Evaluation of Rheological Master Curve Models for Rice Husk Ash-Modified Asphalt: Goodness of Fit Approach

Master curve, a tool for predicting and characterizing asphalt’s rheology, utilizes master curve models. The accuracy of a master curve model varies when neat asphalt is modified, attributed to the changes in the rheology, which necessitate the selection of an appropriate master curve fitting model for modified asphalts. In this direction, an effort was carried out in this research work to analyse the reliability and accuracy of two popular rheological models, the Christensen Anderson (CA) model and the sigmoidal model for Rice Husk Ash Modified Asphalt (RMA), through statistical goodness of fit indicators. In order to arrive at this objective, rheological characterization of RMA was carried out by performing temperature and frequency sweep tests. Shift factors were determined using the Williams–Landel–Ferry equation, and master curves for the complex modulus of the binders were developed. Further, a detailed goodness-of-fit analysis was carried out on the CA and sigmoidal model fitting techniques. The research results showcased that both models exhibit lower accuracy at high temperatures compared to intermediate and low temperatures. When comparing the precision of the models, the sigmoidal model exhibits greater accuracy than the CA model. However, the rate of error accumulation with the increase in RHA dosage is higher in the sigmoidal model in comparison with the CA model. Overall, it can be concluded that RHA modification significantly influenced the performance of the CA and sigmoidal models.