How to perform a concrete core cut | Everything you need to know

Performing a concrete core cut has become quite common in construction. This article will provide you with everything you may need to know about this procedure.

Introduction to concrete core cutting

Concrete core cutting involves cutting a circular hole through concrete and extracting the cylindrical concrete block contained in the drilled hole. Concrete core cutting can be done on floor slabs, walls, and even ceilings. Core cutting, however, is not limited to concrete surfaces only as it can also be done on stone and asphalt, and will therefore be known as stone core drilling or asphalt core drilling.

The drill used for core cutting is known as a Core Drilling Machine. There are dry core drilling machines and wet core drilling machines. The wet drilling machines are the ones mostly used since the drill bit is more protected. Core drilling machines consist of a long cylinder-like drill with diamond bits attached to the drilling end of it.

The ‘cylinder’ is attached to an electric motor that spins the drill. The machine also is attached to a stand that has wheels on its base. Before drilling, the machine is connected to the stand which provides support during drilling. The stand also has a track that allows the drill machine to move up and down, or forward and backward, depending on how you’ve oriented the machine.

The reasons for cutting through concrete is to create space for the passage of utilities such as plumbing, electrical wiring, drainage pipes, or HVAC systems. Drainage holes and manholes can also be created through core drilling.

Tools and Equipment for a concrete core cutting

1. Complete core wet drilling machine (with its accessories) – Accessories include; a washer, setting, anchor bolt, threaded rod, and spanners.
2. Hand drill, with drill bit. The drill bit should be the same diameter as the anchor bolt.
3. Water supply unit.
4. Source of power and water.
5. Mason tools such as a hammer.

How to perform a concrete core cut

Before starting any drilling, ensure that the surface you want to drill has no mechanical works running through it such as electrical wiring, plumbing, and/or other fittings.

1. On the surface you want to drill, use the hand drill to drill a hole a small distance away from where you want to cut the core. The drill stand will be mounted on this hole.
2. From the drill machine accessories, insert the anchor bolt and drive it in to ensure it is tightly held in the hole.
3. Take the threaded rod and screw it tightly into the anchor bolt. The anchor bolt is what will support the drill stand.
4. Once the threaded rod is tightly fitted, take the drill stand (without the drill machine) and at the center of the bottom, there will be a hollow slot where you will insert the stand into the rod.
5. Use the washer and setting tool to secure the stand in place. However, don’t completely tighten the two.
6. Tighten the screws of the stand, around where the wheels are, to level out the stand. Failure to level the stand will make the stand, and consequently the drill itself unstable. This may cause jerking of the machine during drilling and will damage the drill bit. This may also result in a poorly cut core. Once the stand is level, you can finish tightening its center using the washer and setting screw.
7. Take the drill machine and by using the mechanism at the top, slide it through the corresponding slot on the stand. Secure it by tightening the screws around it. This will secure the two together.
8. Connect the end of the water supply unit pipe to the water inlet connector on the drill.
9. Connect the machine to the power source and turn on the machine. The drill should start spinning.
10. The drill operator can now use the drill control lever to push the drill forward toward the wall, floor or ceiling to be drilled. A second person will be pumping water from the water supply unit to the drill.
11. The drill will begin cutting through the surface once it comes into contact with it, thanks to the diamond in the drill bit. Water will be seen splashing from where the drill and surface meet.

The purpose of the water is to reduce friction between the drill and the concrete, which if not checked will severely heat up the drill. The water also significantly reduces the amount of dust produced during the process to almost none. The water being used is why the process is referred to as wet drilling.

12. Slowly, the operator will turn the lever to push the drill until it penetrates through to the other end of the wall, floor, or ceiling.
13. When it finally penetrates through to the other end, the operator will retract the drill by reversing the lever.
14. Once the machine is fully retracted, dismantle the drill stand and set it upright.
15. With the drill machine now at a raised position, remove the concrete core from the device. If the core won’t immediately slide out, you can slightly hit it by using the mason hammer.
16. The core will slide out and you will have the smoothly cut concrete core with you. The extracted concrete core can be taken to the lab for structural strength testing.

And that is how you carry out a concrete core cut. Ensure that you properly wash your equipment afterwards.