Demolition Techniques means to destroy, disassemble, or remove.
The definition of demolition is “destruction, breaking down, or expulsion.”
Building demolition is the pre-planned and managed process of tearing down or destroying a structure after it has served its purpose.
In this article you’ll learn:
So, if you’re ready to go with demolition techniques, this article is for you.
Let’s dive right in.
Introduction to Demolition Techniques:
Building and structure demolition is necessary for a number of reasons.
There are several demolition processes and techniques for buildings and infrastructure.
Every building or structure design is known as a “design life”, the building is constructed with an 80–100-year lifespan.
There are several reasons to Demolition as follows:
- When the building’s design life is completed, it becomes unsafe for occupants and nearby structures.
- The buildings may be demolished to make new construction.
- The building’s stability was lost or there was structural damage.
- To build larger structures, smaller structures are destroyed.
Process of Building Demolition Techniques:
The process of these demolition techniques involves several steps, including:
Studying the various aspects of the structure and its surroundings is meant by surveying.
There are primarily two types of surveying as follows:
Buildings are surveyed before being demolished using the following procedure:
- Materials used in construction.
- Building use both before and after demolition.
- The presence of radioactive materials, hazardous substances, toxic chemical-related matters, flammable or explosive materials, etc.
- A drainage system’s state and potential problems with erosion, flooding, and water pollution.
- Shared amenities with the neighbouring buildings, such as stairwells and partitions.
- Pedestrian and vehicle traffic conditions coexist.
- The neighbourhood’s sensitivity to impacts from traffic, noise, dust, and vibration.
The following steps are involved in demolition techniques during a structural survey:
- The construction processes.
- Basements, underground tanks, or underground vaults’ structural layout and conditions.
- The initial structural framework that was used in the design.
- Building’s state of preservation.
2. Hazardous Waste Removal:
If dangerous substances like petroleum contamination, asbestos minerals, and radioactive metals are discovered during the site investigation for demolition.
Specialized personnel are required to remove the hazardous materials from the area before demolishing the building.
Methods of Demolition Techniques:
1. Non-Engineering Demolition Method:
a) Manual Demolition:
This is typically performed by contractors using portable manual tools such as sledgehammers, jackhammers, and drills.
2. Engineering Demolition Method:
a) Wrecking Balls:
Bulldozers and excavators cannot be used to destroy a building that is more than six stories.
In these situations, a crane and wrecking balls are used to carry out the demolition work.
A massive steel ball that is interrupted from a steel rope is attached to the wrecking ball crack.
The steel ball is pulled before being thrown at the structure.
When the steel ball strikes the building with enough force, a portion of the structure is destroyed.
This demolition techniques is not advised because it is impossible to control the steel ball’s route once it hits the building.
b) Pusher Arm Technique:
The building is destroyed using a pusher arm that is hydraulically powered and mounted on a tracked or wheeled chassis.
This technique is not advised for large masonry structures, but it works well for smaller ones.
c) Thermic Lace Technique:
A supply of pure oxygen is heated to a temperature of 2500 degrees centigrade in order to ignite a flame, melting the reinforcement.
d) Non-Explosive Demolition:
Holes are drilled along the desired separation line and filled with slurry.
After the holes have been filled with slurry, water is poured into them.
After a few minutes, the slurry expands, and cracks start to show on the structures, making it easier to demolish them.
e) Concrete Sawing Method:
A structure is destroyed quickly and easily by using a concrete saw, which operates on a high-power supply.
f) Deliberate Collapse Method:
These demolition techniques are not appropriate for structures made of pre-stressed concrete because it either involve the removal of important structural components like explosives or the pulling of wire rope at a high level of overturning.
3. Non-Explosive Demolition Method:
It describes the use of machinery instead of explosives to demolish a building.
a) Sledge Hammer:
It is a tiny hand-held hammer used for taking down single columns or small walls.
b) Bulldozers and Excavators:
These are large machines that are used to destroy small buildings.
They are employed for tasks like moving debris to trucks or excavating soil.
c) High Reach Excavators:
When it is impossible to demolish a tall building using an explosion, high-reach excavators are used.
This kind of machine is capable of demolishing structures up to 300 feet in height.
High-reach excavators can be fitted with various attachments including excavators that have shear attachments are known as shear attachment excavators.
Utilizing hydraulic hammers, steel reinforcement can be removed.
4. Explosive Demolition Techniques for Building Structures:
a) Building Demolition by Implosion:
The explosive demolition of a building is known as an implosion.
If the supports for the building are taken away, the structure will fall.
The main structural members of the buildings including the columns, beams, and slabs are fixed with explosives using the implosion technique.
The column collapses along with the structure when these explosives detonate.
There are two types of implosion depending on the structure collapses:
Buildings can implode in one of two ways:
Falling Like Tree Or Falling Like A Rock:
This type of implosion is perhaps the most typical.
This kind of demolition is recommended when there is unoccupied space available in addition to the building.
If there is extra space, explosives are positioned on the lower floors of the structure’s left side columns.
The building tends to fall on the left as the explosives explode, bursting the columns.
To control the building’s direction of fall, steel cables are fastened to it.
Falling into Own Footprint:
When there are no open spaces nearby and it is necessary to protect the building’s surrounding structure, then these demolition techniques are used.
Explosives are buried beneath the middle section of the building in this style of demolition.
These explosives must be powerful because the building must be instantly destroyed by the explosion.
If one part explodes, then the building tumbles in the direction of the first blast zone.
There are less businesses worldwide with experience in this kind of demolition.
The upper portion of the building collapses and it is destroyed as the explosions are set off.
Due to the large load and force, the lower part of the building also collapses and spills onto its footprint.
Planning the Demolition of Structures:
A thorough demolition plan is formed that breaks down the various steps involved as follows:
- The location of the building that will be torn down.
- The distances between the building that will be torn down and any nearby streets, buildings, structures, and large pieces of street furniture.
- The building’s systems for structural support.
- A plan outlining the building’s demolition process, the precise order in which structural members are to be destroyed, and the chosen demolition technique.
- A diagram demarcation of all safety measures taken for the public’s protection including hoardings, covered walkways, grab platforms, catch fans, scaffolding, barrier protection screens, and support systems.
- Handling procedures for building debris from demolition.
- The length of time needed to complete the demolition process, etc.
Advantages of Demolition Techniques:
- Removing a building that poses a danger to the public improves safety and increases property values.
- Removing a historic structure in the public’s best interest if it poses a fire risk contains asbestos, or causes other problems.
- It shouldn’t be too difficult to get the city’s approval for its demolition in this circumstance.
- The value of the nearby properties can increase by getting rid of a dangerous or unattractive buildings.
- It is also beneficial to destroy an old building or a structure with historic importance if the land could be used in a way that would be more beneficial to the neighbourhood.
Disadvantages of Demolition Techniques:
- If the structure is salvageable, you are destroying a piece of history.
- You will engage in a prolonged battle when others want to keep the building.
Also read: Types of Buildings | Types of Heavy Equipment | Types of Structures
The demolition techniques will depend on a number of variables including the building’s age, type, height, and economy.
To ensure safety, controlled demolition of the building is required, the most effective and safest method for destroying larger structures is explosive demolition.
Several well-established companies manage almost all significant building implosions worldwide, and blasting is passed down from generation to generation.