Study On Application Of Rubber Asphalt With Warm Additives On Ultra-thin Abrasion Layer

Rubber asphalt has been widely used in road engineering because of its excellent properties of high temperature,low temperature and noise reduction.However,due to its large viscosity and high mixing and compaction temperature,environmental pollution will be caused during the actual construction process.Therefore,four types of warm mix technologies organic wax(RH,Sasobit),zeolite(Aspha-min),surfactant(Evotherm),dilute(Aromatic oil,Kerosene)were added to rubber asphalt to reduce its viscosity,and then the viscosity reduction mechanism was investigated respectively.Subsequently,a optimal warm rubber asphalt technology was recommended to apply to the ultra-thin wear layers through the performance tests in this paper.Firstly,the viscosity curves of rubber asphalt with six kinds of warm additives were tested.The order of the effect of warm additives on the viscosity reduction was as follows: RH>Aromatic oil> Evotherm>Kerosene>Sasobit>Aspha-min.The high and low temperature properties of rubber asphalt with different warm additives were evaluated according to the penetration system,which indicated that the high temperature performance of warm rubber asphalt with Kerosene and the low temperature performance of warm rubber asphalt with Sasobit were the worst.Therefore,three kinds of warm rubber asphalt with RH,Evotherm and Aromatic oil were selected for further performance evaluation.Secondly,the dynamic shear rheometer,bending beam rheometer,optical contact angle meter and infrared spectrometer were used to further evaluate the high,low temperature,adhesion and anti-aging properties of three kinds of preferred warm rubber asphalt.It was found that RH could significantly improve the high temperature performance of rubber asphalt.The rubber asphalt with Evotherm had the best adhesion and anti-aging properties.The low temperature performance of rubber asphalt with Aromatic oil was the best at-12? and-18?,but three kinds of warm rubber asphalt were almost the same at-24?.Therefore,it is preferred to use the warm asphalt with Evotherm and RH.Additionally,the viscosity-reducing mechanism of Evotherm and RH were investigated based on functional groups,surface free energy,molecular weight and micro-nanoscopic morphology.It was found that Evotherm significantly increased the amide group in rubber asphalt,which could interact with colloid and asphalt to form strong hydrogen bonds and reduce the association of asphaltenes.Meanwhile,the free energy of the rubber asphalt surface increased significantly,which could reduce the viscosity of rubber asphalt.RH had a good physical effect on the viscosity reduction of rubber asphalt.It could increase the large molecular weight of rubber asphalt,adsorb around the asphaltenes,and form a wax film,which played a vital role of interface lubrication,and decreased the friction between asphaltene molecules.Therefore,it reduced the viscosity of rubber asphalt.Finally,the anti-sliding,drainage and interlaminar shear resistance of ultra-thin wear layer of rubber asphalt with Evotherm,RH and SBS modified asphalt were tested.It was found that the anti-slip and drainage performance of ultra-thin wear layer of rubber asphalt with Evotherm were better than SBS modified asphalt and rubber asphalt with RH.Therefore,combining with its economic and environmental benefits,it is recommended that the warm rubber asphalt with Evotherm is applied to the ultra-thin wear layers.