Michal Doubrava on the benefits of screed reinforcement
HERE I will discuss the performance criteria of the different types screed reinforcement products available on the market.
Time and cost pressures on contractors can lead to important steps in construction being overlooked. Using a reinforcement material when screeding has sometimes been seen as an ‘extra’ step.
However, skipping the reinforcement puts the responsibility on specifiers and contractors, leaving them liable for any subsequent failures and at risk of facing a costly bill to rectify the situation if cracks appear and grow over time.
There isn’t legislation to enforce the use of such materials, but tests have proven the huge benefits they can bring to construction of a building to give long-term savings.
As the name suggests, it improves the strength of screed constructions, a vital element of what is a fairly time-consuming and costly process. So it’s worthwhile reducing the requirements for further maintenance. The inherent nature of screeds means that they shrink during the drying process. This develops cracks in the surface, so the surface is uneven and can be prone to problems later in its lifetime.
Reinforcement maintains the structure of the flooring, reducing the chance of cracks to leave a smooth, good-quality finish. Traditional wire mesh is a popular choice for reinforcing screed, while polypropylene chopped fibres are also another option, seen as more efficient for unbounded screeds or for over underfloor heating.
Through research and development of products and vigorous testing, there are now solutions to tackle some of the most common problems that floor specialists face on a daily basis.
The three main criteria for a perfect finish are to reduce the number of cracks that appear, reduce the size of the cracks if they do appear, and achieve a smooth and durable final layer once dry.
Although the cracks don’t produce a structural problem, they can make laying tiles or resin far more difficult. The drying period lasts 28 days after the application, so this often leaves ample time for chemical reactions to occur.
If no reinforcement is used, cracks start to appear almost immediately. Testing has found that glass fibre grids can reduce cracks in the surface by 60% compared to metallic mesh.
When looking at the size of the cracks that did develop, flexural tests have been carried out to find that glass fibre grids result in smaller openings by 50% compared to polypropylene fibres, while achieving a flat and smooth finish to work on.
A smooth finish creates the perfect base for tiling or for innovative solutions such as underfloor heating. Although chopped fibres are often chosen for such projects, they create irregularities in the surface as parts of the fibres stick out of the screed. A floor grinder is then required, so the length of the project is extended and the cost of hiring equipment and skills of the labourers would need to be accounted for. Repairing heated floors can be costly, so it’s important to minimise the risk as much as possible.
Glass fibre grids offer screed reinforcement fabrics for mortars and renders, suitable for all types of liquid and traditional screed types to ensure a stable, strong and long-term reinforcement solution.
Michal Doubrava is product manager for Saint-Gobain Adfors www.vertexmesh.com
this article has been reproduced from the Contract Flooring Journal. You can find them at www.contractflooringjournal.co.uk.