Undoubtedly, the most incorrectly referred when making a choice to is the description of the base material or substrate. The exception tends to be concrete, although there are also many types of concrete, self-compacting or PFA and no-fines concretes.
To make this easier to understand we have put the base materials into groups as they directly affect the selection of correct fixings.
Generally, bricks have a reasonable compressive strength which means that anchoring is not a problem. However, when hollow or having perforations this can greater effect the performance.
As a general rule, the plastic fixings that expand are most effective or a resin bonded type of anchor with no expansion (see fixing function or mechanism) is the most effective.
Where the brick is hollow, a special form-locking or resin anchor with a sleeve can be considered.
Brick, Block or Stone; these can also be subdivided into being either hollow or solid and all have various compressive strengths.
In the UK alone there are over five thousand types of brick and they, in turn, can be either solid or hollow. It may also be difficult, in particular with older buildings to determine on the inside walls for example what kind of material either brick or block has been used, as the walls are normally plastered. In this case, a small pilot hole can be drilled to establish the composition of the wall.
Developed originally to act as a larger unit than a brick (depending upon the size), usually equivalent to four bricks and used for internal walls only. The original material was, and is still in use is the waste material (cokes/ash) from a fossil-fired power station. Sometimes known as a “Breeze Block”, a low strength, well-structured material.
Since then the early days of block production methods have greatly improved and therefore the quality of the blocks themselves.
Today there are concrete solid and hollow blocks, hollow blocks (perforated terra cotta type), aircrete a cellular lightweight block with high insulation qualities, but virtually impossible to use a convention expansion steel or plastic anchor.
By far the most common substrate used for structural connections and steel anchors. Manufactured to specific compressive strengths that can typically range from 15N/mm2 to 55N/ mm2. Although, for tall structures, the strength may reach as much as 100N/ mm2.
The main materials used to make concrete basically are aggregate, cement, and water. Modern, material processing equipment has meant that other ingredients are used that may make the concrete lighter without loss of strength such as pulverized fuel ash, PFA as an alternative to aggregate.
As concrete has very high strength in compression but is of low tensile strength, reinforcement bars are used
to improve the concretes tensile capacity.
The inclusion of reinforcement brings problems of its own for the anchor installer. As often due to the amount of reinforcement, there may be problems drilling a hole to the required depth and thus effect the installation of the anchor. The table below indicates the various concrete strengths found in not only the UK but additional countries.
As with bricks, there are many types of stone used in construction throughout the ages not only from the UK but, also many imported types of stone.
Often found in UK buildings are sand and limestones which vary in strength and density. The so-called “softer stones” can be drilled with conventional masonry drill bits and appropriate power tools.
Here it may be possible to use some of the expansion (see function) type fixings either in steel or plastic. A resin may also be a suitable method in which to fix into stone.
However, with much denser stones such as granite, diamond drilling is the only effective way to make a hole and also limits the type of fixing that can be used. More often than not the most effective fixing is the one that does not expand. In this case, again a resin anchor can provide the required solution.
Common to all of the above materials is the mortar used between the joints of the above materials. Generally, composed of sand and cement and often with lime as an additional material. Again, these can vary in strength and composition. However, fixing into a mortar composition. However, fixing into a mortar joint should be avoided where possible. Nevertheless, sometimes this cannot be the case.
As with bricks, there is a large number of panel materials to name but a few, plasterboard, steel sheet, timber panel material (plywood, chipboard) composite panels that include high-pressure laminate (HPL), cement and resin-based materials. By contrast to brick, which tends to be used these days for external cladding, panel materials are used for both interior and exterior decoration of effective ways to construct internal walls and or partitions. By far the most frequently encountered panel material in construction is plasterboard. This is used as part of a ceiling or wall construction for industrial and domestic buildings.
For not only plasterboard but, all of the above materials, a special fixing or fastener that has been manufactured for that specific type of panel must be used.