Grout joints are the physical separation between tiles in a ceramic covering. Tiles cannot be laid with their edges touching as they require these joints to absorb any compression and traction tensions which may be produced in the environment, to remove any vapour from the lower levels, and to absorb any changes in size of the tiles due to changes in humidity or temperature.
GROUT JOINTS.
The first step is to select the grout. Once the grouting material has been defined in terms of its type and characteristics, it is time to set the criteria for selecting the best material in terms of the requirements. Grouting is the final stage of modular coating and how the coating looks finally and how it will last over time will be determined by its being done correctly. For CG cement-based grouting materials, there are a series of preparation, application and cleaning requirements to bear in mind. In the preparation stage, check that the material used has not surpassed its conservation time as set by the manufacturer, carry out the various mixing operations and respect the proportion of water in the mixture indicated in the instruction, amongst others.
APPLICATION STAGE With respect to the application stage, other considerations must be taken into account. For example, the grout joints must be uniformly free of any broken-up materials and adhesives to the approximate depth
of the tile. Suitable tools should be used: sharp, hard rubber grout float for manual grouting and on large surface paving, extruder guns or rotary disc machines in order to achie- ve good performance. In addition, special sponges, stiff enough to avoid sweeping material from the surface of the join for the first cleaning operation.
CORRECT CLEANING The first cleaning stage is carried out using a good-quality, rigid
sponge, always diagonally compared to the joint’s direction. The sponge must be rinsed and squeezed out as often as possible, renewing the rinsing water regularly. The second cleaning stage is done using a dry cloth or chamois. If there are still materials encrusted on the surface, they should be removed with a plastic brush and a scale remover compatible with the tile’s chemical resistance. The preparation, application and cleaning of the reactive resingrouting mortars are, generally, similar to those of cement-based grouting mortars although there are some differences.
MANIPULATION & APPLICATION In preparation, there is a reduced range of manipulation and application temperatures in order to ensure consistency when grouting and achieve acceptable performance. Outside of this interval, grouting must be suspended. When applying, the sides and bottom of the joint must be dry; the presence of water will neutralise the setting reaction or compromise adhesion. The essential tool here is the flexible stainless steel grout float in order to correctly squeeze and scrape the RG materials of medium/high consistency when fresh. And in terms of cleaning, the joints must be dry to ensure the humidity will not affect the setting process. Once the joints are filled and have the correct curvature, the coating surface is dampened with water (a few minutes after application) to neutralise setting on the tile and to clean it with a damp sponge. These are only some of the con- siderations.
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