基于常规、疲劳与愈合-疲劳试验的沥青再生性能研判

Research and Judgment of Asphalt Regeneration Performance Based on Routine,Fatigue and Healing-Fatigue Tests

为充分认知RAP废旧沥青再生性能,分别借助常规力学性能试验、疲劳性能试验和疲劳-愈合-疲劳性能试验,针对不同老化程度废旧基质沥青和废旧SBS改性沥青添加4%~12%再生剂进行评价,并对比探讨不同评价方法及其特征指标的再生规律。结果表明:当再生剂掺量以2%幅度增加时,再生基质沥青和再生SBS改性沥青各项常规力学性能指标呈线性或多项式函数逐步恢复,而复数剪切模量G^(*)和疲劳寿命N_(f)基本以均等程度发生衰减,愈合指数HI以10%~30%增幅显著提高。其中,再生剂对废旧基质沥青和长期老化沥青的改善效应明显分别高于废旧SBS改性沥青和短期老化沥青,并且在应力控制模式下,各项行为结果的变化规律均较应变模式下清晰。以原样沥青为性能还原基准,当采用疲劳性能试验评价时,所需再生剂掺量最多,在12%及以上;当采用常规力学性能试验评价时,所需再生剂掺量居中,在10%~12%及以上,选择高温性能指标进行研判时可取下限值;当采用疲劳-愈合-疲劳性能试验评价时,所需再生剂掺量最少,在8%~12%区间内。推荐采用疲劳-愈合-疲劳试验替代疲劳性能试验,并采用及愈合指数HI替代G^(*)和N_(f)研判再生沥青流变力学性能恢复情况。

To master the regeneration performance of reclaimed asphalt adequately,the conventional mechanics properties test,fatigue properties test and fatigue-healing-fatigue properties test were carried out respectively,and the waste matrix asphalt and waste SBS modified asphalt with different aging degree were evaluated by adding 4%~12%regenerant.And the regeneration laws of different evaluation methods and their characteristic indexes were compared and discussed.The results show that when the amount of rejuvenation agent is increased by 2%,each conventional mechanical performance indes of reclaimed matrix asphalt and SBS modified asphalt is restored gradually by linear equation or polynomial function,while the complex shear modulus G^(*)and fatigue life N_(f) are attenuated by equal range,and the healing index HI is increased by 10%~30%remarkably.Moreover,the improvement effect of rejuvenation agent on waste matrix asphalt and long-term aging asphalt are significantly higher than that of waste SBS modified asphalt and short-term aging asphalt,and the change rule of each behavior result under the stress control mode is clearer than that under the strain control mode.Taking the original asphalt as the performance recovery benchmark,when the fatigue performance test is used for evaluation,the amount of rejuvenation agent required is the most,which is 12%or more.When the conventional mechanics test is used for evaluation,the amount of rejuvenation agent required is the modest,which is 10%~12%or more,and the lower limit value is taken when the high temperature performance indexes are used.When the fatigue-healing-fatigue performance test is used for evaluation,the amount of rejuvenation agent required is the least,which is usually in the range of 8%~12%.It is recommended to apply the fatigue-healing-fatigue test and healing index HI instead of the fatigue test and complex shear modulus G^(*)and fatigue life N_(f) to judge the recovery of rheological mechanical properties of reclaimed asphalt.