Search Results (2)

Permeable-pavement design methodologies can improve the hydrologic and therefore the environmental benefits of rural and urban roadway systems. By contrast, conventional impervious pavements perturb the hydrologic cycle, altering the relationship between the rainfall loading and runoff response. Impervious pavements create a hydraulically conductive interface for the transport of traffic-generated chemicals and particulate matter (PM), deleteriously impacting their proximate environments. Permeable-pavement systems are countermeasures to mitigate hydrologic, chemical, and PM impacts. However, permeable pavements are not always equally implementable due to costs, PM loadings, and design constraints. A potential solution to facilitate environmental benefits while meeting the traffic load capacity is the combination of two filtration systems placed at the pavement shoulders and/or pedestrian sidewalks: a bituminous-pavement open-graded friction course (BPFC) and an aggregate-filled infiltration trench. This solution is presented in this manuscript together with the methodological framework and the first results of the investigations into designing and validating such a combined system. The research was conducted at the laboratories of the Polytechnic University of Bari and the University of Florida, while an operational and full-scale physical model was constructed in Bari, Italy. The first results presented characterize the PM deposition on public roads based on granulometry (particle size distributions (PSDs) and particle number densities (PNDs)). Samples (n = 16) were collected and analyzed at eight different sites with different land uses, traffic, and pavements from different cities (Bari and Taranto, Italy). The PM analysis showed similar distributions (PSDs and PNDs), except for two samples. The gravimetric-based PSDs of the PM had granulometric distributions in the sand-size range. In contrast, the PNDs, modeled by a Power Law Model (PLM) (R² ≥ 0.92), illustrated an exponentially increasing number of particles in the fine silt and clay-size range, representing less than 10% of the PSD mass. Moreover, the results indicate that PM sourced from permeable-pavement systems has differing impacts on the pavement service life. Full article

Open-graded bituminous concrete (OGBC), also known as open-graded friction course or permeable asphalt layer, is a skid-resistant surface applied to pavements with high bitumen content. This mixture contains more coarse aggregates than fine aggregates, which improves subsurface drainage and indirectly reduces hydroplaning potential during wet weather conditions. The objective of the present study was to enhance the properties of the OGBC mix with fibers. Hence, four distinct natural biofibers, namely, sisal fiber, jute fiber, coir fiber, and bamboo fiber, were considered during experimental investigation at different dosages like 0.15%, 0.3% & 0.45% by weight of mix. Binder content levels ranged from 5 to 6% with an increment of 0.25% between the values in the range. Fiber-reinforced OGBC mixes were tested for air voids (%), draindown, resistance to moisture susceptibility, Cantabro loss, and indirect tensile strength of the compacted mixtures. The experimental findings demonstrate that fibers enhance the performance of OGBC mixes. Fiber incorporation reduced binder draindown and the percentage of air voids in OGBC mixes while maintaining the desired characteristics. The optimal fiber content was determined to be 0.30% for sisal, bamboo, and coir fibers and 0.45% for jute fibers. With the addition of sisal fibers at a dosage rate of 0.30%, the tensile strength of the OGBC mixture increased along with resistance to susceptibility to moisture. Full article