Impact Assessment of Fly Ash as Partial Replacement of Cement along with Riverbed Material as Coarse Aggregate

Using supplementary cementations materials as the OPC replacement instead of environmental sustainability is a global trend. Fly Ash is considered an economical and ideal candidate and has been utilized in various projects worldwide since the 1950s. There are ample resources to produce fly ash in Pakistan. The processing expenditure makes it a handy material to economize the concrete mix designs by replacing the OPC in substantial amounts. This study addresses the effect of OPC replacement by fly ash on the compressive strength of three classes of concrete, class–A1, class–A and class–B, using the coarse aggregate from the Jhelum Riverbed–Mangla quarry. The compressive strengths of the three concrete classes were 5000 PSI for class–A1, 4000 PSI for class–A and 3000 PSI for class–B concrete; by utilizing ACI 318 guidelines, the target strengths were enhanced 6200 PSI, 5200 PSI and 4200 PSI respectively. A total of 25 trials were conducted by the 20% to 25% replacement of OPC by the Fly Ash Class-F in all the concrete classes by varying maximum sizes of the coarse aggregates. Results reflect that most of the Concrete Mix designs achieved the required strengths, indicating that the fly ash didn’t hinder the durability of the concrete. There is a potential for achieving higher compressive strengths if a descent in w/cm ratios and ascent in the maximum coarse aggregate size is incorporated. Thus, fly ash is a commendable supplementary cementitious material rendering enhanced paste structure of the concrete and imparting an increase in durability. The reduction in the cost of the CMD makes it an ideal resource to be considered in all the construction projects encompassing bulk concrete quantities across Pakistan.