| The asphalt pavement is subjected to complex traffic loads and external environment during service,resulting in fatigue cracking.This has become a bottleneck technical problem that restricts the realization of"long-life"service of road infrastructure.Asphalt material has a certain healing ability,so that micro-cracks can be actively repaired when there are no traffic loads,prolonging the actual service life of the pavement.The damage healing of asphalt materials widely exists in various periods of pavement service.Therefore,understanding and quantifying the damage healing characteristics of asphalt materials is particularly important for pavement structure and material fatigue resistance design and performance prediction.The objective of this work is to study damage healing characteristics of asphalt and asphalt mastic.Firstly,the healing performance of asphalt is studied based on linear amplitude sweep(LAS)test,and then the characterization method of damage healing characteristics of asphalt binder under different loading modes is explored,and the damage healing criterion is established,and extend to asphalt mastic scale for validation.The healing characteristics and correlation characteristics of asphalt and asphalt mastic are further compared and analyzed.The main conclusions are as follows:(1)Evaluating the healing performance of asphalt by accelerated fatigue test,the healing ability ranking of asphalt of the same penetration grade generally aligned with elevated damage status;For asphalts with different penetration grade,the higher the penetration grade,the better the healing performance;The rate of healing(H~R)of the17 binder sample conditions varied between 0.1 and 0.2 at 10 Hz and 20℃.Furthermore,64 candidate simplified LASH(S-LASH)test of standard healing-based LAS(LASH)test were proposed and compared.Experimental results show that 50%damage status(50%S_f)with a 900s rest period(900s RP)to be a critical LASH teasing condition to obtain identical healing mastercurve(HMC)and H~R for the tested binder.(2)Damage healing(ΔS)and local life compensation(ΔN)is proposed based on a comparative study of LASH and TSH.Although the damage healing and local life compensation are quite different in terms of the asphalt damage healing ability,there is a good correlation between them.Further,in the evolution of asphalt pseudo strain energy considering damage healing,which indicates the average stored pseudo strain energy(Q_H)to offset the damage healing effect during the secondary loading after the interval is only affected by the strain level,and increases with the increase of the strain level,but independent of damage status and rest period,applicable to both LASH and TSH tests.In addition,the asphalt damage healing criterion is established based on theΔS,ΔN and rate of average stored pseudo strain energy(Q_H~R)index system,which lays the foundation for the prediction of asphalt healing performance in the future.(3)The evaluation of the asphalt healing mastercurve and the characterization method of the damage healing characteristics were verified on the asphalt mastic scale.However,the S-LASH test scheme of the standard LASH test has certain limitations in the application of asphalt mastic.Meanwhile,the addition of mineral powder does not change the fatigue damage development trend of the material in the LAS test,but the influence on the healing mastercurve has the dependency of asphalt types,mineral powder has a negative effect on the fitting of the healing master curve of LT-SBS-1.0asphalt mastic.In addition,based on the Q_H and damage healing criteria,the healing correlation characteristics between asphalt and asphalt mastic were explored,and it was found that the addition of mineral powder had a single effect on the Q_H index,regardless of the loading modes and the type of asphalt.The healing performance of asphalt and asphalt mastic based on the Q_H index can be better correlated analysis results,and the damage healing criteria of asphalt and asphalt mastic also have a certain correlation. |
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