Chemical durability evaluation of copper grit aggregate concrete against Alkali-Silica-Reaction, carbonation and chloride penetration

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This study aims to explore the effects of varying proportions of copper grit (CG) as fine aggregate on the alkali-silica reaction (ASR), accelerated carbonation test (ACT), and rapid chloride penetration test (RCPT) of concrete. Other complementary experiments including the rate of water absorption and compressive strength of copper grit aggregate mortar (CGAM), as well as compressive strength, split tensile strength, and sorptivity test of copper grit aggregate concrete (CGAC), were conducted. The results indicate that a higher CG content, particularly at around 80% replacement in the concrete mix, enhances strength without inducing expansive ASR and mitigates carbonation and chlorination rates in concrete. Moreover, the compressive strength of CGAM increases up to a 60% replacement ratio. Water absorption decreases from 62.1 gm/cm2 for the control specimen to 47.9 gm/cm2 for mortar with 100% CG replacement. ASR test results show no significant expansion up to a 20% replacement ratio of CG, with further increases in replacement resulting in expansion below the threshold limit of 0.1%. A notable 27% increase in compressive strength is observed for 80% CG replacement at 28 days of CGAC. Additionally, carbonation depth decreases with an increase in CG quantity in CGAC mixes, with the lowest depth observed for 80% CG replacement. The carbonation coefficient remains below the threshold limit, indicating high-quality CGAC. Furthermore, the service life of CGAC was predicted and microstructural characteristics of both CGAM and CGAC were examined via Field Emissions Scanning Electron Microscopy (FESEM). The findings underscore the potential of utilizing CG as a substitute for conventional sand in mortar and concrete production, offering a promising ecological alternative for conserving natural resources and safeguarding the environment.