Response Surface Methodology and Statistical Investigation of the Strength of Bituminous Sandcrete Blocks

Abstract

Spalling is a serviceability related defect in buildings that degrades their appearance and if unchecked, could be a threat to building sustainability and lead to structural failures. It is associated with the effect of moisture on the building especially the blockwall. This research focuses on the production of low water-absorption Sandcrete blocks. The water absorption and compressive strength of blocks using bitumen as a coat and as part of the sandcrete mix are investigated. In assessing the outcome, eight (8) different sets of Sandcrete blocks with varying bitumen contents were defined and nine (9) samples of standard six (6) inches blocks were produced for each set, with three (3) samples per set being tested at 7,14 and 28 days for water absorption and compressive strength respectively. The water sprinkling curing method was used at 24 hours intervals. The results acquired showed that the sets that contained bitumen showed reduced water absorption rates up to 4.06% at 28 days relative to the control samples. The analysis of the experimental result was done using response surface methodology, the percentage of bitumen replacement with sand and curing days was used as the independent variable. Multiple regression equation was obtained to predict investigated properties. Further analysis of the data shows that Sandcrete blocks coated externally with bitumen give the optimum performance in terms of compressive strength and water absorption.