effects of spraying various nanoparticles at early ages on improving surface characteristics of concrete pavements

In this study, the effects of spraying nanoparticles with different geometries (nano-sio2, nano-halloysite, and nano-montmorillonite) on surface characteristics of concrete pavement in terms of microstructure. the initial and final setting times of mixtures were determined to investigate the proper spraying time for applying on the pavement surface at early ages. to precisely investigate the microstructural properties, scanning electron microscopy (sem), fourier transform infrared spectroscopy (ftir), and atomic force microscopy (afm) were used. the results revealed that spraying nanoparticles improved the abrasion and skid resistance as well as transport properties of the concrete surface, especially at the initial setting time. according to the tribology testing, the surface friction coefficient of sprayed samples compared to the reference sample (not sprayed) was increased 28%, on average. afm results verified that this growth is due to the improved surface roughness and van der waals forces. based on the ftir results, the abrasion resistance of the samples gradually diminished by increasing the depth due to reduction of nanoparticles penetration, thus, reducing its positive effect. in addition, a good relationship with regression coefficient of 0.79 was found between the surface tensile strength and the abrasion resistance of the specimens.