Application of Scheffe’s model in optimization of compressive strength of lateritic concrete

Abstract

In this research work, the use of Scheffe’s simplex theory for the optimization of the compressive strength of lateritic concrete was investigated. The objective of the study is to develop a model that can predict the mix ratio when the desired compressive strength is known or vice-versa. A total of sixty (60) concrete cubes were cast. For each of the twenty mix ratios, three cubes were cast and the average determined. The first thirty cubes were used to determine the coefficients of the model while the other thirty cubes were used to validate the model (control test). The optimum compressive strength of concrete at 28 days curing was found to be 25.04N/mm2 and the corresponding mix ratio was 0.6:1:1.75:1.75 (water, cement, laterite, granite). VISUAL BASIC program was used to ease the use of the model and computer model accuracy was tested using Fisher F-test. The model was found to be adequate for prescribing concrete mix ratios, when the desired compressive strength is known and vice-versa. The highest compressive strength predicted by the model is 26.74N/mm2 when the mix ratio is 0.572:1:1:52:1.54 (water-cement ratio, cement, laterite, granite).