Shrinkage and Creep of Sustainable Self-Compacting Concrete with Recycled Concrete Aggregates, Fly Ash, Slag, and Silica Fume

This paper experimentally studies the drying shrinkage and creep deformation of sustainable self-compacting concrete (SCC) prepared by substituting natural aggregates with recycled concrete aggregates and cement with supplementary cementitious materials (SCMs). A total of 11 mixes with two recycled coarse aggregate (RCA) replacement ratios (50% and 100% by volume) and two SCM replacement ratios (50% and 75% by weight) were manufactured, including binary mixture (cement and fly ash), ternary mixture (cement and fly ash, and slag) and quaternary mixture (cement and fly ash, slag, and silica fume). The influence of various RCAs and SCMs as well as the SCM combinations on the shrinkage and creep characteristics were analyzed in detail. The test results indicate that the shrinkage and creep characteristics of recycled aggregate SCC (RA-SCC) are significantly affected by RCA and SCM, as well as by SCM combinations. Compared to the control SCC, the addition of 100% RCAs increased the shrinkage deformations up to 37.2% and creep deformations up to 33.5% at 420 days, respectively. In addition, the inclusion of fly ash and slag reduced the shrinkage deformation by 27.6% and the addition of SCMs using a combination of fly ash, slag, and silica fume reduced the specific creep of RA-SCC mixes by 27.9%. A comparison between the measured shrinkage and creep strains and calculated values using existing prediction models was conducted. Based on the American Concrete Institute (ACI) prediction models, modified shrinkage and creep models were proposed by considering the influence of RCAs and SCMs.