What is Demolition? What is Deconstruction?

Demolition is the opposite of construction: the tearing-down of buildings and other structures. It contrasts with deconstruction, which is the taking down of a building while carefully preserving valuable elements for re-use.

For all buildings, such as houses, that are only two or three stories high, demolition is a rather simple process. The building is pulled down either manually or mechanically using large hydraulic breakers, elevated work platforms, cranes, excavators or bulldozers.

Larger buildings may require the use of a wrecking ball, a heavy weight on a cable that is swung by a crane into the side of the buildings. Wrecking balls are especially effective against masonry, but are less easily controlled and often less efficient than other methods.

Newer methods may use rotational hydraulic shears and silenced rock breakers attached to excavators to cut or break through wood, steel, and concrete. The use of shears is especially common when flame cutting would be dangerous.

Large buildings, tall chimneys, smokestacks, and increasingly some smaller structures may be destroyed by building implosion using explosives. Imploding a building is very fast — the collapse itself only takes seconds — and an expert can ensure that the building falls into its own footprint, so as not to damage neighboring structures. This is essential for tall structures in dense urban areas.

Any error can be disastrous, however, and some demolitions have failed, severely damaging neighboring structures. The greatest danger is from flying debris which, when improperly prepared for, can kill onlookers.

Even more dangerous is the partial failure of an attempted implosion. When a building fails to collapse completely the structure may be unstable, tilting at a dangerous angle, and filled with un-detonated but still primed explosives, making it difficult for workers to approach safely.

A third danger comes from the blasting shockwave that occurs during the implosion. If the sky is clear, the blasting shockwave, a wave of energy and sound, travels upwards and disperses, but if cloud coverage is low, the shockwave can travel outwards, breaking windows or causing other damage to surrounding buildings.

While controlled implosion is the method that the general public often thinks of when discussing demolition, it can be dangerous and is only used as a last resort when other methods are impractical or too costly. It takes several weeks or months to prepare a building for implosion. All items of value, such as copper wiring, are stripped from a building. Some materials must be removed, such as glass that can form deadly projectiles, and insulation that can scatter over a wide area. Non-load bearing partitions and drywall are removed. Selected columns on floors where explosives will be set are drilled and nitroglycerin and TNT are placed in the holes. Smaller columns and walls are wrapped in detonating cord. The goal is to use as little explosive as possible; only a few floors are rigged with explosives, so that it is safer (less explosives) and less costly. The areas with explosives are covered in thick fabric and fencing to absorb flying debris. Far more time-consuming than the demolition itself is the clean-up of the site, as the debris is loaded into trucks and hauled away.

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Dexpan has amazing 18,000 psi expanding strength of silent cracking, works without noise or vibration. Alternative to blasting, explosives, TNT dynamite, jackhammer, hydraulic breaker, diamond blade concrete saw, diamond wire stone cutter, chain saw stone cutter, rock breaker and other demolition tools, mining equipments or quarry equipments.