20 Feb, 2023

Pavement Investigation Services

Pavement investigation services are essential in the United Kingdom as they provide valuable information about the condition and structural integrity of roads, major highways, runways, and other paved surfaces. This information is used to make informed decisions about maintenance, repair, and reconstruction projects, which can save money, improve safety, and extend the life of the pavement.

There are several types of pavement investigation services available in the UK, including:

Surface condition surveys:

This type of survey involves a visual inspection of the pavement surface to assess its condition, including cracks, potholes, and other defects. These can be carried out as walked surveys, although the use of video capture is becoming more common. This type of survey is often carried out routinely and can be a precursor to a full investigation.

Structural condition surveys:

This type of survey involves more detailed testing of the pavement structure to determine its strength, integrity, and stability. Techniques used often depend on what is to be achieved and what is already known; however, a number of destructive and non-destructive methods are often employed to gain a full picture of the pavement asset.

Intrusive test methods include:

  • Pavement coring to assess the makeup and depths of the bound layers; this also can provide samples for laboratory testing.
  • Dynamic Cone Penetrometer (DCP) testing to assess the strength of the underlying unbound materials giving an estimate of the CBR profile.
  • Window sampling to confirm make up and obtain samples of the unbound pavement materials and subgrade.
  • Trial pitting to obtain larger samples and investigate specific issues.

Non-Intrusive testing:

  • Falling Weight Deflectometer (FWD) to assess layer stiffness moduli of pavement layers and ascertain load transfer characteristics of rigid pavements.
  • Ground Penetrating Radar (GPR) to determine pavement thickness of large areas, plus this can be used to look for specific issues such as voiding and debonding between pavement layers.

Laboratory testing:

When samples of bound and unbound materials are sampled by intrusive methods, these can be subjected to a wide variety of laboratory tests to ascertain specific properties. Common tests include:

Bound Materials - Asphalt

  • Stiffness of layers
  • Air voids content
  • Binder content
  • Aggregate grading

Bound Materials - Cementitious

  • Compressive strength
  • Density

Unbound Materials

  • Moisture content
  • Particle size distribution
  • Optimum moisture content
  • Plasticity index


By combining a range of complimentary techniques, a pavement investigation can be completed to provide accurate and timely information to allow for the design of a cost effective maintenance and remediation strategy, allowing appropriate interventions to ensure that the integrity of the asset is maintained and working life realised or even extended. Appropriate maintenance strategies also ensure safety of the travelling public and limit disruptive unplanned maintenance.


You can find out about the full range of Pavement Investigation Services available from CTS HERE.