考虑老化作用的沥青-集料界面黏附性评价

Evaluation of Adhesion of Asphalt-aggregate Interface Considering Aging effect

沥青路面水损坏的机理即沥青与集料界面的黏附性丧失,而沥青与集料的黏附性在光、氧等的作用下会有所降低。为探究老化作用对沥青-集料界面黏附性的影响,以70#基质沥青和纳米膨润土改性沥青为试验样品,采用躺滴法在不同老化条件下分别测定了沥青与集料的接触角。基于微观表面能理论计算了沥青的黏聚功、沥青与集料体系的黏附功、剥落功及配伍率。然后分析了RTFOT老化、PAV老化和紫外老化对沥青-集料黏附性的变化规律。最后从宏观水稳定性试验的角度对表面能理论作出了验证。研究结果表明:对于同种老化条件,纳米改性沥青与集料的黏附性要优于基质沥青,纳米改性剂可以降低老化作用对沥青-集料黏附性的影响;对于同种沥青-集料体系,RTFOT老化对黏附性能影响最大,紫外老化影响最小。其中,对于基质沥青RTFOT后,剥落功提高了4%,PAV后提高2.2%,室内紫外光照射15 h后提高了1.4%。对于纳米改性沥青,RTFOT后剥落功提高了2.7%,PAV后提高1.4%,紫外老化后提高0.6%;此外,表面能理论分析的规律与冻融劈裂试验具有较高的契合度,即用剥落功表征的黏附性与TSR表征的水稳定性具有一致性。

The mechanism of water damage on asphalt pavement is the loss of adhesion between asphalt and aggregate interface,and the adhesion of asphalt to aggregate will be reduced under the action of light and oxygen.To explore the influence of aging action on the adhesion of asphalt-aggregate interface,taking the matrix asphalt No.70 and nano-bentonite modified asphalt as the test samples,the contact angles of the asphalt-aggregate interface under different aging conditions are measured by sessile drop method.Based on the microscopic surface energy theory,the cohesive work of asphalt,the adhesion work of asphalt and aggregate system,the peeling work and the compatibility rate are calculated.Then,the variations of asphaltaggregate adhesion by RTFOT aging,PAV aging and ultraviolet aging are analyzed.Finally,the surface energy theory is verified from the perspective of macroscopic water stability test.The result shows that(1)The adhesion of nano-modified asphalt to aggregate is better than that of matrix asphalt under the same aging condition,and nano-modifier can reduce the influence of aging on asphalt-aggregate adhesion.(2)For the same asphalt-aggregate system,RTFOT aging condition has the most serious influence on the adhesion performance,but ultraviolet aging condition has the least influence.Among them,the spalling work for the matrix asphalt increases by 4%,2.2% and 1.4%respectively under the RTFOT,PAV and 15 h of indoor ultraviolet exposure.However,it only increases by 2.7%,1.4% and 0.6%for the nano-modified asphalt under the same condition.(3)In addition,the rule of theoretical analysis of surface energy has a higher degree of fit with the freeze-thaw split test,i.e.,the adhesion characterized by spalling work is consistent with the water stability characterized by TSR.