Summary/Reader Respond Draft #2: Porous Asphalt Is King Of Road
The article “Porous Asphalt Is Kind
Of The Road” (PaveGreen n.d.) introduces the features and application of porous
asphalt, a type of road surface used to improve safety, diminish water
pollution and decrease erosion. The article states that porous asphalt
is made up of rocks glued together with asphalt cements while lowering the
amount of fine aggregate. This allows rainwater to seep through the
space between the rocks and limiting the flow rate of water therefore reducing
surface runoff, there are multiple ways to combine porous asphalt to
achieve different objectives. It was further stated in the article that
during winter climate porous asphalt requires less anti icing
which reduces the amount of chloride from being released into the
environment which is toxic to aquatic life. On highways, spaces in between the
rocks allow rainwater to seep in between and reduce the splashes thus improving
visibility and safety for vehicles.
The
article mentioned that the porous asphalt roads cost relatively the same as
conventional asphalt. Typically porous asphalt is used together
with a base layer such as stone recharge bed to achieve optimal result.
However, this results in a higher cost for installing porous asphalt. On
the other hand, the cost difference can be offset from the reduced
amount of stormwater pipe and inlet being built.
The article mentioned the benefits and multi-purpose application of the porous asphalt. While porous asphalt seems to outshine traditional roads, there are disadvantages such as routine assessment and maintenance which are required to ensure porous asphalt are in optimal condition. The durability of porous asphalt is also a cause of concern. When compared with traditional road pavement, porous asphalt have high void content therefore leading to lower durability. These disadvantages significantly affect the applicability and cost of maintaining porous asphalt roads. Porous asphalt roads can only replace traditional road if provided with suitable conditions and specialist personnel. Porous asphalt can be a more ecological and greener alternative to traditional road under these conditions.
Firstly, porous asphalt road allows rainwater to sink through the pavement surface. Rainwater will wash contaminant such as minerals and oils into porous asphalt roads. When occurs over a long period of time, particle ands contaminant tend to get trapped inside porous asphalt. Hence, routine assessment are required to understand the the clogging situation and schedule maintenance, if left unchecked and untreated the pores of porous asphalt roads will be blocked. According to Ma, Y. et al. (2020) the clogging characteristic of the porous asphalt pavement is a common problem owing to deposition of sediments on the pavement surface. Thus, over a period of time the pavement will be clogged and causes 59% - 75% reduction in permeability. Research done by Razzaghmanesh, M. et al (2018) mentioned that there is no one fit for all method of assessment and monitoring porous asphalt. Assessment and monitoring should be conducted early after installation even if there are no signs of blockage while it provides better understanding about the in-situ clogging mechanisms for the particular region. Routine assessment of porous asphalt pavement condition will provide the clogging statistic. Subsequently, maintenance can be schedule for porous asphalt roads, early assessment also enables timely intervention to keep porous asphalt in ideal working condition. In comparison with traditional roads which does not require routine assessment or maintenance.
Secondly, the existence of high void content in between porous asphalt provides its permeability. The high void content causes the structure of porous asphalt to be weaker than traditional dense asphalt, therefore on location such as expressway or areas with high traffic flow, porous asphalt will tend to lose its durability and collapse more often that traditional dense asphalt. According to Alber, S. et al (2017), states the problem with high void content of porous asphalt is intentionally designed for its functional properties and the drawback of such design consist of material deterioration, such as raveling effect and increased physical aging effect. This affects the applicability of porous asphalt in expressways and area that experience a high flow of traffic. The lifespan of porous asphalt roads will be greatly reduced. On the other hand, with proper planning and specialist to determine area that are not suitable for the usage of porous asphalt. Building of porous asphalt roads in such location can be avoided.
Lastly, one of the key characteristics
of porous asphalt that are overlooked is its ability to reduce noise generated. This characteristic is especially useful in countries and
area where lands is limited such as Singapore. In Singapore, roads and expressway are built in the vicinity
of our HDB Flat. Noise will be generated when vehicle travels along the roads. According to Kondo, N (2000) porous pavement are one of the most
effective countermeasures for countering traffic noise, result shown that noise
reduction on porous pavement is about 3-4dB compare with traditional
roads. Therefore, porous asphalt roads can be build on residential area to reduced the noise generated by vehicle, this can improve the quality of life of the resident in the area.
In
conclusion, despite the benefits and advantages of porous asphalt when compared with traditional roads. Assessment and
planning based on the climate and location should be done diligently as application of porous asphalt under poor condition will result increased in cost and effort into maintaining
its functionality.
References:
Alber, S., Ressel, W., Liu, P., Wang, D., Oeser, D., Uribe, D., Steeb, H. (2017) Investigation of microstructure characteristic of porous asphalt with relevance to acoustic pavement performance.
https://www.sciencedirect.com/science/article/pii/S2046043017300722
Kondo, N., Ohnishi, H., Hattori, H., Ishikawa, K. Nakano, T. (2000) Noise reduction effect on double-layer porous pavement
Liu, M., Huang, X., Xue, G. (2016) Effects of double layer porous asphalt pavement of urban street on noise reduction
https://www.sciencedirect.com/science/article/pii/S2212609016000029
Ma, Y.
, Chen, X., Geng, Y., Zhang, X. (2020). Effect of Clogging on the Permeability
of Porous Asphalt Pavement
https://www.hindawi.com/journals/amse/2020/4851291/
Pavegreen.
(n.d).Porous Asphalt is king of the road
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