THE EFFECT OF FLY ASH AS A CEMENT SUBSTITUTION MATERIAL ON THE ELASTIC MODULUS OF CONCRETE

Fly Ash and Bottom Ash are the residue from the coal combustion process originating from the combustion furnace. Fly ash waste will increase every year along with the operation of industries that use coal fuel. Fly ash waste can cause environmental pollution that is quite harmful to human life. On the other hand, the fly ash-forming elements have similarities with the cement-forming elements as a binder in the manufacture of concrete. In this study, fly ash was used as a partial cement substitute for cement as a binder in the manufacture of high-strength concrete. The research objective was to determine the compressive stresses and strains of high-strength concrete with fly ash substitution variations of 10%, 15%, 20%, 25%, and 30%. The results of the compressive strength test of concrete with variations in the percentage of fly ash successively from 0%, 10%, 15%, 20%, 25%, 30% showed that the increase in compressive strength was achieved at a percentage of 20% fly ash, namely 53.376 MPa. The results of the analysis show that the relationship between the elastic modulus of concrete and fly ash is directly proportional to the quality value of the concrete.