MODEL FOR THE PREDICTION OF FLEXURAL STRENGHTS OF SAND STONE-PERIWINKLE SHELL CONCRETE

Abstract

This research work presents the prediction of 28 day flexural strength of lightweight concrete made from equal volume of periwinkle shells and sand stone. Regression equation for a four component mixture developed by Ibearugbulem was utilized. The materials used in the laboratory experiment include; water, Ordinary Portland Cement, river sand, sand stone, and periwinkle shells. Sand stone and periwinkle shells were blended to form a single component thereby reducing the number of material components from five to four. Thirty mix ratios obtained arbitrarily from Scheffe’s simplex latex structure for a four component mixture were utilized. Batching of constituent materials was by weight except for the coarse aggregates (periwinkle shell and sand stone) which were batched by volume. Manual mixing operation was adopted in the laboratory. A total of ninety prototype concrete beams were produced from the given mix ratios. Whereas the first fifteen mix ratios termed the actual mix ratios was used for the formulation of the regression model, the last fifteen mix ratios regarded as the control mix ratios was used for the validation of the formulated model using statistical analysis. Fisher’s statistical tool was utilized. From the analysis, the calculated value of fisher of 2.13 was less than the fisher value of 2.48 obtained from the statistical f-distribution table. This result proved that there was no much difference between the laboratory flexural strength values and the model flexural strength values at 5% significance level. Therefore, this model is adequate for the accurate forecast of the 28 day flexural strength of lightweight periwinkle shell-sand stone concrete when given mix ratios. It is therefore recommended for use in concrete/ construction industry.