Improving the performance of crumb rubber concrete using waste ultrafine glass powder

Abstract

Due to its superior toughness and environmental benefits over traditional concrete, crumb rubber (CR) concrete (CRC) gained considerable attention in both research and practical engineering fields. However, the static mechanical characteristics of CRC exhibit a certain level of decline as CR demonstrates a lower elastic modulus and less effective bonding capabilities with mortar when compared to natural aggregates. Consequently, this study explores the potential of substituting cement with ultra-fine waste glass powder (WGP) to enhance the mechanical characteristics and microstructure of CRC. The impact of varying WGP substitution rates on workability, wet packing density (WPD) in the fresh phase is examined. Moreover, analyses on compressive strength, flexural-tensile strength, ductility index, dynamic elastic modulus, damping ratio, and impermeability post-hardening are presented. The use of scanning electron microscopy (SEM), X-ray diffraction (X-RD), and mercury intrusion piezometry (MIP) provided insights into the influence of WGP on the micromorphology, mineral composition, and pore structure characteristics. The results revealed that WGP introduction enhanced the fresh properties of CRC, notably in terms of workability and WPD. The slump and slump-flow increased to 270 mm and 630 mm for WGP dosing increased to 30 %. A gradual enhancement in strength, dynamic elastic modulus, and impermeability was observed with increased WGP content, alongside a significant improvement in toughness. The compressive and flexural strengths of 30 % WGP were mentioned to be about 11 % and 62 %, respectively, and the permeability coefficient was reduced to 0.78 × 10−12 m2/s. The damping ratio initially decreases, then rises to a peak of 1.6 % at a WGP content of 30 %. Integration of WGP resulted in a progressive decrease in interfacial frictional zone width, average pore diameter, and porosity, while the fraction of harmless pores increased, likely aiding the strength and dynamic elastic modulus.