Influence of admixtures on properties of concrete and optimization using response surface methodology

The study presented here shows the influence of River Sand, M-sand and Admixtures on the properties of concrete which were analyzed. The effect of admixture content on concrete properties was evaluated with two types of admixtures independently. Metakaolin (MK) content was varied at 0%, 5%, 10% and 15% whereas Waste Paper Sludge Ash (WPSA) content was varied from 0%, 6%, 12% and 18%. Response surface methodology was employed to optimize the compressive strength, permeability and sorptivity of concrete when both admixtures (MK+WPSA) were varied simultaneously. The relationship between the concrete properties and level of materials added was derived using a Face Centered Central Composite Design with three levels and three factors. Based on desirable properties obtained in experimental part of the study, the factors considered in the design was M-Sand (0%, 50%, 100%), MK (0%, 5%, 10%), WPSA (0%, 6%, 12%). From the experimentally obtained data, prediction models based on regression analysis were developed which enables the establishment of response contours showing the interaction between the different parameters investigated. The contour plots were overlaid to distinguish the combination of proportions that gives ideal performance of concrete for water-repellency and strength