Reactionary powder concrete based on alkali-activated cement

The development of reactive powder concretes based on alkali-activated cements for the construction and protection of critical infrastructure is of woldwide importance for improving the safety of their exploitation. The factors influencing the kinetics of strength gain and drying shrinkage of reactive powder concretes using sodium silicate pentahydrate as an alkaline activator were determined.It was shown that increasing the ratio of alkali-activated cement to sand from 1:3 to 1:1 and using the activator in the liquid state increased the concrete strength gain: the compressive strength was 52.3 MPa, 85.0 MPa, 100.6 MPa, and 124.7 MPa at the ages of 1, 3, 28, and 90 days of hardening, respectively. The ratio of compressive strength to flexural strength was 5.3...5.9 at an age of 28 days, indicating a high fracture toughness of the obtained material. An increase in the content of alkali-activated cement in concrete determined a decrease in the influence of sand granulometry on concrete strength,due to its “floating” placement in the cement matrix.The introduction of a fine calcite additive ensured to reduce the shrinkage of concrete by 1.3...1.5 times at an age of 90 days due to the densification of the microstructure and the intensification of crystallisation processes. The implementation of these measures resulted in a high strength alkali-activated cement reactive powder concrete of strength classC80/95, high fracture toughness and reduced drying shrinkage.