Investigation on the compressive strength of concrete with seawater and powdered eggshells as partial replacement for cement

The continuous increase in the demand of concrete corresponds to the increase of the cost for the natural resource component while it being depleted rapidly. Furthermore, in efforts to generate a sustainable concrete, alternative mixing constituents are utilized in the study specifically the powdered eggshells and seawater as partial replacement for cement and freshwater, respectively. The experiment consists of two phases, first is the utilization of 50mm x 50mm mortar cubes to determine the effect on compresive strength of 5% powdered eggshells replacement to cement that was heated at varying temperatrures and duration. For processing of powdered eggshells, the variants of heating duraton are 0, 3, 6, and 12 hours of heating while the temperature variants are 100oC and 200oC. Based on the compresive strength test, it was determined that heating of eggshells at 100oC for 12 hours achieved the highest compressive strength from all mortar samples. For the second phase, the better heating method of powdered eggshells that was determined from the first phase was adapted and will be used as a component of cylindrical concrete. The three water cement ratios utilized for the concrete cylinders were 0.4, 0.5 and 0.6. All water cement ratios of conrete cylinders having 28 days curing have a uniform trend with increasing compressive strength as powdered eggshell and sea water were added in concrete. It was determined that the compressive strength further increased when both seawater and powdered eggshells are utilized in concrete