A quick guide to setting up and laying concrete

 

Laying concrete should be an exciting part of you project providing you have prepared your area correctly

Preparing The Base For Concrete:

The preparation needed will depend on:

  • The existing surface
  • What the concrete will be used for
  • Measure and mark out the area where you want to concrete, using a string line and wooden pegs, ensuring that the corners have a 90 degree angle.

Key Points of Advice:

  • Your base must be 75mm larger than the finished slab to allow for formwork
  • Clear the area of stones and plants and excavate to a minimum depth of 100mm (deeper for soft ground)
  • The ground should be levelled and well compacted using a small garden roller or a lump hammer to provide a base for your concrete
  • A layer of hardcore of a minimum of 100mm is needed for a sub-base and should be well compacted

In all cases, if you have an architect design or an engineering design you should seek guidance from them or your architect.

Setting Up A Concrete Framework

The formwork is made up of timber planks 25mm thick that go around the edge of the area you want to concrete. This will support the concrete as it hardens and also is used to form a level.

When building your formwork it is important to remember to allow for run off, allowing water to drain from the surface and to knock some of the timber planks deeper than others (use a spirit level to check this). 

As a guide, an area of concrete 2m wide should have a drop of 25mm to prevent standing water.

If you are laying a circular concrete base, you could use a rope or hosepipe to mark the outline of the curve you want to follow. 

The pegs and string will need to be closer together to maintain the curve and the timber will need to be cut to about half its depth on the side that will form the inside of the curve.

 

Tips For Pouring Your Concrete Into The Project Area

Tamping Concrete:

A tamping tool can be as simple as a piece of wood with a good straight edge ensuring it’s longer than your form. You can also get metal tamps with handle bars, making the tamping movement easier! 

With one person at each end, raise it above the form before bringing it back down. Ideally this process should be repeated twice across the whole area of the poured concrete.

 

Top Tip:

It is best to level the concrete before tamping. To do this, use a sawing motion with the tamping tool across the surface of the concrete against the formwork whilst moving slowly forward. Anyone helping onsite can drag the excess concrete from the approaching tamping tool to make your life easier and help ensure the concrete is distributed more evenly. 

Be sure to check that the concrete gets into the corners of your forms and that there are no low spots. If there are then fill these in and repeat the tamping process. 

Setting And Curing

In order to allow your concrete to cure, and prevent cracking, we have listed some top tips. These should help your concrete drying out too quickly: 

  • Without the sheeting touching the concrete, cover the concrete with polythene sheeting weighted down at the edges
  • Leave covered for ideally seven days in summer and ten in winter to allow it to cure before removing the covering
  • Allow an additional day before removing the formwork to ensure that it is set.

What About Damp Proofing?

Lining the base where your concrete is going to go will help with damp proofing:

  • Use polythene sheeting thicker than 0.010 (known as 1,000 gauge)
  • Spread the sheeting over the sub-base, ensuring the edges are turned up at the wall to form a tray
  • Where there are joints; ensure they are overlapped and secured with waterproof tape. Please contact your local sales office, when you need watertight concrete or jointing materials.
  • Remove any rain water that maybe sitting on top of the sheeting before your concrete delivery

Our Locations

As the UK’s leading supplier of ready mix concrete, we have over 78 plants all across the UK.

Product Range

We have a range of specialist, high performance concrete products to support your project needs.

Calculator Tool

Use our simple and easy concrete calculator to get the right amount of concrete for your project.