ESTIMATION MODEL OF COMPRESSIVE STRENGTH OF CONCRETE CONTAINING EGGSHELL AND TIRE CRUMB

Recycling eggshell waste in concrete materials gives many benefits to minimising the cement demand, conserving natural limestone and recycling waste aggregate. This study is to identify the compressive strength and slump height of the concrete consisting of eggshell and tire crumb by using regression analysis in Excel and Response Surface Methodology (RSM) through Minitab. The method used in strength assessment of concrete is by combining more than one Non-destructive Test (NDT) test, which is Ultra Pulse Velocity (UPV) and rebound hammer (RH). The combination of UPV and RH test results were established with the percentage of eggshell, and tire crumb as partial replacement of cement and sand was used to estimate the compressive strength at 7 days and 28 days. Results had revealed that RSM has the lowest value of root-mean-square error (RMSE), which is 0.6854 for 7 days compressive strength, 1.6613 for 28 days compressive strength and 3.6433 for slump height. The ideal content of eggshell powder and tire crumb that created the maximum compressive strength of concrete is 10% and 0%, respectively, with 6.5 km/s of UPV and 42.1 number of RH, according to this study. The additional percentage of eggshell powder replacement up to 15% has reduced concrete compressive strength. A selected estimation model for compressive strength and slump height can create analysis reduction in the number of experiments, thus reducing the optimisation cost, besides reducing the environmental impact due to uncontrollable waste in landfills.