Did you know that steel mesh fabric and concrete have a similar coefficient of thermal expansion? It means that both materials expand and contract at the same rate, thereby eliminating cracks in extreme weather conditions. It is the reason why industrial contractors prefer reinforcing mesh to other concrete reinforcement options. It is especially the case for construction projects that mainly use concrete slabs. That said, it is crucial to inspect steel mesh fabric before slab-concreting works begin. It allows you to identify defects that might affect the ability of mesh reinforcement to function effectively. This article highlights critical inspection areas of steel mesh fabric.
Mesh Intersections -- Reinforcement mesh consists of several pieces of rebar arranged vertically and horizontally then tied together to form a rigid mat. The intersections need to be tight enough to achieve the desired rigidity. Usually, an engineer specifies the minimum number of intersections on a single reinforcing mesh. Therefore, inspect the tied intersections and ensure that they meet the minimum number based on an engineer's specifications. However, if an expert is not clear on the number of tied intersections, you can inspect a reinforcement mesh visually. Notably, you should reject reinforcing mesh if it is apparent that concreting will displace the intersections. Additionally, discard any steel fabric that has tack welding at the intersections.
Rebar Diameter and Spacing -- Once you have inspected the intersections on reinforcement mesh, move to the rebar. The first step is to examine each rebar's diameter and make sure it matches the specifications on structural drawings. You might find one or two rebars that are slightly bigger or smaller, but these should not cause much concern. However, if the sizes of rebar used vary across reinforcement mesh, then that should cause concern, and you should reject that particular steel fabric. Another vital inspection point is mesh spacing. Different projects use different mesh reinforcement spacing requirements. The spacing must be relatively equal across a mesh fabric, and it should meet structural design specifications.
Mesh Coating -- Reinforcement mesh is covered with a galvanised coating to prevent corrosion. It is common to find steel mesh fabric with light rust coating in slab reinforcement, but you will find some contractors rejecting them. However, that should not be the case because light rust is acceptable for adherence purposes. That said, you must watch out for dirt, grease, and other toxic adhesives when inspecting reinforcement mesh. The reason is that impurities affect the adhesion of concrete to reinforcement mesh, thereby messing up with its thermal expansion properties.
Reach out to someone who supplies reinforcing mesh to learn more.