PWD lab receives 100 samples a month compared to 20-30 three years ago

Nearly 25 per cent of the samples of construction materials that are brought to the Soil Mechanics and Research Division laboratory of the Public Works Department in Taramani here fail the quality test.

Officials of the laboratory said though the awareness of the availability of such tests has increased, the number of individual customers seeking the services of the facility is less when compared to the number of builders and educational institutions.

The laboratory now receives about 100 samples a month compared to 20-30 samples a month three years ago. The annual revenue of the laboratory last year was Rs.6.88 lakh as against Rs.1.53 lakh in 2008.

The facility is sought for testing materials used in both government and private construction projects. It has been found that many samples of steel rods and cement do not conform to the quality standards.

Research conducted by the laboratory has revealed that different grades of cement often provide the same strength to the building. Curing must be done after four hours of plastering with fine cement to avoid cracks in the building.

C. Kalyanasundaram, assistant executive engineer, Concrete Lab, PWD, said that with the increase in construction activity, testing of the materials used is imperative to ensure durability of the structure. On an average, a structure constructed with quality materials has a life-span of 60 years.

More samples of flyash bricks are also brought for testing over the past two years. With the depletion of river sand, manufactured sand made from crushed stones is emerging to be an alternative. However, owing to deficiencies in the production process the M-sand quality is far less than that of fine sand. Further research is under way about the durability of the M-sand, he said.

Mr. Kalyanasundaram said that the lab also provides consultation about earthquake resistant buildings. Ductile steel rods, approved by the Bureau of Indian Standards, are available in the market. The rods that have relatively lesser carbon content are earthquake resistant.

A separate wing has been dedicated for soil testing as soil condition determines the size of the structure's foundation and stability during natural disasters, he said.

M.S. Hemalatha, assistant engineer at the laboratory, said that materials used in various ongoing projects such as construction of stormwater drain network, the flyover at Mint junction and restoration of Ripon Building by Chennai Corporation, were being tested. The period of testing varies from 1 to 28 days depending on the material. For those customers who want results immediately, accelerated curing method is used to give results in 28 hours. Non-destructive tests are also carried out after construction of the buildings, she said. The charges range from Rs.600 to Rs.4,200 according to the material.

Besides workshops for engineers of government agencies, the officials also conduct awareness programmes for people and college students wherein simple tests to check quality are taught.

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