Fly Ash and Hypo Sludge is obtained as waste by-products from the thermal and paper industries. The utilization of thermal industry waste fly ash (Class-F) and paper industry waste hypo sludge can reduce the consumption of natural resources, reduce the quantity of expensive cement and reduce environmental pollution. Investigations were carried out to gainful utilization of fly ash (Class-F) and hypo sludge in concrete mixtures. This research work describes the gainful utilization of the fly ash (Class-F) and hypo sludge in concrete production as partial replacement of cement by weight. The cement has been replaced by fly ash (Class-F) and hypo sludge accordingly in the range of 0% (without fly ash and hypo sludge), 5% + 5%, 10% + 10%, 15% + 15% and 20% + 20% by weight of cement for M-40 mix. Concrete mixtures were produced, tested and compared in terms of compressive strength and flexural strength to the conventional concrete. These tests were carried out to evaluate the mechanical properties for the test results for compressive strength and flexural strength up to 90 days are taken.