Model for Prediction and Optimization of Compressive Strengths of Cement Composites using Nanostructured Cassava Peel Ash as Partial Replacement of the Binder

Authors: Nwa-David, C.D. And Ibearugbulem, O.M.

DOI Info: http://doi.org/10.5281/zenodo.8094024

ABSTRACT

The predictive ability of statistical methods such as Scheffe’s and Osadebe’s models is apodictic as they are often adopted for optimization of concrete properties. But attention is drawn to their limitations. In this paper, Ibearugbulem’s optimization model was applied to predict the compressive strength of nanostructured cassava peel ash (NCPA)-cement composites. Three hundred and six concrete cubes were prepared in the laboratory with varying water-cement ratios and mix ratios with 1.5 % NCPA replacement interval. The 28 days’ compressive strength was varied with that of 56 days’ strength. The experimental results were modelled using Ibearugbulem’s approach. The optimum experimental and modelled outcome of the concrete strength was 24.20 N/mm² and 30.10 N/mm², 22.61 N/mm² and 28.54 N/mm² at 28 days and 56 days curing age respectively. These values were obtained at 16.5% and 19.5% NCPA replacement intervals at water-cement ratios of 0.72 and 0.75 for the model and experiment respectively with their mix ratios being 0.835:0.165:1.5:3 and 0.805:0.195:1.5:3. The percentage difference of 7.03 % and 5.47 % being less than 10 % at 28 days and 56 days for the optimum values reveals the adequacy of the model. Fisher’s statistical tool was used in the analysis and the calculated value of fisher of 1.11 and 1.08 were lower than the fisher value of 1.94 derived from the statistical f-distribution table. This implies that there was no significant difference between the laboratory-strength values and the modelled-strength values at 95 % confidence level. The formulated model is therefore reliable, safe and recommended for production of cement-composites.

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