Homes and gardens

Right solution for flooding, falling water table?

A city engineering college develops concrete blocks that allow rainwater to seep through into the earth. By M.A. Siraj

Paved urban spaces may appear smooth and neat to look at but they cause water logging as rain water does not find any space to seep into the earth. How could the pavements, medians and kerb-sides of the roads be made permeable without leaving scope for their turning slushy?

A Bengaluru engineering college has developed pervious concrete blocks that could be the ideal solution for the situation. A group of students of CMR Institute of Technology led by Prof. Preeti Jacob have come up with porous concrete blocks that allow water to percolate through the earth without compromising on the strength of these spaces for users. These concrete blocks made out of jelly, cement and other chemical aggregates, but no sand, are hard enough to be used on side-walks, medians and the shoulders of the roads where rainwater usually collects.

Ideal for urban spaces

Preeti says the concrete blocks are ideal for even lining stormwater drains. Their porosity would cut down flooding by 70 per cent and would also keep the water table high in urban areas where complete paving of open spaces is leading to flooding during the rains and constant fall of water table. Says Preeti: “Concrete paving of the entire urban space is causing rain run-offs which ultimately leads to water logging in certain areas.

The pervious concrete blocks may be used for paving open spaces in apartments and villa complexes such as tracks marked for jogging, walking or biking, and pathways in the garden. These could also be placed on side-walks, footpaths and medians where trees are planted. These will allow considerable amount of rainwater to be absorbed and keep the ground aquifers charged.”

According to Preeti, the pervious concrete blocks could be made of different sizes and shapes depending upon the spaces to be paved. The blocks were developed in the civil engineering laboratory of CMRIT under her guidance by four final-year B.E. students viz, Nandhini R.T., Nethravathi O., Danish Akhtar and Manoj G.K.

Rain absorbent

According to Preeti, who specialises in water resources, normal concrete is highly impermeable due to which a lot of rainfall gets wasted. It also contributes to rise of temperature. The innovation by the students was awarded the first prize at Srishti-2107, a State-level competition for engineering students in the city.

Vacuum cleaning

Preeti, who has paved a portion of the road in front of her house (in K.R. Puram), however, adds a word of caution. She says spaces paved with the pervious blocks would need some regular maintenance as water on Indian roads generally brings a lot of fine particles of sediments which can clog the pores and cut down the functionality of the blocks. The portions paved by these blocks would need to be vacuum cleaned prior to monsoons.

The team is working to further improve the blocks with eco-friendly material such as quarry dust or GGBS (ground granulated blast furnace slag). More lab tests are on to enhance the compressive strength as the current strength is not sufficient for vehicular movement.

The author can be reached at maqsiraj@gmail.com

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Printable version | Feb 23, 2020 12:13:28 PM | https://www.thehindu.com/life-and-style/homes-and-gardens/right-solution-for-flooding-falling-water-table/article19427848.ece

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