Study On Damage Of Asphalt Stabilized Macadam Under The Coupling Of Load And Sulfate

Corrosion had an external effect on asphalt mixture performance deterioration.The sulfate which is widely present in saline soil will erode asphalt pavement with capillary rise,then crystallization and expansion will occur under the influence of environmental factors.The whole erosion results in attenuation of asphalt pavement performance and intensification of early disease.At present research,sulfate is the only considered factor of the corrosion of asphalt mixture,however,traffic load contributes as well.In view of the above-mentioned fact,this paper studies the damage performance of asphalt mixture in both traffic load and sulfate attack working together,which provides basis for highway design in saline soil areas.Based on the climate and environmental conditions of saline soil areas,the dry-wet cycle accelerated corrosion test was selected and the corrosion coefficient CIC was proposed to evaluate the sulfate corrosion resistance of asphalt mixtures under sulfate attack.The results of uniform test showed that the sulfate type,sulfate solution concentration and the void fraction of asphalt mixture had a significant effect on the mechanical properties attenuation of asphalt mixture.Under the same conditions,the bending tensile strength of asphalt mixture corroded by sodium sulfate solution was 4.4%lower than that of magnesium sulfate solution.The influence of sodium sulfate corrosion solution on mechanical properties of asphalt mixture was more than that of magnesium sulfate solution.According to the actual stress condition of saline soil road surface,mechanical loading mode was carried out to study the influence of sulfate species(environmental factor),sulfate solution concentration(environmental factor),load stress level(mechanical factor),asphalt mixture void ratio(asphalt mixture)on the damage performance of asphalt mixture.Under the coupling of load and sulfate corrosion,the effect of increasing sulfate concentration on the rate of decline of mechanical properties of asphalt mixture was higher than that of load level.The change of the void ratio of asphalt mixture under the coupling of load and sulfate corrosion has a significantly lower influence on the mechanical degradation rate of the asphalt mixture than that of single sulfate corrosion.Corrosion influence coefficient and other correlation factors(void fraction,sulfate concentration,stress level,corrosion age)were selected for ash correlation analysis as follows:.sulfate concentration>corrosion days>void ratio>stress level.The grey system theory and L-M algorithm were used to establish the prediction model of corrosion performance of asphalt mixture.The error analysis showed that the prediction model of L-M algorithm was coincident with the actual,which provided relevant basis for analyzing the service life of asphalt pavement in saline soil areas.The results showed that sulfate ion could not be effectively corroded into the specimen in the early stage of corrosion,and the content of sulfate ion in the mixture increased with the extension of corrosion age.The adhesion between sulfate corrosion aggregate and asphalt was studied by water boiling method.The results showed that the highest adhesion grade decreased by 56%with the increase of dry-wet cycles.Therefore,the stripping of asphalt film caused by sulfate corrosion was one of the important factors affecting the strength attenuation of asphalt mixture.