REBLOCK: Development and Performance Evaluation of Volcanic Sand as a Cement Substitute in Hollow Block Construction for Sustainable and Disaster-Resilient Infrastructure in the Philippines

This study investigates the feasibility of using coarse volcanic sand as a partial or full substitute for Portland cement in the production of concrete hollow blocks. Motivated by recurring volcanic activity and the abundance of volcanic deposits in the Philippines, the research aims to transform a hazardous natural byproduct into a sustainable construction material. Hollow blocks were fabricated using varying cement–volcanic sand replacement ratios and cured for seven days before undergoing compressive strength testing. The results evaluate how volcanic sand affects the mechanical performance of the blocks and assess its potential role in low-cost, disaster-resilient infrastructure. Overall, the study contributes to sustainable materials research by examining an accessible local resource for reducing cement use and supporting environmentally responsible construction practices.