Concreting In Cold Weather

Placing Concrete 

The concrete gang will prepare the area for concrete works in advance, i.e. install screed unit, vibrating units and generally make good the work area.

The operatives will all wear the correct PPE in this case rubber gloves and Wellingtons (safety glasses worn when required).

The concrete ganger will direct the banksman with either the pump or concrete skip to the correct area and commence the concrete pour.

Scaffolding will be provided where necessary.

Concrete placement to high wall pours (i.e.. over 3.0m) will be by concrete pump.  The pump bagging will be initially positioned at the base of walls and then progressively withdrawn.

On high wall pours care will be taken to ensure the concrete is fully compacted at lower levels and around box outs or cast in pipes.

Unformed surfaces will be finished with a steel float.

Upon completion of the pour they will then tidy up equipment and move to the next work area.

All tools and equipment that require cleaning after being in contact with fresh concrete will be cleaned in the wash out area provided at the batching plant.

Concreting During Extreme Weather 

When ambient temperature falls below 20C (5 and falling or 2 and rising) cold weather procedures will be followed.  Ensure that the selected batch plant has a heated water facility, which can be used to ensure aggregates and water are not freezing prior to mixing.

When temperatures of below 00C are forecast or present all exposed surfaces will be covered with a frost blanket and the whole pour area covered in either polythene or a canvas sheet(s).  Space heaters should be provided to maintain the air temperature at not less than 50C until the concrete strength has attained 5N/mm2.

All of this equipment should be on site and daily weather forecasts will be monitored for snap frosts.  Records of on site temperatures should be maintained.

During periods of high temperatures all exposed surfaces will be covered in polythene or damp hessian to prevent either the temperature of concrete exceeding 320C or 60C above the prevailing shade temperature when the latter is greater than 210C.

5.0  Testing & Inspection

Cube sampling rate will be a minimum frequency of 50m3.  Any pours less than this requires one sample.

A sample to be 4 No. 150x150mm cubes

1@ 7 day

2@ 28 days

1 spare

Extra early strike cubes will be taken for roof slabs etc to determine when falsework and formwork can be struck.

Cubes will be stripped as soon as possible after casting i.e. next working day and stored at 200C in a curing tank.

plant that mixes concrtete
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