A Solution to Prevent Floods

India is urbanizing at a fast pace. However, new urban centers are not being created. Existing towns and cities are growing bigger. Further, the density of these centers is increasing. This means that construction is often very dense in most Indian towns and cities. One of the common materials used for construction are cement based materials like concrete.
A large percentage of surface area in urban areas is covered by cement based materials such as cement, pavers, cement tiles and concrete. Areas include roads, parking lots, pavements and compounds of buildings. When surface is covered by such materials, it becomes impervious. Water has to necessarily flow into storm water drains. If the drainage system is inadequate, flooding will occur.

Most cities in India (except Mumbai) are not covered adequately by drainage systems that can evacuate excess rainwater to reservoirs. In the absence of adequate storm water drainage, rainwater stagnates and leads to flooding. To aggravate the situation, weather is increasingly becoming unpredictable. For instance, Chennai witnessed its highest rainfall in a 100 year in 2015; leading to unprecedented flooding. Therefore, water needs to drain via the ground. Since the ground is impervious in nature, there is a need for technologies like porous concrete. Porous concrete also helps in recharging ground water levels.

The first extensive research on porous concrete was done by The National University of Singapore for small pavements and roads. It was shown that such a technology could help in controlling floods in dense urban areas.

Recently, pervious concrete products have been developed by companies like Tarmac. Their product, Topmix Permeable Concrete claims to absorb 1,000 liters of water per minute per square meter. Topmix Permeable Concrete differs from other concrete because fine aggregates are not used while making it. In the absence of fine aggregates, there are gaps left in the concrete structure, making it porous. The concrete made without fine aggregates is less strong and therefore companies like Tarmac use proprietary technologies to ensure that the concrete layer is functional yet permeable. Topmix Permeable Concrete is laid on a base of crushed stone which is in turn laid over soil. Rainwater is absorbed through the top layer followed by the crushed stone layer and slowly released in to the ground.
Pervious concrete can be used on parking lots, roads and pavements. Typically, such products cannot withstand high loads and heavy usage that a standard concrete surface can. As the technology develops, we hope that strength of pervious concrete will become comparable to standard concrete.

Clearly, pervious concrete has potential for usage in Indian market. We hope that this technology will be used widely very soon.
Click the below link to watch the video on how Tarmac’s Topmix Permeable concrete absorbs water.