Hydraulic Asphalt Inspections
Hesselberg Hydro’s advice to clients on essential maintenance depends on regular inspections of previous projects to monitor performance.
While we will inspect any hydraulic asphalt structure, our work is most commonly on asphaltic concrete dam linings.
The linings are protected by a seal coat of either mastic or bituminous emulsion which generally needs to be re-applied at 15 to 20 year intervals. Before covering the asphalt, it is prudent to have the lining inspected and maintained.
Our inspections, which carry on well past any contractual obligation, also provide the knowledge of long-term behaviour of materials and structures that continually inform improvements to technology.
The construction of asphaltic dam linings is an important example of how technique has been modified in the light of experience:
- Older dam linings have two layers of Dense Asphaltic Concrete (DAC). During installation, heat caused adjacent layers to adhere leaving the interface indistinguishable. However, any moisture trapped between the layers during construction can lead to de-bonding and blistering. After initial de-bonding, progressive damage will follow , once blisters start to crack and allow more water in.
- The problem is avoided in modern installations by a single, thicker impermeable layer.
- Finding and repairing de-bonding damage is one of many aspects of the inspection work that has taken Hesselberg Hydro’s team around the UK, and to the Faroe Islands and Norway.