Date:03/05/2008 URL: http://www.thehindubusinessline.com/2008/05/03/stories/2008050352122100.htm

Back New concrete blocks to withstand strong waves

K.V. Kurmanath

Hyderabad, May 2 People who have a chance to walk along the beaches must have seen huge concrete blocks protecting the coast, and breakwater structures that ensure tranquility of water at harbours.

They are not mere concrete blocks. They involve intense structural engineering as the blocks need to face relentless attack from strong waves.

Researchers at the city-based engineering major Navayuga Engineering Company claimed to have developed a new generation armour blocks, christened Kolos, that were tested by IIT, Madras.

“We have used these blocks in both the southern and northern breakwater structures, each having a length of 1.6 km. With a very high Hudson value, they withstood a recent cyclone that hit the Nellore shore,” said Dr P.V. Chandramohan, Director (Technical) of Navayuga Engineering.

The company has applied for a patent for the product.

Explaining the utility of these blocks, Dr Chandramohan said, “Ships need harboured or calm water to get loaded or unloaded. Breakwaters hold the key and are one of the most important structures at harbours. The structure ensures tranquility inside the harbour basin”.

“Waves attack these blocks with full force for a few seconds. It demands a strong structure in order to withstand the wave energy,” he told Business Line.

The breakwater structure is generally protected by small stones. But they could be easily washed away because of the wave activity. On the top, they put bigger stones that take the wrath of the waves on the sides. This actually needs stones with a weight of 25-30 tonnes. As it is impossible to find and transport such huge blocks, engineers started working on the concrete blocks.

These blocks, which are interlocked, are arranged on the sides of the breakwater structures where the action of the waves is more. The efficiency of these blocks is measured by Hudson’s stability number.

In vogue around the globe are blocks called Dolos with South African origin. “Dolos had a history of structural failure,” Dr Chandramohan said.

Citing the failure of the Sines breakwater in Portugal, he said Navayuga had started working on better design to make the blocks to use in the Krishnapatnam Port, another group company, and developed Kolos.