NDTScan assesses the integrity of concrete elements, their reinforcement, cover, carbonation, corrosion activity, strength and internal condition, and reports the record an engineer needs to specify the right repair, or to show that none is needed yet.
What an integrity assessment covers
- Reinforcement and cover. Bar position, spacing and layers by GPR; cover mapped across the area with the Hilti Ferroscan, and flagged where it falls below the minimum in BS 8110 or Eurocode 2. See rebar scanning and Ferroscan surveys.
- Carbonation. Depth measured on cores or drillings with phenolphthalein indicator to BS 1881-210, set against the cover to estimate the time to depassivation.
- Corrosion activity. Half-cell potential mapping to ASTM C876 and BS 1881-201, with the pattern of potentials indicating where active corrosion is likely.
- Internal condition. Voids, honeycombing and delamination by pulse echo, and uniformity by pulse velocity to BS EN 12504-4. See ultrasonic testing of concrete.
- Strength. Rebound hammer and pulse velocity combined, and cores where the engineer needs a tested number, reported to BS EN 13791. See compressive strength assessment.
- RAAC. Plank by plank identification and condition in line with IStructE guidance. See RAAC surveys.
- Movement over time. Where the question is whether a crack or a deflection is still moving, wireless monitoring units record it between visits.
How the methods fit together
No single reading answers an integrity question. Low cover with shallow carbonation is a long way from trouble; low cover with carbonation at the bar and a negative half-cell potential is active corrosion. A hollow sound under a hammer might be delamination or might be a void in the pour; pulse echo tells which. Strength from a rebound hammer alone is a guess; with pulse velocity and a core it is an assessment. NDTScan plans the combination for the element and the question, and the report reads the results together rather than listing them.
What the engineer receives
- Cover, carbonation and half-cell maps on the element drawing, with the zones at risk ranked.
- Reinforcement layout and estimated cover tabulated per area, with the tolerance that applied.
- Pulse velocity and pulse echo results located on the drawing, with the areas of concern dimensioned.
- Strength assessment to BS EN 13791 with the method, the cores and the characteristic value derived.
- The equipment, calibration and standard for each method, and what each could not resolve.
- Findings written so a repair specification can be drawn from them, with the confidence of each stated.
The specialist who surveyed the element writes the report, which follows within an agreed number of working days. Where the engineer wants the surveyor's view on repair priorities, it is given as that: a view, with the evidence beside it.
Where it applies
Car parks, bridges, jetties, reservoirs, industrial frames, post-war housing, hospitals and schools, and any element an engineer has been asked to sign off, strengthen or repair. The service is part of NDTScan's concrete scanning work, carried out from Oxford across the UK, usually within one to two working days and same day where the diary allows.
Can you say whether a crack is still moving?
Not from a single visit. Wireless monitoring units record movement between visits, and the report gives the trend with the period it covers.
Do you design the repair?
No. NDTScan reports the condition and the evidence; the structural engineer specifies the repair. The report is written so that specification can be drawn straight from it.
Questions we are asked
Do you need to break the concrete open?
Rarely, and only where the engineer needs a tested value: a small break-out to confirm a bar diameter, a core for strength or carbonation depth. Everything else is measured from the surface, and the report says which readings came from which.