物理硬化下橡胶复合改性沥青低温抗裂性能研究

Low-temperature Cracking Resistance of CR Composite Modified Asphalt by Physical Hardening

由于研究寒冷地区橡胶复合改性沥青(CRMA)材料物理硬化前、后低温抗裂性能的变化规律对提升寒区公路工程质量具有重要意义,所以采用单边切口弯曲梁(SENB)试验研究了物理硬化作用对CRMA低温抗裂性能的影响机制,即试验前将沥青小梁试样分别在-12、-18、-24℃的无水乙醇溶液中恒温1、12、24、36、48 h来模拟沥青不同程度的物理硬化。研究结果表明:改性沥青恒温24 h后低温抗裂性能下降速度逐渐平缓,物理硬化程度趋于饱和;改性沥青物理硬化程度随温度的降低呈正态分布,而不是温度越低,物理硬化程度就越严重;-18℃时,改性沥青的物理硬化程度最大;SBS改性沥青(SBSMA)的抗物理硬化能力优于CRMA,但物理硬化前后CRMA的低温抗裂性能均远优于SBSMA,更加适用于寒冷地区公路工程。因此推荐采用基于SENB试验恒温24 h后的断裂能指标来表征寒区改性沥青材料的低温抗裂性能。

It is important to study the change rule of low-temperature cracking resistance of crumb rubber composite modified asphalt(CRMA) materials before and after physical hardening to improve the quality of highway projects in cold regions.In this paper,the influence mechanism of physical hardening on the low-temperature cracking resistance of CRMA was investigated by the single-edged notched beam(SENB) test.Asphalt samples had been kept at constant temperature in anhydrous ethanol solution at-12 ℃,-18 ℃ and-24 ℃ before the test,respectively for 1 h,12 h,24 h,36 h and 48 h to simulate different physical hardening of the asphalt.The results show that the decrease of low-temperature cracking resistance of modified asphalt after 24 h of constant temperature is gradually steady,and the physical hardening tends to be saturated;The physical hardening level of modified asphalt show normal distribution with the reduction of temperature,while not the lower the temperature,the more serious physical hardening;The physical hardening level of modified asphalt is the largest at-18 ℃;The physical hardening resistance of SBS modified asphalt(SBSMA) is better than CRMA.However,low-temperature cracking resistance of CRMA is much better than SBSMA before and after physical hardening,which is more suitable for highway engineering in cold region;The fracture energy index based on the SENB test at constant temperature for 24h is recommended to characterize the low-temperature cracking resistance of modified asphalt materials in cold regions.