The contents of silica oxide, so it meets

The well-known palm oil
producers in Asean are Malaysia, Indonesia and Thailand. These three tropical
countries lead the development of the agricultural crop and also act as the
exporter in the world. Since Malaysia is one of the largest producers, it is more
concern on the bio-technology industry with the target of producing better
quality for agriculture products. Palm oil is exported internationally in
frequent as the main goods, therefore it will generate larger amount of palm
oil fuel ash (POFA), which is the industrial by product or also known as
agro-waste. It is resulted from the oil palm plant residue combustion in the
palm oil factory. The contribution from the combustion of kernel shell and palm
oil husks in high temperature of steam boiler will generate almost 5% of POFA
to provide the electricity in palm oil mills for extract palm oil (Tangchirapat
et al., 2007).

Although there is various
used for palm oil, but due to oscillation production of palm oil, it creates
large amount of wastage as well. Therefore, alternative ways are needed such as
landfill or to reuse industrial wastes in construction. There are successful
researches in development of new building material or component by using wastes
as raw materials, but it is a very complex and multidisciplinary task which
require taking consideration on technical, environmental, financial, marketing,
legal and social aspects (John 2001). In addition, recycling the waste material
is also one of the methods to reduce the dumped waste as well to ensure the
environment sustainability.

Palm oil fuel ash (POFA) has
high potential as the replacement for construction materials due to its
pozzolans. It possesses a high contents of silica oxide, so it meets the
pozzolanic property criteria which is able to react with calcium hydroxide
(Ca(OH)2) from the hydration process.  It is deteriorated to concrete and moreover
the pozzolanic reaction generates more calcium silicate hydrate (C-S-H), in term
of gel form compound that contributes to the strength of the concrete. It is
also subsequently providing stronger and denser concrete in order to enhance
the durability and compressive strength of the concrete. Therefore, POFA has high
potential as binder, cement replacement or as filler to produce durable and
strong concrete (Awal and Hussin, 1997). The applications of pozzolans
substance in concrete will give better result in 30% optimum mixing, which is
10% more better than the normal concrete. ASTM C61 8-92a has classified POFA in
Class C as chemical analysis.

Currently, clay is widely
used to produce lightweight aggregate (LWA) and sludge can be used as a partial
replacement for clay in the manufacture of LWA. Production of LWA from
different types of sludge is considered to be a very satisfactory economic and environmental
alternative since a starting material with no value becomes a product is
important for industrial application. The unwanted suspended impurity such as
sand, silt, clay and others humid particles are precipitated by aluminium salt
in process of crude water neutralisation and present in form of sludge
(Tantawyetal et al., 2015). The chemical content for the sludge is variation
depends on the water treatment sources, but it contains the content of silicate
oxide which is considered optimum to be used as construction materials.

Therefore, this research
aims to study the properties of POFA and silt as the artificial aggregate. This
study involves the p rimary study on the raw materials used and also the
laboratory test according to standard method. The optimum mix for the
artificial aggregate is defined to perform the high strength in replacing the
natural aggregate in concrete.