Influence of High-Performance Recycled Aggregates on Mechanical Properties of High-Strength Concrete

One of the major challenges in developing a sustainable construction industry is the reincorporation of construction and demolition waste (C&DW) into the materials cycle. An interesting end-of-life cycle strategy is the recycling of C&DW as aggregates for new concrete. Although promising results have mostly been reported for applications with low mechanical and durability requirements, this research evaluates the use of a high-performance recycled concrete aggregate (HP-RCA), a low-porosity, high-abrasion-resistance aggregate obtained from the demolition of high-strength concrete, with almost no additional treatment, unlike what is traditionally required. First, the production and characterization of the HP-RCA was carried out, to continue with the manufacture of four high-strength concrete mixtures that included one reference (0%) and three with different natural coarse aggregate replacements (10%, 20% and 40%). Then, fresh and hardened properties were evaluated, with the main focus being mechanical properties (i.e., compressive strength, diametric compressive tensile strength and elasticity modulus). Results indicate that when the recycled aggregate content increased, the mechanical properties substantially improved, and the mixture with 40% replacement improved the compressive strength by 37.8% at 56 days. Although durability performance still needs to be further assessed, the mechanical results presented here are very promising for advancing a truly sustainable construction industry, especially considering that the extraction of natural coarse aggregates has significant environmental impacts and that the final disposal of C&DW remains a major environmental and economic challenge.