The well-known palm oilproducers in Asean are Malaysia, Indonesia and Thailand. These three tropicalcountries lead the development of the agricultural crop and also act as theexporter in the world. Since Malaysia is one of the largest producers, it is moreconcern on the bio-technology industry with the target of producing betterquality for agriculture products. Palm oil is exported internationally infrequent as the main goods, therefore it will generate larger amount of palmoil fuel ash (POFA), which is the industrial by product or also known asagro-waste.
It is resulted from the oil palm plant residue combustion in thepalm oil factory. The contribution from the combustion of kernel shell and palmoil husks in high temperature of steam boiler will generate almost 5% of POFAto provide the electricity in palm oil mills for extract palm oil (Tangchirapatet al., 2007). Although there is variousused for palm oil, but due to oscillation production of palm oil, it createslarge amount of wastage as well. Therefore, alternative ways are needed such aslandfill or to reuse industrial wastes in construction.
There are successfulresearches in development of new building material or component by using wastesas raw materials, but it is a very complex and multidisciplinary task whichrequire taking consideration on technical, environmental, financial, marketing,legal and social aspects (John 2001). In addition, recycling the waste materialis also one of the methods to reduce the dumped waste as well to ensure theenvironment sustainability. Palm oil fuel ash (POFA) hashigh potential as the replacement for construction materials due to itspozzolans. It possesses a high contents of silica oxide, so it meets thepozzolanic property criteria which is able to react with calcium hydroxide(Ca(OH)2) from the hydration process. It is deteriorated to concrete and moreoverthe pozzolanic reaction generates more calcium silicate hydrate (C-S-H), in termof gel form compound that contributes to the strength of the concrete. It isalso subsequently providing stronger and denser concrete in order to enhancethe durability and compressive strength of the concrete. Therefore, POFA has highpotential as binder, cement replacement or as filler to produce durable andstrong concrete (Awal and Hussin, 1997).
The applications of pozzolanssubstance in concrete will give better result in 30% optimum mixing, which is10% more better than the normal concrete. ASTM C61 8-92a has classified POFA inClass C as chemical analysis.Currently, clay is widelyused to produce lightweight aggregate (LWA) and sludge can be used as a partialreplacement for clay in the manufacture of LWA.
Production of LWA fromdifferent types of sludge is considered to be a very satisfactory economic and environmentalalternative since a starting material with no value becomes a product isimportant for industrial application. The unwanted suspended impurity such assand, silt, clay and others humid particles are precipitated by aluminium saltin process of crude water neutralisation and present in form of sludge(Tantawyetal et al., 2015). The chemical content for the sludge is variationdepends on the water treatment sources, but it contains the content of silicateoxide which is considered optimum to be used as construction materials.
Therefore, this researchaims to study the properties of POFA and silt as the artificial aggregate. Thisstudy involves the p rimary study on the raw materials used and also thelaboratory test according to standard method. The optimum mix for theartificial aggregate is defined to perform the high strength in replacing thenatural aggregate in concrete.