Investigating use of nano coating over the aggregate surface on moisture damage of asphalt mixtures

Today, to improve adhesion between asphalt binder-aggregate and to reduce moisture susceptibility in asphalt mixtures several methods are used. One of this method is aggregate treatment using coats which cause to change aggregate polarity especially sensitive aggregate against moisture damage such as acidic aggregates. In this study, effect of nanomaterial coating on aggregate over moisture damage of HMA by means thermodynamic and mechanical methods has been probed. Aggregates used in this study are granite and limestone that have been modified by using Iron oxide and Aluminum oxide nanoparticles. Results illustrate that in comparing modified samples through nanoparticles with control samples, tensile strength ratio on moisture condition surpass dry condition. Surface free energy result shows that aggregate coat with nanoparticles lead to decrease differences between free energy of adhesion in moisture condition and dry condition and thus stripping event is diminished. Additionally, aggregate coating with use of nanoparticles led to better wettability over aggregate by asphalt binder. Nanoparticles positive performance of Iron oxide compared with Aluminum oxide nanoparticles in decreasing moisture sensitivity of asphalt mixtures built is more evident about either kind of aggregates.

Keywords:

moisture damage , nanoparticles , modified Lottman test , surface free energy