Properties of cement‐based materials containing calcium stearate and supplementary cementitious materials

Abstract

Calcium stearate (CS) is effective to reduce permeability of different building materials under nonhydrostatic pressure but more actions need to be taken to shed light on its main and side effects on properties of cement‐based materials. This research project investigates the effect of CS on properties of these materials. Compressive strength analysis shows that the addition of CS at the dosage of 1% of cement weight reduces this parameter by approximately 20% but reducing water‐to‐binder ratio, and replacing 7.5% of cement weight with silica fume (SF) compensate for the strength loss caused by CS. Results of drying shrinkage test show that the addition of CS slightly increases drying shrinkage but replacing 7.5% of cement weight with SF can compensate for the negative effects of CS on drying shrinkage. Permeability analysis shows that CS is not as effective as SF and natural zeolite (NZ) to improve impermeability under hydrostatic pressure but it is more effective than SF and NZ to improve impermeability under nonhydrostatic pressure because the addition of CS at the dosage of 1% of cement weight reduces capillary water absorption by roughly 60%. Therefore, the simultaneous use of CS and these supplementary cementitious materials improves not only impermeability under hydrostatic pressure but also impermeability under nonhydrostatic pressure.