NZCSDA Concrete Cutting
A variety of different methods are used for producing fast, clean, dust free and accurate cuts in reinforced concrete and other building materials. These include concrete sawing in wall and soffits, wire sawing and ring sawing.
Handheld Sawing: Handsaws are used in many applications to saw-cut floors, concrete precast walls, concrete pipes and concrete beams. They are probably the most commonly used concrete cutting tool in New Zealand. It is also the tool with the biggest potential to cause harm to an untrained operator. Hand saws in combination with a hand held “ring” saw can cut to a depth of 275mm. Most hand saws are 2-stroke petrol powered. For indoor use, to eliminate carbon monoxide fumes, there is a range of different types of hand held saws such as hydraulic, single phase electric, and hi-frequency. These are used for smaller space applications where a floorsaw cannot operate.
Track Mounted Wall Sawing: As the name suggests, this machine is primarily used to cut concrete and remove walls, mostly to form large openings in the wall for either doorways or air-conditioning ducts. A track mounted wall saw can cut to a depth of 800mm. These machines cut very accurately, typically to within 2mm or 3mm. The saws are remotely controlled so operators are well clear of any potential danger areas.
Wire Sawing: A continuous loop of diamond wire is “wrapped” around the concrete object that is being cut. This concrete cutting technique is very versatile. Cuts up to 20 metres long by 5 metres high have been made and reinforcing steel can be cut. A wire cut is not as accurate as other cutting and drilling techniques. Like a track mounted wall saw, a wire saw is remotely controlled. These saws are very quiet and therefore they are now being specified in noise critical areas such as hospitals and hotels.
Bursting/Splitting/Crushing: A concrete burster or splitter uses hydraulic force to “split” a piece of concrete. This is used mainly to reduce a large section of concrete in size so that it can be removed more easily. These machines are used because they are more economical than cutting techniques available. A crusher has jaws that can crush concrete up to 300mm thick into small pieces. All these machines are quiet so, like a wire saw, they are ideal for noise critical areas.
Floor Sawing, also called road sawing, ground sawing or flat sawing:
All professional concrete cutting companies use walk-behind machines. They range from 15 to 84 horse power and come in a range of petrol and diesel saws, depending on the manufacturer. There are 3 phase electric powered saws available for inside work to eliminate carbon monoxide fumes. The horse power of the machine determines the depth the machine can cut. A high horse power floor saw can cut to a depth of 600mm.
Typical uses for a floor saw are:
- To cut expansion joints in new concrete to stop the concrete cracking over time;
- To cut thick concrete for removal;
- To sawcut asphalt to gain access to sub- base on roads.