| At present,the most widely used road construction is hot mix asphalt mixture(HMA),but the energy consumption and pollution of HMA is high.In order to solve this problem,warm mixing technology emerges as the times require.Warm mixing technology reduces the viscosity of asphalt by adding a warm mixture,thus greatly reducing the construction temperature and ensuring that the performance is not lower than that of the hot mix asphalt.The effect of EC-120 on the performance of asphalt was studied from the macroscopic and microcosmic angles.This paper uses the EC-120 warm-mix agent for two kinds of widely used asphalt(70#asphalt and SBS modified asphalt),prepared into 6 groups of warm mix matrix asphalt samples and 6 groups of warm mix SBS modified asphalt samples with different mixing amount of warm mix agent(0%,1%,2%,3%,4%,5%).Then,the indoor simulated accelerated aging(RTFOT)test and long term aging(PAV)test under the conditions of 148℃ and 163℃were carried out respectively.Then the high temperature dynamic shear rheology test(DSR)and the low temperature bending beam rheological test(BBR)were carried out on the asphalt samples with different aging degree.The test results show that with the increase of EC-120 content,high temperature rutting resistance of two kinds of WMA capabilities continue to increase,after the addition of EC-120 amounts is over 4%,the increase is reduced;at the same time,the low temperature performance of two kinds of WMA decreases continuously,after the addition of EC-120 amounts is over 4%,the decrease increases.According to the above factors,the content of EC-120 warm-mix agent of two kinds of original asphalt should not be higher than 4%.The decrease of aging temperature can reduce the aging degree of warm mix modified asphalt,and meanwhile,the warm-mixed agent itself has a certain delaying effect on long-term aging.Then,the modification mechanism of EC-120 warm-mix agent and aging mechanism of warm mix asphalt were analyzed by means of infrared spectrum,differential scanning calorimetry and other microscopic means.Infrared spectroscopy study found that the chemical reaction with asphalt after incorporation of EC-120,which typically generated in aging after generation of carbonyl groups,carbonyl groups to enhance the performance of asphalt at high temperature and low temperature performance is reduced.In addition,quantitative calculation of carbonyl and sulfoxide functional groups after aging was carried out to verify that lower aging temperature can reduce the aging degree.Differential scanning calorimetry study showed that only a part of the EC-120 warm-mix agent was chemically reacted with the asphalt and partly remained in the asphalt by physical blending.Finally,through 12 groups of different dosage of EC-120 modified asphalt with different water content(0.3%,0.9%,3.1%)boiling test of coarse aggregate,study the influence of moisture content of aggregate and mixing amount of warm mix agent on adhesion property of warm mix modified asphalt.Because of the problems existing in the evaluation of adhesion grade in traditional boiling method,the image method and the mass method are adopted to evaluate the adhesion of asphalt aggregate quantitatively.The results show that the increase of aggregate water content significantly influence the adhesion of asphalt,and the higher water content,the lower the adhesion;the use of EC-120 warm-mix agent can reduce the adhesion of asphalt and aggregate,and the more the amount of EC-120 warm-mixed modifier,the lower the adhesion. |
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