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How to Avoid Cracks Forming in Concrete

April 30, 2014

building-concreteConcrete is undoubtedly one of the strongest, most robust man-made materials available when it comes to construction or floor laying. But even the toughest things can become damaged over time or through heavy duty impact. Concrete often has to withstand a lot of traffic, either from people, vehicles or machinery, making it susceptible to cracks and other faults.

This is largely inescapable. However, cracks can also form if your concrete is incorrectly mixed or laid, which is most definitely avoidable, so long as you’re aware of the reasons that might cause them to occur…


Incorrect Mix
One of the biggest causes of cracking in concrete, especially in a surface that has been recently laid, is with the consistency and make-up of the mix. Ensuring that it contains the right amount of water is often the main issue.

A mix that’s too wet, despite being easier use when pumping or barrowing around a site, will shrink as it dries, forcing the slabs to stretch and ultimately crack while setting.

Similarly, not enough water can also cause problems. A mix that dries too quickly is not seeing the hydrating chemical reaction that’s required to form a strong surface, and is far more susceptible to cracking.

An ideal water to cement ratio in a mix is up to 50:1 for concrete that is to be exposed to freezing or very cold weather conditions, and 45:1 for concrete being used in heavy sulphate areas.

Remember: the lower the water to cement ratio, the higher the strength and durability of the mix.


Weather Conditions
Both the temperature and the level of precipitation present also have an impact on the crack resistance of freshly laid concrete. Pouring concrete onto frozen ground is highly hazardous, as the mix will not cure properly and will likely split when dry. In extremely cold temperatures, an accelerant must be added to speed up the chemical reactions that are needed for curing.


Control Joints
iStock_000003920953XSmallThe key to preventing cracks in concrete that is setting is to control the amount and positioning of any contracting and expanding it does during this period. Your mix will shrink as it dries – this is impossible to avoid – so being able to decide whereabouts this happens is all you can do. Utilising isolating joints is an effective way of doing this, allowing you to mould the shape of the malleable mix using steel or wooden joints.


Roadmaster Concrete Mixers
Here at Roadmaster Concrete Mixers, we stock a range of high quality volumetric concrete mixers for use by those in the industry across the South East and beyond, providing you with the ideal method of concrete mixing and distribution at your site.

Volumetric mixing allows the user to create the mix directly onsite, eradicating the danger of over or under ordering, while also allowing for the mix to be altered on-the-fly depending on the changing weather conditions or the needs of the project.

This means you can avoid cracks in your freshly laid concrete by ensuring that the mix is neither too wet nor dry, and is able to withstand cold conditions.

Get in touch with Roadmaster Concrete Mixers today to discuss how one of our volumetric trucks can help your business.