溶胀胶粉的吸附偏好及其颗粒效应在沥青砂胶中关键力学行为研究

Wet process-asphalt rubber (AR), with rubber swelling as its key influence factor, has been a hot topic for pavement researchers. In recent years, different warm mix asphalt (WMA) additives have been used to enhance the workability of AR binder and mixture. However, warm AR is not equal to the simple mixing of AR and WMA components. During the mixing process, the swelling rubber particles has absorption preference among the asphalt fractions and WMA components, which affects the swelling level of crumb rubber as well as its particle effect and material properties of the interacting area. Therefore, investigation of the preferential absorption of swelled crumb rubber and its mechanical behavior helps to reveal the combined modification effect of warm AR. To systemically study the influence factors of rubber swelling, multi-scale experiments will be conducted to analyze the component distribution of the rubber-asphalt interacting area. The diffusion laws of WMA agents during the mixing process will also be analyzed and the feasibly of using WMA additives to control the rubber swelling level will be verified. Based on the above analysis, numerical simulation with digital image methods will be used to evaluate the effect of swelled rubber particles on mechanical behavior of warm AR mortars. Meanwhile, rheological tests of asphalt mortars will be conducted to provide data for detail simulation inputs. Finally, the design method of warm AR based on the combined modification mechanism will be proposed. Performance tests will be conducted on warm AR mixtures for validation. This study is excepted to provide scientific and technical support for the wide application of this sustainable paving material.

胶粉改性沥青是国内外长期研究热点，其技术核心在于胶粉的溶胀。近年来，温拌剂常用于橡胶沥青的降粘减阻。然而，温拌橡胶沥青并非多材料的简单混合，在混溶阶段，胶粉对沥青轻质组分及温拌剂基团间存在吸附偏好，影响其溶胀程度、颗粒效应及共溶区材料属性。研究溶胀胶粉的吸附偏好及其颗粒效应引发的力学行为，是揭示温拌橡胶沥青复合改性机理的前提和基础。本项目研究拟通过宏、微观测试研究溶胀胶粉共溶区自外到内的成分构成，分析温拌剂组分在交互作用区的迁移规律，量化多因素对胶粉溶胀程度的影响，验证利用温拌剂对胶粉溶胀进行过程控制的可行性。在此基础上，采用数字图像与虚拟力学技术开展含溶胀胶粉等真实细微观结构信息的沥青砂胶力学仿真，结合真实砂胶试件力学实验数据，研究胶粉在砂胶力学体系中的关键力学行为及衍生影响。最后，提出基于复合改性机理的温拌橡胶沥青设计原则并辅以混合料性能跟踪评价，为该环保型铺面材料的推广提供技术储备。

胶粉改性沥青是国内外长期研究热点，其技术核心在于胶粉的溶胀。近年来，温拌剂常用于橡胶沥青的降粘减阻。然而，温拌橡胶沥青并非多材料的简单混合，在混溶阶段，胶粉对沥青轻质组分及温拌剂基团间存在吸附偏好，影响其溶胀程度、颗粒效应及共溶区材料属性。本项目通过宏、微观测试研究溶胀胶粉共溶区自外到内的成分构成，分析温拌剂组分在交互作用区的迁移规律，量化多因素对胶粉溶胀程度的影响，验证利用温拌剂对胶粉溶胀进行过程控制的可行性，进而提出基于复合改性机理的温拌橡胶沥青设计原则并辅以混合料性能跟踪评价，为该环保型铺面材料的推广提供技术储备。.项目研究结论包括：.（1）橡胶沥青的高温与疲劳性能明显优于基质沥青，而橡胶沥青的液态组分高温PG分级比基质沥青提升1-2个等级，但疲劳性能与基质沥青接近；.（2）胶粉的溶解可对沥青液相产生类似聚合物改性的作用，使沥青液相的抗车辙性能获得明显提升，但该改性作用对沥青液相的抗疲劳性能无明显提升；.（3）沥青液态成分中具有较小分子量的轻质成分更容易被胶粉吸附至胶粉共溶区中，而大分子量成分则难以被胶粉吸收。除沥青组分外，有机降粘剂与化学温拌剂组分在混溶过程中也会被胶粉颗粒吸收；.（4）G*sinδ和间接拉伸疲劳试验在评价温拌橡胶沥青时存在的不足之处，建议采用沥青线性振幅扫描试验（LAS）、砂胶剪切疲劳试验或混合料四点弯曲疲劳试验来评价温拌橡胶沥青及其混合料的疲劳性能；.（5）结合力学性能，制备温度等多因素决策分析，对于化学温拌剂，应先利用吸附了化学温拌剂的胶粉制备温拌橡胶沥青，再制备温拌橡胶沥青混合料；对于蜡基温拌剂，则应先制备热拌橡胶沥青，随后加入蜡基温拌剂以制备温拌橡胶沥青，最后制备温拌橡胶沥青混合料。