Durable structural recycled concrete for different exposure environments

Abstract

In this work, the influence of limited percentages of coarse (CRCA) and fine (FRCA) recycled concrete aggregates (Type A recycled aggregates) on the durability properties of structural concrete was analyzed. Concretes were designed using 50% and 60% CRCA with simultaneous additions of 0%, 10%, and 20% FRCA and different types of cement (CEM II/AL 42.5 R, CEM II/AS 42.5 N/SRC, and CEM III/B 42.5 N-LH/SR). Recycled aggregate concrete (RAC) and natural aggregate concrete (NAC) mixtures were produced with similar compressive strength using effective water–cement ratios of 0.47 and 0.5. The drying shrinkage values and durability properties were determined, and they included the chloride permeability, chloride penetration depth, and accelerated and natural carbonation rates. The findings revealed that RAC produced using CEM III/B, which included the mixture produced with 60% coarse RCA and 20% fine RCA, achieved low chloride ion penetrability (up to 850 Coulombs) and exhibited the lowest chloride diffusion coefficient, approximately 7×10-13. Additionally, the RAC-C60-F20 concretes made with CEM II/AS proved suitable for the XC3 and XC4 exposure environments, guaranteeing a lifespan of 50 and 100 years based on the natural carbonation rate. In addition, the RAC-C60-F20 concrete made with CEM II/AL cement exhibited an adequate natural carbonation rate for XC4 environments, which was between 1.6 and 2.4 units higher than the accelerated carbonation rate. This work validates the use of RAC in XC environments (corrosion induced by carbonation) and XS1 environments (corrosion caused by chlorides from seawater).