Mechanical Properties of Structural Concrete with Recycled Concrete Aggregates at High Replacement Ratios

This paper presents the results of a large and systematic experimental investigation of structural concrete cast with recycled concrete aggregates (RCA) at high replacement ratios. The experimental campaign included determination of modulus of elasticity, compressive strength, and tensile strength, and was divided into two series comprising a total of 312 test specimens. The first series investigated the influence of the replacement ratio (RR) at a fixed target compressive strength, whereas the second series examined varying target strengths at a fixed RR. Proportioning of all concrete mixtures was based on achieving maximum packing density, and the RCA was well-characterised regarding water absorption capacity, density, compressive strength, and aggregate types, the latter two often unspecified in previous studies. The experimental campaign shows that even at considerably higher RRs than current recommendations in standards and the literature, RCA is a viable alternative to natural aggregate (NA) with no increase in cement content nor pre-treatment of the RCA, provided systematic handling of mixture design and production.