基于地聚反应的冷拌沥青混合料强度特性与机理探讨

利用马歇尔稳定度(M_S)强度评价指标,对冷拌沥青混合料(简称冷拌料)在不同地聚添加剂、浸水、不同养生龄期等条件下进行宏观强度试验分析,并采用荧光显微镜及离散元模拟等方式,对集料表面的细观结构与地聚物的抗压机理进行研究,结果表明:冷拌料的M_S随地聚物掺量的增加先增大后减小,在基质沥青与地聚添加剂质量比为4∶3时达到峰值,且在4∶2至4∶3区间,残留稳定度(MS0)的减小幅度最小,强度损失率最低,因此基质沥青与地聚添加剂的最佳质量比为4∶3;强度随养生龄期的增加而增加,而强度增长率随养生龄期的增加而逐渐减少,养生时间应不少于3 d;通过荧光显微镜分析,发现集料表面的沥青被地聚物产生的胶凝物裹覆,通过马歇尔稳定度虚拟试验分析,发现试件主要受力方向位于承压点的正下方,集料在受压过程中呈外部受拉内部受压状态,而地聚物产生的胶凝产物可以较好地抵抗竖向荷载,提升冷拌料抗压强度。

Discussion on Strength Characteristics and Mechanism of Cold MixAsphalt Mixture Based on Geopolymerization

Based on the Marshall stability (M_S) strength evaluation index,the macro-strength test analysis of cold mix asphalt mixture was carried out under the conditions of different aggregate additives,water immersion and different curing ages,etc..The research on the microstructure of the aggregate surface and the compression mechanism of geopolymer were studied by fluorescence microscope and discrete element simulation methods.It is found that M_S of cold mix increases first and then decreases with the increase of geopolymer content.The M_S value reaches at peak when the mass ratio of base asphalt and geopolymer additives is 4∶3,and in the range of 4∶2 to 4∶3,the residual stability (MS0) has the smallest reduction meanwhile the strength loss rate reaches the lowest.It is concluded that the optimal mass ratio of base asphalt and geopolymer additives is 4∶3,and the strength increases with the increase of the curing age,while the growth rate of the strength gradually decreases.The curing time should not be less than 3 d.Through fluorescence microscope analysis,it is seen that the asphalt on the surface of the aggregate is glued by the geopolymer.Through the Marshall stability virtual test analysis,the main force direction of the specimen is located directly below the pressure bearing point,the aggregate is externally tensioned and internally compressed during the compression process,and the gelled geopolymer can better resist vertical load and improve the compressive strength of cold mix.