Advantages of Asphalt Core
Asphalt is a viscoelastic-plastic material with a self-healing ability. Dams built with asphalt core are earthquake resistant and can be built with shortened construction time compared to most dams with clay or moraine as core.
A Hundred dams worldwide
More than one hundred asphalt core dams have been built worldwide since 1964, under all climatic conditions. All of them have an excellent performance record with negligible leakage.
Conditions and earthquake risk
Earthquake risk is a decisive factor in many countries for the design of dams. Through extensive research and based on experience, asphalt core dams have proven to be a very attractive option under such conditions. Asphalt is an elastic/ plastic material with a self healing property, quickly adapting itself to embankment displacements and settlements while maintaining its impervious properties even after exposure to severe earthquake strains.
Shortened construction time
With the machinery and technology established, asphalt core dams can be built quickly and efficiently even in areas with high precipitation, in contrast to embankment dams built with clay or moraine cores where construction time is often dramatically prolonged due to rainy conditions. The shorter construction time offers a major financial benefit in areas with high precipitation.
The asphalt core and the embankment are built simultaneously allowing for reservoir filling in parallel with the dam construction. The reservoir can therefore be established when dam construction is completed, and the coffer dams design can often be simplified.
Virtually maintanance free
A well designed and built embankment dam with an asphaltic core has proven to be virtually maintenance free. The asphalt core inside the dam body is protected from oxidation and ageing, and the asphalt’s viscoelasticity (plastic properties) remain unchanged for any over its lifetime. This type of protection also significantly protects the dam from sabotage or acts of war.
Asphalt is completely non harmful to the environment and can be used for potable water and irrigation dams.
The width of the asphalt core varies with the height of the dam, foundation, earthquake risk and the quality of the rock fill. For a medium height dam up to 60/ 70 meters, the core width is typically 50 cm. For higher dams, the core width is wider at the bottom and tapers gradually.
The asphalt is produced in an asphalt batch plant and laid together with the transition zones on each side of the core, in layers of 20 to 25 cm in thickness. Special machinery constructed by Veidekke is required to lay the asphalt. Three layers can normally be laid within one day. The asphalt layers fuse together as one seamless homogenous asphalt wall.