Colas Postset

Colas Postset is a pre-packaged cement based concrete containing graded aggregates and non-shrink additives. Colas Postset is supplied to site ready to use, only requiring the addition of mixing water to produce a stiff rapid-hardening concrete.

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Colas Mortar Products C45 C60 C90 Non-shrink Concrete


The mixed concrete, when placed, will harden in approximately 5 minutes and reach initial set in approximately 10 minutes, depending upon climatic conditions.

Colas Postset can be placed in a single pass from 30mm to 500mm. Thicker sections can be achieved by placing additional layers once the preceding layer has reached initial set. The rapid setting assists the fixing of highway furniture and fence posts. The product is chloride free and can be safely used with cast iron and steel units. After placement, no special curing is required in moderate ambient conditions.

Where to use?

  • Concrete Placing road signs
  • Support for fence posts, minor installations and haunchings
  • Backfill or non-structural void filling


Laitance and all loose material including dust, oil and grease should be removed in order to produce a sound substrate. The work area should be pre-wetted taking are to remove any standing water before placing the Colas Postset concrete. To achieve the most consistent concrete mix, mechanical mixing is recommended.

Thorough hand mixing is suitable but care should be taken to ensure that the mix is fully wetted out without the use of excess water. Mechanical mixing may be carried out in a suitable vessel using a slow speed high torque drill and paddle.

Hand mixing may be carried out using a clean spot board or wheelbarrow. Each 25kg tub or bag of Colas Postset requires 1.0 to 1.75 litres of water to give a stiff concrete. Excess water should not be added. Combine the aggregate and cement portions and gradually add water until a stiff concrete consistency is achieved.

Once setting of the concrete has commenced, further mixing should not be used to re-work the mix. The concrete should be placed within approximately 5 minutes of mixing. The working time may be extended in cold ambient conditions and may be slightly shortened in hot ambient conditions.


Place mixed concrete onto dampened prepared substrate as soon as possible after mixing.

Compact concrete into place using a suitable tamp or float. Tools and mixers should be cleaned with water before the Colas Postset has hardened.

Curing: No special curing is required at temperatures between 5°C and 35°C.


The volume yield of each 25kg bag of Colas Postset is approximately 12 litres.


Colas Postset is supplied in 25kg bags (50 x 25kg bags per pallet) and 25kg buckets (40 x 25kg per pallet).


Colas Postset will have a shelf life of 6 months when kept in unopened packaging. In dry conditions in a temperature range of 5°C to 35°C. Storage at higher temperatures or high humidity may reduce the shelf life.


Manufactured in accordance to BS EN ISO 9001:2015.


Required mixing water is 1.0 to 1.75 litres. Aggregates as supplied contain moisture.

Do not add excessive water for mixing. Variations in water content for particular applications may alter concrete consistency and compressive strength achieved.

Typical Mortar Properties @ 20ºC

Compressive Strength 60mins 5 – 10MPa
1 day 20MPa
28 days 40MPa
Particle Size 0 – 10.0mm
Density 2300 – 2400kg/m³
Approx. Working Life @ 20ºC 10 mins


For full safety information, please request the Colas Postset Safety Data Sheet 124 using the contact information on this webpage.