Summary Reader Response Draft 1: Porous Asphalt Is King of the Road

In the article “Porous Asphalt Is King of the Road”, PaveGreen (n.d.) believes that porous asphalt is “road royalty” as it improves safety, reduces erosion, and mitigates water pollution, all while giving back to the earth. Porous asphalt roads prove to be a sustainable method in reducing pollution due to its natural filtration ability. One of the best applications is found in stormwater management. It can be used on superhighways where it enhances the safety of the road users, especially during winter climates. There is a reduction in the need for deicing and anti-icing practices that contain harmful agents that can be detrimental to the environment and quality of water. It is significantly more cost-effective and environmentally friendly as compared to its conventional counterpart. It is agreeable that porous asphalt is a premium material for surfaces as all the benefits mentioned are non-debatable. However, there are several factors that the article has failed to consider. Porous asphalt's high porosity requires high maintenance. It also has a limit to its application, as well as a short lifespan.

In my opinion, porous asphalt’s forte in its application, which is natural filtration, may be the reason why it is not the best material for pavements. Prolong exposure to water and debris suggests a need for higher maintenance. TrueGrid (n.d.) shares that it is ingenious with the use of porous asphalt to absorb water but in truth, “this porosity and ability to absorb water is very short-lived and super expensive”. Its permeable characteristic allows water to seep through small pores in the pavement. As a result, pollutants get trapped inside and clogging occurs. Porous asphalt becomes susceptible to the freeze and thaw cycles in cold climates, leading to failure. It is necessary for all pavements to undergo periodic maintenance, but permeable pavements require more frequent and routine upkeep. Furthermore, simple broom sweepers are not enough to maintain porous asphalt. Instead, vacuums with a blower system are recommended. For instances where the pavement becomes significantly clogged, a more intensive level of treatment is needed.  Pressure water cleaning is implemented. However, the pressure can neither be too low nor high, as “contaminants may be driven further into the porous surface.” SanDiegoCounty (n.d.).

Another pertinent point is the limit to the application of porous asphalt. Stiffler (2012) compares permeable pavements to “rice crispy roadways” and questions how can its “pervious nature take a pounding from countless cars, trucks, and buses and survive intact”. Its high porosity causes it to exhibit poor durability and strength, limiting its use in pavement applications. Stiffler also shares that this material is restricted for lower traffic areas, such as car-parks, and is not a good fit for commercial areas where there is heavy traffic. However, flooding occurs mostly in areas where there is dense traffic, and what is the good in porous asphalt’s permeability if it is of no use to such areas? Porous asphalt is also vulnerable to soil with high levels of sulfate in them as it causes degradation to its permeable surface. Installers must be extra cautious to ensure that this would not cause any issues in the future (TrueGridPaver, n.d.).  

Finally, porous asphalt has a shorter lifespan. The average life cycle of porous asphalt is assumed to be 20 years, as compared to traditional pavements where it can last up to about 25 years. As observed by Chen, Wang, and Najm (2017), “if the lifespan of porous asphalt pavement is shorter than porous concrete pavement, the environmental benefits of using porous asphalt will be offset by the need for more frequent reconstruction activities.” This implies that the short lifespan causes frequent maintenance, which incurs high economical damage, as opposed to it being cost-effective as mentioned by PaveGreen.

All in all, PaveGreen did educate adequately on the positive aspects of this unconventional pavement but should have reiterated on the other side of the coin to provide a broader perspective regarding porous asphalt. 

Word Count: 644

Reference:

1. PaveGreen. (n.d.). Porous Asphalt Is King of the Road. Retrieved 29 September 2020. From http://www.pavegreen.org/index.php?option=com_content&view=article&id=58:king-of-the-road&catid=35:porous-asphalt&Itemid=110

2. (2020). Porous Asphalt and Concrete Pose Big Problems. TrueGridPaver. Retrieved 6 October 2020, from https://www.truegridpaver.com/porous-asphalt-and-concrete/

3. (n.d.). Porous Pavement Operation and Maintenance Protocol. SanDiegoCounty. Retrieved 9 October 2020, from https://www.sandiegocounty.gov/reusable_components/images/dgs/Documents/Grants_Prop40_AppendIII_.pdf

4. Stiffler, L. (2012). The Porous Road Less Traveled. Sightline Institute. Retrieved 9 October 2020, from https://www.sightline.org/2012/01/03/the-porous-road-less-traveled/

5. Chen X.D., Wang H., Najm H. (2018). Environmental Assessment and Economic Analysis of Porous Pavement at Sidewalk. Lcasymposium. Retrieved 9 October 2020, from https://lcasymposium.ict.illinois.edu/files/2018/01/52_Porous-pavement-conference-paper-2017.1.27-submit.pdf