Designing sustainable cement free compositions with rice husk ash to improve mechanical performance in next generation ecoblocks.

This study examines the use of low-value rice husk ash as a stabilizer to optimize the mechanical performance and strength of compressed earth blocks made with local soil from the Cauquenes Province, Chile. The use of locally sourced earth construction materials in Chile is limited by their lower compressive strength compared to conventional fired bricks, along with the demanding seismic conditions of the region. To address these limitations, this study details the methodology for collecting, preparing, and mixing raw materials to manufacture compressed earth blocks, compacted under 10 MPa using a novel cylindrical polylactic acid mold designed for miniaturized samples. Fourteen different samples representing nine mixtures of rice husk ash and soil were evaluated using an optimized experimental design. The resulting mechanical properties, including fracture analysis correlated with performance, were assessed through statistical analysis to determine the significance of the optimum mix and the observed trends in strength, modulus of elasticity, yield strength, and associated plastic work. The maximum compressive strength achieved was 3.3 MPa. Notably, the optimum mix of rice husk ash-stabilized compressed earth blocks exhibited a 60% increase in strength compared to pure soil compressed earth blocks, demonstrating the potential of rice husk ash as a cement substitute.