PPA复合改性对沥青-集料黏附及其水稳定性影响研究

Effect of PPA Composite Modification on Asphalt-aggregate Adhesion and Water Stability

为探究多聚磷酸(PPA)对沥青-集料之间黏附及其水稳定性的影响,提出了以基质沥青、PPA改性沥青、SBS/PPA和SBR/PPA复合改性沥青与石灰岩、玄武岩和花岗岩集料组合的沥青混合料设计方案。采用分子动力学模拟方法,构建沥青-集料界面模型,并通过原子力显微镜(AFM)、接触角试验、动态剪切流变试验(DSR)以及浸水马歇尔试验和冻融劈裂试验探究了PPA掺加后对沥青-集料黏附及其水稳定性的影响。结果表明:随着PPA改性剂的添加,沥青表面自由能显著增大,沥青与集料间黏附功提高,交互能力增强,沥青混合料的水稳定性更优;通过3种集料的试验结果对比,发现碱性集料对改性沥青-集料的黏附与水稳定性改善效果更好;PPA加入后,使SBS、SBR聚合物改性沥青与集料间的黏附功略有下降,但综合水稳定性得到明显改善;因此,推荐采用SBS/PPA复合改性沥青及石灰岩集料进行混合料组合设计,此组合可以得到最佳的黏附性及水稳定性。

To explore the influence of polyphosphoric acid(PPA)on the adhesion and water stability of asphalt-aggregate interface systems,in this study,a design scheme was proposed for asphalt mixtures with matrix asphalt,PPA-modified asphalt,SBS/PPA,SBR/PPA composite-modified asphalt and limestone,basalt,and granite aggregates.A molecular dynamics simulation method was used to construct the asphalt-aggregate interface model,and the effects of PPA addition on asphalt-aggregate adhesion and water stability were investigated via atomic force microscopy(AFM),contact angle test,dynamic shear rheological test(DSR),immersion Marshall test,and freeze-thaw splitting test.The results show that with the addition of the PPA modifier,the surface free energy of the asphalt increases significantly,adhesion between the asphalt and aggregate increases,the interaction ability increases,and the water stability of the asphalt mixture improves.By comparing the test results of the three types of aggregates,it is determined that the alkaline aggregate has a better effect on the adhesion and water stability of the asphalt-aggregate.The composite modification of SBS,SBR polymer,and PPA slightly decreases the adhesion between asphalt and aggregate.However,the improvement in comprehensive water stability is more evident.Hence,SBS/PPA composite-modified asphalt and limestone aggregate are recommended for the mixture combination design.This can lead to the best adhesion and water stability.