乳化沥青胶浆对RAP裹覆程度的量化评价

Quantitative Evaluation of Emulsified Asphalt Mortar on RAP Coating Degree

针对乳化沥青与再生集料RAP黏附性不足而导致沥青与集料界面黏附性能薄弱,引发沥青路面耐久性差、服役年限短等问题,以不同掺量水泥作为外掺剂,制备乳化沥青胶浆,利用布氏黏度计测试其黏度,动态剪切流变仪(DSR)测试胶浆复数模量G^(*)和相位角δ,Zeta电位仪测定胶浆电位变化特性,确定了水泥和乳化沥青合理掺量;通过改进水煮法、光电比色法以及FTIR-ATR,GPC等微观分析手段研究了乳化沥青胶浆对RAP的裹覆特性,构筑了乳化沥青胶浆对RAP的"接触-裹覆-破乳-胶结"四阶段裹覆模型,并提出裹覆评价指标RCD,从而量化分析了乳化沥青胶浆对RAP的裹覆程度。研究结果表明:固定乳化沥青含量,随着水泥掺量增加,乳化沥青胶浆黏度增大直至凝固;最佳水泥与沥青质量比(30∶48)能够提高乳化沥青胶浆黏度,增加复数模量G^(*)并延缓相位角δ增长速度,提高胶浆抵御高温变形能力;水泥加入不利于保持乳化沥青胶浆体系稳定性;改进水煮法和光电比色法都能有效评价乳化沥青胶浆对RAP的裹覆性能,其中,纯乳化沥青对RAP裹覆程度最低,合适的水泥掺量利于增强乳化沥青胶浆对RAP裹覆程度,当水泥与沥青质量比为30∶48时达最佳;GPC测试结果和改进水煮法及光电比色法的结果具有一致性,且RCD能够从微观角度定量地评价乳化沥青胶浆对RAP裹覆程度。

For the low adhesion between emulsified asphalt and RAP(Recycled Asphalt Pavement), which leads to the weak bonding performance between asphalt and aggregate interface, causes the poor durability and shorter service life of asphalt pavement, this work took cement of different dosage as the additive agent, emulsified asphalt mortar was prepared;and the Brookfield viscometer was used to test the viscosity of the mortar, DSR(Dynamic Shear Rheometer) was chosen to test the complex modulus G^(*) and phase angle of the delta;zeta potentiometer was used to test the potential change characteristic of the mortar;then the reasonable content of cement and emulsified asphalt was chosen. By means of microscopic analyses, such as improved boiling method, photoelectric colorimetry, FTIR-ATR(Fourier Transform Infrared Spectrometer-Attenuated Total Reflection), GPC(Gel Permeation Chromatography), the coating characteristics of RAP by emulsion asphalt slurry were studied, and a four-stage model of "contact-coating-demulsification-adhesion" between emulsified asphalt mortar and RAP was constructed. RAP coating degree(RCD) was proposed to quantitatively evaluate the coating degree of RAP from emulsified asphalt mortar. The results show that, when the content of emulsified asphalt is fixed, with the increase of cement content, the viscosity of emulsified asphalt mortar increases until solidification. When it keeps a suitable mass ratio of cement to asphalt(C∶A is 30∶48), the viscosity of emulsified asphalt mortar is higher, and the complex modulus G^(*) increases and the increase speed of phase angle is slowed down, the ability to resist high-temperature deformation is enhanced. The addition of cement is not conducive to maintaining the stability of emulsified asphalt mortar system. The improved water boiling method and photoelectric colorimetric method can effectively evaluate the coating degree of RAP with emulsified asphalt mortar;the coating rate of RAP is the lowest when coated with emulsified asphalt while a suitable mass ratio of cement to asphalt in mortar(C∶A is 30∶48), which is beneficial to improve the coating degree of the mortar to RAP. The GPC test results are consistent with the improved boiling method and photoelectric colorimetric method. Moreover, RCD can quantitatively evaluate the coating degree of emulsified asphalt mortar on RAP from the micro perspectives.