Diamond core drilling

What is diamond core drilling used for on site?

It cuts a clean, round hole through concrete, masonry, asphalt or stone using a diamond-tipped barrel, either to recover a core for examination and testing or to form an opening. Common uses are checking slab or pavement thickness, exposing the layers beneath a surface for further testing, recovering cores from an existing structure and putting services or drainage through a floor or wall. It cuts rather than hammers, so the surrounding concrete is not shaken about.

What core diameters and depths can you drill?

Everything from small anchor and resin-fixing holes of 20 to 30 mm up to openings of 350 mm and more, with the barrel and rig chosen to suit. Cores taken for strength assessment are usually 75 to 150 mm, because the standards want a diameter of at least three times the largest aggregate size. Depth is limited by the barrel length and by what sits behind the slab, so through-drilling a suspended floor needs the space underneath checked first.

Do you scan for reinforcement and buried services before drilling?

Yes, every position is scanned before the barrel goes near it, using a covermeter or ground-penetrating radar to locate bars, ducts, conduits and voids, with positions moved slightly where that avoids cutting a bar. Scanning is not infallible in heavily congested or deep concrete, so drawings, as-built records and your own knowledge of what is in the slab matter as well. Post-tensioned slabs need particular care and should always be flagged before we attend.

Do we need structural approval before an opening is cut?

Yes, and it needs to come from someone competent to give it. Cutting through a slab, beam or wall changes how the structure works, and severing reinforcement or a tendon can be serious, so the position, size and sequence should be agreed by your structural engineer or the building owner's engineer before we attend. We drill to an agreed and marked-out position. We do not decide whether an opening is structurally acceptable, and we will not cut without that confirmation.

Do you drill wet or dry, and how is the water and slurry handled?

Wet drilling is standard for concrete, because water cools the diamond segments, clears the cut and keeps dust down. The water is caught at the bit by a collection ring and vacuum, with bunding or mats where the floor must stay clean, and the slurry is collected for disposal rather than washed into a drain. Dry coring with on-tool extraction is used where water cannot be allowed near finishes, live services or occupied space below.

What power and water supply does the rig need?

A 110 V site supply runs most of our handheld and small rig work, with larger core rigs needing 230 V or a generator. For water, a standpipe, tap or IBC within hose reach of the position is usually enough, and we can bring water where the site has none. Tell us how far the position is from the nearest supply and whether it is above ground floor, because hose and cable runs and lift or stair access affect how long the work takes.

How is the drilling rig fixed to the structure?

Usually by an anchor bolt drilled into the slab or wall next to the core position, which is the most secure method and works on most surfaces. A vacuum base can be used on smooth, sound, flat concrete, and a jack or strut braced between floor and soffit suits positions where neither of those works. Anchor holes leave a small hole of their own, so tell us if the surface is finished or exposed.

Can you form openings larger than a single core?

Yes, by stitch drilling, which is a line of overlapping cores that cuts out a panel of almost any size or shape, including square and rectangular openings. Larger openings are often done as corner cores with saw cuts between them, which is quicker where a saw can reach. The section that comes out has to be supported, broken down or lifted away safely, so weight, headroom and a route off the floor all need thinking about beforehand.

Can you work in an occupied building, and how are dust and noise controlled?

Yes, and most of our work in occupied buildings is planned around when the space is free. Wet drilling produces very little airborne dust and dry work uses on-tool extraction, with sheeting and floor protection to keep the area clean. Noise is the bigger issue, because the vacuum and water pump carry and anchor fixing is percussive. Evening, night and weekend working is normally how this is handled, subject to any local authority restriction on hours.

Do you make good the holes after drilling?

That depends on what is agreed beforehand, so tell us at enquiry stage whether reinstatement is wanted and whether the cores are to be left with you. Small holes and anchor holes are commonly filled with a non-shrink grout or a resin mortar, and cores taken through surfacing can be reinstated with the appropriate material. Reinstating waterproofing, fire-stopping or a finished floor covering is specialist work and usually stays with the trade responsible for it.

Is diamond core drilling covered by your UKAS accreditation?

Drilling is a site operation rather than a test, so the accreditation question normally applies to the testing carried out on the recovered cores. Hixtra holds UKAS accreditation to ISO/IEC 17025 for the tests listed in its schedule of accreditation, number 8996, and accreditation is specific to the listed methods and scope. Ask us to confirm whether the testing you need is covered. Coring for a strength assessment also has its own requirements for core size, position and handling.

What information do you need to quote for diamond core drilling?

The site postcode, the number of holes, their diameters and depths, the material being drilled and where the positions are in the building. Add access details, the floor level, available power and water, whether services or reinforcement are known to be present, the hours you need us to work and whether reinstatement is included. If the cores are going on for testing, say so, because that affects how they are cut and handled.