Evaluation on High Temperature Rheological Properties of Nano-Montmorillonite Modified Asphalt Binder

Abstract

Abstract The requirements for modified asphalt are increasing due to heavier load conditions and worse serving environments in modern highway construction. One of the methods for improving the properties of asphalt binder is to combine it with nano-montmorillonite (nano-MMT) because of the special nanolayer structure. This paper presents a study to evaluate physical and rheological properties of nano-MMT modified asphalt binders. The nano-MMT modified asphalt binder was prepared by melt blending different nano-MMT amounts. The physical properties of asphalt binder, including penetration, softening point, ductility, and viscosity, were tested. The dynamic shear rheometer (DSR) was carried out to evaluate high temperature rheological characteristics. Additionally, the high temperature storage stability was also discussed. Moreover, the effects of nano-MMT content on the abovementioned properties of nano-MMT–modified asphalt binder were investigated. Experimental results indicate that the penetration and ductility were decreased and the viscosity of the asphalt binder was increased by the addition of nano-MMT; however, the values enhancement represented more significantly when the content was up to 5 %. The modified asphalts especially exhibited higher complex moduli (G*), lower phase angles (δ), and higher rutting factors (G*/sin δ). These indicate that the addition of nano-MMT into the asphalt matrix can greatly improve the dynamic rheological and viscoelastic properties, which results in enhanced resistance to rutting at high temperatures. The storage stability tests disclosed that the asphalts modified with nano-MMT were very stable when nano-MMT content was less than 5 wt. %.