Conjet robot speeds dam repair in Venezuela
By Lindsay Gale20 October 2011
A Conjet Robot 364 hydrodemolition machine was used by Venezuelan contractor Fapco C.A, based in Puerto Ordaz, to remove concrete from the spillways of the Guri Hydroelectric Power Station on the River Caroni. The concrete, gravity and earth dam across the Necuima Canyon stands 162 m (532 ft) tall and has a crest length of 7,426 m (8,121 yd). Steel gates on the top of the concrete section control overflow down three adjacent spillway channels. The spillways have been in use for 30 years and the force of fast flowing water and continuous exposure to the elements had eroded the surface of the concrete. The Conjet unit has been mounted to a custom-built platform and removed concrete to depths ranging from 20 to 150 mm (0.8 to 6 inches).
Concrete was removed from an area covering 7,500 square metres (80,730 square feet) at a rate of up to 69 square metres (743 square feet) per day and was intermittent due to a combination of moving the platform, adjusting the Robot to the spillway geometry and refilling the water tank supplying the Robot. After concrete removal, Fapco followed on with a spray applied 800 kN/square metre strength mortar in areas less than 100 mm deep and 500 kN/square metre strength concrete in the deeper areas.
Fapco started on repairs to the first spillway in late 2009 and completed its contract in May 2011. Work on the project had to stop several times for several months, during the rainy seasons, when the spillway channels, not being repaired, had to be opened to control the level of the reservoir.