Published online by Cambridge University Press: 22 February 2011
Substantial increases of the strength of cement paste and mortars may be obtained in conventional processing by optimizing the materials components, the rheology and the curing, and thereby improving the microstructures. Cementitious materials with high proportions of granulated blast-furnace slag have been investigated. Higher strengths of ASTM C 109 mortars were obtained with 40 to 65% substitution of portland cement by slag, than with ordinary mix compositions and processing.
For one set of mixtures, 28 day strengths ≥ 100 MPa (some as high as 240 MPa) were consistently attained after curing at temperatures ranging from 27 to 250°C. The slag substitutions developed finer pore structures as revealed by intrusion porosimetry measurements, than those with pure portland cement. This is believed to be a major reason for their enhanced durability. At each stage from 3 to 28 days, increase of curing temperatures from 27 to 90°C decreased porosity and increased the strength, reflecting an increased maturity.
Implications for practice and suggestions for further work are discussed.