Evaluation of Mechanical, Ecological, Economical, and Thermal Characteristics of Geopolymer Concrete Containing Processed Slag Sand

This manuscript highlights the mechanical, economical, ecological, and thermal investigations performed on paving quality geopolymer concrete (PQGC) incorporating processed steel slag (PSS) as a substitute for river sand (RSa). The replacement of RSa with PSS ranged from 0 to 100% in the PQGC mix. The mix with 100% PSS content exhibited enhanced geopolymerization, resulting in a denser and more amorphous matrix. This improved the mechanical properties, increasing compressive strength by 10.9%, flexural strength by 23.5%, and splitting tensile strength by 8.3%. The replacement of RSa with PSS in PQGC led to a marginal reduction in (embodied energy) EE and CO₂ emissions. However, compared to conventional Pavement Quality Concrete (PQC) and Fly Ash PQC (FPQC), the reduction in EE for PQGC was 44% and 34%, while the CO₂ emissions of PQGC were reduced by 1.22 and 1.49 times. Despite these benefits, PQGC with 100% PSS was 19% and 30% more expensive than PQC and FPQC, respectively. The Global Warming Potential (GWP) of PQGC was approximately one-third that of PQC and FPQC at all levels of replacement of RSa in PQGC when compared to PQC and FPQC. Additionally, thermal conductivity decreased from k = 0.67 W/m °C to k = 0.51 W/m °C with 100% replacement of RSa, keeping the concrete cooler. Therefore, PQGC with 100% PSS, when practically implemented, may help reduce surrounding temperatures. This study concludes that PSS is a feasible and reliable alternative to RSa, enhancing the sustainability of PQGC.