Abstract

Industrial waste management has increased in recent years and, at the same time, the production of more sustainable and high-performance concrete has become one of the most important challenges related to the built environment. To contribute to face the previously mentioned challenges, this paper presents an experimental study on the influence of copper slag (CS) as a supplementary cementitious material (SCM) on the physical and mechanical concrete performance at both short- and long-terms. The CS was incorporated to concrete using five increasing levels (0 %, 10 %, 20 %, 30 % and 50 % vol.) as SCM and both fresh state (slump) and hardened state (compressive strength, indirect tensile strength, flexural strength, porosity and capillary suction) properties of concretes were evaluated. The results showed that the highest slump was achieved by the concrete mixture with 50 % CS, reaching a 27 % increment compared to the reference concrete (0 % CS). In the hardened state, both average compressive and splitting tensile strength values monotonically decreased with increasing CS content at short ages (28 days). However, at 360 days, the 10 % SC concrete mixture presented average compressive and splitting tensile strengths of 57 MPa and 4.9 MPa, respectively, reaching and exceeding the corresponding strength values of the reference concrete, respectively. In addition, the mixture with 10 % CS obtained the highest average flexural strength, reaching a 3.2 % and 3.5 % increment compared to the reference mixture at 28 and 360 days, respectively, which might be attributed to the more angular shape of the CS particles compared to the cement particles. In terms of physical properties, voids and absorption values increased as the CS content increased, yet at 360 days of curing, the only concrete that presented higher values than the reference concrete was the mixture with 50 % CS (increments of 5.6 % and 5.4 % for voids and absorption, respectively). In conclusion, this study showed the advantageous potential use of CS as SCM at low percentages (between 10 % and 20 %), especially in long term performance of concrete mixtures.