Contribution of coal waste as a partial substitutional material for cement for increasing concrete compression strength

Concrete is the most widely used building material in construction. Starting from
buildings, roads, bridges, and other construction work that uses concrete as a basic
material in its construction. In general, concrete consists of a mixture of water, cement,
fine aggregate and coarse aggregate. The purpose of this study was to measure the
effect of coal waste as a substitute for cement on increasing the compressive strength
of concrete. In this study, the method used is laboratory-based research. The initial
stage of the research was in the form of material inspection including inspection or
testing of coarse and fine aggregate materials, after the inspection of the materials was
carried out and met the standard requirements, then proceed with making a job mix
design. In this study, researchers used fly ash as a partial substitution for cement. The
specimen will be tested by compressive strength test. The test object used is cylindrical
in shape. The use of fly ash is 0%, 5%, 10%, 15%, 20% and 25% of the amount of
cement. The test was carried out when the concrete was 28 days old for the
compressive strength test. The contribution of coal fly ash to compressive strength
made a positive contribution to the addition of coal fly ash up to 12.49%, there was an
increase in compressive strength, whereas an addition above 12.49% resulted in a
decrease in compressive strength. The optimal percentage obtained is 12.49%
resulting in a concrete compressive strength of 35.59 MPa.Concrete is the most widely used building material in construction. Starting from
buildings, roads, bridges, and other construction work that uses concrete as a basic
material in its construction. In general, concrete consists of a mixture of water, cement,
fine aggregate and coarse aggregate. The purpose of this study was to measure the
effect of coal waste as a substitute for cement on increasing the compressive strength
of concrete. In this study, the method used is laboratory-based research. The initial
stage of the research was in the form of material inspection including inspection or
testing of coarse and fine aggregate materials, after the inspection of the materials was
carried out and met the standard requirements, then proceed with making a job mix
design. In this study, researchers used fly ash as a partial substitution for cement. The
specimen will be tested by compressive strength test. The test object used is cylindrical
in shape. The use of fly ash is 0%, 5%, 10%, 15%, 20% and 25% of the amount of
cement. The test was carried out when the concrete was 28 days old for the
compressive strength test. The contribution of coal fly ash to compressive strength
made a positive contribution to the addition of coal fly ash up to 12.49%, there was an
increase in compressive strength, whereas an addition above 12.49% resulted in a
decrease in compressive strength. The optimal percentage obtained is 12.49%
resulting in a concrete compressive strength of 35.59 MPa.