Statistical Design of Portland cement Modified with Water Treatment Plant Sludge

Abstract

One-Way Analysis of Variance (ANOVA) was applied in this investigation to study the feasibility of modifying ordinary portland cement through Water treatment plant sludge (WTSP) addition. Cement pastes were obtained from mixtures of water treatment plant sludge (WTPS), calcined sludge and ordinary portland cement (OPC) using the standard water consistency. The variation in bulk density, apparent porosity, chemically combined water and compressive strength of the prepared samples were determined over time. In most cases the addition of sludge results in a decrease in apparent porosity (26.36 - 20.40) %, but an increase in chemically combined water (22.46- 29.35), bulk density (1.78 - 1.845) g/cm3 and compressive strength (21- 85) MPa with time. The results show a recognized improvement in densification parameters when using calcined sludge which recommend their use in cement manufacturing so one could expect better economical and environmental benefits. The data obtained were analyzed using a one-way (Analysis of Variance) ANOVA. The determinations were performed in triplicate (n= 3), mean ± standard deviation (SD) values were calculated. A comparison between the means of three different groups and four curing time was performed at 5% level of significance. The ANOVA results show that there are statistically significant difference in chemically combined water property between different combination groups whereas insignificant between the different curing times, for bulk density it shows significant difference between groups in curing times and insignificant difference in combination of groups and mechanical strength shows significant difference between group of curing times and insignificant difference in groups of combination finally for apparent porosity property we didn’t find any significant difference between groups for combination of groups and curing times for the hardened pastes.