【作者】 况栋梁；

【导师】 余剑英；

【作者基本信息】 武汉理工大学 ， 复合材料学， 2012， 博士

【摘要】 废旧沥青混合料再生利用既能保护环境,又可节约大量的新石料、新沥青等不可再生资源,是一项符合可持续发展要求的沥青路面再生技术。废旧沥青混合料由于沥青老化导致其路用性能恶化,无法满足使用要求,因此再生剂通过渗透至裹覆在回收集料表面的老化沥青薄膜内部恢复老化沥青的化学组分和胶体结构从而改善老化沥青的物理性能,对提高再生沥青混合料的路用性能具有重要的影响。然而目前再生剂的渗透性尚未得到足够的重视,以致现有再生剂渗透性能差,对废旧沥青混合料路用性能的改善效果有限,制约了再生沥青混合料在高等级公路中的推广与应用。因此,开发具有优良渗透性能的沥青再生剂对促进废旧沥青混合料再生利用技术的发展具有重要的意义。基于组分调节理论和溶解渗透新思路,本文采用催化裂化油浆为沥青组分调节剂、含有极性环氧基团的化学油分作为溶解渗透剂,制备了渗透型再生剂,评价了渗透型再生剂的渗透能力；采用沥青质溶解实验和红外光谱分析探讨了渗透剂对再生剂渗透性能的改善机理；将渗透型再生剂用于老化沥青的再生,研究了渗透型再生剂对不同老化程度老化沥青再生性能的影响；将渗透型再生剂用于制备再生沥青混合料,评价了渗透型再生剂对废旧沥青混合料路用性能的改善效果。主要研究结论如下：(1)基于再生剂渗透对老化沥青针入度和化学组分的影响,本文提出了一种再生剂渗透性能评价方法,即通过测试再生剂渗透至老化沥青内部后老化沥青化学组分和针入度的变化对再生剂的渗透性能进行评价。(2)采用含有极性环氧基团的化学油分和催化裂化油浆作为主要原料制备了渗透型再生剂,并采用上述方法评价了再生剂的渗透性能,研究结果表明渗透型再生剂向老化沥青内部渗透的能力远强于普通再生剂向老化沥青内部渗透的能力。(3)沥青质溶解实验和红外光谱测试研究表明渗透剂之所以能增强再生剂的渗透能力是因为渗透剂不仅能有效溶解分散老化沥青中的沥青质,而且其含有的极性环氧基团还能与沥青质发生化学反应削弱沥青质分子之间较强的吸引力,促使老化沥青中凝聚的沥青质重新均匀溶解分散在沥青胶体体系中,使沥青质团聚形成的空间网络结构受到破坏,削弱沥青质空间网络结构对再生剂渗透的阻碍,从而改善再生剂的渗透能力。(4)渗透型再生剂和普通再生剂对不同老化程度老化沥青的物理性能影响研究结果表明,在相同用量下,渗透型再生剂能更有效地改善老化沥青的物理性能,使老化沥青的物理性能恢复接近新沥青的物理性能水平,这可能是因为普通再生剂只能改变老化沥青中的芳香分和沥青质的相对含量,对老化沥青胶体结构的恢复作用有限,而渗透型再生剂不仅能调节老化沥青中的芳香分和沥青质的相对含量,而且其含有的极性环氧基团还能与沥青质发生化学反应促进老化沥青中凝聚沥青质的重新分散,能更有效地恢复老化沥青的胶体结构。(5)低温弯曲梁流变实验结果表明,向老化沥青中加入15%的渗透型再生剂之后,老化沥青的蠕变劲度下降至294MPa,蠕变速率上升至0.317,而加入同等掺量的普通再生剂之后,老化沥青的蠕变劲度下降至327MPa,蠕变速率上升至0.273,表明渗透型再生剂对老化沥青低温抗裂性能的改善作用更加显著,这同样可归因于渗透型再生剂能更有效地恢复老化沥青的胶体结构。(6)渗透型再生剂和普通再生剂对老化沥青胶体结构的影响研究结果表明向老化沥青中加入15%的渗透型再生剂后,其胶体稳定指数由2.76增加至3.85,针入度指数由3.36下降至1.14,老化沥青的胶体结构由凝胶型转变成为溶—凝胶型；而向老化沥青中加入相同掺量的普通再生剂后,其胶体稳定指数由2.76增加至3.25,针入度指数由3.36下降至2.23,其胶体结构仍为凝胶型结构,这一结果证实了渗透型再生剂能更有效地恢复老化沥青的胶体结构。(7)原子力显微镜研究结果表明向老化沥青中加入渗透型再生剂之后,老化沥青体系中因沥青质团聚所形成的“蜂形”结构的尺寸减小、分布变均匀、微观形貌变平滑,接近新沥青表面的微观形貌,而向老化沥青中加入相同掺量的普通再生剂之后,其微观形貌并未发生明显的变化,进一步证实了渗透型再生剂能更有效地溶解分散老化沥青中凝聚的沥青质,使老化沥青的胶体结构得到更有效的恢复。(8)再生沥青混合料路用性能测试结果表明,掺加15%渗透型再生剂后,再生沥青混合料在20%加载应力比下的疲劳寿命达到10005次,抗弯拉应变达到2473,而添加相同掺量的普通再生剂后,再生沥青混合料的疲劳寿命为7473次,抗弯拉应变为2077,说明渗透型再生剂能更显著地提高废旧沥青混合料路用性能,这是因为渗透型再生剂能更有效地渗透至裹覆在回收集料表面的老化沥青薄膜内部,使老化沥青的胶体结构得到更好的恢复,从而更显著地改善了老化沥青的性能。更多还原

【Abstract】 The recycling of reclaimed asphalt pavement (RAP), which can protect the environment and conserve nonrenewable resources, is a recycling technology for asphalt pavement in conformity with the principle of sustainable development. The road performance of RAP deteriorates due to the ageing of bitumen wrapping around the surface of reclaimed aggregates, thus the diffusing of rejuvenator into the aged bitumen, which can restore the properties of aged bitumen by reconstituting the chemical component and colloidal structure, is crucial to the road performance enhancement of recycled asphalt pavement. However, the diffusibility of rejuvenator is commonly not considered highly, making the diffusibility of rejuvenator too poor to improve performance of recycled asphalt mixture effectively, therefore the the popularization and application of recycled asphalt mixture in high-grade highways is restricted. Therefore it is necessary to develop a rejuvenator with good diffusibility for the popularization and application of recycling of RAP.Based on the theories of dissolving-diffusion and chemical component reconstituenting, catalytic cracking slurry and chemical oil with epoxide group were selected as chemical component reductant and penetrant respectively for the preparation of diffusible rejuvenator. Influence of penetrant on the diffusibility of rejuvenator was investigated; asphaltenes dissolving experiment and infrared spectrum were employed to explore the mechanism of penetrant on the diffusibility enhancement of rejuvenator. Effects of rejuvenator on the properties of recycled bitumen and recycled asphalt mixture were studied. The main conclusions are as following:(1) Based on influence of rejuvenator diffusing on the penetration and chemical components of aged bitumen, a new method, which employs the changing of penetration and chemical components of aged bitumen after rejuvenator diffusing into aged bitumen to characterize the diffusibility of rejuvenator, was developed.(2) Diffusible rejuvenator composed of chemical oil with epoxide group and catalytic cracking slurry was prepared, its diffusibility was evaluated by the method mentioned above, the result indicates that the rejuvenator with penetrant exhibits better diffusibility than the rejuvenator without penetrant.(3) Asphaltenes dissolving experiment and infrared spectrum results reveal that the asphaltenes can be dissolved in the penetrant with epoxide group and the attraction force between asphaltenes can be reduced by the chemical reaction between epoxide group and asphaltenes, which can facilitate the dispersion of accumulated asphaltenes of aged bitumen and destory the network model dimensional structure caused by asphaltenes accumulating, therefore the physical obstacle of the structure on the rejuvenator diffusing into aged bitumen declined and the diffusibility of rejuvenator into aged bitumen was enhanced.(4) Investigations on influence of diffusible rejuvenator and common rejuvenator on the physical properties of aged bitumen indicate that the diffusible rejuvenator can restore the physical properties of aged bitumen with different aging degree more effectively; it can restore the physical properties of aged bitumen with different aging degree to the condition that is of the virgin bitumen. which can be explained as that the commom rejuvenator can only restores the colloidal structure of aged bitumen by changing the contents of aromatic and asphaltenes, the effect is finite; however, for diffusible rejuvenator, it can restore the colloidal structure of aged bitumen by both changing the contents of aromatic and asphaltenes and dissolving asphaltenes at the same time, therefore the effect of the diffusible rejuvenator on the colloidal structure restoration of aged bitumen is more effective than commom rejuvenator.(5) Result of Bending-Beam Rheometer testing indicates that the creep stiffness of the aged bitumen declined to294MPa and the creep rate increased to0.317after adding15%diffusible rejuvenator, however, after adding the same content of commom rejuvenator, the creep stiffness of the aged bitumen declined to327MPa and the creep rate increased to0.273, which indicates that the diffusible rejuvenator is more effective on the improvement of cracking resistance under low temperature than commom rejuvenator, which can be also explained as that the influence of diffusible rejuvenator on the colloidal structure restoration of aged bitumen is more effective than commom rejuvenator.(6) The colloidal stability index of the aged bitumen increased from2.76to3.85, penetration index declined from3.36to1.14after adding15%diffusible rejuvenator, indicating that the colloidal structure of aged bitumen transformed from Gel to Sol-Gel; however, after adding the same content of commom rejuvenator, the colloidal stability index increased from2.76to3.25, penetration index declined from3.36to2.23, the colloidal structure of aged bitumen was still Gel structure, which can prove that the diffusible rejuvenator on the colloidal structure restoration is more effective than commom rejuvenator.(7) The investigation of Atomic Force Microscope (AFM) indicates that after adding diffusible rejuvenator into aged bitumen, the size of bee structure caused by asphaltenes accumulating in aged bitumen declined, the distribution of the bee structure got even, the microstructure of aged bitumen became smooth, which was close to the microstructure of virgin bitumen; however, when adding the same content of commom rejuvenator, the microstructure of aged bitumen changed slightly, which can further prove that the diffusible rejuvenator on the colloidal structure restoration is more effective than commom rejuvenator.(8) Road performance testing of recycled asphalt mixture indicate that the fatigue life under0.2stress ratio and of the failure strain of the recycled asphalt mixture containing15%diffusible rejuvenator were10005and2473respectively; whereas for the recycled asphalt mixture containing the same content of commom rejuvenator, the fatigue life at0.2stress ratio and the failure strain were7473and2077respectively, indicating that the diffusible rejuvenator can improve the road performance testing of recycled asphalt mixture more significantly than common rejuvenator, which can be explained as that the diffusible rejuvenator can diffuse into the aged bitumen wrapping around the surface of reclaimed aggregates more deeply and restore the colloidal structure of aged bitumen more effectively, so as to improve the properties of aged bitumen better more significantly.更多还原