The article “Porous Asphalt..,” on the website Pave Green (n.d.), stated that porous asphalt is advantageous to the environment, enhances safety and is cost-effective. Porous asphalt is manufactured such that gaps are present for water to pass through and to a filtration bed underneath. As a result, it prevents flooding, filters contaminants in the water and enhances water standard. The article also mentioned that water spatter from vehicles vanishes, hence improving visibility for motorists, and reducing traffic accidents. Maintenance during winter is low, in view that minimal salt is required to remove snow on roads since snow liquefies at a faster rate on porous asphalt. Consequently, the use of pollutive de-icing agents is eliminated. The article also stated that porous asphalt costs about the same as standard asphalt, however, the overall construction cost is lesser due to the reduced need for building of pipes and ground excavation.
While the article “Porous Asphalt…,” on the website Pave Green (n.d.), addresses the boons offered by porous asphalt (PA) in stormwater management and traffic safety, the lack of information regarding its design constraints and material performance due to climate change, makes the article less than satisfactory in promoting the material’s status as ‘King of the Road’.
A key factor of climate change that affects PA is the increase in moisture due to heightened precipitation. Makkonen et al. (2010) projected that the most significantly affected area where precipitation is expected to increase in Europe, due to increased heavy rain spells, is in northern European regions in contact with the Atlantic Ocean, as well as mountainous and elevated areas. The impact of additional precipitation on PA will be dependent on the ability of the underlying mixtures of the pavement. In the event the underlying pavement is not well compacted and becomes impermeable, water will accumulate under the surface and lead to scouring (loss of soil) of the lower layer mixture (D’Angelo & Anderson, 2003; Solaimanian et al., 2003). Most importantly, moisture causes functional deterioration of a pavement mixture by loss of the adhesive bond between the asphalt cement and the aggregate surface, hence threatening the strength and durability of the layer.
PA, like any other conventional asphalt mixtures, can also be affected by temperature increase due to climate change. In the event of increased temperatures, it is possible that porous pavements will experience permanent deformation if the pavement temperatures exceed the design temperatures. This may lead to uneven road compaction and release of trapped water within the air void structure. Thodesen and Hoff, 2010 concluded that continued temperature variation could also lead to cyclic loading of the saturated pavement, thus leading to the development of increased pore pressures and ultimately increased possibility of moisture damage. In some cases porous pavements retain moisture longer than conventional pavements. Additionally, studies have shown that when using porous pavements stripping occurs in the layers underlying the porous section of the pavement. Therefore, according to Roberts et al., 1996, in the event that a porous pavement solution is used it is of utmost importance for the underlying pavement section to be tested for moisture susceptibility (as cited in Thodesen and Hoff, 2010).
Ultimately, as with all other pavement types, the success of PA is dependent upon proper design and construction. When properly designed and built, the PA surface should be a viable option when working in tandem with an integrated pavement system to serve a more deserving recognition for the title of ‘King of the Road’.
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Bibliography
Thodesen, C., & Hoff, I. (2010, June). Study of Water Effects on Asphalt and Porous Asphalt(Rep. No. 5). Retrieved February 4, 2018, from RoadERA.net website: http://www.cedr.eu/download/other_public_files/research_programme/eranet_road/call_2008_climate_change/p2r2c2/08_Deliverable-N5.pdf
umar abdul aziz 