CONTROLLED DEMOLITION : A SYSTEMATIC WAY OF KNOCKING DOWN CONCRETE

December 9, 2016
MABUHAY!

Tired of using the usual sledgehammer, jackhammer or even explosives in your concrete demolition works? 

Since sledgehammer requires a large amount of manual human strength, Jackhammers sounds like World War 2 machine guns and the use of explosive is strictly regulated in the Philippines, we now use concrete cutters, coring drill and other tools and equipment for a demolition technique called controlled demolition. Whenever there is a  revision in construction plan and a need to free up some space that is already concreted, this technique is used.

Advantages of controlled demolition:
1. To make the demolition safe.
2. To make the debris manageable for hauling.
3. To lessen the excessive use of Jackhammers

PROJECT DESCRIPTION
To demolish a 120mm thick concrete slab to free up some space for a high ceiling.

METHODOLOGY
1. Determine the size of the square cut. The weight of the concrete has a significant impact on the size of the cut. The normal weight of 1 cubic meter of concrete is 2,400 kgs. So for 1 meter by meter square cut with the thickness of 120 mm weighs around 288 kgs.

2. Determine also the direction where you will pull out the concrete slab already cut. Make a hallow preliminary thin cut with a concrete cutting machine to mark permanently the square.

3. Set up the coring machine. For this particular project, the diameter of the coring bit is 100mm diameter.

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4. Bore the hole at the center of the slab. This is to balance the weight of the concrete slab when lifted.

5. Cut the 3 sides of the square deep enough that the blade of the cutter must penetrate through the slab.

6. Position the scaffolding on top of the concrete for the pull-out. Place a steel beam at the top center to anchor the chain block.

7. Place the end of the lifting chain on the bored hole. Provide pipe or reinforcing bar stopper at the end of the chain.

8. When the slab is already secure by the chained block, cut the end of the square.

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9. Start pulling up the sliced concrete slab by the chained block until it snaps out of its place. Put two round steel pipe at the back of the slab to serve as rollers.

10. Once the slab was placed on the top of the steel pipe, roll them out to the nearest stock area using a 20mm reinforcing bar.

11. Stockpile the slabs for hauling. The vehicle to be used for hauling must be a boom truck.

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The cleared needed space 

Now you have an idea of an alternative method of demolishing concrete other than the usual use of sledgehammer or jackhammer. On top of these procedures, secure your work place properly to prevent unnecessary accidents. Make SAFETY a way of life!

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