Creep of recycled aggregate concrete: Experimental database and creep prediction model according to the fib Model Code 2010

Abstract

Recycled aggregate concrete (RAC) is a promising solution to addressing the sustainability issues raised by concrete production. However, its long-term properties are not fully characterised, especially creep behaviour, which is significant for the design of RAC structures. This study presents the results of a meta-analysis of previously published research on the creep behaviour of recycled aggregate concrete (RAC). The main goal of the study is to formulate an analytic expression for the creep coefficient of RAC as an extension of the fib Model Code 2010 creep prediction model. A database of experimental results on the creep of RAC and companion natural aggregate concrete (NAC), produced with the same effective water-cement ratio, was compiled from available literature and using strict selection criteria. The database is comprised of results from 10 studies, 46 creep curves (14 NAC and 32 RAC) and 233 data points. Compared with companion NAC, RAC displays a larger creep coefficient; the difference between RAC and NAC increases with increasing recycled concrete aggregate (RCA) content and decreases with increasing RAC compressive strength. When predicting the creep coefficient of RAC using the fib Model Code 2010's creep prediction model, relative to the model's performance on companion NAC, the creep coefficient of RAC is underestimated. A correction coefficient for the creep coefficient of RAC, xi(cc.RAC), is proposed for use with the fib Model Code 2010 model, dependent on RAC compressive strength and RCA replacement ratio.