Development of rubberized concrete with mineral admixtures for sustainable concrete

With the increasing demand for concrete, there are environmental concerns relating to the dwindling natural aggregates and high carbon footprint produced due to the cement industry. Current research, therefore, aims to determine if rubberized concretes can be made sustainable by ‘partial replacement of fine aggregates with waste’ rubber along with 20% GGBS and 10% metakaolin for partial replacement of Portland cement. The experimental program intended to study the fresh and hardened properties, namely, slump, density, ‘compressive strength,’ split tensile strength,’ flexural strength,’ microstructural and spectroscopic properties (SEM and FTIR). The results showed that slump decreases by 18.37% and density by 7.5% at 10% rubber replacement. While compressive strength improved by 8.8% with the addition of mineral admixtures and declined by 30.5% when 10% rubber was added. Likewise, split tensile and flexural strengths at 0% rubber showed improvements of 2.8% and 8.25%, respectively, while at 10% rubber showed reduction of 38.1% and 18.75%, respectively. In spite of these decrements in strength, microstructural analysis demonstrated that the GGBS and metakaolin enhanced the hydration process and densified the matrix, which mitigated strength losses. Thus, an optimum sustainability-structural balance was noted at 2.5% rubber replacement, thereby rendering rubberized concrete a promising eco-friendly alternative for construction uses.