Minimum cement content requirements: a must or a myth?
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The objective of the present work was to systematically investigate the issue of minimum cement content requirements, by studying the behavior of concretes with different water to cement ratios ( w/c) in the range of 0.45–0.70, in which the cement content was varied, by controlling the water content, using water reducing admixtures. The effect of cement content was noted to be different for various properties: strength was a function of w/c and independent of cement content; total water absorption was proportional to the paste content at a given w/c, while capillary absorption and chloride ingress reduced with a reduction in the cement content for a given w/c, to an extent which was much greater than the reduction in total porosity. Carbonation and shrinkage were largely independent of cement content for a given w/c. The trends observed were discussed in terms of the effect of paste content on concrete properties, and the influence of admixtures on the paste properties. These results suggest that requirements for minimum cement content in standards should be revisited.
KeywordsConcrete Cement content Durability Standard Chloride penetration Carbonation
The support of the Ministry for Construction and Housing is gratefully appreciated.
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