Experimental investigation of compressive strength for fly ash on high strength concrete C-55 grade

Abstract

High-strength concrete is used for resisting high compressive load and improved strength. The Cement content of the mix proportion for high-strength concrete is incredibly high compared with conventional concrete strength. Fly ash is the by-product of coal burning. Such material was used as a partial replacement of cement in high strength concrete, reducing carbon-dioxide gas emissions into the atmosphere and minimizing the negative impact on the environment released from industrial waste disposal as landfill. The objective of this study is to investigate the effect of fly ash on high-strength concrete properties. Experimental laboratory tests were conducted. Slump height is measured to determine the workability of fresh concrete. The Cube size is (150mmx150mmx150mm) which is used for testing compressive strength for the age of 7, 14, and 28 days of curing. Cement's percentage replacement with fly ash varies from 0% to 30% by the increment of 5%. The total numbers of samples conducted are one hundred twenty-six. The study results show that the replacement of cement by fly ash up to10% increases the slump values. However, the replacement of cement beyond 10% by fly ash decreases the workability of fresh concrete. Regarding density and compressive strength, the replacement of cement by fly ash decreased the density of concrete. The compressive strength of concrete becomes improved and increased when the cement is replaced by fly ash up to 10%. At the curing age of 28th days, the concrete containing 5% and 10% fly ash as cement gained 1.66% and 2.97% of strength, respectively. This study suggests that the partial replacement of cement by fly ash up to 10% increases the capacity of high strength concrete and fresh concrete's workability. The optimum percentage of fly ash to replace cement is 10% for high strength concrete.