基于正交设计和灰色关联理论的DCLR改性沥青优化与机理研究

Study on Optimization and Modification Mechanism of DCLR Modified Asphalt Based on Orthogonal Design and Grey Correlation Theory

基于不同工艺条件下煤直接液化残渣(direct coal liquefaction residue,DCLR)改性石油沥青,通过设计三因素三水平正交试验,得到DCLR改性沥青的最佳工艺条件为剪切搅拌时间45 min、剪切搅拌温度150℃、剪切搅拌速率4000 r/min;通过灰关联度分析,发现针入度、软化点、延度、PI这4个指标的影响权重不一,主次顺序分别为针入度>PI>延度>软化点.利用BP神经网络对改性沥青的性能(针入度)进行模拟和预测,预测值与实验数据拟合度为0.993,证明了该方法的有效性.采用红外光谱、热重和扫描电镜对改性沥青进行分析.结果表明:DCLR与沥青之间没有发生明显的化学变化.在确定其最优配比的基础上,通过车辙试验、小梁弯曲试验、冻融劈裂试验来评价混合料的高温性能、低温性能和水稳定性能,结果表明:DCLR能明显改善沥青的高温性能和水稳定性,但对其低温性能影响不大.

Based on the modification of petroleum asphalt by direct coal liquefaction residue(DCLR) under different technological conditions, the orthogonal experiment of three factors and three levels was designed, and the optimum technological conditions of DCLR modified asphalt were obtained as follows: shear stirring time 45min, shear stirring temperature 150℃ and shear stirring rate 4 000 r/min. Through the analysis of grey correlation degree, it is found that the influence weights of penetration, softening point, ductility and PI are different, and the primary and secondary order is penetration >PI>ductility>softening point. The performance(penetration) of modified asphalt was simulated and predicted by BP neural network, and the fitting degree between the predicted value and the experimental data is 0.993, which further proves the effectiveness of this method. The modified asphalt was analyzed by infrared spectrum, thermogravimetry and scanning electron microscope. The results show that there is no obvious chemical change between DCLR and asphalt. On the basis of determining the optimum proportion, the high-temperature performance, low-temperature performance and water stability of the mixture were evaluated by rutting test, trabecular bending test and freeze-thaw splitting test. The results show that DCLR can obviously improve the high-temperature performance and water stability of asphalt, but has little effect on its low-temperature performance.