Effects of coal fly ash as partial replacement for cement towards concrete properties

Abstract The use of industrial waste, particularly fly ash (FA), as a substitute for ordinary portland cement (OPC) has gained attention due to global trends promoting the recovery and utilization of waste materials in construction. Previous research has demonstrated that fly ash has the potential to replace cement without compromising the strength of concrete, driving further exploration and validation of this concept. In a study investigating the effects of fly ash replacement in concrete, different percentages of fly ash were used to replace OPC in C25 grade concrete. Various tests were conducted, including X-ray fluorescent (XRF) analysis, sieve analysis, workability test, compression test, and water absorption test, to assess the characteristics, properties of the materials, fresh and hardened concrete. The results indicated that the replacement of FA in cement showed significant effects, with the strength at 12.5 % and 15 % replacements reaching the target strength of pure concrete at both 7 days and 28 days. These findings suggest that fly ash, at these replacement levels, exhibits desirable strength comparable to OPC, making it a viable alternative.