Why does Concrete Crack?
Newly poured concrete is wet and as it dries, it solidifies and shrinks, because the water used in the mix evaporates. This causes conflicting forces within the concrete, which can pull the slab apart. The bigger the slab and the more water used in the mix, the greater the chance of cracking. Similarly, if a concrete slab dries out too quickly, it can be liable to crack. Using the wrong type concrete or screed for the application can also cause these problems, as different types have different strengths.
How to Prevent Cracks in Concrete
One way to prevent newly laid concrete cracking is to not let it dry out too quickly by keeping it damp on top. Getting the mix right, with the correct type of concrete and not too much water initially, is also important but there are a few extra measures you can take to make cracking even less likely. Adding control joints to control where the concrete cracks is one measure. Another is to add polypropylene fibres to the concrete to minimise shrinking and, thus, cracking.
How Do Fibres Prevent Concrete from Cracking?
Using fibres to reinforce concrete is an age-old concept, but instead of the horsehair and straw of yesteryear, we now use synthetic fibres. Made from polypropylene, Siteworx Concrete and Screed Fibres minimise shrinkage and cracking in concrete by dispersing in the mix and forming a matrix, which helps to bind the material together. Adding these fibres reduces the tension created in the concrete when drying, often negating the need for reinforcement mesh, and also making the concrete more resistant to impact and abrasion. When adding fibres to concrete, make sure they are evenly mixed throughout the concrete and don’t clump together. Fibres aren’t a replacement for steel in structural concrete but are very helpful in preventing small cracks caused by shrinkage.
Siteworx Concrete and Screed Fibres are suitable for use in concrete floors, drives, paths, footings, bases, foundation and screed floors amongst others.
Working on the same principles, Siteworx Plaster and Render Fibres can be used in most types of render, as well as in base coat and finishing plaster, including lime-based plasters.
Find out more about the Growtivation Product That Works range by downloading our Product Guide.
Or to find out where you can buy Growtivation products visit our online Where to Buy facility or contact the friendly team at Growtivation for advice on 0800 197 8885 or email sales@growtivation.com.
