Microsilica applications: Dams
Alta Dam, Norway
Microsilica was used to reduce the cement content and thus the heat of hydration of the 135 000 m3 concrete. Completed in 1987, the dam is 145 metres high, 140 metres long at crest and 15 metre thick at base.
Kinzua Dam Stilling Basin, USA
Extensive testing showed that high strength microsilica concrete, made with local aggregates, provided concrete with the best abrasion-erosion resistance for this rehabilitation project.
Kinzua Dam is an earth-fill and concrete gravity structure located on the Allegheny River in northwestern Pennsylvania. It was completed in 1967.
The stilling basin slab was originally 1.5 metre thick and contained 150 mm nominal maximum sized aggregate. In September 1969, divers reported that the stilling basin was damaged. The damage appeared to be caused by abrasion-erosion, manifested by severe loss of concrete in patterns, indicating that eddy currents were being developed in the stilling basin. These currents were causing debris to be moved about within the basin and to abrade the slab.
Subsequent inspections have shown that the microsilica concrete placed in 1983 is outperforming previously used concretes by a wide margin. For example, neither of the previously used PC concretes cast in the Kinzua Dam stilling basin floor lasted longer than seven years.