Yun Jihyeon, Vigneswaran Shyaamkrishnan, Lee Moon-Sup, Choi Pangil, Lee Soon-Jae
Texas State University, San Marcos, TX 78666, USA.
Korea Institute of Civil Engineering and Building Technology, Goyang-si 10223, Republic of Korea.
Materials (Basel). 2023 Jan 20;16(3):978. doi: 10.3390/ma16030978.
Crumb rubber modifier (CRM) binders easily suffer from instability at high temperatures, with many suggestions being developed to evaluate their storage stability. However, much uncertainty around CRM binders still exists regarding the relationship between mixing methods and experiments in order to calculate the separation index. In this study, a laboratory investigation into how CRM binders behave regarding storage stability using different mixing methods and experiments was conducted. The CRM asphalt binder in this study was prepared through a wet mixing process with the addition of 5% and 10% crumb rubber modifier (by weight) at 200 °C. The three main modification methods were method A: high-shear mixing (8000 rpm) for 2 h, method B: low mixing (300 rpm) for 8 h, and method C: high-shear mixing (8000 rpm) for 2 h + low mixing (300 rpm) for 6 h. In addition, the effect of separation index (SI) on storage stability was assessed, measuring viscosity, G*/sin , and percentage recovery. In general, the results of this study revealed that method C appeared to have the most prominent effect on decreasing the difference between the values of the top and bottom parts; the results for 5% CRM using method C showed that there were no differences among the values for the top, middle, and bottom parts; from the MSCR test, method C was effective in decreasing the difference between the values of the top and bottom parts. It was observed that method C improved storage stability. However, the results for percentage recovery were relatively higher than the separation index when using rotational viscosity and G*/sin .
橡胶粉改性剂（CRM）结合料在高温下容易出现不稳定情况，人们已提出许多方法来评估其储存稳定性。然而，在计算分离指数时，关于混合方法与实验之间的关系，CRM结合料仍存在诸多不确定性。在本研究中，开展了一项实验室调查，以研究使用不同混合方法和实验时CRM结合料在储存稳定性方面的表现。本研究中的CRM沥青结合料是通过在200℃下添加5%和10%（按重量计）的橡胶粉改性剂，采用湿拌工艺制备的。三种主要改性方法分别为：方法A：8000转/分钟的高剪切搅拌2小时；方法B：300转/分钟的低搅拌8小时；方法C：8000转/分钟的高剪切搅拌2小时+300转/分钟的低搅拌6小时。此外，评估了分离指数（SI）对储存稳定性的影响，测量了粘度、G*/sinδ和恢复百分比。总体而言，本研究结果表明，方法C在减小顶部和底部值的差异方面效果最为显著；采用方法C的5%CRM的结果表明，顶部、中部和底部的值之间没有差异；从多重应力蠕变恢复（MSCR）试验来看，方法C在减小顶部和底部值的差异方面是有效的。可以观察到方法C提高了储存稳定性。然而，在使用旋转粘度和G*/sinδ时，恢复百分比的结果相对高于分离指数。
