Hyderabad: Pervious concrete can check global warming

Hyderabad: Pervious concrete could be this country’s answer to many effects of global warming, including the urban heat island (UHI) phenomenon.

Compared to conventional concrete, which is impermeable, pervious concrete is porous in nature. This entails a host of advantages over conventional materials: if used correctly, pervious concrete can help reduce ambient temperatures around it and recharge groundwater.

A team of researchers from IIT Tirupati have been working on the subject for the past several years. Poonrachandra Vaddy, a Masters student and a part of this team, presented his technical paper at a conference on UHI in Hyderabad on Wednesday.

Vaddy said the biggest advantage of using pervious concrete was its heat absorption capacity.

“The characteristics of this material are very distinct. In conventional concrete, the heat is absorbed and reflected by the top layer. Here, the heat is conducted throughout the material,” he said.

Explaining this further, B Krishna Prapoorna, assistant professor at IIT Tirupati, department of civil and environmental engineering, said, “The absorption of heat is a very important advantage. Due to this, the light is not reflected into the atmosphere. This means the ambient temperature can be reduced by nearly 10-15 degrees celsius. Also, the surface of pervious concrete slabs are cool to touch. One can walk barefoot on them, something that is impossible on conventional concrete slabs.”

Prapoorna explained that the porosity of the material also answers the problem of water run-off. “In the case of conventional concrete, the water is unable to seep through and is wasted in the form of run-off. But in pervious concrete, the water seeps through and goes on to recharge the groundwater table,” he said.

Also, he added, this helps in cooling down the surroundings through evaporative cooling. This is a principle that is used in water or desert coolers.  “Since the material absorbs water, on a hot day, the water will get evaporated. This will cool down the surroundings,” he said.

Pervious concrete also does not use any sand, making it cheaper than conventional concrete. “The cost of pervious concrete is cheaper. Typically, it is a mixture of cement, rock aggregate and admixture,” said Prapoorna.

Research on the subject currently is still in the nascent stage. While the principle of pervious concrete has existed since the nineteenth century, it has gained popularity due to its relevance to global warming mitigation.

In the current form, pervious concrete is durable enough to be used for applications such as footpaths, walkways, parking lots and bicycle tracks.