Optimization of Strength Properties of Reactive Powder Concrete by Response Surface Methodology

Abstract

The main objective of this study is to optimize the fresh and strength properties of reactive powder concrete incorporated with industrial by-products like ultra-fine ground granulated blast furnace slag as cement substitute and added with coal bottom ash and recycled concrete fines as partial replacement of quartz sand by response surface methodology through design of experiment approach. Totally four responses namely slump, compressive strength (C-28), flexural strength (F-28), and split-tensile strength (S-28) after 28 days of curing period were considered. The statistical study on the reactive powder concrete includes the modeling of regression, normal probability plots, surface plot analysis, and optimization of process variables. The regression models of the considered responses (slump, C-28, F-28, and S-28) were tested. The results obtained from the analysis of variance (ANOVA) and Pareto chart were used to determine the statistical significance of the process variables. The influence of the variables on the responses was studied by means of the surface plot analysis. The optimal proportion of the variables against the responses was obtained through optimization response. The resulted regression equations were in the form of second-order polynomial equation and the prediction of strength properties was found to be in line with the experimental results. The difference of proportion of variance indicated that only 0.43%, 6.42%, 5.15%, and 9.7% of deviations cannot be expressed by the analysis. The ANOVA and Pareto charts represented the high significance and appropriateness of the linear term of slump response and the two-way interaction term of strength responses. The results of the optimization response revealed the optimal proportions of recycled concrete fines and coal bottom ash as 19.15% and 7.02%, respectively.

摘要

本研究的主要目的是通过响应面法设计实验方法优化活性粉末混凝土的新拌和强度性能。该活性粉末混凝土利用超细矿渣等工业副产物替代混凝土, 加入粉煤灰和再生混凝土粉末部分替代石英砂。28 天的养护期后共考虑了4 个响应, 即坍落度、抗压强度(C-28)、弯曲强度(F-28)和劈裂抗拉强度(S-28)。活性粉末混凝土的统计研究包括回归建模、正态概率图、曲面图分析和过程变量优化。对考虑的响应(坍落度, C-28, F-28 和S-28)进行回归模型检验。采用方差分析(ANOVA)和帕累托图来确定过程变量的统计显著性。通过曲面图分析研究各变量对响应的影响。通过优化响应得到变量相对于响应的最优比例。所得回归方程为二阶多项式方程, 强度性能的预测结果与实验结果基本一致。方差比例的差异表明, 只有0.43%、6.42%、5.15%和9.7%的偏差不能通过分析来表达。ANOVA 和帕累托图反映了滑塌响应线性项和强度响应双向交互项的高显著性和适合性。优化响应结果表明, 再生混凝土粉末和粉煤灰的最优配比分别为19.15%和7.02%。