Surfactants effects on the self-healing properties of asphalt mixtures in a water environment

Under a certain temperature, cracks in asphalt mixtures can heal themselves, but water in the cracks will reduce the self-healing performance of the asphalt mixture. In this study, surfactants were added to asphalt mixtures. In the presence of water, the characteristics of amphiphilic surfactants are used to promote the adsorption between asphalt and aggregates; In this paper, the ability of surfactants to promote the formation of adsorption of asphalt on the crystal surface is verified using a combination of molecular simulations and macroscopic experiments. Molecular simulation results show that the adsorption energies of asphalt and surfactants, surfactants and silica, and asphalt and silica are all negative. Adsorption can occur between the three interfaces, and the surfactants effectively pulls the asphalt molecules onto the silica molecules, achieving adsorption similar to that between asphalt organic polymers and crystals. Macroscopic experiments show that in asphalt mixtures with active agents added, the active agent can be adsorbed on the surface of the aggregate, part of the asphalt is adsorbed on the surface of the active agent, and part is directly adsorbed on the gravel. Some asphalt is also adsorbed on the aggregate under the action of pure water, but the total adsorption capacity is lower than that of asphalt mixtures containing surfactants.