多聚磷酸改性沥青改性机制

Modification mechanism of polyphosphoric acid modified asphalt

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。

Polyphosphoric acid （PPA） is a newly modifier with advantages of low prices and simple process, which has a good application prospect. For study the modification mechanism of PPA modified asphalt, the 0.5%, 1%, 1.5%, 2%（mass ratio of PPA to asphalt） PPA modified asphalt were prepared. Three main indexes test shows that penetration index decreases and softening point increases, moreover ductility decreases as mixing amount of PPA increases, indicating improvement of high-temperature property and a little bit weakness of low-temperature property when asphalt is modified by PPA. The content of asphahene is increased with the decrease of the content of colloid and the content of aromatics and saturation stay around same test by SARA. The FTIR spectrogram of PPA modified asphalt shows that the whole curve changes and a new absorption peak appears compared with pure as- phah, which reveals the modification mechanism of PPA modified asphalt is chemical modification. Topography ima- ges and phase images of PPA modified asphalt were obtained by atomic force microscopy（AFM）, which shows that compared with pure asphalt, the area of para-phase is smaller, while the area of pert phase is larger moreover, and the valley of catana-phase become wider, which means the content of asphaltene increasing and weakening of low temperature anti-cracking performance.