REMOVING BITUMEN FROM LIMESTONE


PART 1---GENERAL

1.01 SUMMARY

     A.   This procedure includes guidance on cleaning and removing
          localized bitumen residue from limestone surfaces.  For
          guidance on the general cleaning of surface dirt on
          limestone, see 04460-03-R.
     
     B.   See 01100-07-S for general project guidelines to be
          reviewed along with this procedure.  These guidelines
          cover the following sections:

          1.   Safety Precautions

          2.   Historic Structures Precautions

          3.   Submittals

          4.   Quality Assurance

          5.   Delivery, Storage and Handling

          6.   Project/Site Conditions

          7.   Sequencing and Scheduling

          8.   General Protection (Surface and Surrounding)

          These guidelines should be reviewed prior to performing
          this procedure and should be followed, when applicable,
          along with recommendations from the Regional Historic
          Preservation Officer (RHPO).

1.02 QUALITY ASSURANCE

     A.   Qualifications:  

          1.   Contractor performing the work shall have a minimum
               of 5 years experience in masonry restoration work
               of the type described for this project.

          2.   If requested by the Owner, furnish a statement of
               the experience and qualifications of the firm and
               of the key personnel who will work on this project. 
               Include the names and addresses of successful
               projects completed, and for each, the name and
               address of the owner and the architect.

     B.   Reference Standards:

          1.   Secretary of the Interior's "Standards for
               Rehabilitation".

          2.   Preservation Brief No. 1, "The Cleaning and
               Waterproofing of Historic Masonry Buildings".

     C.   Test Panels:  Each alternative method for each type of
          cleaning.


PART 2---PRODUCTS

2.01 MANUFACTURERS

     A.   Hydrochemical Techniques, Inc.
          P.O. Box 2078
          Hartford, CT 06145
          203/527-6350

     B.   ProSoCo, Inc.
          755 Minnesota Avenue
          P.O. Box 1578
          Kansas City,  KS  66117
          800/255-4255 or 913/281-2700

     C.   KRC Research Corp.

2.02 MATERIALS

     A.   Alkaline cleaners and water rinse, such as "HT907"
          (Hydrochemical Techniques, Inc.), "Sure-Klean Limestone
          Pre-Wash/After-wash" (ProSoCo, Inc.), "Ion 417 fluoro-
          surfactant" (KRC Research Corp.), or approved equal.

     B.   Bitumen removal:  Following scraping to remove bulk,
          apply solvent containing petroleum distillate (in
          poultice, if required) equal to Sure-Klean Asphalt and
          Tar Remover.

     C.   White absorbent material (molding plaster, untreated
          white flour, white tissue, paper towels, powdered chalk,
          talc, fullers earth or laundry whiting).

     D.   Mineral water

     E.   Plastic sheeting

     F.   Clean dry towels for blotting the area after treatment

     G.   Masking tape

     H.   Clean, potable water

2.03 EQUIPMENT

     A.   Pressure water rinsing equipment (measuring between 100
          and 400 psi for low-pressure; between 400 and 800 psi for
          medium pressure).

     B.   Fan-type spray tips (15 degree fan spray)

     C.   Soft fiber-bristle brushes 

     D.   Stiff natural fiber-bristle brush (Tampico)

     E.   Glass or ceramic container for mixing the solution

     F.   Wooden utensil for stirring the ingredients

     G.   Wooden spatula


PART 3---EXECUTION

3.01 ERECTION, INSTALLATION, APPLICATION

     A.   General rinsing of unsoiled stone:  

          1.   All limestone surfaces shall be water rinsed in
               order to blend in areas that are chemically cleaned
               to remove stains with unsoiled areas of stone.

          2.   Water rinse:  Maximum 600 PSI, 5-10 GPM, 15  fan
               angle, not less than 6" from stone surface, at an
               angle of 45  to 90  from wall surface, hot water
               (180 F).

     B.   Cleaning of soiled limestone with alkaline cleaner:

          1.   Pre-wet area to be cleaned.

          2.   Apply alkaline cleaner with soft fiber brush or
               spray.  Allow to stand on surface approximately one
               hour.  Agitate with a stiff natural fiber bristle
               brush.

          3.   Pressure rinse surfaces.  Repeat rinsing until all
               traces of chemical have been removed.

          4.   Apply acid neutralizer.  Repeat pressure rinse.

          5.   Repeat the process as required.

     C.   Bitumen Removal:  

          1.   Protect adjacent stone with polyethylene sheeting.

          2.   Scrape off bulk of bitumen using a wooden spatula,
               taking care not to damage the stone surface.

          3    Dissolve remainder with specified solvent.  Swab
               run-off immediately.  

          4.   If required to dissolve deep stains, apply solvent
               in poultice and keep wet for 4-8 hours by sealing
               in plastic sheeting.  For guidance on preparing and
               applying poultices, see 04455-02-R.

                          END OF SECTION