Following some basic steps will help you achieve the perfect concrete pour, saving you the extra time and cost of having to redo a poor job.
Here, we’ll look at the entire premix concrete pouring process and how to avoid the pitfalls that can make it tricky.
Armed with this insight, you should breeze through your next concrete pour, whatever the weather.
PREPARATION
- Ensure clear, safe access for concreting trucks.
- If working outside, clear and level the area of anything that would hinder the pouring process. Remove any old concrete, rocks, trees, shrubs and grass until you’ve exposed the raw earth.
- Prepare the sub-base. If necessary, use a vapour barrier like polythene.
- Confirm the type of concrete and volume required. Check the weather – a retarder or accelerator may be needed in cold or hot conditions
THE CONCRETE POUR
- Keep within the stipulated maximum water content – adding too much water will reduce concrete strength.
- Vibrate or rod the concrete to ensure adequate compaction.
- Smooth off the surface, without overworking the wet concrete.
FINISHING
You can’t begin the finishing process until the concrete has hardened sufficiently and bleed water has evaporated from the surface. How long this takes is largely down to the weather.
The finishing method will depend on how durable – and therefore how dense – you need your concrete surface to be.
FINISHING TECHNIQUES INCLUDE:
- Mechanical power floating – for a robust, smooth surface (the standard internal finish).
- Bull floating – for most external surfaces.
- Decorative finishes – exposed aggregates, polished or ground.
CURING
A good curing environment is necessary immediately after finishing, and for seven days to get the best results. This entails preventing early loss of moisture from the concrete, which could cause cracking through shrinkage. After finishing and before curing, an evaporation retardant might be needed to avoid excessive moisture loss in hot weather.
CURING METHODS INCLUDE:
- Ponding – building up sand around the perimeter and covering the slab with water.
- Spraying – using sprinklers to keep the slab wet.
- Covering – trapping moisture on the surface to minimise evaporation, typically with a plastic sheet.
CONCRETE CURING IN COLD WEATHER
Freezing temperatures can trigger curing issues such as cracking and strength problems. Use curing blankets to address this problem. If curing coloured concrete, install a barrier of landscape fabric between the blanket and the concrete to avoid a mottled appearance. After removing the blankets, rinse the slab surface straight away to reduce white discoloration.