Response prediction for strength and Durability properties of laterite-cement bricks using the Scheffe Mixture Approach

Abstract

Ail attempt is made in this paper to present a procedure for selecting constituent proportions for lateritc-cement bricks capable o f meeting user-defined requirements of strength, cost and durability. The response prediction was developed using the Scheffe \s mixture theory. In using this mixture experimental design approach, a three component mixture using water, cement and laterite to produce lateritc-cement bricks was carried out with cement content ranging between 8-20 percent by weight o f laterite. The physical and geotcchnical properties o f the laterite sample were determined. The Hydraform Twin-M7 machine was used for the compaction and curing was carried out in a laboratory environment. The compressive strength at the ages o f 7 and 28 days were measured using Testometric FS300CT Universal Testing Machine and responses were modeled as a second order quadratic polynomial. The guidelines for development o f constraint formulation were carried out for optimization process. An inverse relationship for strength was obtained and compressive strength achievable ranges between 8.40 - 18.32N/mm\ Durability test using ASTM D 559 otherwise called wire brush method was carried out yielding a percentage particlc eroded less than 10% which was satisfied within the domain of constituents proportions selected. This procedure is intended to replace the traditional trial method o f mixture proportioning which is incapable of developing specifications writing procedure to meet user-defined requirements.