水泥对泡沫沥青冷再生混合料强度影响机理

Influence mechanism of cement on the strength of foamed asphalt cold recycled mixture

采用扫描电镜对掺加水泥前后回收沥青路面材料(RAP)、新集料、泡沫沥青胶浆微观形貌的分布特征等进行对比研究,进而采用工业CT的无损检测技术定量揭示了水泥对泡沫沥青冷再生混合料马歇尔试件内部孔隙特征的影响。研究结果表明,泡沫沥青冷再生混合料中水泥水化产物显著改善了集料表面的棱角性,从而增加了沥青与集料的粘附性;水泥水化物与沥青形成的胶浆复合物所构成的空间立体网格结构在混合料中起到"加筋"、填充作用,且显著增强了泡沫沥青胶浆的整体稳定性,从而提高了混合料的强度;水泥水化产物起到次级结合料的同时,还改变了混合料内部孔隙分布特征,增加了微孔隙数量,降低了内部孔隙的平均孔径,从而提高了混合料的水稳定性。

Surface micro-profiles characters of RAP,new material and foamed asphalt mortar were studied by SEM,then quantitative nondestructive detection of CT was adopted to reveal the influence of the cement on internal pore characteristics of Marshall specimen made by foamed asphalt.The results indicate that cement hydration products in foamed asphalt cold recycled mixture significantly improve the aggregate angularity,therefore the adhesion between asphalt and aggregate increase;composite mastics consisting of cement hydration products and asphalt film form a spatial structural network which had fiber-reinforcement and filling effect in mixture,significantly enhance the overall stability of the foamed asphalt mortar and the strength of the mixture;As a secondary binder,cement hydration products also change the gradation of inner pore,increase the number of micro pores and reduced the average diameter of internal pore,so as to improve the water susceptibility of foamed asphalt mixture.