盐分侵蚀对沥青和混合料性能影响及作用机理

Effect and mechanism of salt erosion on performance of bitumen and asphalt mixtures

针对沿海地区降雨、海雾、大气中海盐粒子侵蚀路面材料的问题,开展海水中盐分对沥青及混合料性能的影响及作用机理研究。基于沥青主要技术指标和组分试验,分析了海水及其中各类盐分对沥青主要技术指标和组分的影响;设计了室内盐蚀循环加速模拟试验,评价了盐分和高温耦合作用下沥青混合料的高温稳定性、低温性能、水稳定性以及抗疲劳性能,并结合接触角试验和室内试验结果探讨了盐分和高温耦合作用下沥青混合料性能衰变机理。研究结果表明:经过不同盐分侵蚀后,沥青组分中芳香分和饱和分的含量减小,沥青质含量相对增大,在沥青技术指标上反映为软化点增大,针入度减小;各种侵蚀环境中,海水对沥青针入度和软化点的影响最大,其余依次为NaCl溶液、MgCl_2溶液、KCl溶液、NaSO_4溶液、空气和纯水;海水较纯水更容易浸润集料,也更易侵入沥青和集料的界面,从而降低沥青/集料界面黏结强度;同时,可溶性盐结晶过程中会发生体积膨胀,产生结晶压;这些因素的综合作用使得沥青混合料的高温稳定性、低温抗裂性、水稳定性和疲劳特性均发生了不同程度的衰减。

It is possible that the sea salt particles existed in the rainfall, the sea fog and the atmosphere in coastal areas can erode the pavement materials. Therefore, this paper studied how the chemical salt in the seawater affected the performances of asphalt and mixtures as well as the mechanism. Based on the main technical indicators and component measurements of asphalt, the effects of seawater and its various types of salt on the main technical indicators and components of asphalt were analyzed. The high temperature stability, low temperature performance, moisture sensitivity and fatigue performance under salinity and high temperature coupling were investigated via the salt erosion and cycling acceleration simulation test. Additionally, the decay mechanism of asphalt mixtures under salinity and high temperature were also been discussed on the basis of the results of contact angle test and laboratory test. The results show that the content of aroma and saturated fraction in asphalt component is decreased and the asphaltic content is relatively increased after the erosion of different types of chemical salt, while the softening point is increased and the penetration is reduced on the generate indicators of asphalt. In all kinds of eroded environment, seawater has the greatest influence on the penetration and softening point of asphalt binders, followed by NaCI solution, MgCl2 solution, KCl solution, NaSO4 solution, air and pure water. Seawater is not only easier to infiltrate the aggregate than pure water, but also easier to penetrate the interface of asphalt and aggregate, thus reducing asphalt/aggregate interracial bond strength. Meanwhile, the volume of expansion will happen in the crystallization process of the soluble salt, resulting in crystallization pressure. The high temperature stability, low temperature crack resistance, moisture sensitivity, and fatigue performance of asphalt mixtures will be degraded in different degrees because of these integrated factors. 7 tabs, 5 figs, 21 refs.