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为了研究新加沥青标号的性能差异对高掺量回收沥青路面材料(RAP)再生沥青混合料强度和疲劳性能的影响,制备了3种不同类型的再生沥青混合料:新集料和70#沥青制备的AC-20沥青混合料;RAP掺量为50%并添加70#沥青的AC-20再生沥青混合料;RAP掺量为50%并添加90#沥青的AC-20再生沥青混合料(简称AC-20参照组、AC-20-50%RAP-70#和AC-20-50%RAP-90#,下同),3组沥青混合料采用相同的目标级配设计和沥青含量。通过强度试验和疲劳试验分析沥青混合料的性能;采用不同温度下单轴压缩试验和劈裂试验评价沥青混合料的强度;采用控制应变的UTM四点弯曲疲劳试验研究沥青混合料的疲劳性能;同时,根据再生沥青实测针入度和软化点的变化规律,探索利用公式预测再生沥青疲劳性能的可行性。研究结果表明:掺入50%RAP能使再生沥青混合料的强度提高,沥青混合料强度随试验温度升高而降低,在试验温度范围内,3组试件强度的高低排序不随试验温度变化而改变,AC-20-50%RAP-70#再生沥青混合料强度最高;再生混合料的疲劳性能与添加新沥青的标号有关,AC-20-50%RAP-90#再生沥青混合料疲劳性能最好,而AC-20-50%RAP-70#再生沥青混合料的疲劳寿命低于新制备沥青混合料,选用合适标号的新加沥青可有效改善再生沥青混合料的疲劳性能。
In order to study the effect of the differences in the performance of newly added asphalt grades on the strength and fatigue properties of RAP recycled asphalt mixtures, three different types of recycled asphalt mixtures were prepared: new aggregate and 70 # asphalt AC-20 asphalt mixture with RAP content of 50% and 70 # asphalt added; AC-20 recycled asphalt mixture with RAP content of 50% and 90 # asphalt added AC-20 reference group, AC-20-50% RAP-70 # and AC-20-50% RAP-90 #, the same applies below). The three asphalt mixtures used the same target grading design and asphalt content. The asphalt mixture performance was analyzed by strength test and fatigue test. The strength of asphalt mixture was evaluated by uniaxial compression test and splitting test at different temperatures. The fatigue behavior of asphalt mixture was tested by UTM four-point bending fatigue test with controlled strain. At the same time, according to the measured law of penetration and softening point of reclaimed asphalt, the feasibility of predicting the fatigue performance of reclaimed asphalt by using the formula is explored. The results show that the strength of recycled asphalt mixture can be improved with the incorporation of 50% RAP and the strength of asphalt mixture decreases with the increase of test temperature. The order of strength of three groups of specimens does not change with the test temperature in the range of test temperature The AC-20-50% RAP-70 # recycled asphalt mixture has the highest strength. The fatigue properties of the recycled mixture are related to the addition of new asphalt. The fatigue properties of AC-20-50% RAP-90 # , While the fatigue life of AC-20-50% RAP-70 # recycled asphalt mixture is lower than that of the newly prepared asphalt mixture. The selection of the new asphalt with the appropriate label can effectively improve the fatigue performance of the recycled asphalt mixture.