Study On The Factors Influencing The Freezing Adhesion Strength Of Asphalt Materials

Asphalt pavement freezes in winter after snow or rain which results in a significant reduction of friction coefficient between vehicles and pavement.The driving safety and transportation efficiency would be affected and property and life would be lost.It is difficult to remove the ice on the pavement because of the solid freezing between the ice and pavement materials.The fundamental purpose of the road anti-icing is to destroy the bonding interface between the ice and the pavement.It is necessary to start with the low-temperature freezing-bonding characteristics of pavement materials.As the main component of asphalt pavement,it is of great significance for the development of anti-icing and deicing technology of asphalt pavement to study variation law of freeze-bond strength of asphalt surface.Based on the theory of ice surface liquid like layer,a model of freeze-bond between ice and asphalt surface is proposed and the factors affecting the freeze-bond strength of object surface are analyzed.Asphalt samples with different surface properties were prepared by modifying emulsification and adding additives.The samples were iced at low temperature.The effects of wettability,surface freezing point and temperature on the freeze-bond strength of asphalt materials were tested by drawing instrument.The asphalt four-component test method,dielectric constant test and photoelectron spectroscopy were conducted to analysis the influence of asphalt surface micro-characteristics on asphalt freeze-bond strength.The results showed that the main factors affecting the frozen adhesion strength of asphalt surface are contact angle,surface freezing point and temperature according to the theory of liquid like layer.The contact angle of asphalt can be obviously increased by adding silicone rubber in the emulsification process.With the increase of silicone rubber content,the contact angle increases first and then decreases,reaching the maximum of 122~o at 6%content.The influence of contact angle and ambient temperature on freeze-viscous strength basically conforms to the simplified formula of liquid like layer.The relationship between asphalt contact angle and freeze-bond strength can be expressed.The relationship between temperature and freeze-bond strength of asphalt can be expressed.Based on the test results,empirical formulas of asphalt contact angle,ambient temperature and freeze-bond strength are proposed.There is a logarithmic relationship between the freezing point dropΔT(the opposite number of freezing points)and the freezing bond strength of asphalt surface,the influence of temperature and surface freezing point on the freezing bond strength can be expressed.The higher the asphaltene content in asphalt,the greater the contact angle of asphalt.The contact angle of asphalt increases with the decrease of dielectric constant,but there is no obvious linear relationship.Silicon element in silicone rubber modified emulsified asphalt concentrates on asphalt surface to increase contact angle.