In today’s world of technology there is little that can astonish people, but Concrete Canvas is probably the product that can. Concrete Canvas (CC) – a versatile construction material that has a wide variety of applications across a range of sectors has predominantly been used for ditch lining in the private civil construction industry, but increasingly CC is being specified in the mining sector for general water management projects across the globe.
CC is a flexible, concrete impregnated fabric that hardens when hydrated to form a thin, durable, waterproof and fire resistant concrete layer. CC allows concrete construction without the need for plant or mixing equipment. CC can be installed quickly, and is uniquely suited for installation in remote, difficult to access sites of all terrains and in all weather conditions making it ideal for time-critical mining works. Simply position CC then just add water. CC consists of a three-dimensional fibre matrix containing a specially formulated dry concrete mix. A PVC backing on one surface of the Canvas ensures the material is completely waterproof. The material can be hydrated either by spraying or by being fully immersed in water. Once set, the fibres reinforce the concrete, preventing crack propagation and providing a safe plastic failure mode. CC is available in three thicknesses: CC5, CC8, and CC13, which are five, eight, and 13 millimetres thick respectively.
Following the recent success of a 52,000-square-meter CC installation in the Alta Montaña III region of Chile, Ledcor Group, acting on behalf of Walter Energy, specified CC as a protective liner for a large carrier ditch, directing mining industrial wastewater from Willow Creek mine to a nearby settling pond. Willow Creek is a large open-pit mine located 45 kilometers west of the town of Chetwynd in Northeast British Columbia. The mine is a truck-and-shovel operation and is capable of producing both hard-coking coal and low-volatile PCI coal for steelmaking. The customer specified that the lined ditch had to be as waterproof as possible, handle freeze/thaw conditions, and be easy to repair. The carrier ditch was 10.5-12 metres wide, between three and five meters deep and approximately 650 meters long. The overall size, performance requirements of this particular application, as well as the cost potential meant that Ledcor were reluctant to use shotcrete. CC was dispensed in bulk rolls from spreader beam equipment and was cut to length on site, minimizing waste as lengths were cut specifically to each section of profile. No perishable formwork or additional reinforcement was required.
“As an engineer, I liked the fact that CC was adaptable to changes in channel shape as we had segments of trapezoidal shape that had to transition to a rectangular shape. The drape characteristic allowed the CC to be placed on a pretty rough surface,” states Michael Graham, senior geotechnical engineer, Northwest Corporation. “Finally, it seems that any future damages to the CC will be easily fixed by patching. This should result in very low maintenance costs.”