Enhancing the properties and environmental performance of fired clay bricks through lignocellulosic additives an investigation of oil palm mesocarp fibre (OPMF) as a sustainable alternative

This article investigates the role of lignocellulosic additives, specifically Oil Palm Mesocarp Fibre (OPMF), in modulating the properties and environmental performance of fired clay bricks. OPMF, a readily available material containing high levels of lignocellulose, possesses desirable properties for use in brick making. Clay soil was substituted with OPMF at varying levels (0%, 1%, 5%, and 10%), and bricks were fired at 1050 °C with a controlled heating rate of 1 °C/min. A systematic experiment was employed, combining physical-mechanical properties (density, shrinkage, water absorption, porosity, compressive strength, and thermal conductivity), microstructural analysis (XRD, SEM-EDX, TGA-DTA), and and leaching analysis (TCLP and SPLP tests) were evaluated. The results revealed that incorporating 10% OPMF significantly reduced the mechanical properties, with compressive strength decreasing from 24.6 MPa to 4.1 MPa. This decrease was attributed to increased firing shrinkage (0.7 to 2.5%) and porosity (13 to 25%). However, OPMF addition resulted in a lighter brick (density decreased from 1799 to 1563 kg/m³) and enhanced thermal conductivity (improved from 0.54 to 0.34 W/m.K), primarily due to the increased porosity. Leaching tests confirmed that heavy metals (Pb, Cr, and Zn) were successfully immobilized, meeting USEPA and WHO guidelines. This indicates that heavy metals were effectively immobilised and encapsulated within the clay matrix, forming a stable mineral phase. These findings suggest that incorporating up to 5% OPMF offers a sustainable approach to brickmaking, promoting circular economy while reducing environmental impact.