沥青种类对混合料拌和流动性的影响

Impact of Bitumen Types on Mixing Flow Behavior of Mixtures

摘要: 为了模拟沥青混合料的拌和流动性，认识沥青种类对拌和流动参数及和易性的影响，试验选取了70#基质沥青、SBS改性沥青、橡胶沥青、Evotherm温拌沥青、ACMP1和ACMP2温拌沥青等6种不同性质的沥青，配制了AC-13C型沥青混合料，利用自主开发的一种变速拌和试验装置，在不同拌和温度(140℃~180℃)和不同拌和速率(20~50 r∙min−1)下，对6种不同沥青混合料进行了变速拌和试验，测试了拌和功率，绘制了拌和功率–拌和速率流变图，建立了拌和流动模型，分析了混合料的拌和流动参数(拌和塑限F与拌和黏度λ)，定义并研究了混合料的拌和和易性指数。研究结果表明：拌和功率与拌和速率具有很好的线性相关性，拌和流变特性服从线性黏塑性的宾汉模型；不同沥青种类的混合料具有相同的拌和流动模型，但拌和流动参数值有较大变化，从而影响了拌和的和易性；基于拌和流动参数F和λ，可以定量评价混合料的拌和和易性，定义和易性指数为流动模型直线对拌和速率之面积的倒数；与70#基质沥青混合料相比，SBS改性沥青和橡胶沥青混合料的和易性指数降低了9.8%~21.4%，温拌沥青混合料的和易性指数提高了8.4%~35.4%；拌和温度由140℃升高到180℃时，拌和和易性指数提高了21.5%~49.1%。

Abstract: In order to simulate the mixing flow behavior of bituminous mixture, and to recognize the influence of bitumen type on the mixing flow parameters and its workability, six types of 70# matrix bitumen, SBS modified bitumen, rubber modified bitumen, Evotherm and ACMP1 and ACMP2 warm bitumen are selected to prepare AC-13C asphalt mixtures, respectively. Using a self-developed experimental device of mixing power measurement at variable velocity, the variable mixing velocity experiment was carried out on the six different asphalt mixtures at different mixing temperatures (140˚C~180˚C) and mixing velocities (20~50 r∙min−1), the mixing powers were recorded, the mixing power-mixing velocity diagrams were drawn, the mixing flow model was established, and the mixing flow parameters of the mixtures (mixing plastic limit F and mixing viscosity λ) were analyzed, and the mixing workability index of the mixtures was defined and studied. The result shows that the mixing power has an obvious linear correlation with mixing velocity, the mixing rheological model obeys the linear visco-plastic Bingham’s model. The mixing flow behavior is same for different bitumen mixtures, but the values of mixing rheological parameters are changed, thus the workability is influenced. Based on the mixing flow parameters F and λ, the mixing workability of asphalt mixture could be quantitatively evaluated by defining the workability index as the area reciprocal of the Bingham’s line with mixing velocity. Compared to 70# matrix asphalt mixture, the workability indexes of SBS modified asphalt and rubber asphalt mixture decrease by 9.8% and 21.4% respectively, and the workability indexes of warm mix asphalt mixture increase by 8.4%~35.4%; When the mixing temperature increases from 140˚C to 180˚C, the mixing workability indexes for all mixtures increase by 21.5%~49.1%.