The interaction between asphalt binder and aggregate is fundamental to ensure adequate performance of asphalt mixtures, mainly in the presence of water. The work of adhesion generated between both materials directly affects the resistance of asphalt mixture to moisture damage, because it measures the ease with which water can displace asphalt binder from the aggregate surface. The objective of this study was to characterize the bond strength between asphalt and several aggregate sources. A PG 64-22 neat binder was modified with several additives to determine the effect on adhesion: polymers, nanomaterials, and adhesion promoters. To measure the strength of adhesion, the bitumen bond strength (BBS) test and contact angle measurements between asphalt binder and the aggregate surface by means of goniometry were used. The surface energy of the asphalt and the aggregate, with and without the presence of water, was estimated also. Testing was performed on all binders and on each binder–aggregate combination after ( a) rolling thin-film oven (RTFO) aging and ( b) RTFO and pressure aging vessel aging. The BBS results identified differences in bond strength as a result of moisture conditioning and aging. The differences depended on the aggregate source and binder type. Different failure modes were also observed (i.e., cohesive, adhesive). The results also indicated an increase in strength of adhesion associated with the aging process: the main resistance gain was observed after RTFO aging. Finally, changes in bond strength were compared with functional composition changes associated with the aging process and related to changes in performance.

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The environmental impact of road construction and rehabilitation can be associated with the increase of greenhouse gas (GHG) emissions, which are highly related to climate change. Consequently, departments of transportation have recently focused on the development and implementation of tools to evaluate the performance of projects and minimize GHG emissions. An example is the use of life cycle assessment (LCA) to analyze and quantify the environmental impact of a product, system, or process, from cradle to grave. In this regard, the present case study quantifies the carbon footprint associated with the construction of the La Abundancia–Florencia highway, located in the province of San Carlos in Costa Rica. The analysis is also intended to generate consciousness both in the public and private sectors on the environmental impacts of road construction. After an LCA study, it was determined that the construction of the hot mix asphalt (HMA) layer generates a carbon footprint of 65.8 kg of CO2e per km of road. In addition, it was evident that HMA production generates the greatest environmental impact, among all the considered LCA production and construction stages, with a GHG contribution of 38% to 39% from bitumen only. Consequently, special attention to HMA production is required in order to minimize GHG emissions.

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