Reinforcement Mesh Fabric
Reinforcement mesh is an incredibly versatile solution for use in construction projects where concrete structures need to be strengthened. Embedded into concrete slabs, ground beams and walls, mesh fabric greatly improves the structural integrity and rigidity of any concrete structure. Steel shares similar thermal expansion properties to concrete, making it the perfect material for concrete reinforcement.
Reinforcement mesh is available in a number of grades, each suitable for different applications. Each grade of mesh fabric differs in the size of its longitudinal wires and its cross wires, and these differences affect the relative reinforcement properties of each type. Mesh sheets are generally supplied in standard sizes of 4.8m length and 2.4m width, although smaller merchant sizes are also available, with a length of 3.6m and a width of 2.0m. Bespoke sizes can also be cut and bent to specific project requirements.
One of the most widely used grades of mesh fabric is British Standard A142, which has 6mm longitudinal wires and 6mm cross wires. This grade of mesh is typically used in light domestic applications, such as garden groundworks, patios, pathways and light-traffic driveways.
Where heavier loads are expected, grades A193 and A252 are used. A193 has longitudinal and cross wire sizes of 7mm and A252 has longitudinal and cross wire sizes of 8mm. Residential extensions, domestic foundations and heavy load driveways would typically require reinforcement mesh of these grades.
In commercial construction projects, stronger grades of reinforcement mesh are used, including A393, B503, B785 and B1131. To highlight the difference in strength between the various grades, B1131 has longitudinal wires of 12mm and cross wires of 8mm, compared with the 6mm x 6mm wire size of the lightest grade of mesh fabric, A142. B ‘spec’ structural steel mesh is made with rectangular apertures, making it more dense (in terms of steel per cross section), and therefore stronger.
Another critical factor in the correct use of reinforcement mesh is the vertical positioning of the sheets. It’s vital that mesh sheets are positioned so that there is at least 50mm concrete coverage both above and below the mesh. If the positioning of the mesh is not correct and there is insufficient concrete coverage at any point, the reinforcement may be compromised and the structural strengthening could be significantly reduced. There are a number of products available to help with the correct vertical positioning of mesh reinforcements, including padstones, plastic spacers and steel highchairs. Of course, all structural reinforcement plans should be verified by a qualified structural engineer before work is started.