The winter benefits of admixtures

The winter benefits of admixtures

With winter upon us, builders should recognise the benefits of admixtures on site.

Building admixtures can be found on sites across the country, providing numerous benefits to the workability of mortar, concrete, screeds and render. They become especially useful during winter months, when temperatures drop, and working with these materials becomes increasingly difficult. Accelerators and air entraining plasticisers are the two most common types of admixtures available, offering many benefits, not only during the winter months but all year round.

As the name suggests, accelerators increase the setting and hardening times of mortar, concrete, screed and render, and help offset the effect low temperatures have on these types of applications to provide faster finishing times, even in cold weather. Products such as Everbuild’s 203 Accelerator and Frostproofer provide frost protection to the wet mortar during the setting period; even in sub-zero temperatures down to -8°C and can also be used as a plugging aid when mixed neat with fresh cement.

Where can Everbuild 203 Accelerator and Frostproofer be used?

  • In mortars
  • Flooring screeds
  • External and internal cement based rendering
  • Non-structural concrete
  • As an emergency repair plugging aid when mixed neat with cement

Air entraining plasticisers are used all year round and form small, extremely stable air bubbles within the mix, giving it a “buttery” consistency, which is easy to work with and prevents shrinkage, cracking and crazing during the setting process. These air bubbles also provide a degree of frost-resistance during the setting process, as well as giving continued resistance to freeze/thaw cycles. Whilst these air bubbles improve the workability of the mix, they do reduce its stability so shouldn’t be used for structural concretes or flooring screeds.

An example of an air entraining plasticiser is Everbuild’s 201 Mortar Admix which replaces lime in the mix to reduce the chance of efflorescence and smooths out variations between separate batches of sand and cement.

Where can Everbuild 201 Mortar Admix be used?

  • Load bearing brickwork
  • Block laying
  • External/Internal rendering
  • Pointing/repointing brickwork

The benefits of these admixtures can be found together in products such as Everbuild 207 Zeromix CFF and Sika Wintermix, which incorporate the fast setting times of an accelerator with the improved workability of an air entraining plasticiser.  Products such as these are classic examples of the incorporation air entraining technology, both of which also act as an accelerator for use in sub-zero temperatures. These chloride-free liquids improve freeze/thaw resistance and also eliminate the need for a separate frost-proofer.

Admixtures are also available in concentrated formulations, such as MaxMix Frostproofer and Accelerator which will treat 100kg of cement with just 1L. Not only does this mean that less product needs to be carried, but the amount of waste packaging is also greatly reduced; a topic which is currently high on the agenda.

Working in winter can often be a difficult time for the trade but by simply using the correct products for the time of year, work can continue even when the snow starts to fall.

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