Impact of entrained air on the temperature dependency of storage modulus growth in mortars

Abstract

Reducing the temperature dependency of fresh concrete’s rheological behavior is required by new technologies that need better workability control. This research studied the effect of airentraining admixture (AEA) as a rheology-modifying agent in mortars, and its interaction with primary mixture design parameters (cement to binder ratio (C/B) and aggregate to cement paste ratio (A/CP)) and temperature on the structural build-up of cementitious materials. Smallamplitude oscillatory shear (SAOS) test was used to characterize cement paste’s and mortar’s initial critical shear strain and storage modulus (G’) growth over time, which are two parameters that govern the structural build-up of cementitious materials. Results showed that the effect of entrained air on the growth rate of G’ is different in cement pastes and mortars. In addition, the effect of temperature and entrained air on G’ intensifies over time, while the effect of mixture design parameters on G’ diminishes with time. Furthermore, a rise in A/CP, C/B and temperature increases the initial critical shear strain of mortar, while the entrained air does not produce a significant effect on this property.