Novel eco-friendly high-strength concrete based on slag activated with calcium oxide: Environmental, thermal, and mechanical performance

High-strength concrete (HSC) utilizes a significantly larger amount of cement than ordinary concrete. The cement production process and the provision of stone aggregates cause severe environmental effects. Therefore, substituting waste materials not only introduces an eco-friendly composite but also has the potential to enhance specific properties of concrete. This research has investigated a novel eco-friendly high-strength concrete devoid of cement, employing slag activated with calcium oxide (HSC-CAM) as a replacement for cement. Additionally, rubber powder and polyethylene terephthalate (PET) were utilized as substitutes for aggregates to improve the thermal characteristics and energy absorption capacity of the HSC-CAM, with PET powder and rubber replacing fine aggregates at volume percentages of 10, 20, and 30. A Life Cycle Assessment (LCA) analysis was conducted using the Impact 2002+ + and ReCipe Midpoint methods to evaluate waste materials' application on environmental parameters. Tests were performed to assess impact resistance, thermal conductivity, thermal performance, and mechanical properties, contributing to the assessment of ductility and thermal insulation of the developed concrete. The LCA analysis demonstrated that the developed concrete yielded a 66 % improvement in human health indicators and a 48 % in ecosystem quality indicators. Furthermore, it exhibited a substantial reduction of 78 % in embodied carbon footprint and a notable decrease of 61 % in resource indicators compared to ordinary high-strength concrete (HSC). The results also indicated that including 30 % rubber and PET powder led to a 28 % increase in impact resistance for HSC-CAM and a significant decrease of 31 % and 26 % in thermal conductivity, respectively.