Natural sand substitution by copper mine waste rocks for concrete manufacturing

Abstract

The management of waste rocks, generated by the mining industry, has become a global concern due to its high quantity, environmental impact, human health risks and high disposal costs. Thus, developing effective and sustainable solutions to properly manage this waste become necessary. In this study, the feasibility of using copper mine waste rocks (CMWR) as a substitute of natural sand in C25 concrete category (25 MPa at 28 days) was evaluated. In The first stage, the physical, chemical, mineralogical, geotechnical, and environmental characterizations of CMWR were conducted. Then, three concretes mixtures were designed and prepared including, reference concrete (CM-0), CMWR based concrete with 50% (CM-50) and 100% (CM-100) of natural sand substitution by CMWR sand. The concrete samples were tested to evaluate the mechanical performance and durability prediction of each mixture. The results showed that physical-mechanical and geotechnical properties of CMWR sand are so close to natural sand used in concrete manufacturing. Moreover, environmental finding confirmed that the CMWR is classified as non-dangerous materials. Furthermore, CMWR-based concretes met the requirements of the C25 concrete grade standard at all replacement levels. In terms of mechanical strength, the values were higher than that required by the standard (25 MPa). For the water absorption rate, which influences the durability of concrete, it was lower than the limit required by the standard (6%). Through the reuse of CMWR in concrete as a replacement for natural aggregates, environmental problems, costs and the depletion of natural resources can be minimized.