Sound management and maintenance for older asphalt revetments
The Netherlands has approximately 600 kilometres of dikes, and sea dikes in particular, that are covered with asphalt. Something like 70% of those dikes are now older than thirty years. The assessment conducted every five years has shown that improvements are needed in the monitoring procedures for these dikes, especially in the case of the older revetments, since it is not clear how long the dikes will remain fit-for-purpose.
A strategy for management and maintenance, which should also include an adequate approach to risk assessment, is also required so that the asphalt revetments will last as long as possible. Large sections of asphalt revetment will be replaced in the near future. A guideline for functional specifications will be drafted for the selection of more durable asphalt structures.
In a joint project with STOWA and the Rijkswaterstaat Centre for Water Management, we are working on extending the lifetimes of existing and new revetments by means of sound management and maintenance, including improvements to periodical assessment. This will involve:
- Improvements to the modelling of the behaviour of revetments under extreme loads, including breaking strength and residual strength. Validation will draw on field data and the results of laboratory tests.
- Improvements to the assessment procedure and an approach to monitoring asphalt revetments after an initial detailed assessment.
- A failure probability approach will be established to make clear how certain it is that the revetment complies with national requirements and standards.
- A management and maintenance approach will be established that managers can use to plan periodical maintenance and make estimates of how often revetments need replacement or major repairs.
- Specifications for functional requirements are being drafted for maintenance and upgrade operations.
The main outcomes of the planned research will be: a guide for the ongoing monitoring of the strength of asphalt revetments, a guideline for the functional specifications for asphalt revetments, and an appraisal method for asphalt revetments (WTI-2017).
In this project Deltares works together with TU Delft and KOAC NPC.