DC-Ⅰ型混合植物沥青混合料路用性能评价及改善

摘要

Based on DC-Ⅰ bio-asphalt,the by-product of corn processing,blended bio-asphalt (BDC-Ⅰ) and SBS modified blended bio-asphalt (BMDC-Ⅰ) were prepared.The pavement performance of the two asphalt mixtures was evaluated,and the improvement measures to the water stability were put forward.First,atomic force microscopy (AFM) was employed to investigate the component compatibility of DC-Ⅰ bio-asphalt and SBS modifier in the asphalt.Second,according to the different asphalt performance requirements in different pavement layers,the blended bio-asphalt BDC-[and SBS modified blended bioasphalt BMDC-Ⅰ were used to prepare AC-25 and AC-20 asphalt mixtures,respectively,and their pavement performances were measured comprehensively.The results show that the presence of bio-asphalt increases dynamical stability of the mixture,has little effect on the low-temperature performance,but reduces the moisture resistance.Finally,based on the results of the Marshall specimen water immersion 20 d test,water-solubility is the mainfactor which causes low moisture resistance.Subsequently,three kinds of additives(modifier Ⅰ,Ⅱ,Ⅲ) were chosen to chemically modify the bio-asphalt.The water immersion Marshall tests and freeze-thaw splitting tests results reveal that the modifier Ⅰ obviously improves the moisture resistance of bio-asphalt mixture.The performances of bio-asphalt mixture is excellent after modified by additives,and its chemical modification is the focus of future researches.%采用玉米加工过程中的副产品DC-Ⅰ型植物沥青,制备了混合植物沥青(BDC-Ⅰ)及SBS改性混合植物沥青(BMDC-Ⅰ),评价了其混合料的路用性能,并针对混合料水稳定性提出了改善措施.首先,采用原子力显微镜(AFM)研究了2种沥青的组分相容性;其次,针对不同路面层位对沥青材料性能的要求,利用BDC-Ⅰ及BMDC-Ⅰ分别拌制AC-25和AC-20混合料,并综合评价了其路用性能,结果表明DC-Ⅰ型植物沥青的掺入使混合料的高温性能有所改善,对低温性能影响不大,但明显降低了其水稳定性;最后,基于马歇尔试件浸水20 d的试验结果,明确了造成混合料水稳定性不足的主要原因是DC-Ⅰ型植物沥青具有一定的水溶性.因此,选用3种外掺剂Ⅰ,Ⅱ和Ⅲ对其进行化学改性,通过浸水马歇尔试验和冻融劈裂试验发现外掺剂Ⅰ的效果较明显,其混合料水稳定性大幅改善.研究表明,经外掺剂改性后植物沥青混合料路用性能优良,其化学改性将是未来研究的重点.