Factorial analysis and modeling of chemical admixtures’ influence on Portland cement paste rheology

Abstract

The influence of the amount of superplasticizer (SPA) and air-entraining (AEA) admixtures on the rheological properties of a Portland cement paste was investigated based on a statistical approach. The factorial design had the yield stress (YS) and flow as response variables, while the factors of 0.5 ml/kg-cem < SPA < 1.5 ml/kg-cem and 1.2 ml/kg-cem < AEA < 3.6 ml/kg-cem were evaluated, considering main effects, factor interactions, correlation analysis and modelling. The main effects analyses showed that the flow decreased as the AEA or the SPA increased, while the opposite was observed for the YS. The interactions analyses showed that the AEA promoted a reduction trend using the lowest SPA for the flow, but the highest SPA nullified the effect of AEA on flow, which maintained the highest value of 113.7%. Similarly, the AEA favored an increasing trend for the YS due to the interaction with the low SPA content, but a high SPA changed this trend, which decreased to the lowest value of 2652.6 Pa. The flow model (R2 = 84.9%) indicated that the linear effect of the SPA was the most significant, but the linear effect of the AEA and the SPA*AEA interaction were similar in terms of their significance (p-value < 0.001), while the YS model (R2 = 99.6%) showed that the AEA’s linear effect and the AEA*SPA interaction were similar and the most significant (p-value < 0.001). This research provides insights that could facilitate modeling, prediction, and optimization of efficient mixture designs while also gaining clarity considering potential inhibitory effects or synergies, which promotes the responsible consumption and production of construction materials.Graphical