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November, 2005 It is the law of nature. The old give way to the new and the process goes on. This has become applicable to the structures also. Technology has radically changed the way we live and work thereby necessitating vacation of the limited space we have and re-plan it to suit present requirements. Then there always are some outlived structures — required to be dismantled and disposed of. There are old foundations, canal lining panels and a variety of concrete components. With the passage of time, number of such structures to be demolished has been on the rise. Dismantling masonry is easy. Manual chisel-and-hammer work is productive. Real problem is faced by the engineers when it comes to breaking RCC or even plain concrete. Chisel and hammer give way. No significant progress is achieved after a day’s work. Even sledge hammer doesn’t produce desirable results. To solve the problem, a breakthrough in breakers has been achieved by the construction industry. Many types of breakers have now been developed and any sort of dismantling problem can be handled without much of manual labour. Weighing as little as 20 kg and as much as 13 tonnes, these breakers can do all types of quarrying, demolition, tunneling, trenching and foundation breaking. The range available is expanding day by day as the competition among the manufacturers get tougher. Features These breakers are either electricity driven, hydraulic or pneumatic. Depending upon the job to be done, the breaker chosen may be light, medium or heavy. For use, these breakers are to be mounted on some equipment such as backhoes, excavators etc. Here, these equipment are called Carriers. Barring lightweight breakers which can be hand-held, it is not possible to operate these breakers directly as the vibrations transmitted to the operator are very strong and unbearable. There is hardly any manufacturer in the world who makes both breakers as well as carriers. Breakers procured are, therefore, versatile enough to suit any type of carriers made by different manufacturers. Hand-held breakers have T-shaped handles and are applied vertically to the structure to be broken. These can offer controlled breaking and chipping action and a particular area of a big structure can be concentrated upon. Their blows to the structure range between 900 and 3000 blows per minute. As the operator has to tolerate their vibrations, the manufacturers are now concentrating most on minimising these vibrations. Even when mounted on carriers, it is difficult to isolate the operator from the breaker-vibrations. International law has now been enacted to limit and fix the maximum amount of vibrations per day transmitted to operators. Similarly, control limits for noise produced have also been defined. A breaker’s weight indicates its power. Heavier the breaker, more powerful it is in demolition. A 30-kg hydraulic breaker can break RCC panels, concrete roads, foundations and even high strength airport runways. Different types of bits and tools can be installed on these breakers. These may be twisting type for drilling holes, flat chisels for breaking or hammer type for demolition. Some desirable features of breakers are as under: Vast range Atlas Copco, a leading international company for manufacture of all types of breakers, has recently unveiled the largest hydraulic breaker in the world. With an operating weight of 13 tonnes, it can do any type of demolition. Another model weighing just 25 kg delivers 2600 blows per minute, drilling 12 inches per minute even in solid granite. For heavily reinforced structures, the Cobra breaker with its steel cutting jaws opening 100 cm wide and delivering 440-tonne cutting force is ideal — rather awesome. Caterpillar’s breakers include auto shutoff feature saving the carriers and operators from a backfire that occurs when the piston strikes the cutting tool not in contact with the material to be broken. The number of blows can also be adjusted. Now, Caterpillar is coming out with breakers that allow the operator to use an on-board computer to select one of the five attachment settings to suit the structure to be broken. Indian scene
Though most of these highly versatile breakers of big international companies are available in India, Indian manufacturers have taken up manufacturing of lightweight breakers suitable for breaking concrete, roads, rocks, asphalt surfaces, trimming of RCC pile heads etc. A number of such manufacturers provide breakers at highly competitive rates. For larger jobs however, only imported breakers fulfill the requirements. Desirable features of breakers: 1. More impact power. 2. Minimum vibration. 3. Minimum noise. 4. Lesser cost. 5. Unbreakable tool. 6. Mounting compatibility. 7. Low maintenance. 8. Long life. 9. Easier to operate. 10. Balanced power-to weight ratio. 11. Low consumption of power or gas.
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