Core Drilling

Core drilling is the part of diamond drilling that produces a clean circular hole and a solid cylinder of the material you drilled through. A hollow barrel set with industrial diamonds is rotated under water and load, grinding rather than hammering its way through concrete, reinforced concrete, masonry or stone, and leaving a straight-sided hole that needs no making good.

We core from 10mm up to over 500mm. At the small end that is anchor and resin fixings, conduit and instrumentation. In the middle it is drainage, ducting, service penetrations and balustrade sockets. At the large end it is manhole formation, major service routes and structural openings that would otherwise need breaking out.

Depth is effectively unlimited, because barrels are extended in sequence and the core is removed between extensions. Multi-metre cores through bridge structures and multi-storey foundations are routine rather than exceptional. What limits a job is almost never the depth: it is access, water, power and what the barrel might meet on the way through.

On investigation work the hole is a by-product and the core is the deliverable. A extracted cylinder gives verified slab thickness, the real reinforcement layout and depth of cover, the construction build-up layer by layer, and a specimen that can go for compressive strength testing. That is worth doing before a cutting or reinstatement programme is priced, because the alternative is pricing from a drawing that may be forty years old and was never as-built.

Electric rigs for internal and enclosed work, hydraulic for heavy and large-diameter drilling, petrol where there is no power at all. Mounting is chosen for the substrate rather than convenience: a vacuum base on a smooth power-floated floor, bolt anchors where the surface is textured or the rig will load unevenly, and a wedge-and-strut frame braced floor to ceiling where nothing can be fixed to.

We bring our own water, power and access. That sounds like a detail until the site has none of the three, which on airfield, port and highway work is normal rather than unusual.

Most of our coring is done on sites that stay open: airside aprons and taxiways where the pavement is handed back serviceable before the first movement, live port estates working to vessel calls, occupied buildings, and highways inside a night closure. That drives the method more than the material does. Slurry is contained and removed rather than washed to drain, cores are accounted for and taken off site, and every penetration is surveyed for embedded services first. On airside work a single core plug left behind is a foreign object debris incident, not untidiness.

We are based at Little Westerhill Farm near Maidstone in Kent. Kent, London, Sussex, Essex and the wider South East are covered from our own yard, and longer programmes are mobilised UK wide. For the wider technique, see diamond drilling, and for a plain explanation of the process, what core drilling is.