Study On Properties Of Asphalt And Asphalt Mixture Modified By Phase Change Materials

Asphalt pavement is widely used in the field of highway engineering because of its good smoothness and convenience in construction and maintenance.Asphalt and asphalt mixture materials are temperature-sensitive materials.When it is hot in summer or cold in winter,it is easy to produce high and low temperature diseases,which can cause the asphalt road can not be used normally when it is serious.And because asphalt is black material,asphalt pavement is easy to absorb solar radiation and heat up in summer,causing the "heat island effect" of the city.In this paper,based on the principle of latent heat of phase-change material,polyethylene glycol(PEG),a phase-change material,was applied to modified asphalt,so as to obtain the active temperature regulating phase-change modified asphalt and mixture,so as to alleviate the structural damage caused by high temperature of asphalt pavement in summer.The main research contents and conclusions are as follows:(1)Phase-change asphalt was prepared with polyethylene glycol(PEG-1000)as a modifier.The short-and long-term antiaging performances were characterized by rolling-thin-film-oven(RTFOT)and pressure-aging vessel(PAV)tests,respectively.The functional groups and “bee structures” of PEG-modified asphalt and base asphalt were characterized by Fourier transform infrared absorption spectroscopy(FTIR)and atomic force microscopy(AFM).The research results indicate that the additive of PEG can improve the high-temperature and the anti-aging properties of asphalt.The FTIR reveals that only physical blending and no chemical reaction occurs between PEG and asphalt.AFM topography indicates that smaller “bee structures” appear on the surface of PEG-modified asphalt and these structures do not change during aging.(2)PEG/diatomite composite phase change material(CPCM)was prepared.The microstructure and chemical structure of CPCM were investigated using scanning electron microscopy(SEM)and FTIR.By means of differential scanning calorimetry(DSC),AFM and dynamic shear rheometer(DSR),the effects of CPCM on the thermal properties,morphology and rheological properties of modified asphalt were studied.It was found that the phase change enthalpy of CPCM is approximately 9.0332 J/g,which is up to 60% of the theoretical enthalpy.In the laboratory test,the highest temperature variation of the temperature-adjusting asphalt specimens was ~9.0℃,which plays an effective role in regulating pavement temperature.Small“bee structures” were observed on the surface of CPCM modified asphalt and showed no obvious changes from before to after aging.(3)Using CPCM to regulate the temperature of asphalt pavement is an innovative method to alleviate the hot cracking and rutting of temperature-related pavement.In this study,using CPCM as substitute filler and SMA-13 as the target asphalt mixture,the effect of CPCM on the performance of asphalt mixture was studied.And the self-temperatures-regulating performance of asphalt mixture was evaluated.When the optimal content of CPCM is about 4 %,the maximum temperature change of CPCM modified asphalt mixture specimen is about 7.3 ℃.CPCM may affect the mechanical properties,high temperature stability,water stability and microstructure/microstructure properties of CPCM modified asphalt mixture.The results showed that the high temperature stability increased with the increase of CPCM content,while the water stability decreased with the increase of CPCM content,but still met the requirements of the specification.This study provides some suggestions for the design and application of phase change material PEG in asphalt and asphalt mixture,which has certain theoretical and application value.