Prediction Adequacy of Creep of Recycled Concrete Influenced by the Water Absorption in Recycled Aggregates

Abstract

Abstract A recycled concrete aggregate (RCA) has much higher water absorption content compared to a natural aggregate and could significantly influence the creep properties and durability of concrete. This article investigates the influence of RCA and its water absorption content on the creep properties of concrete and develops a model to predict the creep of recycled aggregate concrete (RAC). Two types of RCA obtained from the lab and field with different water absorption contents were used to prepare RAC. RCAs were mixed with natural aggregates at four replacement ratios (0, 50 %, 70 %, and 100 %). Creep and shrinkage tests were conducted to measure the specific total creep, specific basic creep, coefficients of total creep and basic creep, and shrinkage of sealed and unsealed concrete specimens subjected to sustained compression loads. The existing total creep model was modified by considering the influence of water absorption of residual mortar in RCAs, and a new model was calibrated and verified with experimental data. The results show that both the total and basic creep of RAC increased with the RCA replacement ratio and the water absorption of RCA. The total creep values of RAC were much higher than the basic creep values of RAC. Type II RCA, with RCA that had a higher water absorption, produced higher creep values than Type I RCA. The modified total creep model presented high accuracy in predicting the total creep of RAC, and thus may be potentially used to predict total creep of RAC when mixed with dry RCAs in practice.