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为了研究多聚磷酸(PPA)对沥青的改性作用,分别制备了掺量为0.5%、1%、1.5%和2%(PPA与基体沥青的质量比)的PPA改性沥青。三大指标实验结果显示,随着PPA掺量的增加,针入度减小,软化点升高,延度减小,说明在沥青中掺入PPA使沥青高温性能得到改善而低温性能略有减弱。通过四组分分析(SARA)发现随着PPA掺量的增加,沥青中的胶质逐渐减少,沥青质逐渐增多,饱和分与芳香分基本不变。利用FTIR发现,相比基质沥青,PPA改性沥青的红外光谱整体图线发生了迁移,且出现了新的吸收峰,说明PPA改性机制为化学改性。利用AFM得到基质沥青与PPA改性沥青的形貌与相位图,分析发现掺入PPA后相位图中连续相(para-phase)面积明显减小,而分散相(peri-phase)面积明显增加,且蜜蜂结构(catana-phase)谷地尺寸变大,说明掺入PPA后沥青中沥青质含量将会增多,而低温抗裂性将有所减弱。
In order to study the effect of polyphosphoric acid (PPA) on asphalt modification, PPA modified asphalt was prepared at 0.5%, 1%, 1.5% and 2% (mass ratio of PPA to matrix asphalt) respectively. The experimental results of the three indexes showed that with the increase of PPA content, the penetration decreased, the softening point increased and the ductility decreased, which indicated that the incorporation of PPA in asphalt improved the high temperature performance of asphalt and slightly weakened the low temperature performance . Through the four component analysis (SARA), it was found that with the increase of PPA content, the asphaltene gradually decreased, the asphaltene gradually increased, and the saturated and aromatic fractions remained unchanged at all. FTIR showed that compared with matrix pitch, the whole infrared spectrum of PPA modified asphalt migrated and new absorption peak appeared, which indicated that the modification mechanism of PPA was chemical modification. The morphologies and phase diagrams of the asphalts and PPA modified asphalts were obtained by AFM. The results showed that the para-phase area of the phase diagram obviously decreased and the peri-phase area increased obviously when PPA was incorporated. And the size of the catana-phase valley becomes larger, indicating that the content of asphaltene in asphalt will increase and the low-temperature crack resistance will be weakened after being incorporated into PPA.