A good use for old car tyres.

http://www.cardiffcanoeslalom.com/
Re-profiling to the slalom course sides.
In order to create the turbulent water flow required by the canoeists who will use the completed facility, the shape of the course has been specially designed by the consultant responsible for this part of the centres performance, Hydrostadium. During August and early September the first stage of re-profiling the uniform reinforced concrete sides to the slalom course was completed using concrete blocks and backfilling the voids between the block work and concrete sides using a combination of single sized free draining stone and more interestingly bales of old car tyres. The use of car tyres has been chosen because it is an excellent way of utilising what is an abundant waste material which normally has to be disposed in landfill. It fulfils the performance requirements of the material required to fill these “dead zones” between the block work and vertical reinforced concrete walls, in that it is free draining and inert when in contact with water. But on top of this has several environmental benefits including reducing material to landfill and reducing the requirement of primary aggregates sourced from quarries.
After the block work was complete and the voids back filled, the final surface is formed by spraying concrete onto the blocks after first fixing a layer of steel mesh reinforcement to prevent cracking. The shotcrete, as this type of concrete is known, is then finished using wooden trowels as can be seen in the photographs. This work is expected to take about 5 weeks, weather permitting