Determination of the performance of hot asphalt mixtures of nominal size 9.5 mm and in 12.5 mm modified with nano-silica

Nanomaterials have been considered as good modifiers of the performance of asphalt mixtures due to their excellent mechanical and thermal properties. Costa Rica only has one type of asphalt, which is why the need arises to implement techniques to adapt it to the requirements of the country. The project intends to evaluate the benefits that the addition of nano-silica in the asphalt mix brings in different concentrations and using granulometries of 12.5 mm and 9.5 mm. The modification of the asphalt with 3% and 6% of nano-silica is carried out, the performance of the binder is characterized and evaluated. The performance of the mixtures is then evaluated by the following tests: Hamburg wheel, repeated semicircular bending test, retained resistance to diametral stress and dynamic modulus. First, the results of the binder of the mixture are evaluated individually, to finally compare the performance of both. It is obtained that the effects produced by the nano-silica in the binder and in the asphalt mix are congruent. The modification generated an increase in stiffness, which translates into less permanent deformation, however it caused a decrease in fatigue life, in terms of moisture damage, asphalt mixtures do improve, however the modified asphalt with 6% presents negative effects. In general, the asphalt that presented the best performance was modified with 6% nano-silica and the mixture was 12.5 mm with 6% nano-silica. Taking into account the manufacturing process of the mixture, transportation and placement, in addition to the economic cost of using nano-silica in the asphalt, the 12.5 mm mixture with 3% NS could be recommended, since the difference between the benefits of using one mixture or the other is very little