关键词: 道路工程；高黏改性沥青；胶体体系；稳定性；Heithaus参数；溶解调合值；不溶性值

Abstract: In order to accurately quantify and evaluate the colloidal system stability of high viscosity modified asphalt, the light transmittance and initial flocculation point of different samples at three dilution concentrations were observed by flocculation titration test. The variation rule of flocculation ratio (FR) and dilution of samples (C) as well as the Heithaus parameter of the colloidal structure were analyzed. The insolubility value (IN)and solubility coordination value (SBN) of different sample solutions at the flocculation point were calculated. The results show that the material flocculation ratio (FR) and dilution value C obtained from the transmittance-time curve during the flocculation titration test have a good linear fitting relationship. From the perspective of solubility parameters, it can be demonstrated that using the gelation state index P to comprehensively evaluate the gelation solubility of asphaltene and the gelation ability of soluble substances in the sample has a specific physical characterization significance. With the addition of high viscosity modified materials, the gelation state index P decreases gradually, and the stability of colloidal structure decreases obviously. As the amount of high viscosity modifier increases, the material colloid system gradually tends to become unstable from a relatively stable compatibility state, resulting in asphaltene flocculation or phase separation phenomena. The curve of ΔTR&B and P value with better correlation could be established through experiment results. Based on the current specification requirement that the softening point difference should not exceed 2.5 ℃, the critical solubility index P value corresponding to this kind of high viscosity modified asphalt is 2.876, and the critical dosage for its colloidal system to maintain relative stability is about 6.4%. Flocculation titration method is a quantitative method to evaluate the overall stability of sample colloid system.

Key words: highway engineering; high viscosity modified asphalt; colloidal system; stability; Heithaus parameters; solubility value; insolubility value