An Experimental Study Using Fly Ash and Steel Fiber to Partially Replace Cement for the Production of Green Concrete

The primary objective of the study is to reduce the use of cement and to find a substitute for cement in concrete in the form of fly ash (FA) without compromising the compressive strength of the concrete. Silica Fume (SF) is utilized in the study to enhance the strength of concrete, making it a greener concrete by utilizing waste materials. In this study, cement is partially replaced with FA at proportions of 20%, 25%, and 30%, and SF is added at 1%, 1.5%, and 2% for each mix. The investigation is carried out for M 25 and M 30 grade concrete, evaluating properties such as workability, compressive strength, flexural strength, and split tensile strength. For both M 25 and M 30 concrete grades, the compressive strength is maximum effective when cement is partially replaced with FA at 20%, 25%, and 30%, combined with 1% SF. However, for M 25 grade, the optimal compressive strength is achieved with 20% FA and 1.5% SF. The highest split tensile strength 2.75 N/mm² for M 25 and 3.60 N/mm² for M 30 is obtained with 20% FA and 1% SF. Maximum flexural strength is observed at 30% FA replacement with 2% SF. Furthermore, workability improves with 30% FA replacement in both grades.