Strength prediction model and methods for improving recycled aggregate concrete

This paper examines the effect of various parameters on the performance of recycled aggregate concrete (RAC) and proposes a strength prediction model. Relations that link the properties of recycled aggregate (RA) to the strength of RAC are developed using multi-linear and non-linear regressing analysis. To enhance the compressive strength of RAC, the effect of surface treatment of RA using small quantities of reactive and non-reactive microfillers is examined. For the same purpose, two mixing methods and the addition of recycled tyres steel fibres (RTSFs) are also investigated. The results show that RTSF as well as reactive and non-reactive microfillers can enhance the strength of RAC by 30%. Furthermore, density separation can be used to produce high quality RA from construction and demolition waste (CDW).