Highway Structures and Asset Surveys

Bridges, tunnels, retaining walls and other roadside structures


Concrete highway structures are subject to deterioration from multiple fronts such as corrosion, chemical attack, weathering and abrasive damage.   Visual inspection is arguably the most useful NDT tool for identifying signs of deterioration.  However, structures which carry traffic such as bridge and tunnel decks are commonly overlaid with asphalt to help prevent deterioration therefore hampering the effectiveness of visual inspection.  When visual inspection is impaired and even when it is not, non-destructive testing is extremely valuable for determining the cause and extent of deterioration.  

Below decks


Zetica’s ground coupled CWSF GPR solution is an excellent tool for investigating defects within and beneath deck surfacing material.  It can provide:

  • accurate measurements of surfacing thickness, optimised with one or more cores or trial pits to provide calibration data,
  • cover depth and spacing or rebar,
  • overlay debonding and delamination,
  • concrete delamination at the rebar
  • evidence of rebar corrosion.


We can also utilise other tools to support our findings.  For example, whilst GPR is excellent at detecting delamination between materials, especially if water is trapped it can be compromised by changes in surfacing material.  Infrared thermography can be used to capture temperature gradients in the deck as it is heated in the sun.  Hot spots can occur over delamination as heat is not transferred into the concrete as quickly compared to areas where the bond is good providing supporting evidence.


NDT of concrete structures

Zetica can also perform non-destructive testing of concrete structures such as retaining walls and VRS (vehicle restraint system) barriers.

Keen to find out more?

To discuss road surveys with one of our experts or to get an estimate for our services, please call (0)1993 886 682, email roads@zetica.com or contact us online.