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Brazilian researchers have developed a new type of permeable pavement that can store rain water and ease the impacts of floods. They say the pavement could save lives and money in flood-prone countries around the world. Let’s find out more.
With each passing year, rainy seasons in Brazil are getting stronger and stronger. So researchers at Brazil’s University of Sao Paulo have developed an innovative permeable pavement which they say may be key to preventing floods.
Watching water levels rise to waist-height in minutes is common in Brazil. And according to hydraulics expert Afonso Luis Virgiliis, the porous pavement being tested at the university’s parking lot could be the solution to this problem.
[Afonso Luis Virgiliis, Pavement Researcher]:
“In reality this is a drainage system. It is composed of a permeable coating and a series of granular layers that have stones of different sizes.”
Pervious roads are basically made up of crushed stones, sand and asphalt binder.
They’re widely used to prevent water build-up and runoff.
But the secret to this new pavement is under its surface coating.
Stones of different sizes are put side by side in a kind of trench under the surface.
This lets large volumes of water to be stored for longer periods during heavy showers.
[Afonso Luis Virgiliis, Pavement Researcher]:
“What happens is that when the rain falls over this coating, this coating allows the water to flow down through it and the water is stored in the empty spaces that exist between these stones. This storage is done in such way that when the rain stops, once it goes away, then the water stored in the grainy reserve is slowly driven out to the city’s conventional drainage systems.”
One of the downsides of this new system is the cost.
Like other porous asphalts, it costs around 30 percent more than regular pavement.
It also has a lower load-bearing capacity.
In fact, Virgiliis says heavy trucks could quickly deform the permeable pavement, which has a lifespan of about eight years.
[Afonso Luis Virgiliis, Pavement Researcher]:
“What we always recommend is for this type of pavement, due to its characteristics, should not take a lot of heavy traffic, in fact, no heavy traffic at all. Only light traffic can pass over it — that is, cars, small trucks and large trucks on rare occasions, because it is a pavement designed especially to absorb water.”
Virgiliis says the new design can store rainwater for hours before it drains into the city’s sewers. And after one of the rainiest summers in history, results so far have been positive at the parking lot where the new technology is being tested.
The parking lot is being monitored for storage capacity and time, durability and pollution absorption.
Virgiliis says the main goal is to come up with more resistant combinations of porous asphalt.
[Afonso Luis Virgiliis, Pavement Researcher]:
“We have been seeing very good results in terms of slowing down the time water takes to flow down to the drainage system. We have also seen positive results in terms of improving the general conditions of the parking lot itself — the noise levels were lowered, because this pavement also absorbs noise. Our main expectation for the future is to develop a type of pavement that can endure heavier traffic and this depends, of course, on a bigger technological investment and more research.”
Sao Paulo’s government plans to start testing the new pavement this year in areas where traffic is light.
Post time: Jun-19-2017