Nowadays, Porous Asphalt is the latest trend. Porous asphalt is widely employed for the construction of different pavements. The name itself suggests the quality of asphalt that is “porous,” as it refers to the holes in the asphalt material that securely manages stormwater drainage problems.
Porous asphalt pavements offer developers and planners a new tool in their toolbox for managing storm water. It is produced and placed using the same methods as conventional asphalt concrete; It differs in that fine (small) aggregates are omitted from the asphalt mixture. The remaining large, single-sized aggregate particles leave open voids that give the material its porosity and permeability. To ensure pavement strength, fiber may be added to the mix or a polymer-modified asphalt binder may be used.
Generally, porous asphalt pavements are designed with a subsurface reservoir that holds water that passes through the pavement, allowing it to evaporate and/or percolate slowly into the surround soils.
It acts as a low maintenance option for homes and businesses that regularly suffer from drainage problems. Its usage graph has seen a considerable increase in different municipal projects including driveways, fire lanes, sidewalks, road shoulders and roadways under new stormwater regulations. It has been majorly used for the flooring of parking lots, as it doesn’t confine the water flow, which gets infiltrated into the soil beneath the pavement surface.
How Does Porous Asphalt Pavement Work?
Porous asphalt allows water to drain through the asphalt and into the stone bed below. It then works its way into the soil as nature intended. If toxins are on the surface, they get swept along with the rainfall through the stone bed. From there, they travel into the sub-base so that they are subjected to the natural processes that cleanse water. The size and depth of the stone bed must be designed so that the water level never rises into the asphalt.
Construction that involves usage of porous asphalt material has shown positive results in handling uncontrollable water flow during storms and floods by removing sediment and nutrients to protect local waterways. Many public work departments are focusing towards building an innovative, new road surface to elucidate flood control concerns since the porous asphalt prevents polluted water from running off into rivers and lakes.
Open-graded friction courses (OGFC) are a porous asphalt surface course used on highways to improve driving safety by removing water from the surface. Unlike a full-depth porous asphalt pavement, OGFCs do not drain water to the base of a pavement. Instead, they allow water to infiltrate the top 3/4 to 1.5 inch of the pavement and then drain out to the side of the roadway. This can improve the friction characteristics of the road and reducing road spray.
During the hot summers, higher electricity usage in metropolitan areas can lead to an urban heat island effect, which can be reduced by installing porous asphalt pavements in places such as offices, schools, colleges, etc.
The Bottom Line
Since the 1970’s, porous asphalt has been in use for constructing parking lots for its large number of benefits. And today, it has developed a repute of being a high-performance material involved in wider applications.
National Asphalt Pavement Association – http://www.asphaltpavement.org