Evaluating the Compressive Strength of Artificial Aggregate Blended with Fly Ash and Rice Husk Ash

Abstract

In response to the severe environmental consequences of traditional aggregate mining, such as land subsidence, land damage, and contributions to climate change, this research explores a sustainable solution. The study focused on developing and testing artificial aggregates made from industrial by-products, aiming to reduce the construction industry’s reliance on destructive mining. The primary material was fly ash, with varying amounts of rice husk ash used as a substitute to evaluate the effects on both specific gravity and strength. The manufacturing process centered on a geopolymer reaction, using an alkali activator solution of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) to bind the silica and alumina present in the ashes. A specific silica-to-alumina (SiO2/Al2O3) ratio of 2.6–3.6 was maintained. After forming the mixture into pellets, the aggregates were subjected to two distinct curing regimens for hardening: a rapid, hightemperature treatment at 600 °C for four hours, and a long-term cure over 28 days at ambient temperature. The results of strength testing conclusively validated the approach. The primary finding was that incorporating rice husk ash significantly enhanced the aggregate’s durability. An optimal mixture was identified where a 5% substitution of fly ash with rice husk ash yielded the strongest final product. This successful outcome confirms the viability of using these industrial wastes as high-quality construction materials, presenting a promising pathway toward a more sustainable building industry.