木屑基生物油再生老化沥青的疲劳特性研究

Fatigue Characteristic of Wood Dust-Based Bio-oil Regenerate Aged Asphalt

为分析木屑裂解制备的生物油对老化沥青疲劳特性的影响,采用动态剪切流变仪(DSR)在应力控制模式下对生物油再生老化沥青进行流变试验以评价其疲劳特性。选取复数剪切模量降低至50%时对应的剪切次数(N_(f50)),耗散能变化率拐点(N_(fm)),沥青复数模量变化曲线拐点所对应的循环加载次数(N_(fG*))作为疲劳特性评价指标,研究不同生物油含量、不同老化程度及不同应力水平对生物油再生老化沥青疲劳特性的影响,并分析生物油再生老化沥青的官能团变化。结果表明:不同测试条件下,生物油再生老化沥青的疲劳寿命评价指标具有一致的排序性,即N_(fG*)>N_(fm)>N_(f50);生物油的最佳含量在15%~20%之间。各指标中N_(fG*)对再生沥青的疲劳性能评价区分度最大、N_(f50)最易得到。生物油可降低老化沥青中亚砜基官能团的含量,增加羰基官能团及低波数指纹区的含量,促进老化沥青的再生。

In order to analyze the influence of bio-oil prepared from wood dust pyrolysis on the fatigue characteristics of aged asphalt,dynamic shear rheometer(DSR)was used to conduct rheological tests on bio-oil regenerate aged asphalt(BRAA)under stress control mode to evaluate its fatigue characteristics.The corresponding number of shear times when the complex shear modulus decreased to 50%(N_(f50)),the inflection point of the dissipated energy change rate(N_(fm))and the number of cyclic loading times corresponding to the inflection point of the asphalt complex modulus change curve(N_(fG*))were selected as the evaluation indexes of fatigue performance.The effects of different bio-oil contents,different aging degrees and different stress levels on the fatigue characteristics of BRAA were studied.And the functional group changes of BRAA were also analyzed.The results show that under different testing conditions,the evaluation indexes of fatigue life of BRAA have a consistent ranking,namely N_(fG*)>N_(fm)>N_(f50).The optimal content of bio-oil is ranged from 15%to 20%.Among all evaluation indexes of BRAA,N_(fG*)has the highest and easiest discrimination in evaluating the fatigue performance of recycled asphalt,N_(f50)is simple and efficient.Bio-oil can reduce the content of sulfoxide functional groups in the aged asphalt,increase the content of carbonyl functional groups and low wave number fingerprint regions and promote the regeneration of aged asphalt.