Effects of glazed hollow beads on the drying shrinkage value and trend of recycled aggregate concrete

Recycled concrete aggregates (RCA) generally result in higher drying shrinkage of concrete. In this study, glazed hollow beads (GHB) were incorporated in concrete with different RCA contents as a possible way to mitigate drying shrinkage and improve insulation properties. A new drying shrinkage model of recycled aggregate thermal insulation concrete (RATIC) was developed to confirm the effects of RCAs and GHBs. To verify the model, a 450-d drying shrinkage experiment was performed to test the longitudinal length shrinkage of 100 mm x 100 mm x 400 mm prism specimens, three of which were made for the proportion of each concrete mixture. The experi-mental study explored the effects of incorporating RCAs and GHBs on the drying shrinkage and drying shrinkage developmental tendency regarding RATIC; 0%, 50%, and 100% RCA replace-ment rates and 0, 65, and 130 kg/m3 GHB contents were studied. According to the study, 1) GHBs are capable of remarkably mitigating the way RCAs negatively affect concrete drying shrinkage and 2) GHBs and RCAs affect the developmental trend of drying shrinkage in concrete. A modified RATIC model of drying shrinkage is proposed to achieve the abovementioned results. The pro-posed model can accurately predict the drying shrinkage value of RATIC.