Development of an effective rainwater harvesting system using sponge concrete

ABSTRACT Conventional concrete systems for rainwater harvesting often face challenges with water absorption and clogging. This study proposes an innovative approach: sponge concrete. By integrating absorbent sponge pieces, this method enhances rainwater absorption, overcomes limitations of conventional concrete, and improves water management during rainfall. Five different types of sponges were evaluated for their water absorption capabilities and the quality of water passing through them, assessed based on parameters such as pH, dissolved oxygen (DO), total dissolved solids (TDS), and electrical conductivity. Concrete was cast using these sponges to investigate properties such as density, void ratio, and compressive strength with various mix proportions. Among the sponges tested, the one with the lowest density showed the best water absorption results. The quality of water passing through all sponges remained within safety standards. A lower water-to-cement (w/c) ratio proved effective for achieving higher void ratio and lower density which is required for thereby achieving higher water absorption capacity. Although a higher void ratio resulted in relatively lower compressive strength, incorporating supplementary cementitious materials mitigated this issue to some extent. Hence, this study suggests that sponge concrete provides a promising solution for enhancing rainwater harvesting efficiency, offering an environmentally sustainable alternative to conventional concrete systems.