Towards a codified design of recycled aggregate concrete structures: background for the new fib Model Code 2020 and Eurocode 2

Abstract

The use of recycled aggregate (RA) to produce recycled aggregate concrete (RAC) is a proven way of decreasing the consumption of natural aggregate (NA) and landfilling of construction and demolition waste. However, adoption of codes for the design of RAC and RAC structures has been lacking. Within the framework of the new fib Model Code 2020 and Eurocode 2, provisions for RAC can be adopted. Therefore, in this study, a comprehensive and critical review of literature on RAC and own meta-analyses of results are performed. Material properties of RAC and structural behaviour of reinforced and prestressed RAC members are analysed, and based on the findings, code adjustments for RAC are proposed. The results show that, in order to incorporate RAC into design codes, changes are necessary in expressions for physical–mechanical properties (volumetric mass, modulus of elasticity, tensile strength, fracture energy, peak and ultimate strains, shrinkage strain and creep coefficient), durability-related properties (minimum concrete cover for durability) and structural behaviour (shear strength of members not requiring shear reinforcement and deflections). The recommendations are formulated in terms of the total mass substitution rate of RA that can be classified as Type A according to standard EN 206 for concrete. The results and findings presented herein can provide an important contribution towards the codification of RAC use and the wider utilization of RA in construction.