Prediction of Mix Ratios for Grade 30 Superplasticized Concrete Using Osadebe’s Regression Model

S. Sule; Temple Nwofor; C. Onuekwusi

Abstract

This study developed a model for estimating the compressive strength of grade 30 super-plasticized concrete. The regression model was built using a total of 15 experimental mix ratios. The results of compressive strength at 28 days from the concrete cubes were used for model development. Two cubes (150 mm × 150 mm × 150 mm) were produced per mix ratio, totaling 30 cubes for the 15 trial mix ratios. Osadebe’s regression model was used to model this work. For model validation, a total of 15 mix ratios were used as control points. Two cubes were also made per mix ratio. The constructed regression model was assessed for adequacy using the F-statistics at a 95% level of confidence and was found to be adequate. After 28 days of curing in water, the maximum compressive strength of 41.93 N/mm2 was achieved; this is higher than the intended mean strength of 38.25 N/mm2 . The mix ratio was 0.31:0.85:0.15:1.353:2.987 (fluid/binder:cement:sawdust ash:sand:granite). The produced superplasticized grade 30 concrete can be utilized to build reinforced concrete bridges, dams, retaining walls and other structures. A computer program was developed using Visual Basic software to aid in the mix ratio prediction process and vice versa. Keywords: Compressive strength, concrete cubes, mix ratios, Osadebe’s regression model, super plasticized concrete