HIGH EARLY STRENGTH CEMENT-SCM BLENDS

摘要

Hydraulic cements, such as Portland cements and other cements that include substantial quantities of tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and/or tetracalcalcium alumino-ferrite (C4AF), are particle size optimized to have increased reactivity compared to cements of similar chemistry and/or decreased water demand compared to cements of similar fineness. Increasing hydraulic cement reactivity increases early strength development and release of reactive calcium hydroxide, both of which enhance SCM replacement and 1-28 day strengths compared to blends of conventional Portland cement and one or more SCMs, such as coal ash, slag or natural pozzolan. Decreasing the water demand can improve strength by decreasing the water-to-cement ratio for a given workability. The narrow PSD cements are well suited for making blended cements, including binary, ternary and quaternary blends.

主权项

1. A cementitious blend comprising:
a hydraulic cement fraction selected from the group of Portland cement and hydraulic cement having a tricalcium silicate content of at least 50% by weight, the hydraulic cement fraction having a d90 greater than 10 μm, a d50 greater than 5.75, and a d10 greater than 1.0 μm; a first supplementary cementitious material (SCM) fraction that contributes ultrafine SCM particles below the d10 of the hydraulic cement fraction so that at least 30% of combined SCM and hydraulic cement particles in the cementitious blend less than 3 μm comprise SCM and less than 70% comprise hydraulic cement; and a second SCM fraction that contributes coarse SCM particles above the d90 of the hydraulic cement fraction so that at least 50% of combined SCM and hydraulic cement particles in the cementitious blend larger than 20 μm comprise SCM and less than 50% comprise hydraulic cement.