Absorbing effect of air entraining agent on early frost expansion of mortar: Calculation model and application

The use of air-entraining agents (AEA) is one of the powerful means to reduce frost damage of concrete. In this study, the effect of AEA on frost deformation, coefficient of thermal expansion, and frost absorption capacity of early-age frozen mortar was investigated using a self-designed device. The results show that the addition of AEA can reduce or even counteract the frost expansion deformation of mortar. The frost deformation of mortar can be decomposed into temperature deformation, phase change expansion of freezable water, and absorption of frost expansion by air pores. A calculation model of the relationship between the above deformations is established. The air pore absorption efficiency coefficient γ is introduced to characterize the effect of frost expansion absorption by air pores. Based on the calculation model, the optimal dosage of AEA and the minimum pre-curing time for early-age frozen mortars can be determined.