Improvement Mechanism of Adhesion Performance of Anti-stripping Agents and Coupling Agents on Asphalt-Aggregate Interface Based on Molecular Dynamics

This study examined the mechanisms for improving the adhesion performance of the asphalt-aggregate interface with two anti-stripping agents and two coupling agents.The investigation of contact behavior between various asphalt-aggregate surfaces was conducted using molecular dynamics(MD)simulations.The interaction energy and the relative concentration distribution were employed as the parameters to analyze the enhancement mechanisms of anti-stripping agents and coupling agents on the asphalt-aggregate interface.Results indicated that the adhesion at the asphalt-aggregate interface could be strengthened by both anti-stripping agents and coupling agents.Anti-stripping agents primarily improve adhesion through the reinforcement of electrostatic attraction,while coupling agents primarily upgrade adhesion by strengthening the van der Waals.Hence,the molecular dynamics modeling and calculation techniques presented in this study can be utilized to elucidate the development mechanism of the asphalt-aggregate interface through the use of anti-stripping agents and coupling agents.

Evaluation on High-temperature Adhesion Performance of Hot-applied Sealant for Asphalt Pavement

In order to investigate the high-temperature performances of the asphalt pavement hot-applied sealant, as well as to reduce failures of the sealant pullout, the softening point test and the flow test（two existing methods for evaluating high-temperature performances） were conducted. It was found that both tests could not accurately reflect the adhesion performances of the sealant at high temperatures. For this purpose, the adhesion test for PSAT（pressure sensitive adhesive tape） has been taken as a reference to develop a device that is suitable for evaluating the adhesion performances, by modifying relevant test parameters according to the road conditions at high temperatures. Thirteen common sealants were tested in the modified adhesion test, softening point test and f low test. The experimental results show that no significant correlation（p〉0.05） exists between the adhesion value, softening point, adhesion value and flow value; while a significant correlation（p〈0.05） exists between the softening point and flow value. The modified adhesion test is efficient in distinguishing the hightemperature adhesion performances of different sealants, and can be used as a standard method for evaluating such performances.

New Adhesive Material for Construction Joint of Tunnel Lining

The new adhesive material for the construction joints of tunnel lining(named as SZC) was studied based on the structural characteristics of interfaces and the characteristic of bonding construction, and the performance indexes were verified by tests. The experimental results show that the adhesive capability of interface is improved effectively by using SZC material, the properties, such as anti-freezing, erosion-resistance and anti-shrinkage are improved greatly as well as durability.

Improved performance of aluminum pigments encapsulated in hybrid inorganic-organic films

An organic silane acrylate resin （PMBK） was synthesized by free-radical solution polymerization using methyl methacrylate, butyl acrylate and （3-methacryloxypropyl）trimethoxysilane as monomers. Aluminum （AI） particles were then encapsulated in inorganic-organic hybrid films that were prepared by hydrolysis and condensation of PMBK and tetraethyl orthosilicate （TEOS） on the surface of AI pigments. Characterization results showed that PMBK and TEOS could simultaneously hydrolyze ancl condense with hydroxyl groups on the surface of the A1 particles to form composite AI particles coated with inorganic-organic hybrid films. Compared with raw AI particles, the corrosion resistance and adhesive properties of paint films containing the composite AI particles were improved greatly, while the glossiness of the paint films decreased slightly, from 48.6° to 47.0°. In alkaline media （pH 11 ）, the volume of evolved H2 of composite AI particles was only 3.5 mL, whereas that of raw AI was 83.5 mL. The glossiness of paint films containing composite A1 particles decreased by 1.66% after immersion in alkaline media for 24h, whereas that of raw AI decreased by 14.82%. Peel-off tests of the paint films showed that the composite particles moved slightly away from the paint films. In contrast, the raw A1 particles were seriously desquamated, suggesting encapsulation of hybrid films can greatly improve the adhesive properties of A1 particles in paint films.