基于简化能量耗散率的岩沥青改性沥青疲劳性能

Fatigue Performance of Rock Asphalt Modified Asphalts Based on Reduced Dissipated Energy Ratio

关键词:  岩沥青改性沥青  疲劳性能  加载模式  简化能量耗散率

Key words:  modified asphalt by rock asphalt  fatigue performance  loading mode  reduced dissipated energy ratio(RDR)

摘要:

将纯岩沥青组分从布敦岩沥青（BRA）中抽提出来，作为基质沥青的天然改性剂，研究了岩沥青改性沥青的疲劳性能.首先分析了表征沥青疲劳性能的评价指标G50（复数剪切模量衰减至初始值50%时所对应的荷载作用次数）和RDR（简化能量耗散率），然后基于时间扫描试验，分别在应力035，040，045，050MPa和应变20%，25%，30%，35%的控制模式下，对不同掺量的岩沥青改性沥青疲劳性能进行了研究.结果表明：RDR由于反弯点的存在，可以很方便确定沥青的疲劳寿命；岩沥青改性沥青的疲劳性能依赖于加载模式，在应变控制模式下，纯岩沥青掺量小于15%（质量分数）时，有助于改善其疲劳寿命，但是，当纯岩沥青掺量继续增加，由于其本身沥青质含量较高、属于硬质沥青的特点，会缩短改性沥青的疲劳寿命；在应力控制模式下，随着纯岩沥青掺量的增加改性沥青疲劳寿命大幅延长，但是，纯岩沥青掺量过大会提高改性沥青对应力水平的敏感程度.

Abstract:

The rock asphalt which extracted from the Buton rock asphalt(BRA), served as a natural asphalt modifier for base asphalt. The aim was to study the fatigue properties of rock asphalt modified asphalts. The evaluation indexes of fatigue performance, G*50(50% of the initial modulus) and RDR(reduced dissipated energy ratio), were discussed. Then，the time sweep tests based on rheology theory were applied in stress control mode(035, 040, 045, 050MPa) and strain control mode(20%, 25%, 30%, 35%) for modified asphalt with different content. The results show that RDR is a good evaluation index, because there is an inflection point in the curve and it is very easy and convenient to determine the fatigue life for researchers. The fatigue properties of rock asphalt modified asphalts depend on the loading mode of the test. Rock asphalt can improve the fatigue life of the base asphalt in strain control mode, if the content is smaller than 15%(mass fraction); however, rock asphalt can short the fatigue life of the modified asphalt if the content continues to increase. This is because the rock asphalt itself belongs to hard asphalt. In stress control mode, with the content of rock asphalt increasing, the fatigue life of the modified asphalt becomes longer. But the modified asphalt with the large content of rock asphalt will be sensitive to stress level.