Effect of kenaf core as fine aggregate replacement material to brick properties for non-load bearing wall application

Transformation of agricultural and industrial waste into a functional construction material is a crucial step in reducing environmental implication and supporting a circular economy. In Malaysia, the kenaf core, a low value by product of kenaf cultivation, and quarry dust, the residue of quarrying are normally discarded despite their potential value as construction materials especially as fine aggregate replacement. This disposal practice is particularly problematic given that conventional sand cement bricks are extremely dependent on natural aggregates, which causes resource depletion and greenhouse gases that can be avoided through reutilization of these easily accessible waste products. But very few research works have fully utilized the combined use of quarry dust and kenaf core in mechanical and fire properties for non-load bearing wall systems. The aim of this study was to develop, investigate, and evaluate the feasibility of substituting Kenaf Core Fine Aggregate (KECOFA) in the production of brick as a fine aggregate. Objectives included establishing the best mix design, developing a database for KECOFA properties of the bricks, comparing wallette performance and failure mode, and fire resistance and hose stream performance testing. The experimental plan involved sequential optimisation where at first to set the amount of quarry dust replacement, then incremental KECOFA replacement as variable in Design Expert software with Response Surface Methodology (RSM) to identifying the optimum brick mix design. The optimum mix design obtained was then used in further to investigate the performance in comparison with four control bricks which are 100% river sand (Ml), 100% quarry dust (M5), 100% KECOFA (M6), and 50% river sand-50% quarry dust (M4). Laboratory testing included physical, mechanical, thermal, and fire performance characteristics. The optimal mix, 10% KECOFA and 50% quarry dust with cement sand ratio of 1:8 recorded a compressive strength of 8.16 N/mm2 and density of 1830 kg/m3, comparable to regular bricks and superior to 100% KECOFA bricks. Water absorption (21%) and porosity (30%) were within acceptable levels. In terms of thermal performance, the inclusion of kenaf core reduced thermal conductivity by introducing porous structures that enhanced insulation. The optimum mix (M10) balanced thermal insulation with adequate strength and durability, making it suitable for non-load bearing walls. Wallettes were able to withstand up to 100 kN axial loads with failure behaviour similar to conventional units. Fire testing also confirmed compliance with standards, with the optimum mix brick wall also providing 7 minutes of insulation time compared to other brick walls. This research is the first to optimize and evaluate a KECOFA quarry dust composite brick for mechanical and fire performance in non-load bearing applications. Beyond that of achieving technical specifications, the research deepens the understanding in cellulosic based aggregates' bonding behaviour, forms a new industry-ready database of properties of KECOFA brick, and is in line with Malaysia's green construction policies. The findings offer the brickmaking sector a bio-composite, lightweight alternative to conventional products where reducing the consumption of natural aggregates, stimulating demand for the kenaf core, and recycling agricultural and quarry wastes to create valuable, sustainable building products.