Feb 14 2008
Despite the recent warm weather – which may lull us into false security - winter is still upon the Northern Hemisphere and there’s plenty of time for a cold snap. That means we should not forget that in a colder ambient air temperature concrete and mortar mixes will take longer to harden.
There are, however, many precautions you can take to protect a job for a longer period of time while material hardens. There are also quick-setting products that can be particularly helpful to the user.
Freshly laid concrete or mortar is at risk of damage if the water in the mix freezes. That’s because ice expands as it forms and can disrupt the crystal structure and weaken the bond between the aggregate particles and cement paste.
Ultimately this reduces the strength of the concrete or mortar, increasing porosity and leading to a loss of durability and the possibility of spalling, which is when small pieces of concrete break off a surface.
Work should never be carried out when the temperature is lower than 5°C or when frost is expected within the following 24 hours.
Consider using warm water for the mix instead of cold when the temperature starts to get low and make sure bricks and blocks are covered so that they don’t become saturated and frozen.
Think about protecting freshly laid slabs with polythene sheeting and/or insulation but take care to support them clear of the slabs in order to prevent them marking the surface.
Erecting windbreaks is also a useful way of adding protection from cold winds because even at moderate temperatures strong winds can be detrimental to unprotected concrete or mortar.
There’s even more you can do, particularly during mixing and batching and that includes making sure that both the mixing equipment, and the aggregate used, are free from ice. Always remember that applications that are shallow, or have a thin cross section, are more at risk of damage from freezing conditions than thicker units and require greater protection.
Completing a job as early as possible in the day is also a good idea, before the evening temperature drops below freezing.
With winter in mind Castle Cement is putting the spotlight on its Readybag High Performance Post Mix and Quickcem products with a trade press advertising campaign.
Castle Readybag High Performance Post Mix is formulated to produce high early strength concrete for setting all types of post in less than ten minutes.
It’s quick setting and easy to use because you just add it to water in a hole, without mixing. It saves time spent on a job and is economical to use because it creates less waste than some other methods.
You can also rely on the consistency of the quality, because the High Performance Post Mix is factory produced to ensure high quality.
Castle Quickcem is a quick setting and hardening Portland based cement containing additives, specially developed to give quick setting and strength development.
It can be used for repair, maintenance, fixing and cold weather applications where increased speed of set and strength are required and normal service can be resumed after only a few hours.
Typical uses include fixing manhole covers, fitting ridge tiles, repair of rendering and floor screeds, patch repairs and concrete paths and steps.
I hope I have shown that work doesn’t have to come to a standstill in a cold snap and that by using the right products and using the correct precautions you can keep jobs ticking over.