Performance Of SBS Modified Asphalt Research Articles

Experimental study on the effect of Coumarone resin on the performance of SBS-modified asphalt.

An inexpensive and high-performing solid Coumarone resin was added to Styrene-butadiene-styrene (SBS) copolymer-modified asphalt to enhance its storage stability and road performance. To assess the effect of Coumarone resin dosage on the SBS-modified asphalt, a series of laboratory tests were conducted. The composite modified asphalt's segregation test was used to evaluate its storage stability, Dynamic Shear Rheometer (DSR) and Multiple Stress Creep Recovery (MSCR) tests were employed to investigate its high-temperature performance and permanent deformation resistance, and the Bending Beam Rheology (BBR) test was utilized to measure its low-temperature performance. Fluorescence microscopy was used to observe the composite modified asphalt's microstructure, and Fourier Transform Infrared Spectroscopy (FTIR) was conducted to study the changes in chemical structure during the modification process. The results showed that Coumarone resin can improve the compatibility of SBS and asphalt, improve the high-temperature performance and deformation resistance of SBS-modified asphalt, and adding an appropriate amount of Coumarone resin can help enhance the low-temperature cracking resistance of modified asphalt. The optimal dosage of Coumarone resin recommended for SBS-modified asphalt performance enhancement is 2% under the test conditions, as determined by comparing the test results of samples with various dosages.

Investigation on Preparation Method of SBS-Modified Asphalt Based on MSCR, LAS, and Fluorescence Microscopy

The preparation method of SBS-modified asphalt has a direct effect on its overall performance. Currently, the optimal process is usually determined by conventional performance properties, such as softening point, ductility, and penetration, which may deviate from practical field performance. This study aims to investigate the influence of different preparation methods on the performance and microstructure of SBS-modified asphalt based on fluorescence microscopy testing, the multiple stress creep recovery (MSCR) test, the linear amplitude sweep (LAS) test, as well as Burgers model fitting. SBS-modified asphalt was prepared with different shear rates, shear temperatures, shear times, development time, and sulfur addition. The results show that the optimal process for preparing SBS-modified asphalt is 2 h of shearing at 180 °C and 4000 r/min, followed by sulfurization and 6 h of development. The performance of SBS-modified asphalt is most notably influenced by sulfurization, which forms C–S bonds to make the polymer network stronger, thereby improving the high-temperature performance as well as the fatigue resistance. However, due to high-temperature sensitivity, C–S bonds may break during development, leading to weakened performance. The performance of SBS-modified asphalt without sulfur addition shows a monotonically increasing trend with the extension of development time.

Development of bio-based stabilizers and their effects on the performance of SBS-modified asphalt

Polymer-modified asphalt has been widely used in pavement engineering thanks to its excellent road performance. However, differences in the molecular structure, molecular weight, and density of polymer modifiers and base asphalt binders make modified asphalts prone to phase separate into the modifier and the base asphalt binder during static processes, such as transportation and storage. To ensure the storage stability of polymer-modified asphalt, stabilizers are usually added in the polymer-modified asphalt preparation process. Sulfur powder is a commonly used stabilizer with a good stabilizing effect for the preparation of modified asphalt but faces the problems of fire hazard and environmental pollution. In this study, based on the compounding process, three environmentally friendly and safe bio-based sulfur stabilizers were developed. Based on the preparation and performance evaluation of styrene-butadienestyrene block copolymer–modified asphalt under the same conditions, the effects of bio-based stabilizers on the performance of the modified asphalt were investigated. A comparative evaluation of the physical properties of modified asphalts was used to infer the high-temperature performance from the rutting factor measured by a dynamic shear rheological test. The low-temperature performance was inferred from the stiffness S and the m value measured by the bending beam rheological test. The elastic recovery performance of asphalt was characterized in terms of the average percent recovery R and the nonrecoverable creep compliance Jnr, as measured by a multiple stress creep recovery test. The microscopic morphology of the modified asphalt was observed under a fluorescence microscope. The results showed that the modified asphalts prepared with bio-based stabilizers all had low 135 °C viscosity and good high- and low-temperature performance. The best rheological parameters were found for modified asphalt prepared with Stabilizer A, followed by that prepared with Stabilizer C and then Stabilizer B. Both the original and the short-term-aged modified asphalt containing Stabilizer A showed good network structure under the fluorescence microscope. In addition, the costs of bio-based stabilizers were similar to that of traditional sulfur powder.

Effect of dithiodimorpholine and tetraethylthiuram disulphide on ageing properties of SBS-modified asphalts

Effect of additives dithiodimorpholine (denoted as D) and tetraethylthiuram disulphide (denoted as T) on high-temperature storage stabilities and thermal oxidative ageing performance of SBS-modified asphalt were studied. Considering cost and performance, the content and ratio of D:T should be 0.2% and 1:3, respectively, and the result was confirmed by dynamic shear rheological testing of the samples before and after ageing. Mixtures of SBS-modified asphalt with D and T were prepared by physical high-speed shearing. The thin film oven test was used for simulating thermal degradation during short-term ageing. The results show that appropriate content and ratio of additives D and T can improve anti-ageing properties of SBS-modified asphalts; moreover, the advance of high-temperature storage stabilities of the mixture was significant.