Evaluation of Micro-Mechanism and High- and Low-Temperature Rheological Properties of Disintegrated High Volume Crumb Rubber Asphalt (DHVRA)

Abstract

The aims of this paper are to prepare disintegrated high volume crumb rubber asphalt (DHVRA) with low viscosity, good workability and low-temperature performance by adding disintegrating agent (DA) in the preparation process, and to further analyze the disintegrating mechanism and evaluated high-temperature and low-temperature rheological properties. To obtain DHVRA with excellent comprehensive performance, the optimum DA dosage was determined. Based on long-term disintegrating tests and the Fluorescence Microscopy (FM) method, the correlations between key indexes and crumb rubber (CR) particle diameter was analyzed, and the evaluation indicator and disintegrating stage division standard were put forward. Furthermore, Fourier transform infrared spectroscopy (FT-IR) and Gel Permeation Chromatography (GPC) was used to reveal the reaction mechanism, and the contact angle test method was adopted to evaluate the surface free energy (SFE). In addition, the high-temperature and low-temperature rheological properties were measured, and the optimum CR content was proposed. Results indicated that the optimum DA dosage was 7.5‰, and the addition of DA promoted the melt decomposition of CR, reduced the viscosity and improved the storage stability. The 135 °C rotational viscosity (RV) of DHVRA from mixing for 3 h could be reduced to 1.475 Pa·s, and the softening point difference was even less than 2 °C. The linear correlation between 135 °C RV and the diameter of CR particle in rubber asphalt system was as high as 0.968, and the viscosity decay rate (VDR) was used as the standard to divide the disintegrating process into a fast disintegrating stage, stable disintegrating stage and slight disintegrating stage. Compared to common rubber asphalt (CRA), DHVRA has an absorption peak at 960 cm−1 caused by trans olefin = C-H, and higher molecular weight and polar component of surface energy. Compared with CRA, although the high-temperature performance of DHVRA decreases slightly, the low-temperature relaxation ability can be greatly improved.

Special Issue: Characterization of Innovative Asphalt Materials for Use in Pavement Design and Analysis

“…Twenty universities and scientific centres contributed with their original research papers to this Special Issue of Materials . The issues covered can be divided into five main topics: Characterization of recycled materials in asphalt concrete mixtures, such as waste of sanitary ceramics [ 23 ], crumb rubber (CR) from waste tires [ 24 , 25 , 26 ] and reclaimed asphalt (RA) [ 27 , 28 ]; Investigation of natural [ 28 ] or bio-based [ 29 ] materials used as rejuvenators in recycled asphalt applications; Study of rheological and fatigue behaviour of bituminous materials with [ 30 ] and without [ 31 ] the use of renewable bio-materials; Evaluation of lubricant characteristics of graphite nanoplatelets [ 32 ]; Fatigue life prediction model for materials employed on long-span steel bridge decks [ 33 ]. …”

“…Characterization of recycled materials in asphalt concrete mixtures, such as waste of sanitary ceramics [ 23 ], crumb rubber (CR) from waste tires [ 24 , 25 , 26 ] and reclaimed asphalt (RA) [ 27 , 28 ];…”

“…The aim of the research presented by Li et al [ 26 ] concerned the possibility of preparing disintegrated high-volume crumb rubber asphalt (DHVRA) by adding a disintegrating agent in the asphalt rubber preparation process. This new procedure tried to solve the problems related to the traditional production method of the asphalt rubber (AR) by maximizing the recycling of waste CR and obtaining a homogeneous AR with low viscosity and good storage stability and improving its poor low-temperature performance.…”