Scheffe’s models for optimization of tensile and flexural strength of recycled ceramic tile aggregate concrete

Abstract

The large amount of wastes generated by the ceramic industry is presently not reused in any significant quantity. Incorporation of these wastes into concrete production is a win-win proposition for both the ceramic and concrete industries. However, there are presently no mathematical models for predicting the properties of these concretes. While there has been extensive research on the use of ceramic wastes as coarse aggregates, there are very limited research data on their use as fine aggregates. In the current study, augmented Scheffe’s simplex lattice theory was used to formulate mathematical models for predicting and optimizing the tensile and flexural strengths of concrete into which recycled ceramic tiles (RCT) are incorporated as a fine aggregate. Preliminary tests on RCT show that it is a suitable fine aggregate material and further testing shows the feasibility of using it in concrete production. It has also been established that addition of RCT improves the strength of concrete. The formulated models can predict the mix ratio for desired tensile and flexural strengths of RCT concrete and vice versa. Responses from these models are in agreement with corresponding experimental data. Adequacy of the models was confirmed using analysis of variance and normal probability plots of model residuals at a 95% confidence level. With the model equations, tensile and flexural strength of potential mix proportions of RCT concrete can be monitored and optimized. This is especially important for concrete used in pavement, airfield slabs and water retaining structures, among other applications.