Influence of Rice Husk Ash on Crystalline Phases and Mechanical Characteristics of Sustainable Bricks

Abstract

This study investigates the use of rice husk ash (RHA) as a sustainable additive in ceramic brick production. RHA from the Chaco region of Argentina was analyzed using DTA/TG and XRD, revealing a decrease in the amorphous phase and an increase in crystalline phases, mainly quartz and albite, with higher RHA content. The incorporation of RHA increased porosity from 25% to 40%, while theoretical density remained stable. Mechanical tests showed a decrease in elastic modulus (72.76 GPa for 5% RHA to 71.74 GPa for 15% RHA) and modulus of rupture (MOR) (8.5 MPa for 5% RHA to 5 MPa for 30% RHA). Several models were analyzed to predict the elastic modulus, and the DEM model provided the best predictions, with a relative error of 1.43% for 15% RHA. The analysis of mechanical properties of porosity was conducted using various theoretical models, which allowed for a better understanding of the relationship between the porous structure of the bricks and their mechanical behavior. Theoretical models, such as the DEM, proved effective in describing how porosity influences mechanical properties, particularly elastic modulus and modulus of rupture. Despite the reduction in mechanical properties, bricks with up to 15% RHA are suitable for non-structural applications, offering an eco-friendly alternative to conventional bricks. This research provides a circular economy approach by transforming agricultural waste into valuable construction materials.