| WMA technology is a new green road construction technology and new materials.Compared with HMA,the construction temperature of WMA is reduced by about 30°C,as well as reducing energy consumption by nearly 35%,reducing greenhouse gas emissions by30%and dust emissions by 45%.Due to the lower aggregate heating temperature of WMA,there is more residual moisture in the aggregate,resulting in lower adhesion ability of the warm mix asphalt-aggregate interface,so the water damage is more likely to occur than HMA.At the same time,asphalt as a polymer material is prone to aging under the influence of light and heat,thus affecting the road performance.In the aging research of WMA,many heat-aging researchs have been completed and a unified test procedure has formed.However,there are few ultraviolet aging research and have no clear standard;especially in the selection of ultraviolet light source and application of equipment has no consensus yet.Although ultraviolet light accounts for only 5%in the solar spectrum,it has the shortest wavelength and the highest energy,which can destroy the molecular structure of the asphalt material,leading to the attenuation of asphalt pavement performance and accelerating the attenuation of the adhesion performance of the warm asphalt-aggregate system.So the UV aging of warm mix asphalt cannot be ignored.In order to investigate the effect of raw materials and dosage on the adhesion characteristics of warm mix asphalt,Evotherm M1?0%,0.5%,1.0%?and Sasobit?0%,1.5%,3.0%?warm mixing agent were added to the matrix asphalt?SK,ZH and KL?to prepare warm mix asphalt.Accelerated UV aging of asphalt samples by self-developed asphalt ultraviolet aging indoor acceleration simulation system.On this basis,,,the contact angles of warm mixed asphalt with distilled water,glycerol and formamide before and after UV aging were measured by the lying drop method.Based on the surface energy theory,the surface energy and its components,cohesive work,adhesion work,exfoliation work and compatibility rate of warm mix asphalt before and after UV aging were obtained.The effect of UV aging on the adhesion properties of warm mix asphalt was studied.This is used to characterize the adhesion properties of the warm mix asphalt.Combined with the infrared spectrum image,the influence of the type and amount of raw materials on the warm mix asphalt was analyzed based on the characteristic functional groups.In order to further explore the effect of UV aging conditions on the adhesion properties of warm mixed asphalt,the SK90#matrix asphalt commonly used in Gansu Province was selected as the original asphalt to prepare warm mixed asphalt.Rotating film oven aging?RTFOT?,ultraviolet aging?UV?and pressure aging?PAV?tests were performed on the warm mix asphalt.Evaluation of adhesive properties of warm mix bitumen by using surface free energy and functional group index as.,and compare the changes of infrared spectrum of warm mix asphalt before and after UV aging.At the same time,according to the change of the functional group index in the infrared spectrum,the influence of UV aging on the chemical structure of the warm mix asphalt was quantitatively characterized.On this basis,the correlation analysis between different adhesion characteristics index and warm mix asphalt functional group index was carried out to establish the intrinsic relationship between chemical structure and adhesion performance of warm mixed asphalt under UV aging conditions.Research indicates:?1?Among the three kinds of matrix asphalts,KL asphalt has the largest surface energy and its component,SK asphalt is the smallest;KL asphalt has the strongest resistance to cohesive failure,and SK asphalt has the highest possibility of cohesive failure.Combined with the changes of adhesion work and exfoliation work of three kinds of asphalt and limestone aggregates,it is known that the adhesion of ZH asphalt and limestone aggregates is the best,SK asphalt is the second,and KL asphalt is the smallest.Comparing the contact angle of warm asphalt with oxygen and photo-oxygen coupling,it was found that the participation of oxygen in UV aging accelerated the aging process of asphalt.?2?The addition of Evotherm M1 warming agent makes the surface energy and its component,cohesive work,adhesion work and compatibility rate of warm mix asphalt greatly improved compared with matrix asphalt,and the peeling work is relatively reduced.Evotherm M1 warming agent can improve the adhesion performance of asphalt to a certain extent;on the contrary,the contact angle,surface free energy and its components,cohesive work,adhesion work,exfoliation work and compatibility ratio of asphalt after the addition of Sasobit warming agent develop toward the direction of reduced adhesion properties.UV aging resulted in overall poor adhesion of Evotherm M1 and Sasobit warm mix asphalt to limestone aggregates.?3?The sulfoxide-based?S=O?stretching vibration absorption peaks are common at1032cm-1 for the three kinds of matrix asphalt and the two kinds of warm asphalt.The carbonyl?C=O?characteristic functional group generally appears at 1700cm-1 after UV aging and PAV aging,and the peak and area of the functional group increase with the aging time;the peak and area of the sulfoxide group?S=O?functional group at 1030cm-1 slightly increased,and the sulfoxide group undergoes slight thermal oxygen aging under short-term hot oxygen conditions.?4?The carbonyl index has a good correlation with the adhesion properties of matrix asphalt and 3%Sasobit warm asphalt after UV aging;The adhesion work and exfoliation work of Evotherm M1?0.5%,1%?warm mix asphalt and 1.5%Sasobit warm mix asphalt after UV aging are highly correlated with sulfoxide base index;Comparative analysis found that the Evotherm M1 warming agent dosage is 0.5%,and the Sasobit warming agent dosage is 3%,which is relatively more suitable for use in strong UV areas. |
PDF Full Text Request