Characterization and Evaluation of Micronized Tire Rubber Asphalt Surface for Improved Hydrophobicity

Abstract

A simple method for developing a superhydrophobic (SH) asphalt binder surface was developed and examined. This was achieved by thermally fusing micronized tire rubber (MTR) particles on to the asphalt binder surface. Two MTR particle size ranges were prepared, dispersed on the asphalt binder surface, and then cured for durations of 25, 45, and 70 min to investigate the effect of curing time on the contact angle (CA) of MTR–asphalt surface. Sessile drop method was used for CA measurement. Surface profile and morphology of MTR–asphalt interaction were studied and characterized using optical profilometer and scanning electron microscope, respectively. All prepared MTR–asphalt surfaces exhibited an increased CA with a minimum of 36% improvement as compared to the reference. MTR with a higher percentage of smaller particle size cured for 25 min demonstrated the maximum improvement of 42%. In general, the MTR particles transformed the asphalt binder surface by inducing subsurface and surface stresses through embedding and surface bonding to the asphalt, respectively. Effectively stretching the asphalt and altering its surface texture to radially stretched and fine asphalt surface. The intrinsic hydrophobic property of MTR and its induced modification of the asphalt surface can be associated with the improved hydrophobicity of the develop MTR–asphalt surface.