Concrete Pre-Pour Checklist
Before proceeding with any concrete pour on a construction site, there are a number of checks required to ensure quality work is being carried out. You, as a responsible project engineer, should NOT authorize a concrete pour without undertaking the following checks. If you don't do these pre-pour checks and your contractor knows this, they can start taking shortcuts to make life easier for themselves at the expense of quality and (potentially) safety.
Must Have References
Whether you're pouring a concrete slab or a wall, you need to check that your formwork has been adequately prepared to receive the concrete. Make sure you check:
- Dimensions of the forms are as per the construction drawings
- The forms are plumb (ie dead vertical) and square (90 degrees at the corners)
- Forms are oiled with "form release" or "bond breaker" so they can be stripped easily away from the concrete when the concrete has sufficient strength.
- Forms are oiled with "surface retarder" to expose the aggregates at locations where concrete will be poured against that surface in the future.
- Forms are secured and adequately supported/braced so that when concrete is poured they will retain their shape. (The last thing you need is to have a concrete wall with a bulge in it because the forms were not sufficient for the concrete pressures.)
- Joints between formwork shutters have been sealed.
- The formwork is clean ie no extra nails, debris or sand on the bottom of the form that could imbed itself on the base of the concrete.
Checks on reinforcement in concrete:
- The amount of reinforcement placed is as per the construction drawings - the right spacings and quantity of bars.
- No shortcuts have been taken for the contractor's convenience ie steel has been cut for ease of placing.
- There are re-entry bars around openings (to avoid cracking)
- Reinforcing bars are sufficiently tied - not loose.
- Cover to reinforcement is adequate - if you stand on reinforcement for a ground slab, it should support your weight and not sag too much.
- No loose tie wire is left on the ground where the concrete will be poured.
- Water down reinforcement slightly prior to a concrete pour to ensure it is not too hot (if pouring on a hot day).
Check that all cast-in items have been installed in the right location prior to a concrete pour. This could include small ferrules, plates or large steel beams. If lifting anchors are required, ensure they are placed as per the manufacturer's specifications to ensure safety when lifting the concrete unit afterwards.
Equipment & Hand Tools
Do you have sufficient hand tools ready to place the concrete?
- Spare vibrators?
- Fuel for vibrator available?
- Equipment to screed and finish the concrete (shovels, trowels, bullfloats)
- Concrete pump is available?
- Contingency if the pump breaks down - can you use a crane and kibble in this case?
- Protective clothing is available for working with concrete - boots, safety glasses, gloves etc
There are a lot of other checks that must be carried out before a concrete pour. Make sure an experienced person is available on site in case something does go wrong. Instead of panicking, they will be able to assist with other options. If you undertake the checks listed in this hub, at least you will have taken some reasonable steps to ensure the product is of a high quality.