876)A waste repository for the below ground disposal of low-level radioactive waste, labelled IRUS (Intrusion Resistant Underground Structure), is planned at Chalk River Nuclear Laboratories. It relies greatly on the durability of concrete for a minimum of 500 years of service life. A research program based on laboratory testing to design a durable concrete and predict its useful engineered service life is in progress. Durability of concrete depends on its resistance to deterioration from both internal and external causes. Since the rate of degradation depends to a major extent on the rate of ingress of aggressive ions into concrete, laboratory testing is in progress to establish the diffusion rates of ions, especially chlorides, sulphate and carbonate ions. The paper presents the initial results from the research program and the longevity predictions to qualify concretes for the IRUS waste repository, based on twelve months of diffusion testing on laboratory specimens.
3185
Pigeon, M., Saucier, F., and Plante, P.
"AIR-VOID STABILITY, PART IV. RETEMPERING"
ACI Materials Journal, May-Jun 1990, Vol. 87, No. 3, pp 252-259.Eight laboratory mixes and eight field mixes were prepared to study the influence of retempering by adding water to the characteristics of the air-void system, and to study air entrainment when an air-entraining admixture is added significantly after the initial mixing period. For each mix, four sets of samples were cast over a period of 90 min after initial water-cement contact: two before retempering (at 45 min) and two after. The modified point-count method (ASTM C 457) was used to determine the characteristics of the air-void system on each set of samples. The results show that retempering by adding enough water to increase the slump from approximately 50 to about 100 mm has no significant influence on the value of the air-void spacing factor, although it often causes a small increase in air content.
3186
Rasoulian, M.
"EVALUATION OF MICROSILICA ADMIXTURE FOR PRODUCTION OF HIGH STRENGTH CONCRETE"
Final Report; Louisiana Transportation Research Center, Baton Rouge, LA, 1990, 32 pp. (FHWA/LA-90/227; RR-227; PB91-205591)This study consisted of a laboratory evaluation of the effect of microsilica on the physical properties of both plastic and hardened portland cement concrete. Microsilica (silica fume) is a by-product of the industrial manufacture of ferro silicon and other metallic silicones in high-temperature electric arc furnaces. Microsilica is a very fine material, pozzolanic in nature. Due to its physical and chemical characteristics, microsilica when used as an admixture has the potential of enhancing the properties of portland cement concrete. In this study the variable selected for evaluation is the dosage rate of microsilica. Other variables included the microsilica source, the cement factor and the dosage rate of the other admixtures. All experimental and control mixes contained cement and aggregate of the same type and from the same respective source. When utilized, air entraining and high-range water reducer admixtures were also of the same type and from the same respective source. The results of this evaluation indicate that the inclusion of microsilica in a portland cement concrete mix can improve compressive and flexural strengths, increase the modulus of elasticity, improve resistance to scaling and decrease permeability. Physical properties that may be adversely affected by this admixture include freeze/thaw durability and workability. No conclusions could be drawn on the effect of microsilica on set times and length change and abrasion resistance. A recommendation is made to further evaluate microsilica admixtures by and through the utilization of the product on selected project(s).
3187
Rear, K. and Chin, D.
"NON-CHLORIDE ACCELERATING ADMIXTURES FOR EARLY COMPRESSIVE STRENGTH"
Concrete International, Oct. 1990, Vol. 12, No. 10, pp. 55-58.A laboratory test program was devised to compare the early compressive strength performances of three commercially available non-chloride accelerating admixtures with five different Type I and Type I/II portland cements (ASTM C 150), two different Class C fly ashes, and two different Class F fly ashes. The portland cement concrete mixtures were tested at an ambient temperature of 72o F (22o C) and 50o F (10o C) while the cement-fly ash combinations were tested at an ambient temperature of 72o F (22o C) only. The non-chloride accelerating admixtures tested were effective in increasing early compressive strength with both cement and cement-fly ash combinations. However, the range of performance with different cements, fly ashes, and addition rates points out to the user the importance of testing with local materials to determine the most effective combination.
3188
Roller, J. J. and Russell, H. G.
"SHEAR STRENGTH OF HIGH-STRENGTH CONCRETE BEAMS WITH WEB REINFORCEMENT"
ACI Structural Journal, Mar-Apr 1990, Vol. 87, No. 2, pp 191-198.An experimental investigation of the shear strength of high-strength concrete beams with web reinforcement was conducted. Two series of beam tests were performed, each series consisting of five beams. All beams were designed in accordance with the provisions of ACI 318-83. Primary design variables were concrete compressive strength and the quantity of shear reinforcement. Concrete with compressive strengths of approximately 10,000, 17,000, and 18,000 psi (69, 117, and 124 MPa) was used in the beam specimens. Results of the investigation indicate that for nonprestressed high-strength concrete members subject to shear and flexure only the minimum quality of shear reinforcement specified in ACI 318-83 needs to increase as the concrete compressive strength increases. Results from the tests conducted in this investigation confirm the applicability of the new proposed provision for minimum web reinforcement.
3189
Ronneberg, H. and Sandvik, M.
"HIGH STRENGTH CONCRETE FOR NORTH SEA PLATFORMS"
Concrete International: Design and Construction, Jan 1990, Vol. 12, No. 1, pp 29-34.Norwegians have used high strength concrete for offshore structures in the North Sea since 1973. This paper discusses the critical demands of such concretes due to high strength, durability, and constructibility requirements, the magnitude of the structures, and the rate of construction, and the special cements and pozzolans, hydraulically processed sand, and refined superplasticizers and other chemical admixtures that have been developed.
3190
Russell, H. G.
"CONCRETE: USE OF HIGH-STRENGTH CONCRETES"
Batiment International/Building Research and Practice, May-Jun 1990, Vol. 18, No. 3, pp 146-152.Initially, high-strength concrete was used mostly in high-rise buildings for column construction. Based on current applications, this paper describes the use of high-strength concrete for lower-rise buildings, where it has been specified because of its improved durability.
3191
Sakai, Y., Hibi, J., Otani, S., and Aoyama, H.
"EXPERIMENTAL STUDY ON FLEXURAL BEHAVIOR OF REINFORCED CONCRETE COLUMNS USING HIGH-STRENGTH CONCRETE"
Transactions of the Japan Concrete Institute, 1990, Vol. 12, pp 323-330.Flexural behavior, especially ductility, of reinforced concrete columns using high-strength concrete of about 1000 kgf/cm2 compressive strength was investigated experimentally. Restoring force characteristics, axial deformation and strain of hoops were examined. It was found that the ductility of columns was closely related to lateral confining stresses in hoops and that the use of high-strength hoops and interior hoops contributed to the increase of the ductility of columns.
3192
Sanchez, A. and Hester, W. T.
"DESIGNER/CONTRACTOR DIALOGUE AND HIGH-STRENGTH CONCRETE CONSTRUCTION"
Construction Specifier, Dec 1990, Vol. 43, No. 12, pp 56-59, 62.In principle, designer and contractor maintain a healthy dialogue about projects from design development through construction. The open exchange of ideas and information yields a better structure for the owner - finished without difficulties - and improves the designer's and contractor's respective skills. In practice, however, there is often much less substantive designer - contractor interaction than needed. This article discusses how a cooperative approach between designers and contractors is vital for high-strength concrete construction.
3193
Sardina, F.
"THE USE OF RHEOPLASTIC MORTARS IN THE STATIC STRENGTHENING OF ROAD TUNNELS"
Strade, Oct 1990, Vol. 92, No. 1270, pp 1129-1133.Rheoplastic mortar is a concrete mixture obtained by adding to the correct dosage of accurately selected aggregate, a special high strength cement containing accelerating and highly fluidifying additives. The result is a mortar of high workability and very low water-cement ratio, free from segregation and bleeding. During setting and hardening this mortar is slightly expansive, thus eliminating the microcracking due to shrinkage. This article describes and illustrates the use of a rheoplastic mortar (EMACO) in strengthening and retaining the LEMMEN tunnel on state road SS 370.
3194
Sarkar, S. L. and Aitcin, P-C.
"IMPORTANCE OF PETROLOGICAL, PETROGRAPHICAL AND MINERALOGICAL CHARACTERISTICS OF AGGREGATES IN VERY HIGH STRENGTH CONCRETE"
ASTM Special Technical Publication, 1990, No. 1061, pp 129-144.Aggregate intrinsic strength, particularly that of coarse aggregates, receives scant attention from concrete technologists and researchers as long as the w/c ratio falls within the 0.50-to-0.70 range, primarily due to the fact that the cement-aggregate bond or the hydrated cement paste fails long before aggregates do. This, however, does not hold true for very high-strength concretes, with very low w/c ratios of 0.20 to 0.30. Compressive strength testing of very high-strength concrete has indicated that aggregates can assume the weaker role, exhibited in the form of transgranular fractures on the surface of failure, as has already been observed in some lightweight concretes. The authors have carried out detailed petrological, petrographical and mineralogical characterization of twelve different coarse aggregates that have performed with variable success in very high-strength concrete in Canada and the United States. Suitability for such an application has been linked to a special set of lithological characteristics: the minerals must be strong, unaltered, and fine grained. Intra- and intergranular fissures, partially decomposed coarse-grained minerals, and the presence of cleavages and lamination planes tend to weaken the aggregate, and therefore the ultimate strength of the concrete.
3195
Sarkar, S. L., Aitcin, P-C., and Djellouli, H.
"SYNERGISTIC ROLES OF SLAG AND SILICA FUME IN VERY HIGH-STRENGTH CONCRETE"
Cement, Concrete and Aggregates, Summer 1990, Vol. 12 No. 1, pp 32-37.A study was conducted on the microstructure of concrete to examine the characteristics of hydration progressing from 1 to 28 days. The microstructural changes occurring during this period are discussed. A very high-strength concrete (10% silica fume and 30% slag for cement replacement, HRWRA (high-range water-reducing admixtures), W/C = 0.20) was found to attain 94 MPa compressive strength at 28 days. The process of silica fume dissolution appears to begin early, within 1 day, and it is followed by the formation of a silica-rich gel at 7 days, and a final transformation into dense C-S-H (calcium-silicate- hydrate) within 28 days. Other study findings are also discussed.
3196
Schaller, I., de Larrard, F., and Fuchs, J.
"ADHESION OF PASSIVE REINFORCEMENTS IN VERY HIGH PERFORMANCE CONCRETE"
Bulletin de Liaison des Laboratoires des Ponts et Chaussees, May-Jun 1990, No. 167, pp 13-21.The authors discuss the adhesion (bond) between 'very high performance' concrete (BTHP, strength after 28 days greater than 80 MPa) and passive reinforcements in reinforced concrete. The adhesion was measured by means of a series of beam tests in which the nature of the concrete (a BTHP compared with a conventional concrete), the diameter of the reinforcements (between 10 and 25 mm) and their surface characteristics (smooth round bars and high-adhesion reinforcements) were varied. The adhesion between the concrete and the steel increases in general with the tensile strength of the concrete, more markedly so for small reinforcements (the effect of scale is more pronounced). It would be interesting to verify the consequences of this improved adhesion in reinforced concrete structures (evolution of the parameters of length of anchorage, occurrence and spacing of cracks).
3197
Schemmel, J. J. and Zia, P.
"USE OF HIGH-STRENGTH CONCRETE IN PRESTRESSED CONCRETE BOX BEAMS FOR HIGHWAY BRIDGES," Transportation Research Record, 1990, No. 1275, pp 12-18.A study was conducted to determine the structural and economic benefits of using high-strength (6,000 to 12,000 psi) concrete in box beams for highway bridges. The goal was to establish a range of application of various beam designs in terms of span capacity. The study focused on long-span, simply supported, prestressed concrete box beams. The application of high-strength concrete was investigated in two ways. First, high-strength concrete was substituted for normal-strength concrete in the design of standard beam sections. Second, to improve structural performance, modifications were made to the geometry of the standard beams in conjunction with use of the high-strength material. In both cases a parametric study was performed to identify the most structurally efficient designs. Results indicate that the maximum attainable span of the box beam can be significantly increased by using high-strength concrete in conjunction with a modified internal void shape. In addition, attainable span lengths were generally longer and had 1/2-in. rather than 0.6-in. strands for the beam sections studied. Those designs found to provide the greatest structural benefit were subsequently examined for their relative cost-effectiveness. Comparisons were made on the basis of a total superstructure cost per square foot of bridge deck. For shorter span lengths, spread box beams 3 ft wide were found to be the most cost-effective. For longer spans, the 4-ft-wide adjacent box sections were less costly. Strand size does not appear to significantly influence the cost of a box beam.
3198
"SEGMENTS LINE 93 MILES OF TUNNELS"
ENR, May 3, 1990, Vol. 224, No. 18, pp 20-22.Some details are summarized of the construction of the English Channel Tunnel between England and France. From coastal sites in England and France, nine TBMs (tunnel boring machines) are used to drive two large diameter running tunnels and a smaller central service bore between inland rail terminals. All 93 miles of tunnel are being lined with precast concrete rings, except in complicated locations where cast iron is used. The tunnel is longer on the English side where the ground is better and the rail terminal is further inland. Different lining designs have been adopted for the two sides of the channel because of differing ground conditions. Segment production in the two countries is described. Accuracy in meeting tight tolerances is discussed. A major concern is the 120-year tunnel design life and the factor of concrete durability.
3199
Seki, H. and Fujii, K.
"PROTECTION AGAINST CORROSION OF REINFORCING BARS USING HIGH-STRENGTH CONCRETE"
Protection of Concrete, Proceedings of the International Conference held Sep 11-13, 1990 at the University of Dundee, Scotland, UK; Ed. by Ravindra K. Dhir and Jeffrey W. Green; E. & F. N. Spon, London, 1990, pp 441-450.The paper mainly discusses the relationship between crack width and corrosion of bars. High-strength concrete was examined for its potential to prevent corrosion of bars. Accelerated test of duration from 1 week to 2 years was adopted. Main test results were as follows: (1) the corroded area showed the quantitative tendency with corroded length; (2) the high-strength member had clear relationship between crack and corrosion compared to normal strength concrete members; (3) there was no clear tendency between crack width and corrosion, but corrosion tended to become deeper and larger over the range of crack width 0.2 mm-0.25 mm, and (4) high-strength concrete contained less chloride compared to normal strength concrete.
3200
"SERVICEABILITY AND DURABILITY OF CONSTRUCTION MATERIALS," Proceedings of the First Materials Engineering Congress, held Aug 13-15, 1990, Denver, CO; Ed. by Bruce A. Suprenant; ASCE, New York, 1990, 2 Vols.The first volume contains 61 papers presented at the meeting. The papers are grouped under general topics that include large aggregate hot-mix asphalt, structural wood, concrete-steel bond behavior, geosynthetics, geomaterials, and masonry construction. The second volume contains 75 papers, and the papers are classified under the following topics: current issues in concrete use, structural plastics: utilization and serviceability, durability and performance of fly ash concrete, high performance cement-based materials, durability of asphalt concrete pavements, enhancing the properties of construction materials: polymer concrete and ceramics, enhancing the properties of construction materials: cementitious composites, drying and shrinkage of concrete, durability of pavement materials as affected by environment, fracture and size effects in quasi-brittle geomaterials, enhancing the properties of construction materials: fiber-reinforced composites, nondestructive testing, and effects of material behavior on structural stability. Some topics discussed by papers are cited as examples: practical prediction of concrete shrinkage and its uncertainty, a prestressed Kevlar/FRP structural system, and AE instrumentation and deconvolution techniques.
3201
Setunge, S., Attard, M. M., Darvall, P. Le P.
"ENGINEERING PROPERTIES OF VERY HIGH STRENGTH CONCRETE"
Second National Structural Engineering Conference Oct 3-5, 1990, Adelaide, Australia; National Conference Publication - Institution of Engineers, Australia, 1990, No. 90, Pt. 10, pp 120-126.A comprehensive experimental study was carried out at Monash University to investigate the engineering properties of very high strength concrete with compressive strengths in the range of 80 to 120 MPa. The study included the determination of the static modulus of elasticity, Poisson's ratio, direct and indirect tensile strength and flexural strength of very high strength concrete produced using micro silica, locally available aggregate cement and superplasticisers. Three concrete mix designs were adopted and tests were carried out at three test ages. Test results were obtained for 126 cylinders, 27 beams and 24 direct tensile test specimens. Experimental results are presented along with other established relationships reported for normal and high strength concrete and are compared with values predicted by AS3600. Recommendations are made for relationships between compressive strength and engineering properties of very high strength concrete.
3202
Setunge, S., Attard, M. M., and Darvall, P. Le P.
"STATIC MODULUS OF ELASTICITY AND POISSON'S RATIO OF VERY HIGH STRENGTH CONCRETE," Department of Civil Engineering, Monash University, Clayton, Victoria, Australia, Civil Engineering Research Report No. 1/1990, ii, 32 pp.Research work reported on the static modulus of elasticity and Poisson's ratio of higher strength concretes is limited and only covers concrete strengths in the range of 20 to 83 MPa. This report covers the first part of a comprehensive study carried out on the engineering properties of very high strength concretes with compressive strengths in the range of 60 to 120 MPa. Comparison of results with those obtained using existing empirical relationships for the static modulus of elasticity has shown that even the lower limit suggested by AS3600 would overestimate the static modulus of elasticity of very high strength concrete which is highly sensitive to the type of coarse aggregate used. The Poisson's ratio of very high strength concretes was found to increase with an increase in compressive strength. An empirical equation was proposed for the Poisson's ratio which is a function of the square root of the compressive strength.
3203
Shah, S. P.
"FRACTURE TOUGHNESS FOR HIGH-STRENGTH CONCRETE"
ACI Materials Journal, May-Jun 1990, Vol. 87, No. 3, pp 260-265.In this paper, the concepts of linear elastic fracture mechanics are summarized. It is shown that a single fracture parameter, such as the critical stress intensity factor, cannot be simply applied to quasi-brittle material like concrete. A two-parameter fracture model is presented. The two parameters can be calculated from an (ASTM-type) notched-beam test. This model accurately predicts fracture toughness, as well as split cylinder strength and modulus of rupture strength of high-strength concrete.
3204
Svenkerud, P. J., Fidjestol, P., and Artigues, J. C.
"MICROSILICA BASED ADMIXTURES FOR CONCRETE"
Admixtures for Concrete: Improvement of Properties, Proceedings of the International Symposium held by RILEM, May 14-17, 1990, Barcelona, Spain; Ed. by E. Vazquez; Chapman and Hall, London, 1990, pp 346-359.A new class of admixtures has been developed and commercialized based on the combination of microsilica and high range water reducers. Microsilica is amorphous silicon dioxide with a mean particle size of 0.15 micrometers. This makes the material suited both as a pozzolan and as a filler in concrete. Water reducing admixtures give concrete improved properties due to low water requirements. These two materials are combined to give a new class of admixtures which has special properties in the fresh and hardened concrete. This paper discusses the combined effects of microsilica and water reducing admixtures on the durability of concrete. Specifically, the sulphate resistance is discussed through an exposure test of concretes exposed to moderate sulphate attack. Even moderate dosages of the new class of admixtures give sulphate resistance to concretes made with ordinary portland cement. This concrete compares favourably with concrete made with sulphate resistant cement.
3205
Swamy, R. N. and Bouikni, A.
"SOME ENGINEERING PROPERTIES OF SLAG CONCRETE AS INFLUENCED BY MIX PROPORTIONING AND CURING"
ACI Materials Journal, May-Jun 1990, Vol. 87, No. 3, pp 210-220.This paper presents a simple method to obtain a 50 MPa 28-day strength concrete having 50 and 65 % by weight cement replacements with slag having a relatively low specific surface. The method produces slag concrete with strengths comparable to ordinary portland cement concrete from 3 days onward. The compressive and flexural strengths and the elastic modulus of these two concretes as affected by curing conditions are then presented. Prolonged dry curing is shown to adversely affect tensile strength and elastic modulus, and to create internal microcracking, as identified by pulse velocity measurements. High swelling strains at high slag replacement levels show the need for longer wet curing for such concretes. The results emphasize that even 7-day wet curing was inadequate for high levels of slag replacement, and that continued exposure to a drying environment can have adverse effects on the long-term durability of inadequately cured slag concrete.
3206
Tachibana, D., Imai, M., and Okada, T.
"QUALITIES OF HIGH-STRENGTH LIGHTWEIGHT CONCRETE USED FOR CONSTRUCTION OF ARCTIC OFFSHORE PLATFORM"
Journal of Offshore Mechanics and Arctic Engineering, Feb 1990, Vol. 112, No. 1, pp 27-34.Concrete employed in oil exploration and production platforms for use in shallow offshore zones of the Arctic Ocean is required to be lightweight, yet high strength, and moreover possess adequate resistance to freezing and thawing. Generally speaking, lightweight concrete, using artificial lightweight aggregate, has lower freeze-thaw resistance and this presents a serious problem. The study reported here was carried out on the freeze-thaw durability, constructibility and other properties of high-strength lightweight concrete. This paper especially points out the governing factors influencing freeze-thaw durability of this type of concrete and describes a method of manufacturing concrete possessing superior durability.
3207
Tanigawa, Y., Mori, H., Watanabe, K., and Miwa, M.
"CONSISTENCY TESTING METHODS FOR HIGH-STRENGTH AND ULTRA-HIGH-STRENGTH CONCRETE," Transactions of the Japan Concrete Institute, 1990, Vol. 12, pp 49-56.High- and ultra-high-strength concretes have been applied to RC buildings. In most studies on these concretes, the mechanical properties and durability of hardened concrete have been investigated. However, the workability of these concretes has not been investigated sufficiently. In this study, the fresh properties of low water-cement ratio concrete with high-performance AE water reducing agent and silica fume are measured by using various consistency test methods. The fundamental data for evaluating the consistency of high-strength concrete are reported.
3208
Tanigawa, Y., Yamada, K., Hatanaka, S., and Shibata, T.
"TESTING METHODS AND STATISTICAL ASPECTS OF COMPRESSIVE STRENGTH OF HIGH-STRENGTH CONCRETE"
Transactions of the Japan Concrete Institute, 1990, Vol. 12, pp 69-76.Two series of uniaxial compressive tests were carried out. One was to examine the effect of testing method on the compressive strength of high- and ultra-high-strength concretes. The other was to examine the variation of compressive strengths of confined high- and ultra-high-strength concretes. Based on the test results, modifications of the testing methods for high- and ultra-high-strength concretes were recommended. The variations of the compressive strength of those concretes were discussed.
3209
Tia, M., Bloomquist, D., Yang, M. C. K., Soongswang, P., and Meletiou, C. A.
"FIELD AND LABORATORY STUDY OF MODULUS OF RUPTURE AND PERMEABILITY OF STRUCTURAL CONCRETES IN FLORIDA"
Final Report, Department of Civil Engineering, University of Florida, Gainesville, FL, 1990, 258 pp.An extensive laboratory study was conducted to evaluate the effects of various mix parameters and curing conditions on the modulus of rupture and permeability of structural concretes used in Florida, and the relationship of other concrete strength properties to these two properties. An efficient laboratory test set-up for performing forty permeability tests simultaneously was developed and used in the study. In addition, concrete samples obtained from six concrete projects in Florida were tested to evaluate the differences between the in-service concrete and the laboratory-cured concrete. The scope of the laboratory study covered three aggregate types (a Florida porous limestone, a river gravel, and an Alabama dense limestone), three cement types (Type I, II and III), three water/cement ratios (0.45, 0.38 and 0.33), three maximum aggregate sizes (3/8, 3/4, 1 inch), two pozzolans (fly ash and silica fume) and six curing conditions (steam curing, air curing, curing compound and three moist curing conditions). The results of the study indicated that water/cement ratio and curing condition are the major factors affecting the properties of concrete.
3210
Tordoff, M. A.
"ASSESSMENT OF PRE-STRESSED CONCRETE BRIDGES SUFFERING FROM ALKALI-SILICA REACTION"
Cement and Concrete Composites, 1990, Vol. 12, No. 3, pp. 203-210.Seven pre-stressed post-tensioned concrete bridges, known to be suffering from alkali-silica reaction (ASR) were inspected in 1989 and their structural capacity assessed by measuring their load bearing capacity using methods laid down in the current British Standards. The sixteen-year-old bridges are mainly of 42.3 m span through girder construction and carry farm access tracks over dual carriageway trunk roads. As the assessment progressed the author became increasingly aware that research into ASR has concentrated on petrography, chemistry and the microstructure of concrete. There has not been sufficient research to assess the structural consequences of ASR and no work has been done on concrete members which are truly representative of the prototype. From the evidence it was concluded that the bridges have not been weakened by ASR and that there is no reason to suspect that durability will be a greater problem than in other typical bridges in similar locations. The results showed that there had been negligible ingress of chlorides or of carbonation, even in areas that were cracking due to the effects of ASR. In 70% of the tests the depth of carbonation was no more than 5 mm, and nowhere was it as much as 10 mm. The chloride levels were so low (ranging from 0.015 to 0.03mm% weight of cement for a depth of 5-30 mm) as to suggest that the bridges were not in an aggressive environment. However at least two are in an area where de-icing salts were used regularly.
3211
Valenchon, C., Warland, T. A., and Gudmestad, O. T.
"OFFSHORE APPLICATIONS OF HIGH STRENGTH CONCRETE SPACE FRAME"
Proceedings of the Ninth International Conference on Offshore Mechanics and Arctic Engineering, Feb 18-23, 1990, Houston, TX; ASME, New York, 1990, Vol. 3, Pt. A, pp 77-84.This paper presents the results of studies on the offshore application of concrete trusses and space frame techniques including a concrete module support frame for a North Sea gravity based structure (GBS), a concrete module structure (MSF) and a concrete space frame roof for subsea cells. After a brief historic review of triangulated structures, the use of concrete trusses is illustrated with the presentation of the main features of three civil works realizations, showing the evolution of both design and construction methods. Emphasis is placed on the correlation of the space frame technology with development of high-strength concrete.
3212
Veilleux, M.
"COMPUTER AIDED INFRARED THERMOGRAPHIC ANALYSIS: TWO TECHNOLOGIES JOIN TOGETHER TO EVALUATE CONCRETE HIGHWAY STRUCTURES"
Routes et Transports, 1990, Vol. 22, No. 1, pp 17-25.The use of infrared thermography combined with a computer aided system is a very new and effective approach to determine concrete slabs deterioration in highway bridges and continuously reinforced concrete pavements (CRCP) as compared to conventional non-destructive methods. Used in the United States since 1981, this technology is now available in Canada from Beauchemin-Beaton-Lapointe Inc., a consulting firm based in Montreal. Using the latest innovations in computers, this firm has adapted and enhanced an American proven technology developed and used by Donohue & Associates. The purpose of this paper is to explain the basics of infrared thermography and to describe the equipment used to gather the data as well as to describe the computer hardware and software used for the analysis and interpretation of the infrared data. Examples of practical applications of this technology to Quebec highways are provided. In French.
3213
Walker, B.
"FAST CURING CONCRETE OVERLAYS TO CHALLENGE BLACKTOP SUPREMACY"
Highways, 1990, Vol. 58, No. 1966, pp 16-17.This article reports on the development of concrete pavement overlays in the USA, and lists some of their applications and advantages. Fast track concrete (FTC) is a concrete designed to give high strength at a very early age without using special materials or techniques; it simply uses current knowledge effectively and it is very durable. The early strength is controlled by the water-cement ratio, cement content and characteristics. Fast track concrete paving (FTCP) was developed by the successful concrete paving industry in Iowa, USA. A British study team, visiting Iowa in 1989, identified the following applications of FTCP in the USA: (1) complete carriageway reconstruction; (2) partial replacement by an inlay of at least one lane; (3) strengthening of existing bituminous or concrete pavements by a concrete overlay; (4) rapid maintenance and reconstruction processes; (5) airfield pavements. The benefits of applying FTCP in such situations are: (1) a reduced contract period, reducing the contract overhead cost; (2) trafficking the pavement at an early age; (3) minimizing the use of expensive concrete paving plant and traffic management systems; (4) reduced traffic delay costs. FTCP was introduced to the UK in late July 1990.
3214
Yamakawa, C., Kishitani, K., Fukushi, I., and Kuroha, K.
"SLUMP CONTROL AND PROPERTIES OF CONCRETE WITH A NEW SUPERPLASTICIZER. II: HIGH STRENGTH IN-SITU CONCRETE WORK AT HIKARIGA-OKA HOUSING PROJECT"
Admixtures for Concrete: Improvement of Properties, Proceedings of the International Symposium held by RILEM, May 14-17, 1990, Barcelona, Spain; Ed. by E. Vazquez; Chapman and Hall, London, 1990, pp 94-105.One method of increasing the strength of concrete is to use high range water reducing agents. However, high range water reducing agents greatly reduce the slump value during delivery and, therefore, are not suitable for practical application. To solve this problem, a slump retentive high range water reducing agent (hereafter referred to as "new superplasticizer") was developed. The new superplasticizer has both high water reducing ability and slump-value retaining ability provided by the slow-release of a component reactive polymer. The present study confirmed the physical properties of high strength concrete using a ready-mixed concrete of high slump value prepared by adding the above admixture in an on-site experiment. Concrete was prepared at mix designs for required average strength of 540, 430 and 360 kgf per square centimetre, required slump of 18 centimetres, and 4% air content. Compressive strength was not required on the 28th day. The following properties were measured: (a) the change in slump value and air content with time; (b) bleeding; (c) setting time; (d) compressive strength; (e) drying shrinkage; (f) freeze thaw resistance and (g) carbonation.
3215
Yamamoto, T.
"CREEP AND SHRINKAGE OF HIGH-STRENGTH REINFORCED CONCRETE COLUMNS"
Transactions of the Japan Concrete Institute, 1990, Vol. 12, pp 101-106.In high-rise reinforced concrete buildings, creep and shrinkage may be more important for floor levelness and exterior wall movement. However, the available information for high-strength reinforced concrete members is insufficient, because most creep and shrinkage tests have been conducted with similar small standard specimens. Furthermore, the creep deformation of high-strength reinforced concrete columns after subjected to seismic loading is unknown. An experimental investigation was performed to ascertain the creep, the shrinkage, and the creep after subjected to seismic loading of high-strength reinforced concrete columns.
3216
Zhang, M-H. and Gjorv, O. E.
"MICROSTRUCTURE OF THE INTERFACIAL ZONE BETWEEN LIGHTWEIGHT AGGREGATE AND CEMENT PASTE"
Cement and Concrete Research, July 1990, Vol. 20, No. 4, pp 610-618.In recent years much attention has been given to the influence of the interfacial zone between aggregate and cement paste on the various properties of concrete. Most of the research work in this area has been carried out using normal weight aggregate. In the present paper experimental work on the interfacial zone between different types of lightweight aggregates and cement paste is presented. For high strength lightweight aggregate with a dense outer layer the nature of the interfacial zone between aggregate and cement paste is similar to that for normal weight aggregate. For lightweight aggregate with a weaker and more porous outer layer and for aggregate without any outer layer, the interfacial zone is more dense and homogeneous. Also for such aggregates the bond appears to be better due to an improved mechanical interlocking between the aggregate and the cement paste. The nature of the interfacial zone appears to depend on the microstructural characteristics of the aggregate.
3217
Zia, P., Leming, M. L., and Ahmad, S. H.
"RESEARCH ON HIGH-PERFORMANCE CONCRETE"
The United States Strategic Highway Research Program: Sharing the Benefits, Proceedings of the Conference Organized by the Institution of Civil Engineers in Cooperation with U.S. Strategic Highway Research Program, Oct 29-31, 1990, London; Ed. by J. Porter; T. Telford, London, 1990, pp 63-75.The paper presents a discussion of the objectives, scope and progress of a 4-year research project on the mechanical properties of high-performance concretes with particular reference to highway applications. High performance concrete is defined by certain requirements of strength and durability.
U.S. Department of Transportation
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