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Drill IT was contacted by one of our valued clients after a design error was uncovered onsite. A concrete slab 2500mm x 1800 x 350mm thick had been cast the wrong end of a stairwell and needed to be removed. The issue was that the slab was tied in to 3 structural walls and the client was concerned how to remove the slab without damaging the remaining structures.

After sitting down with the client, running through the process of removal and mocking up some diagrams to demonstrate the method and each stage of the removal process, the client and engineers were happy to instruct us to proceed with the works.

— The area below was sectioned off and warning signs installed. Water control was set up in the form of polythene taped to the wall, all water/slurry was collected into a bin and then bagged along with the core and disposed in the nearest bin/skip on site.

— Step one – We first set up our Diamond drills using 110v power and fixed to the slab with x1 M12 fixing and tight stitch drill the two far corners with a 107mm drill bit, with seven holes in each corner. The next step is to drill 48mm diameter bursting holes throughout the slab 300mm apart in a diamond layout. Once the drilling was complete we moved on to the flush cut sawing.

— Step two – We then set up the Pentruder diamond saw on the marks as set out by our client; We flush cut both sides 1000mm x 350mm deep both sides

—Step three – We set up the C9 Darda burster and burst the 1000mm section in the direction of the front which is not tied in. We then proceeded break up into manageable lumps and cut the steels with a 9” grinder. We also removed the rubble and stock piled in an area advised by the client. At this stage we had removed 1000mm x 2500mm x 350mm of the weight of the slab, so in effect over half of the slab.

—Step four – We set up the Pentruder diamond again and continue to cut the two sides, 800mm x 350mm deep R/C. The remaining slab was only now tied in along the 2500mm side.

—Step five – We set up again the C9 Darda burster and burst the 800mm section in the direction of the front which is not tied in. We then broke up in to manageable lumps and cut the steels with a 9” grinder. We also removed the rubble and stock piled in an area advised by the client. At this stage we had removed the majority of slab.

—The Final step was to set up the Pentruder diamond again and flush cut the remaining slab which one cut along the 2500mm side. Because at this stage we will have removed the bulk of the slab, we set up the track saw on the back wall, using L shaped steel brackets. This was fixed using x2 M12 fixings. This way when the remaining slab came away from the wall, the track saw was safe still fixed to the wall. The remaining rubble on the crash deck was then broke up and removed to the stock pile area.

—Once the job was complete the equipment was removed and the area of works were cleaned up and left neat and tidy as with all good housekeeping.

Our method we feel was the safest and most efficient method of removing the slab whilst leaving a flush finish to the side walls

We also carried out various track sawing works, diamond drilling for services, angled diamond drilled holes, diamond drilling and hand digging with he installation of bollards and lamp post protectors. Please see examples below: