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THE CHALLENGE: Erosion damage in the concrete
faces surrounding underwater penstock gates in a concrete dam face prevented
proper sealing. Water loss was excessively high in the closed position, and
since reservoir water is "money in the bank" to an operator something had to be
done. Lowering the water level to effect repairs was an unacceptable, "last
ditch" alternative.
THE SOLUTION: TFT Kevlar reinforced BIO-DUR
561 epoxy coating was chosen to effect repairs to the sealing faces
underwater. This material has unlimited potable water approval granted in
Australia and has no effect on the environmental quality of reservoir water. A
diving company with experience using BIO-DUR 561 to repair worn manholes
was chosen by the dam operator to rebuild the concrete sealing faces. A trial
application was closely monitored for one year to confirm the practicality of
the application before commencing full-scale repairs the following summer.
BIO-DUR 561 is a completely solvent-free, 1/1 volume
mix product. 1/1 volume ratio mixing is the ideal ratio from a practical point
of view since minor mixing errors in mixing have the minimum effect on
performance. The components were supplied in contrasting colours of Red Oxide
epoxy base and White curing agent to yield a uniform Red mixture.
The concrete surfaces were prepared for coating by high
pressure water blasting. About 3,000 psi held close in to the surface is
effective at removing all organic fouling from submerged concrete surfaces.
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BIO-DUR 561 was applied to the freshly blasted surface using
straight-edged plastic spreaders. Unlike traditional "Splash-Zone" type products
its viscosity permits application by "buttering" which gives a very smooth
surface. Since BIO-DUR 561 is smoothed onto surfaces rather than having
to be pressed on in a "patty-cake" style its production rate is much higher.
During the repair work the divers became so adept that losses became negligible.
THE RESULT: Application by spreader was effective and
yielded an excellent, tightly adherent film. The BIO-DUR 561 applications
cured well overnight and formed a tough, tightly adherent protective coating
over the concrete sealing surfaces. After repairs were completed the dam
operators reported that they were able to achieve a proper seal for the first
time in years.
For more information regarding this project contact:
Paddy Atkinson Director
TFT Epoxies (UK) Limited
13 Ryecroft Lane, Belmont Village
Bolton, Lancashire BL7 8AH
Telephone: +44 (0) 7973 553 447
FAX: +44 (0) 1204 811 212
E-mail: info@TFT-epoxies.co.uk
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