Weymoor Culvert Camp Week 2
Weymoor Culvert Camp Week 2
by: Neil D.
Following straight on from week 1 of the WRG’s summer camps at Weymoor Bridge, the main task for week 2 has been the construction of the steel reinforcing bar matrix and shuttering for the cast concrete slab that will cover the culvert and form the bed of the Canal. This slab will abut the one cast under the bridge that formed the (originally absent) invert. The restored bridge having been built to a much higher standard than the original to take modern vehicles. Just as well considering the heavy concrete mix lorries that would soon be passing over it! The steel reinforcing consists mainly of lengths of rebar at the edges where it had to be cut and bent to shape to go over the pipes that form the Culvert and also turn through 90 degrees to provide further reinforcing for the side walls. The reinforcing over the central Canal channel would consist mainly of reinforcing mesh. Around all this would be placed wooden shuttering that would contain the concrete slab when cast and also form the first 150mm of the side walls.
Whilst the WRG volunteers concentrated on the onerous task of assembling and fixing together all of the Steel reinforcement, the local East End Depot construction team installed all of the wooden shuttering. This had mainly been pre-cut and assembled back at the Depot (see one of the previous blogs) but, required some final adjustments and had to be set square, level and secured together on site.
The shuttering to form the base of the side walls had to be so designed to work around the upright rebars and consisted of around 30 ‘Hangman’ bridging pieces that suspended the inner wall forming planks 350mm from the outer walls and at the correct level of the concrete slab. The ready mix concrete for the cast slab had to be pre ordered and so there was a deadline to get all of this formwork completed. Suffice it to say that many hours of overtime and much burning of the midnight oil was required to meet this deadline! Our thanks go out to all those involved for such a mammoth effort! After a late finish on the Tuesday, all was nearly ready for the concrete poor midday on Wednesday.
Some last minute sealing of any gaps in the shuttering and the placement of one last reinforcing mesh Wednesday morning and all was ready for the concrete pour. Two large vehicles arrived, one containing the concrete and the other a bespoke pump and pipe work to pump the concrete mix under Weymoor bridge to the work site. Several more deliveries would be made as required and the great pour began.
The concrete pour had to be a stiff mix in order for that forming the base of the side walls not to sag during setting. The equipment used could actually alter the water mix ratio during the pour and adjustments were made as required. The whole process took several hours to complete. The following day saw the shuttering removed and a start made to installing the reinforcement for the side walls. This reinforcement will eventually continue on both sides to form the wing walls that will also be made from cast concrete. To this end, the first part of the wing wall reinforcement will protrude from the side walls so that the wing wall reinforcement can be joined to it when the time comes to construct them.
This will likely be next year’s project. Both wing walls will also have a cast concrete base and the first part of the reinforcement bars for them was similarly left protruding from the Culvert concrete slab cover.
The final task for this week’s camp was to install special steel shuttering for producing the side walls. This is being clamped to the previously cast bases of the side walls and supported over its height to provide the formwork for the concrete pour. As with the wooden shuttering, this is being coated in non-stick compound for easy removal. This last concrete pour is scheduled for a week’s time when we have a further WRG weekend camp. Other work will include casting the concrete ‘Aprons’ on each side of the culvert pipes to aid the flow of water through them.
Finally, our thanks once again to all involved for such a successful & professional fortnight’s work.
