Mechanical properties of multi-recycled coarse aggregate concrete, with particular emphasis on experimental and numerical assessment of shrinkage at different curing temperatures

Abstract

This study investigates the behaviour of concrete manufactured with recycled coarse aggregate (RCA) derived from multiple recycling cycles, with a particular emphasis on experimental and numerical assessment of shrinkage at different curing temperatures (20, 40, and 60 °C). Four types of concretes have been produced: a natural aggregate concrete (NAC) with 100 % natural coarse aggregate (NCA) and three generations of recycled aggregate concrete (RAC) where NCA is replaced by RCA with volume percentages of 50 % and 100 % in each generation. Moreover, silica fume is used to improve the mechanical performance of the third-generation recycled concrete with 100 % RCA. In addition, the total shrinkage was predicted by combining the maturity method with finite-element analysis (FEA), using ANSYS© software. The results revealed that the multi-recycling and the replacement ratio of RCA have a detrimental impact on the mechanical properties. The total shrinkage increases considerably with both increasing curing temperature and increasing RCA replacement ratios in each generation. Furthermore, silica fume has a beneficial effect on the mechanical performance of the multi-recycled concrete; nevertheless, it causes an increase in the total shrinkage. Finally, the comparison between the experimental and numerical data shows that the FEA model, using the maturity method and two-phase serial model, can yield an accurate prediction of the total shrinkage of multi-recycled concrete.