Predicting the permanent deformation behaviour of the plant produced asphalt concrete mixtures: A first order regression approach

Recent studies have shown that Flow number (FN) alone may not be able to describe the permanent deformation (PD) behaviour of a mix, rather additional parameters are considered, e.g., dynamic modulus (|E∗|), gradation, and mix volumetric, to get better insights into PD behaviour. However, stiffness in terms of Resilient Modulus (MR) has not been considered even after its appealing efficacy in 1993 AASHTO design guide. As such, the objective of this study is to characterise the mixtures that do not attain tertiary flow state by a new parameter, Flow Number Prime (FNP). Furthermore, the developed parameter is used to study the relationship of PD behaviour with MR. Seven plant produced mixtures were compacted using Superpave gyratory compactor. FN test was carried out at a single temperature while MR test was conducted at two temperatures. The MR results show a good consistency with the FN test results. A first-order multiple linear regression model for predicting the PD behaviour is developed as a function of the MR, the mix volumetric, and the gradation parameters. The developed model is validated, and sensitivity analysis is performed to determine the change in the PD with respect to explanatory variables. The developed model is also compared to an existing model in the literature and results indicate a better performance of the model developed in this study. The findings of this study are expected to provide valuable insights to the characterisation of plant produced mixtures and its relationship with PD behaviour, and can also help in QA/QC of the pavements during construction phases of projects whereby engineers and/or practitioners can ensure the quality based on a lesser time consuming test (MR) on different sections of the same project.