Research On The Characterization Model For The Ice-pavement Adhesion Strength Based On The Quasi-liquid Layer Theory

The traditional research on anti-icing pavement mainly focuses on the development and design of anti-icing materials,while the adhesion mechanism and adhesion strength between ice and pavement between are not yet clear.The Quasi-Liquid Layer(QLL)model is a relatively well-developed theory which can explain the icesubstrate adhesion on the basis of the capillary adhesion phenomenon,and therefore be used to predict the icesubstrate adhesion strength.However,for the QLL model of the ice adhesion on pavement materials,the model parameters have not been determined yet,and correspondingly the impact of the pavement features on the ice adhesion strength has not been studied quantificationally.Based on the Low Surface Energy(LSE)or Low Freezing Point(LFP)asphalt and asphalt mixture,this dissertation studies the adhesion models between ice and asphalt-based materials.The main research content includes:Based on the ice-adhesion strength variability and the fracture interface stability,a set of ice-adhesion strength characterization methodologies were proposed,which included the optimizations on the interface modification,ice layer thickness and freezing period.Anti-icing asphalt-based materials were developed including LSE and LFP asphalt and asphalt mixture,based on which a novel synchronous characterization method for freezing point and ice-adhesion strength was proposed,and the empirical relationships between the freezing point,contact angle,environmental temperature and the ice-adhesion strength were built.On the basis of the QLL theory and capillary adhesion model,a three-factors prediction model was established,which can accurately predict the adhesion strength between ice and asphalt-based materials with three inputs including freezing point,contact angle and environmental temperature.The main findings includes:i.With the environmental temperature decreases,the interface fracture form in pulling-off test transforms from adhesion fail to cohesion fail.Due to the influence of the pavement surface texture,the interface fracture form of shearing test is cohesion fail under the temperature involved,which indicates that the shearing test can not reveal the actual adhesion strength between ice and asphalt.The variabilities of pulling-off strength between ice and three types of asphalt-based materials all decrease as the temperature drops down.The pulling spins made with cement mortar or covered with polyester mat on bottom side have better bonding with the ice,and lead to a lower variability during pulling-off test.The experimental parameters for pulling-off test conducted on three types of asphalt-based materials were optimized with the principle of best data stability.ii.LSF emulsion and micro surfacing were developed,and the relationships between their engineering performances and hydrophobic modifier dosage were studied,which demonstrated a optimal dosage of 2% by mass.LFP asphalt matrix and mixture were developed,and the correlations between their engineering performances and the dosage and usage of the anti-freezing filler were investigated.The results suggest that the anti-freezing filler be added by replacing the mineral filler by volume,and the maximum dosage of it in the LFP mixture is 75% by the volume of mineral filler.iii.A novel synchronous characterization method for freezing point and ice-adhesion strength was proposed,and the impacts of freezing point and contact angle on ice-adhesion behavior of asphalt-based materials were studied.The ice-adhesion strength on asphalt-based materials has a negative logarithmic correlation with the contact angle and freezing point,and a negative linear relationship with the environmental temperature.The LSE asphalt-based material mainly achieved anti-icing by reducing the growing rate of the ice-adhesion strength,while the LFP asphalt-based material can lower the ice adhesion strength through reducing strength increasing rate and postponing initial adhesion temperature.The asphalt with larger proportions of asphaltene and resin tends to obsess a higher polarity and lower contact angle,which leads to a stronger adhesion with ice.iv.Based on the QLL theory and capillary adhesion model,single-factors theoretical relationship formulas were built between the ice-adhesion strength and the contact angle,freezing point,and environmental temperature.And the QLL wetting parameters and thickness parameters were proposed.The changing rules of the QLL parameters were studied with the experimental data of ice-adhesion strength on LSE and LFP asphalt-based materials,and furthermore a three-factors prediction model were established the parameters changing rules,which can predict the ice-adhesion strength with a error smaller than 15% for normal asphalt and LSE asphaltbased materials,and a error smaller than 25% for LFP asphalt-based materials.