Numerical calculation and influencing factors of the volume fraction of interfacial transition zone in concrete

Abstract

The determination of volume fraction of interfacial transition zone (ITZ) is very important for investigating the quantitative relationship between the microstructure and macroscopical property of concrete. In this paper, based on Lu and Torquato’s most nearest surface distribution function, a calculating process of volume fraction of ITZ is given in detail according to the actual sieve curve in concrete. Then, quantitative formulas are put forward to measure the influencing factors on the ITZ volume fraction. In order to validate the given model, the volume fractions of ITZ obtained by numerical calculation are compared with those by computer simulation. The results show that the two are in good agreement. The order of the factors influencing the ITZ volume fraction is the ITZ thickness, the volume fraction of aggregate and the maximum aggregate diameter for Fuller gradation in turn. The ITZ volume fraction obtained from the equal volume fraction (EVF) gradation is always larger than that from the Fuller gradation for a given volume fraction of aggregate.