Hidden Meaning of Water-Cement Ratio.
Hidden Meaning of Water-Cement Ratio.
(442 K)
Bentz, D. P.; Aitcin, P. C.
Concrete International, Vol. 30, No. 5, 51-54, May
2008.
Keywords:
water; cements; stress (mechanics); volume fraction;
particle size distribution; cement paste
Abstract:
Concrete is always characterized by the mass ratio of
water to cement (w/c) in the mixture. Unfortunately,
for most students and many engineers, the w/c is an
abstract number without any particular meaning.
Furthermore, this number is inversely related to
concrete strength: the lower w/c, the greater the
strength.l People generally understand and can remember
direct relationships better than inverse relationships.
In fact, w/c has a hidden meaning: it's directly linked
to the spacing between cement particles in the cement
paste. The smaller this spacing, the faster the cement
hydrates fill in the gaps between cement particles, the
stronger the links created by these hydrates, and most
importantly, the stronger the concrete. Additionally,
the smaller this spacing, the smaller the sizes of the
pores created by seIf-desiccation and the larger the
stresses generating autogenous shrinkage.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899