Principal Demolition Methods
Demolition methods can vary depending on the area where it will be held on, the building material, the purpose of the demolition and the way that debris is going to be disposed. In the article we present with some of the most used methods for demolition of structures.
Demolition Method: Implosion
Implosion is a violent bursting inward that allows the sequential elimination of structure supports. Enough explosives are used to eliminate the critical vertical structural supports. The placement of the charges and the sequential detonation timing is if vital importance, allowing the collapse of the building induced by the weight of the structure. Implosion demolition methods are used in urban areas and often involve large structures.
For a successful demolition a complete set of structural blueprints must be analyzed to study the main component of such building. Also another important step is to have the blaster crew complete an assessment of the structure of the buildings to identify other areas that need to be blasted, in addition to the ones identify on the blueprints. As a final step is important to decide the type of explosives to use, where to position them in the building and how to time their detonations.
High Reach Arm
High reach arm is another traditional method of demolition. The threshold for defining a high reach demolition is when it reaches a height of more than 20 meters. This method is usually formed by a base machine (excavator, tank, engine, counterweights), a demolition arm consisting of three sections or by a telescopic boom and a primary tool attached to the base machine (crushers, shears, hammers).
High reach demolition machines can be equipped with different tools to make them suitable for executing demolitions of structures. This method is used on reinforced concrete, masonry, steel and mixed material structures. The machines used in this type of demolition are not the only machines used in the process; there must be additional components used for secondary operations such as crunching of material. Several factors control the method like the height of the structure being demolished, site conditions and structure shape.
Demolition Method: Crane & Ball
One of the oldest and most commonly used methods for building demolition, the ball and crane use a wrecking ball weighing up to 13,500 pounds to demolish concrete and masonry structures. During the process, the ball is either dropped onto or swung into the structure that is to be demolished. The ball and crane, however, is unsuitable for all demolition applications. Some limitations:
- Additional work removing rebar in concrete structures is needed.
- Only highly skilled and experienced crane operators should be used on ball and crane demolition
- Smoothness in controlling the swing of the ball is CRITICAL since missing the target may tip or overload the crane.
- The size of the building that can be demolished with this method is limited by crane size and working room, including proximity to power lines.
- This form of demolition creates a great deal of dust, vibrations and noise.
Demolition Method: Selective Demolition
Also known as strip-out, this process is very popular right now. As recycling and salvaging of material are very attractive to builders during these days, allowing them to re-use material or recycle it. Selective interior / exterior demolition or recycle of wood, brick, metals and concrete are all recycled for future use in new structures blending the old with the new. This demolition process is not limited to removal of interior equipment, walls, floor, ceilings and exterior components. The main purpose of this method is to recover the maximum amount of primarily reusable and secondary recyclable material in a safe and cost-effective procedure. Although it is a labor intensive process and can be very difficult to achieve in a timely and economical manner for light framed buildings.