| Abstract |
Coal-fired thermal power plant produces million tonnes of coal ash as an
industrial by-product and is significant to be used as raw material for
fabrication of bricks. Coal ash could potentially substitute the traditional
materials i.e. clay and sand that were used to produce fired clay and cement
sand bricks. Clay and sand were continuously extracted from depleting and
dwindling non-renewable natural resources that could gradually degrade the
environment in the long run. Meanwhile, lime and Portland cement are
popular binding materials that could eventually damage and pollute the
environment if continually used without control. Alternatively, ground
granulated blastfurnace slag (GGBS), an industrial by-product could be used
as substitution. However, GGBS requires activation in an alkaline
environment for self-cementitious acceleration. For now, the reliable source of
alkali is lime or Portland cement. Most researchers have used either fly ash or
bottom ash as raw material and either lime or Portland cement as binder.
There is also less evidence in effort to lightweight the bricks that were using
industrial by-products as raw materials. Therefore, the combination of fly ash
and bottom ash as raw material with hydrated lime-activated GGBS (HL-
GGBS) as binder and the incorporation of foam need to be investigated. In the
present study, coal ash was used as raw material, HL-GGBS system was
used as binder and foam was used to reduce weight for the fabrication of coal
ash foamed bricks. Portland cement-activated GGBS (PC-GGBS) system was
established for comparison to HL-GGBS system. The amount of water was
constant at 30% of total weight of dry materials. Pre-foam foaming method
was applied. The ratio of foaming agent to water was 1:30. Steel moulds size
of 215 mm x 102.5 mm x 65 mm were used and the bricks were dried for 48
hours before demould and wrapped with cling film for several layers prior to
air curing. |