Concrete coring success

Citi-Con deployed its stitch-core drilling capabilities to create openings for the installation of two new bin silo chutes as part of a large upgrade at a silo complex. This is over-and-above the many other professional silo bin rehabilitation services that we have already supplied to this prominent steward of raw food materials to prolong the service life of its structural assets.

Well over 1,5t of concrete was removed to create the 1,2mm x 0,400mm and a slightly smaller opening in which the chutes will be installed. More than 48 closely spaced cores were drilled according to the engineering design to shape the openings to the client’s exact specifications. This will ensure that the chutes fit precisely.

We completed the project in only six days, using a Hilti DD 200 coring machine equipped with a 450mm x 110mm diamond-tipped barrel from Diamond Products Group. The machine was expertly operated by Dion Rudolph, a seasoned Citi-Con Project Manager who brings extensive concrete-core drilling knowledge to the team to ensure the job is done correctly the first-time round!

Dion made light work of coring through the 500mm-thick concrete, extensively reinforced with high-tensile Y25 and Y32 steel reinforcing. The diamond tips were, therefore, kept well lubricated with a constant flow of water mixed with washing powder when cutting through congested reinforcing at the top, middle and bottom of the concrete slab. Sand was then added to the water to allow the dull or glazed bits to grind against the aggregate sharpening them before encountering reinforcing steel again.

Considering the sheer size of the openings, the blocks were divided in half with a line of stitch-drilled holes. Rigging eyes were then installed at strategic points on the block and the isolated section broken out with jackhammers before carefully hoisting it out.

Working in an operational area and within close proximity of other Citi-Con employees tasked with various aspects of the silo bin repairs, extra safety precautions were implemented. This included installing a canvas safety barrier to prevent injuries in the event of kickback. Again, an impeccable safety track record was maintained throughout and praised by our client.