Effect of waste rice husk ash (RHA) on structural, thermal and acoustic properties of fired clay bricks

A potential use of rice husk ash (RHA), a residual of brick firing process on the manufacturing of fired clay bricks was identified. Although addition of waste RHA may influence the structural properties of building materials, it is not clear how this affects on thermal and acoustic performances. For these reasons, industrial scale productions of fired-clay bricks were used for experimental investigation on structural, thermal and acoustic properties of the fired clay bricks manufactured with the waste RHA. Clay was mixed manually with six different RHA contents: 0%, 2%, 4%, 6%, 8% and 10%, by weight of the brick. Bricks having the dimensions of 195 mm x 95 mm x 50 mm were prepared and fired in an industrial scale kiln. Physical properties (Atterberg's limits, particle size distribution), chemical composition of materials, structural properties (compressive strength), thermal performance and acoustic performance of the bricks were evaluated. Clay mixed with waste RHA improved the mixture for brick manufacturing. Lightweight bricks produced with waste RHA show the optimum compressive strength of 3.55 N/mm(2), (32.7% improvement compared to the conventional fired clay brick) and water absorption of 19% at 4% RHA, implying that the RHA has a potential to improve the structural properties. At 4% RHA, the brick shows 6 degrees C in-door temperature reduction and 10 dB noise reduction compared with that of the conventional fired clay brick. Waste RHA added clay brick showed better structural, thermal and acoustic properties compared with the conventional clay bricks, while managing waste RHA by decentralization, which will be a remarkable environmental and ecological achievement.