Investigation on the effect of entrained air on pore structure in hardened concrete using MIP

The influences of entrained air on the pore size distribution and pore parameters of hardened mortar and concrete were investigated by MIP. It was found that the dosage of AEA does not affect the critical diameter for mortar or concrete. For air-entrained mortar with w/c of 0.38, the absence of superplasticizer leads to the critical diameter and threshold diameter shifting significantly to larger pores; and the AEA combined with SP can enhance the ink-bottle effect. As for air-entrained concrete, it is evident that the ITZ peak goes higher and shifts to coarser pores as the entrained air content increases; the ITZ fraction is most highly correlated with the air content (with R-square of 0.9385); also, it was indicated that more entrained air voids in concrete led to a high ITZ fraction. Therefore, together with larger ITZ pores (d(c-ITZ)), it promotes the ITZ percolation. (C) 2021 Elsevier Ltd. All rights reserved.