Effects Of Additives and The Volumetric Variation on Thermal Properties and Heat Transfer Characteristics of Clay Bricks

<p dir="ltr">This study investigates the production of porous, lightweight clay bricks with improved thermal insulation and mechanical properties, targeting applications in energy-efficient construction. Utilising oat husk, an organic waste product, as an additive, this research aims to overcome the longstanding challenges associated with incorporating additives in energy-brick production. By employing an innovative pre-treatment process, both the mechanical strength and thermal conductivity of the fired clay bricks were enhanced, crucial for building applications.</p><p dir="ltr">In this study, raw materials, including oat husk in normal and ash-converted forms, were selected, pre-treated, and blended with clay at varying additive concentrations up to 30% by volume. The semi-dry mixtures were then mechanically compressed, dried, and fired over 12 hours, reaching a peak temperature of approximately 800°C. Both experimental and modelling approaches were employed to evaluate the thermophysical properties of the resulting samples, specifically thermal conductivity and compressive strength.</p><p dir="ltr">The results indicated that the addition of oat husk created porous, lightweight bricks with strong insulating qualities. Notably, the 30% additive sample achieved a thermal conductivity of approximately 0.41 W/mK, showing a reduction of over 31% compared to the control sample (0.60 W/mK), though with a decrease in compressive strength. An optimal balance was observed in samples with a 5% oat husk additive, which exhibited a compressive strength of 6.05 MPa, exceeding the control sample's 5.24 MPa by more than 15%, and retained a favourable thermal conductivity of approximately 0.566 W/mK.</p><p dir="ltr">These findings suggest that oat husk pre-treated with hydrochloric acid (HCl) can be effectively utilised to produce energy-efficient fired clay bricks with enhanced mechanical and thermal properties. This research contributes a viable solution for sustainable construction, addressing the challenge of organic additive incorporation in energy-brick production for building technology.</p>