Yu Hao, Mo Liantong, Zhang Yonghan, Qi Cong, Wang Yulu, Li Xiang
State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China.
Shandong Haiyun Asphalt Co., Ltd., Binzhou 371600, China.
Materials (Basel). 2023 Mar 23;16(7):2564. doi: 10.3390/ma16072564.
Slightly SBS-modified bitumen binders have been applied for the asphalt concrete impermeable layer of pumped storage power stations (PSPSs) in China. However, the storage stability and aging resistance of slightly SBS-modified bitumen are big concerns. In this study, three different types of slightly SBS-modified bitumen binders were evaluated by using a commonly used virgin bitumen and a normal SBS polymer-modified bitumen as references. All of the bitumen binders were subjected to short-term and long-term aging that were simulated by using a 5 h and 24 h thin film oven test (TFOT), respectively. A Fourier transform infrared (FTIR) spectroscopy test, storage stability test, dynamic shear rheological test, stress relaxation test, and direct tensile (DT) test were carried out to obtain insight into the storage stability and aging resistance. FTIR analysis indicated that slightly SBS modified bitumen exhibited serious aging of base bitumen together with higher polymer degradation. The aging indexes obtained from the carbonyl index and the polybutadiene (PB) index can well rank the aging resistance. Slightly SBS-modified bitumen binders had excellent storage stability, and even after a long-term period of 7 days of storage, the complex modulus and phase angle remained fairly constant. The rheological master curves were constructed to investigate the effects of short-term and long-term aging. Slightly modified bitumen binders were well identified by the plateau of the phase angle master curves. The aging resistance was well distinguished by the deviation of the complex modulus master curve using unaged bitumen as a baseline. It was found that three types of slightly SBS-modified bitumen binders exhibited inconsistent aging resistance in terms of rheological aging index. The relative change of the initial instantaneous modulus and the modulus relaxation rate was able to explain the relaxation properties. With respect to the direct tensile test, the increase in stiffness modulus and the loss of ultimate tensile strain can be used to evaluate the susceptibility of bitumen aging. An attempt was made to establish the relationship of the aging index between FTIR analysis, rheological properties, and low-temperature performance. It was found that the relationship among these aging indexes was weak. In general, slightly SBS modified bitumen should be well designed to obtain good aging resistance and low-temperature performance. Highly modified bitumen is foreseen to be promising in the case of extremely low temperatures and long-term durability.
轻度SBS改性沥青已应用于我国抽水蓄能电站沥青混凝土防渗层。然而，轻度SBS改性沥青的储存稳定性和抗老化性是人们非常关注的问题。在本研究中，以一种常用的基质沥青和一种普通的SBS聚合物改性沥青为参照，对三种不同类型的轻度SBS改性沥青进行了评估。所有沥青均分别通过5小时和24小时的薄膜烘箱试验（TFOT）模拟短期老化和长期老化。进行了傅里叶变换红外（FTIR）光谱试验、储存稳定性试验、动态剪切流变试验、应力松弛试验和直接拉伸（DT）试验，以深入了解储存稳定性和抗老化性。FTIR分析表明，轻度SBS改性沥青的基质沥青老化严重，聚合物降解程度较高。由羰基指数和聚丁二烯（PB）指数得到的老化指数能够很好地对抗老化性进行排序。轻度SBS改性沥青具有优异的储存稳定性，即使在储存7天的长期时间后，复数模量和相位角仍保持相当稳定。构建了流变主曲线以研究短期和长期老化的影响。轻度改性沥青通过相位角主曲线的平台得到很好的识别。以未老化沥青为基线，通过复数模量主曲线的偏差可以很好地区分抗老化性。发现三种轻度SBS改性沥青在流变老化指数方面表现出不一致的抗老化性。初始瞬时模量和模量松弛率的相对变化能够解释松弛特性。关于直接拉伸试验，刚度模量的增加和极限拉伸应变的损失可用于评估沥青老化的敏感性。尝试建立FTIR分析、流变性能和低温性能之间老化指数的关系。发现这些老化指数之间的关系较弱。总体而言，轻度SBS改性沥青应进行良好设计，以获得良好的抗老化性和低温性能。在极低温和长期耐久性的情况下，高度改性沥青有望具有良好前景。
