Experimental evaluation of the influence of surface coating on fiberglass geogrid performance in asphalt pavements

In road infrastructures, the maintenance of existing pavements is one of the most important issues to deal with. In order to optimize rehabilitation costs and increase pavement service life, innovative technical solutions have been developed. One of the most widespread techniques introduced for this scope, consists in the application of geogrids at the interface between different layers of pavement structures. Geogrids provide different performance depending on their characteristics, such as constituent materials, surface coating, mesh geometry and dimensions, and on their position in the pavement structure. In fact, these materials can be placed between different layers (bounded and/or unbounded) carrying out different functions. In this survey, the reinforcement of asphalt concrete layers was studied in laboratory, paying particular attention to the effects that different surface coatings, consisting in different treatments of the surface of the mesh elements of the geogrid, produce on the performance of fiberglass reinforced asphalt concrete specimens. The experimental analysis was carried out in two different stages. During the first stage, the coatings themselves were investigated, studying their adhesion properties with a conventional asphalt binder, in order to check their capability to adhere to the constitutive material of an asphalt concrete. During the second stage, a specific testing protocol was followed in order to investigate the performance of double-layered asphalt concrete specimens by means of interlayer shear tests and four-point bending tests. The results showed that the testing protocol used is suitable for studying, in laboratory, the performance of reinforced pavements, that could be influenced, both in terms of interlayer bonding between asphalt concrete layers and four-point bending test characteristics, by the application of a coating on the surface of the geogrids.