Enhancing the Mechanical and Durability Properties of Self-Compacting Concrete Using Graphene Oxide-Coated Crumb Rubber

Due to its low carbon footprint and suitability for in situ applications, crumb rubber (CR) is acknowledged as a viable alternative to fine aggregate. However, a challenge in utilizing CR in concrete lies in its less effective bonding with the cement matrix compared to traditional aggregates, leading to weaker overall concrete mixtures and hindering mass concrete manufacturing adoption. In this experimental work, CR was pretreated with graphene oxide (GO) to create self-compacting concrete (SCC). Response surface methodology (RSM) was used to optimize the combination of GO-coated CR in SCC (GO-RSCC). Fresh properties including slump flow (700–758 mm), L-Box ratio (0.81–0.9), V-funnel time (7–12 s), T-500 (2–4 s), and Visual Stability Index were determined. Hardened properties like compressive strength (32–47 MPa), splitting tensile strength (1.89–4.86 MPa), and flexural strength (3.1–6.86 MPa) were also evaluated. The crumb rubber content ranged from A% to B%, while the Graphene Oxide dosage was varied from X% to Y%. However, increasing CR replacement to 15% reduced the compressive strength by X% and workability by Y%. The optimal mix, by weight, for GO-RSCC was found to be 10% CR replacement and 1.0 mg/ml of GO pretreatment, resulting in a Z MPa increase in compressive strength and a W% improvement in workability. Microstructural analysis revealed that GO pretreatment of CR reduced the interfacial transition zone (ITZ), enhancing bonding among CR and cementitious composites, thus improving mechanical strength. Model equations developed through RSM and artificial neural network (ANN) optimization further optimized the strengths of GO-RSCC, achieving predicted strength improvements.