A study on ITZ percolation threshold of air-entrained mortar: Numerical simulation and analytical model

Abstract

The percolation threshold of the interfacial transition zone (ITZ) of cementitious materials is a crucial parameter related to the bulk transport property. This study contains a theoretical investigation on the ITZ percolation threshold of the air-entrained mortar. To this end, the meso-scale model of the mortar containing both fine aggregates as ellipsoidal particles and air voids as spherical particles was explicitly simulated. Then, a series of meso-scale models were tested to determine the percolation probability that was further used to obtain the ITZ percolation threshold. The effects of the particle gradation and air-void content on the threshold were comprehensively investigated. The results showed that: (1) the specific surface areas of the fine aggregate and air void, ITZ thickness and air-void content are four crucial parameters to the ITZ percolation threshold; (2) the ITZ thickness and air-void content have the first and second dominant effects on the threshold, respectively; (3) the effect of the specific surface area of the air void on the ITZ percolation threshold increases with the ITZ thickness. Finally, based on a multiple linear regression analysis, an analytical model was proposed to fast calculate the ITZ percolation threshold of the air-entrained mortar.