Limestone addition effects on concrete porosity

The effect on porosity (including absorption and sorpitivity) of cement paste and mortar/concrete, of limestone addition to Portland cement is assessed. Based on globally sourced literature published in English since 1993, consisting of 171 publications from 35 countries. The data analysed were from wide ranging tests. The effect on pore structure was also examined in terms of type of Portland cement and limestone, cement fineness and method of producing it, curing, maturity and water-cement ratio, as well as the cement composites with fly ash, slag (GGBS), silica fume and metakaolin and related to strength. Overall, it is suggested that though the use of limestone up to 25% with Portland cement should not impair the pore structure, limit on limestone content for its effect on strength is likely to be about 15%. This should be considered where higher proportion of limestone content is allowed in the Standards.