Performance Evaluation of Sustainable Lightweight Concrete Incorporating Recycled Brick Aggregates

Abstract

This study investigates the performance of lightweight concrete incorporating crushed waste bricks as a partial replacement for natural coarse aggregates, focusing on optimizing the mixing proportions and evaluating the influence of silica fume content and superplasticizer dosage. The experimental results demonstrated that replacing 25% of the natural aggregates with crushed bricks improved the 28-day compressive strength, with higher cement contents mitigating the adverse effects of increased brick incorporation. The optimal silica fume content for enhancing compressive strength was identified as 15%; beyond this, the strength decreased due to reduced workability and microstructural inefficiencies. The dosage of superplasticizer significantly affected the compressive strength, with an optimum range observed at 2.0%, whereas excessive dosages resulted in strength reduction. The study also revealed that the early age compressive strength is more sensitive to brick incorporation, particularly at lower cement contents. However, mixtures with higher cement contents exhibited superior early-age strength retention. The splitting tensile strength consistently improved with increasing normal aggregate content, highlighting the role of aggregate stiffness and bond quality in controlling the tensile behavior. These findings contribute to the development of sustainable, high-performance lightweight concrete utilizing recycled materials, with potential applications in structural and non-structural elements where reduced self-weight and enhanced mechanical properties are desired.