超热高温拌合下浇注式沥青热解机理研究

Due to the excellent deformation compliance and waterproof, gussaphalt is widely used for steel deck pavements on super-long-span bridges. However, ultra-high temperature aging of gussaphalt is found during the mixing condition with the temperature from 220 to 240 degree Celsius and 4 hours, which results in the damage of gussasphalt pavement. In this proposal, the variation of the composition and molecular structure of gussaphalt will be studied with element analysis, component analysis, Fourier transform infrared spectrum and thermal gravimetric analysis in the micro perspective. The variation of the mass of saturates, aromatics, resins and asphaltene in gussasphalt during the thermal degradation will be obtained. From the macro-mechanics perspective, the performance indexes including needle penetration classification index, rutting factor, fatigue factor, bending stiffness modulus, creep rate and viscosity will be evaluated for gussaphalt under different temperatures. The dynamic shearing test, bending beam rheometer test and viscosity test will be conducted. Based on micro-structural model and colloid structure theory, a relational model for aging gussasphalt between the microscopic molecular structure and macro-mechanical performance will be established. The ultra-high temperature aging rules for gussalphalt will be explored, and the thermal degradation mechanism for gussalphalt will be revealed. The research findings will provide technical guidance for the development of recycling agent for aged gussasphalt.

浇注式沥青混凝土以其优异的协同变形能力和密水性，被广泛应用于超大跨径钢桥面铺装中。但220~240°C超热高温和4小时以上长时间拌合环境，导致了浇注式沥青的超热老化，危及到铺装层使用质量。本项目旨在从微观角度利用元素分析、组分分析、红外光谱分析、热失重等技术手段，研究浇注式沥青热解过程的组成成分与分子结构变化趋势，探究超高温热解前后浇注式沥青中饱和分、芳香分、胶质和沥青质各组分含量的变化规律。从宏观力学角度，采用动态剪切试验、弯曲流变试验、粘度试验，评价不同超热高温对浇注式沥青的针入度分级指标、车辙因子、疲劳因子、弯曲劲度模量、蠕变速率和粘度等性能指标的影响规律。结合沥青微结构模型和胶体结构理论，建立浇注式沥青超热高温老化前后的微观分子结构与宏观力学性能间的关系模型，探寻浇注式沥青超热高温老化规律，揭示浇注式沥青超热高温热解机理，为浇注式沥青混合料的抗超高温老化再生材料的研制提供技术指导。

浇注式沥青混凝土在施工过程中存在220~240℃的超热高温和4小时以上长时间拌合的老化环境，导致了浇注式沥青的超热热解现象严重，危及浇注铺装质量。针对此问题，本项目从微观角度利用红外光谱技术、凝胶渗透色谱技术和热重分析技术对浇注式沥青热解过程中的杂原子官能团与分子结构变化规律进行了测试研究。从宏观力学角度，测定了不同温度老化前后浇注式沥青的针入度、延度、软化点以及动态剪切与弯曲流变性能。在此基础上，对浇注式沥青微观分子结构与宏观力学性能之间的相关参数指标进行统计分析，构建出浇注式沥青宏微观指标之间的关系模型。研究发现：超高温下浇注式沥青的小分子物质易聚合为大分子物质且轻质物质挥发是浇注式沥青超热老化的主要原因，浇注式沥青在不同超热温度老化前后的微观参数指标与宏观力学性能之间存在很好的相关性。研究成果较好地揭示了浇注式沥青的超热老化机理，为浇注式沥青混合料的抗超高温老化材料设计提供了技术指导。