Fly Ash and Rice Husk Ash Utilization to Enlarge Clay Brick Dimension

Burnt clay bricks, mostly used as non-structural wall unit materials in Indonesia, contain only clay in Bengkulu Province. A large amount of clay is used during clay brick production as a shrinkage effect of burning, while clay is a limited natural resource. Available non-plastic materials that can withstand combustion contraction are required to reduce the use of clay. Ash materials like fly ash and rice husk ash are non-plastic materials. The purposes of this research are to reduce clay usage, enlarge dimensions, and improve brick performance at the same time by adding coal fly ash (FA) and rice husk ash (RHA). This research is an experimental study of FA clay brick (FCB) and a combination of 50% FA and 50% RHA clay brick (FRCB). The ash was added to the mixture at weights of 10%, 20%, and 30% of clay. The factory-specified production method was used to create bricks. After the materials and water meltdown process to produce plastic material, bricks were molded, dried, and burned. Green and burnt brick measurements and weights were gathered. The Brick Indonesian Standard Code (SNI 15-2094-2000) was used while determining the bricks' compression strength and absorption. The mean values of the quantitative data were used after being analyzed through coefficient of variation values less than 10%. The result shows that the compressive strengths and absorption of 10% and 20% of the ash content of FCB meet the Indonesian code. Both brick volumes expand as the ash content increases. FRCB volume weight is 11%, 7.8%, and 8.1% lighter than FCB for 10%, 20%, and 30% ash content, respectively. Both brick varieties meet the ASTM code for nonload-bearing concrete masonry units. The use of FA and a mixture of FA and RHA enhances shrinkage, increases brick dimensions, and simultaneously lowers brick weight. Using lighter and larger bricks for the walls helps to recycle waste, reduce the mass of the building, and reduce the use of clay resources. Application 10% and 20% fly ash is recommended for increasing the size of clay bricks in Bengkulu Province, Indonesia.