Karakteristik Mortar Dengan Menggunakan Bottom Ash Sebagai Subtitusi Agregat Halus

Steam Power Plants (PLTU) produce large amounts of waste coal every year in some
developing countries. Bottom ash is one of the ashes produced from the coal combustion
system which settles. Bottom ash contains B3 which can cause environmental pollution and
health hazards for living things. For this waste, this study uses bottom ash as a mixture in
the mortar because bottom ash also has a finer gradation value than aggregate, namely
1.6, while thirsty aggregate yields 2.4. Whereas for SEM-EDX analysis, bottom ash
analysis contains Carbon (C) 7.52%, Oxygen (O) 52.87%, Sodium (Na) 2.36%,
Magnesium (Mg) 0.68%, Aluminum (Al) 11.43%, Silicon (Si) 20.70%, Potassium (K)
1.76%, Iron (Fe) 2.68%. This content can react with air which is called the hydration
process. This process makes the micro and nano crystals fill and compact the empty mortar
cavities. This makes the binding between the aggregates stronger and can increase the
compressive strength of the mortar. So that in this study it is expected that bottom ash can
be used as an ideal material in a mortar mixture. This study uses bottom ash as an
ingredient for removing fine aggregate in a mortar mixture of 30%, 40%, and 50%
variations with added silica fume 5% by weight of cement and 0.5% superplasticizier by
weight of air. The mortar compressive strength test was carried out at the ages of mortar
3, 7, 14, and 28 days as many as 72 specimens with water curing and seal curing. The
compressive strength of mortar based on age always increases based on this age in
accordance with normal mortar and bottom ash mortar that is substituted for fine
aggregate with water curing and seal curing methods. Based on the test results, the
optimum compressive strength value is obtained from 29.85 MPa obtained from mortar
with 30% water curing method of bottom ash variation.