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.
Highlights
When the size was more than 40 mesh, it was more favorable for desulfurization and degradation, and the performance of rubber asphalt (RA) at high temperature and low temperature was better
As the disintegrating agent (DA) dosage increased from 0.5% to 7.5‰, the conventional index of high volume crumb rubber asphalt (HVRA) changed significantly
In order to maximize the utilization of waste crumb rubber (CR), obtain the homogeneous RA with low viscosity and good storage stability and solve the poor low-temperature performance at the same time, the disintegrated high volume crumb rubber asphalt (DHVRA) is proposed
Summary
Waste tires have strong heat resistance, mechanical resistance and degradation resistance. If they are piled up for a long time, it will cause a waste of land resources but can cause fire, breed mosquitoes and spread diseases [1]. The way to use waste tires effectively has become an urgent problem. The United States, Europe and Japan and other developed countries mainly use waste tires to burn heat and produce crumb rubber (CR) [2]. The annual output of waste tires in China is about 12 million tons, and 70% of waste truck tires were used to produce recycled rubber and modified asphalt [3,4]. For common rubber asphalt (CRA), it is difficult to get the content of CR to exceed 25% [9,10]
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