A unique class of construction material supplied by Kaytech not only solved logistical problems but also saved the Department of Rural Development and Land Reform time and money, due to its speed and ease of installation. The 22 km long Mooi River Irrigation Canal, supplying water to the remote Keate’s drift area of KwaZulu-Natal, was in dire need of rehabilitation. There were numerous badly cracked sections leaking untold volumes of water.
Realising the prohibitive transportation costs of a conventional concrete lining, Element Consulting Engineers sought an alternative solution from Kaytech, who recommended the patented product Concrete Canvas; an ideal solution for the areas inaccessible to vehicles. This led to numerous sections of the canal, totalling 5 km in length, being remediated using Concrete Canvas.
A state-of-the-art product, Concrete Canvas is a Geosynthetic Cementitious Composite Mat (GCCM) consisting of a three-dimensional fibre matrix containing a specially formulated dry concrete mix that simply requires hydration, either by spraying or complete immersion in water. Once hydrated, the concrete impregnated fabric hardens rapidly to form a thin, durable, fire-resistant layer. PVC backing on one surface of the mat ensures complete waterproofing. Since Concrete Canvas requires no mixing, measuring or compacting, less logistical complexity is needed.
Prior to commencement of the project, Kaytech supplied on-site training for the contractors. The correct installation methodology for Concrete Canvas CC5 (5 mm thick) was then implemented including the method for joining the 50 mm overlaps between each length. A sock of bidim A2 filled with river sand was used to temporarily weigh down each joint. Bidim is Kaytech’s renowned nonwoven, continuous filament, needlepunched geotextile manufactured from 100% recycled polyester. In total, 10 600 m2 of Concrete Canvas CC5 was installed along numerous sections of the canal. For each section, the CC5 was pre-cut to the required length to line the canal. The jointing method used for the CC5 was a simple folded prayer overlap. With the Mooi River close by, water was readily available for water bowser trucks to hydrate the Concrete Canvas.
Compared to standard OPC concrete, Concrete Canvas has better abrasion resistance, while its low mass and low carbon technology results in an eco-friendly product that uses up to 95% less material. Once set, the fibre matrix reinforces the concrete. Further properties include excellent chemical resistance, root resistance, as well as good weathering and UV stability. The flexibility of Concrete Canvas prior to hydration provides unique drape characteristics that closely follow the surface of the canal.
With installation rates of up to 240m2/day, using Concrete Canvas drastically reduced construction time for this project. Due to the rapid installation and curing of Concrete Canvas, the canal could be re-opened within 24 hours, minimising disruption of the water supply to the surrounding communities. Transportation costs were considerably reduced since 1200 m2 of Concrete Canvas can be transported on one 10 ton truck. In comparison, 19 truckloads of ReadyMix concrete would have been required to line an equivalent area with a 100 mm thick conventional concrete lining.
The local community was overjoyed with their “new” canal. The client and consulting engineer were very pleased with the performance of the product and will consider it for future projects.
