Demolition methods can vary depending upon the area where it will be held on, time available, building material, the purpose of demolition, the way of debris is going to be disposed.
There different methods of demolition are explained below:
Piecemeal Demolition (Hand Demolition):
This method manually dismantles reinforced concrete using tools like breakers, jackhammers, and oxy-acetylene torches for reinforcements. Key elements such as cantilevered canopies, balconies, and exterior walls are removed step by step, keeping reinforcements until surrounding concrete is cleared.
Mechanical Demolition Methods:
Excavators and bulldozers demolish low-rise buildings by undermining foundations to control collapse. For taller structures, cranes with steel wrecking balls deliver impact energy to bring them down. The pusher arm technique, using hydraulically powered machines, progressively demolishes small masonry structures by applying horizontal thrust.
Thermic Lance Technique:
A thermic lance uses a steel pipe with metal wires and pure oxygen to reach 2000–4000°C, melting steel and reinforced concrete. It allows fast, precise demolition with minimal noise and vibration but requires strict safety measures and is used only when no other alternatives are viable.
Water Jet (Hydrodemolition):
High-pressure water jets are used to erode concrete by washing out softer aggregates, a process called hydrodemolition. Abrasive additives allow cutting of reinforcing steel. Water can be disposed of or recycled through filtration and sedimentation for continuous operation.
Cutting and Lifting:
This method involves segmenting structures into manageable pieces, which are then lifted by crane for further demolition or removal. Slabs and precast elements are cut and lifted in a controlled sequence, allowing safe removal of projections like canopies, balconies, and bay windows.
Non-Explosive Demolition (Soundless Chemical Demolition Agents – SCDA):
SCDAs are chemical mixtures (e.g., CaO, Al₂O₃, MgO, Fe₂O₃, SiO₂, CaF₂) that expand when hydrated in confined spaces, breaking concrete without explosives. They generate destructive pressure within 15 minutes to 24 hours and are ideal where noise or vibration must be minimized, though they are more costly than conventional explosives.
Concrete Sawing:
High-powered concrete saws, including disc, chain, wire, and diamond core saws, are used to cut slabs, walls, and structural elements into precise segments. This method is suitable for accurate demolition, alterations, or additions, especially in environments sensitive to noise and vibration.
What are the common, controlled methods used to demolish massive mine infrastructure during mine closure? Share your insights!
