Enhancing fire resistance in geopolymer concrete containing crumb rubber with graphene nanoplatelets

Abstract

Geopolymer concrete (GPC) has a tendency to spall and lose its strength at high temperatures, rendering it brittle. This research incorporates graphene nanoplatelets (GNPs) to enhance the fire resistance of GPC. A comprehensive experimental framework, comprising 20 distinct mix designs, was developed. Crumb rubber (CR) was substituted for natural sand in the mixture proportions, ranging from 10% to 30% by volume, while GNPs were incorporated in quantities ranging from 0.1% to 0.4% by weight of fly ash. The objective of this study is to assess the mechanical properties of these mixtures after exposure to 30, 60, and 90 min of ISO 834 standard fire. The properties of GPC were analyzed both before and after exposure to fire. The attributes and properties investigated include spalling, mass loss, stress-strain behavior under compression, compressive strength, compressive toughness, modulus of elasticity, and porosity. Furthermore, the study examined the interfacial interaction between the aggregates and the geopolymer matrix, as well as microstructural and morphological changes due to fire exposure, utilizing field emission scanning electron microscopy (FESEM). The results indicated that GNPs significantly mitigated the loss of post-fire compressive strengths of GPC. The Response Surface Methodology (RSM) was employed to develop statistical models and optimize the mixture proportions of CR and GNPs, aiming to maximize the compressive strength and the modulus of elasticity while minimizing the mass loss of GPC after exposure to fire. The optimization outcomes suggested that a mixture containing 10% CR and 0.3% GNPs represented the optimal composition for enhancing the fire resistance of GNP modified rubberized GPC.