Use of solar-driven sustainable graphene for enhancing the performance of cement composites

Graphene-based admixtures can enhance the performance of cement composites, but conventional graphene production remains costly and energy intensive. This study evaluates two solar energy produced graphene types, solar graphene (SGr) and solar graphene intermediate (SGI), as sustainable nano-admixtures for cement mortars, benchmarked against traditional reduced graphene oxide (rGO) under identical conditions. The solar graphene is produced in-house at an energy demand of only 2.135 MJ/kg and a production cost of USD 11.1 per kg, substantially lower than in conventional graphene production. Mortars containing 0–0.12 wt% graphene (by cement mass) were assessed for workability, compressive strength, flexural strength, and capillary water absorption, while hydration and microstructural development of the mortar were investigated using XRD, FTIR, TGA/DTG, and SEM. The graphene materials were characterised by particle size analysis, BET surface area, AFM thickness, Raman spectroscopy, XPS, SEM, and zeta potential analysis. The incorporation of SGr and SGI caused a dosage dependent reduction in flow; however, at the optimum dosages of around 0.04–0.06 wt%, the loss of workability remained moderate. At these dosages, compressive strength increased by up to 20%, flexural strength by up to 27%, and the water absorption decreased by up to 17% relative to the control mix. Microstructural results show a denser hydrate network and a refined interfacial transition zone, consistent with enhanced hydration, matrix densification, and crack resistance. Overall, the findings demonstrate that solar graphene can function as a sustainable and cost-effective nano-admixture for enhancing cement composites, with performance reasonably comparable to that of traditional graphene types like rGO.