Interface parameters of recycled aggregate concrete considering the distribution of old mortar content

The amount of Interface Transition Zones (ITZs) in Recycled Aggregate Concrete (RAC) is affected by the mass content of old mortar of Recycled concrete Aggregate (RA). However, quantifying the amount of ITZ and its influence on the properties of RAC is challenging due to the considerable variability in old mortar content among RAs. In this study, the experiments were conducted to examine the old mortar content and its distribution of RA derived from nine different parent concrete mixtures. According to this experimental investigation, a normal-distribution-based function was proposed to describe the distribution of the old mortar content of RA. Subsequently, an interface parameter for individual RA, xi RA , was proposed to quantify the influence of old mortar content of RA on the amount of ITZ. Utilizing the xi RA in conjunction with the distribution function of old mortar content, an overall interface parameter for RAC, xi RAC , was established. The overall interface parameter is able to reflect the influence of the content and its distribution of old mortar of RA on the amount of ITZ in RAC, and it has been proven that xi RAC can be used to predict the compressive strength of RAC.