Performance of recycled aggregate concrete using copper slag as fine aggregate

Abstract

The present study experimentally investigates the mechanical and durability performance of recycled aggregate concrete (RAC) incorporating copper slag as fine aggregate. The coarse aggregate obtained from recycling of construction waste is used as natural coarse aggregate and copper slag, the industrial by-product is used as fine aggregate in the current research work. Recycled aggregate concrete formed by substituting 50 % recycled aggregate as natural coarse aggregate is considered as the control mix for this experimental work. A total of seven RAC mixtures are made with copper slag as a substitution of fine aggregate of varying proportions (0%–100 %) giving an increment of 20 %. Compressive strength, split tensile strength, and microstructural behaviour of RAC mixtures were carried out for up to 90 days of curing to assess the mechanical property of RAC mixes. To evaluate the effect of copper slag on long-term properties of RAC mix water absorption, rapid chloride permeability and resistant to sulphate attack test is carried out for up to 90 days. The findings revealed that the mechanical properties of RAC mixes are improved up to 40 % substitution of copper slag. When exposed to sulphate, RAC mixtures gained weight while losing compressive strength. Results of water absorption and RCPT test showed a remarkable improvement with the incorporation of copper slag up to 40 %; beyond that point, the results were comparable to RAC mix (control). The progression of calcium silicate hydrate gel formation within the RAC blend was verified through scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction analysis across a range of curing periods spanning from 7 to 90 days.