Although the apron was repaired in 1997, erosion in the sacrificial wear layer of 2 to 30 cm has been observed, and the reinforcing steel was visible. The secondary concrete and part of the stone concrete were eroded, allowing uplifted water to leak. When opening no. 4 was closed and dried in 2009, specifications were prepared to repair the eroded apron with Ductal® with metallic fibres.
The apron structure of the Caderousse Dam hydroelectric power plant is subject to continuous abrasion caused by solid elements (sand, pebbles and a variety of waste materials) that are carried by the river. There is a rake designed to remove the solid matter, which also entails scraping the concrete, exacerbating wear caused by abrasion.
"We have developed two specific tests", adds Jacques Perrier, Construction Materials Manager at CNR. "The first is to test abrasion by reproducing the effects of wear from sand on the apron, and the second simulates the impact of pebbles. Ductal® was the chosen material because of its high performance in the impact test and its good resistance to abrasion."
"This is completely different from traditional concrete, which hardly spreads in an even way. Ductal® behaved almost like using a self spreading material. Our solution enabled us to place Ductal® in a single operation and avoid the need for a concrete joint." said Tony Mérillon, President of Mérillon.
Why Ductal® with metallic fibres?
The mixing of ready-mix concrete, transport by truck and the pumpability of Ductal® were keys for success on the worksite. With impact and abrasion resistance comparable to granite, (reference rock), Ductal® is the ideal concrete for renovating structures subjected to high impact and abrasion.