Systemic Response Analysis of Final Setting Time of Concrete Based on Initial Setting Time and Cement Replacement with Bagasse Ash

Abstract

This paper presents a systemic response analysis of the final setting time of concrete based on initial setting time and cement replacement with bagasse ash. The response coefficient was evaluated to ascertain the viability and reliability of the final setting time dependence on the considered input process variables. A two-factorial empirical model was derived and validated for the analysis and evaluation. The validity of the model; ζ = 2.7832 ϑ + 0.9615ɤ + 34.965 was rooted on the core model expression 0.0286 ζ - 1.0001 = 0.0796 ϑ + 0.0275ɤ where both sides of the expression are correspondingly approximately equal. Regression model was used to generate results of final setting time of concrete, and its trend of distribution was compared with that from derived model as a means of verifying its validity relative to experimental results. The results of this verification translated into very close alignment of curves and significantly similar trend of data point’s distribution for experimental (ExD), derived model (MoD) and regression model-predicted (ReG) results. Evaluations from generated results indicated that the final setting time per unit input of bagasse ash and initial setting time as obtained from experiment, derived model & regression model were 2.0131, 1.9737 & 1.9252 hr/% and 5.548, 5.4393 & 5.3058 respectively. Standard errors incurred in predicting final setting time for each value of the bagasse ash input and initial setting time considered as obtained from experiment, derived model & regression model were 4.0687, 3.8533, & 2.0163 x 10-5% and 8.403, 3.960 & 7.9206% respectively. Deviational analysis indicates that the maximum deviation of model-predicted final setting time of the concrete from the experimental results is less than 12%. This translated into over 88% operational confidence and response level for the derived model as well as over 0.88 response coefficient of final setting time (of formed concrete) to the collective operational contributions of bagasse ash input and initial setting time.