The importance of the substrate:
Before starting to install the proper flooring for a warehouse, it is essential to analyze the soil substrate or firm layer on which the floor must be firmly supported. The soil substrate is very variable and can present enormous differences between two places, although they are very close and even within the same space, which means that there may be substantial variations between different points in the same place.
The most outstanding parameters that must be observed in the soil substrate are: compressive strength, tendency to slip and the possibility of absorbing water. To know the values of these factors at a given location and find out how they can vary at different depths, it is necessary to carry out an in situ analysis.
It is essential to ensure that the warehouse floor substrate will provide a behavior that is completely adequate to the load that will be placed on the floor that will rest on it. Depending on the results obtained with the necessary analyses, the place and exact area where the installation should be erected is chosen.
The characteristics of this very important part of the soil decisively influence the foundation. For its realization, from simple support shoes or running shoes of greater or lesser width to, in the most extreme cases, a reinforced shoe can be used. On some occasions, the characteristics of the soil substrate make it necessary to vary the position of the shelves’ pillars so that they can coincide with the points that offer the necessary guarantees.
The floor itself is placed on the substrate. The pavement is usually composed of a sub-base of agglomerated material and firmly compacted to support the load. This layer is composed of any type of material, whether natural or filling. On the sub-base, there is a concrete slab designed to withstand the pressure. Warehouse forklift tips
Concrete slabs have a high compressive strength, however, they do not have much tensile strength. During its curing process, the concrete undergoes contractions, which does not occur with the conglomerate sub-base. These contractions cause tensions in the slabs, which can cause, consequently, fortuitous breakages and warping. To alleviate these problems it is necessary to ensure that the substrate surface on which the board rests is completely smooth and smooth.
Once this point is verified, a kind of membrane or film is introduced between the sub-base and the substrate to reduce the friction between them. During the curing process, this film allows the slab to move independently and also acts as a moisture barrier needed to limit water loss from the concrete and achieve better curing.
Another measure to alleviate the problem of potential breakage and frequent warping is to install a light reinforcement wire mesh that is close to the surface. This is a very common practice that allows the construction of longer slabs and with fewer expansion joints.
Likewise, a reinforcement based on steel bars can be included, which can increase the resistance of the cured layer, despite the inevitable contractions and slippages suffered by the concrete during the process. However, whether or not this reinforcement is included, it is inevitable that cracks may appear in the cured slabs, even when the most extreme care has been taken in their construction. If these cracks appear in a casual and uncontrolled way, the impossibility of carrying out an adequate filling, considering their irregularity, will always cause a problem of fluctuation in the loads.
It is common to induce these cracks to appear in specific places, in order to be properly observed and controlled. This is done by sawing along the slab a certain strip, with a cut to a depth between one quarter and one third the thickness of the layer. In this way, the break develops in this position and not in another, and can be easily filled in a simple and clean way.
The joints that can be found in the floors of the installations can have different origins: they were caused by individual strips along the floor, they were the result of the construction itself, caused by the end of a working day and the beginning of the next day, they were created to avoid or surround columns or walls, or have been caused by saw cuts. Whatever their origin, they can be a source of problems as they can wear out due to the continuous passage of forklifts.
The joints must be interconnected or bolted to the sub-base structure to avoid the transfer of adjacent movements, which take place under the slabs. In expansion joints, the screws must be properly embedded and located in a completely aligned way. These screws must have a free-sliding end, equipped with a plastic sleeve incorporated into one of the slabs.
On the other hand, the expansion joints must have a width proportional to the thickness of the slab, although never above 10 mm. Even though it is possible to do them at any point, it is always preferable to avoid places where high specific loads occur, that is, far from the shelving struts.
The finishing layer:
On the sub-base and the slab, a third layer, the finishing layer, is installed. It is a monolithic layer and forms the working surface itself. The finishing layer is usually composed of a 50 mm thick granular cement mixture. The smoothness, hardness and work ability of this material are the most suitable for the flooring to withstand the conditions when the equipment is used in the warehouse.
The granular layer is applied on the wet industrial concrete slab, forming a block with it and, therefore, acquiring its joints. At this point, a question arises on which a decision must be made: should the finishing layer be carried out with the slab and, therefore, also be subject to its problems and treatments, especially with regard to joints? Or should it be installed completely independently?
It is possible to apply this layer independently and separately on a dry slab, but the thickness of the latter must be at least approximately 125 mm. In this case, a new layer of concrete is prepared with the same brittleness and warping problems as the main slab, as the finishing surface will behave and contract independently.
To avoid this, it is necessary to add a new separating film or membrane, which forms a very thin layer where there are no visible joints. By adding bituminous material or a wide variety of co polymers it is possible to obtain concrete mixtures of extraordinary fineness. If synthetic resins are used, it is possible to reach a layer of only 3 mm thick, being a floor with an excellent finish. On the other hand, if you want to obtain a more comfortable surface, resins with greater resilience can be used, that is, with a greater elastic capacity to absorb deformation and recover when pressure is no longer exerted.