Development of Scheffe's Model to Predict the Compressive Strength of Concrete using SDA as Partial Replacement for Fine Aggregate

Abstract

Saw Dust Ash (SDA) despite being an industrial waste, has played a vital role in concrete mix research. It has served as an alternative or complementary material to some of the traditional materials of concrete. In this study, it served as a fifth ingredient of concrete blend as it replaced 5% of the fine aggregate (sand). The other four ingredients were cement, sand, granite, and water. Scheffe’s simplex theory was used for five mix ratios in a {5,2} experimental design which resulted in additional ten mix ratios. For purposes of verification and testing, additional fifteen mix ratios were generated. The thirty concrete mix ratios were subjected to laboratory experiments to determine the 28 days compressive strengths. The results of the first fifteen compressive strengths were used for the calibration of the model constant coefficients, while those from the second fifteen were used for the model verification using Scheffe’s simplex lattice design. A mathematical regression model was derived from the experimental results, with which the compressive strengths were predicted. The derived model was subjected to a two-tailed t-test with 5% significance, which ascertained the model to be adequate with an R2 value of 0.8336. The study revealed that SDA can replace 5% of fine aggregate and promote sustainability, without compromising the 28 days compressive strength.