Posted: Fri May 20, 2011 4:57 am
I have a nightmare problem rescuing a 4Mx4M slab just poured.
Yesterday we poured what was supposed to be a 4M x 4M slab, 110mm thick with A142 renforcement mesh, fibres and retarder. The C30 was delivered by tipper truck and was semi dry. The problem was the mix was 0.5 cubic metres short of the required amount.
I am left with a base that is 30mm lower than the shuttering (required level).
The semi dry mix was watered a little, vibrating poker applied and a fairly gentle tamp. Since we were short of premix the surface was then scarified with a wire rake for later bonding.
This slab must be a perfectly smooth base for a PV array turntable. Four 200mm nylon castors bearing the 500Kg weight as the PV array rotates to follow the sun. The surface was to be epoxy painted. (The surface is obviously exposed to all weathers.)
I now need to build up the level by 30mm. The danger is that over time the weather will cause the slab to break up or otherwise delaminate.
The solutions offered to this nightmare scenario are the following alternatives.
1. Rip it all up (mesh and all) and start again.
2. or Build up the shuttering and raise the level by 75mm allowing a new 100mm pour plus more mesh. (and upsetting landscaping plans)
3. or Allow the new concrete to fully harden and use SBR bonding coat followed by a granolithic mix. (30mm thick) Would this be weather proof?
4. or Use very expensive polymer screeds costing £1,000 plus and a lot of work.
Question…. are there any affordable screeds that can withstand the weather and the pressure of the castors each bearing 150Kg. what is the best affordable solution other than rip it all up.
Yesterday we poured what was supposed to be a 4M x 4M slab, 110mm thick with A142 renforcement mesh, fibres and retarder. The C30 was delivered by tipper truck and was semi dry. The problem was the mix was 0.5 cubic metres short of the required amount.
I am left with a base that is 30mm lower than the shuttering (required level).
The semi dry mix was watered a little, vibrating poker applied and a fairly gentle tamp. Since we were short of premix the surface was then scarified with a wire rake for later bonding.
This slab must be a perfectly smooth base for a PV array turntable. Four 200mm nylon castors bearing the 500Kg weight as the PV array rotates to follow the sun. The surface was to be epoxy painted. (The surface is obviously exposed to all weathers.)
I now need to build up the level by 30mm. The danger is that over time the weather will cause the slab to break up or otherwise delaminate.
The solutions offered to this nightmare scenario are the following alternatives.
1. Rip it all up (mesh and all) and start again.
2. or Build up the shuttering and raise the level by 75mm allowing a new 100mm pour plus more mesh. (and upsetting landscaping plans)
3. or Allow the new concrete to fully harden and use SBR bonding coat followed by a granolithic mix. (30mm thick) Would this be weather proof?
4. or Use very expensive polymer screeds costing £1,000 plus and a lot of work.
Question…. are there any affordable screeds that can withstand the weather and the pressure of the castors each bearing 150Kg. what is the best affordable solution other than rip it all up.