Grout

Grout is a dense fluid which hardens to fill gaps or used as reinforcement in existing structures. Grout is generally a mixture of water, cement and sand, and is employed in pressure grouting, embedding rebar in masonry walls, connecting sections of pre-cast concrete, filling voids, and sealing joints such as those between tiles. Common uses for grout in the household include filling in tiles of shower floors and kitchen tiles. It is often color tinted when it has to be kept visible and sometimes includes fine gravel when being used to fill large spaces (such as the cores of concrete blocks). Unlike other structural pastes such as plaster or joint compound, correctly mixed and applied grout forms a water resistant seal.

Although both grout and its close relative mortar are applied as a thick emulsion and harden over time, grout is distinguished by its low viscosity and lack of lime (added to mortar for pliability); grout is thin so it flows readily into gaps, while mortar is thick enough to support not only its own weight, but also that of masonry placed above it.

Varieties

Grout varieties include tiling grout, flooring grout, resin grout, non-shrink grout, structural grout and thixotropic grout. The use of enhancing admixtures increases the quality of cement-based materials and leads to greater uniformity of hardened properties.

Tiling grout is often used to fill the spaces between tiles or mosaics and to secure tile to its base. Although ungrouted mosaics do exist, most have grout between the tesserae. Tiling grout is also cement-based, and comes in sanded as well as unsanded varieties which affects the strength, size, and appearance of the grout. The sanded variety contains finely ground silica sand; unsanded is finer and produces a non-gritty final surface. They are often enhanced with polymers and/or latex.

Structural grout is often used in reinforced masonry to fill voids in masonry housing reinforcing steel, securing the steel in place and bonding it to the masonry. Non-shrink grout is used beneath metal bearing plates to ensure a consistent bearing surface between the plate and its substrate, which adds stability and allows for higher load transfers.

Portland cement is the most common cementing agent in grout, but thermoset polymer matrix grouts based on thermosets such as urethanes and epoxies are also popular.DM Harrison, The Grouting Handbook, A Step-by-Step Guide for Foundation Design and Machinery Installation, Elsevier Press, 2013,

Portland cement-based grouts come in different varieties depending on the particle size of the ground clinker used to make the cement, with a standard size of around 15 microns, microfine at around 6–10 microns, and ultrafine below 5 microns. Finer particle sizes let the grout penetrate more deeply into a fissure Because these grouts depend on the presence of sand for their basic strength, they are often somewhat gritty when finally cured and hardened.

From the different types of grout, a suitable one has to be chosen depending on the load. For example, a load of up to 7.5 tons can be expected for a garage access (2-component pavement joint mortar (traffic load)), whereas a cobbled garden path is only designed for a pedestrian load (1-component pavement joint mortar (pedestrian load)). Furthermore, various substructures determine whether the type of grout should be permanently permeable to water or waterproof for example by concrete subfloor.

There are many types of grouts available, and Each has its benefits & drawbacks. Another kind of grout is Epoxy grout which is popular in commercial tiling projects as it has many good qualities by providing good adhesion between the tiles. It also has excellent resistance to staining and scratches. Epoxy grout offers protection against moisture. It also won't crack, shrink, or discolour, making it ideal for applying in wet areas. It is also a perfect choice for swimming pools and commercial kitchens.

Tools

Tools associated with groutwork include:
* Grout saw or grout scraper, a manual tool for removal of old and discolored grout. The blade is usually composed of tungsten carbide.
* Grout float, a trowel-like tool for smoothing the surface of a grout line, typically made of rubber or soft plastic
* Grout sealer, a water-based or solvent-based sealant applied over dried grout that resists water, oil, and acid-based contaminants
* Grout cleaner, a basic cleaning solution that is applied on grout lines and removes the dirt and dust.
* Die grinder, for faster removal of old grout than a standard grout saw
* Pointing trowel, used for applying grout in flagstone and other stone works
* Multi-Tool (power tools), This tool is another option for removing tile grout between tiles when fitted with a specified diamond blade.
* Grout clean-up bucket, A professional clean-up kit for faster grout washup. It consists of a specialised bucket on rollers with a sponge.

Methods

Joint grouting as the rule is carried out next day after laying when cement glue sets.
# Joints are soaked a bit with wet, screwed sponge. It shouldn't be too wet, but it's appropriate to work on dry surface - it'll deteriorate grip of grouting and joint.
# Grouting is applied with rubber putty knife while popping material on the joint. Putty knife should be held perpendicular to the joint at an angle of 45 degrees with the surface. Grouting spillovers are removed and applied again along the joint. It allows to completely fill the joint with the material.
# Then the joint is spread with rubber putty knife (cabel). While grouting the joints of floor tiles it's necessary to make the joints plain and at the level of the tile surface. Otherwise they'll accrue dirt. Applying round putty knife on the wall joints allows to make their shape beautiful and concave.
# After spreading the joints are treated with wet sponge to smooth their surface. Sponge removes grouting spillovers well and allows to make the joint beautiful and smooth. It's important to correctly choose the time for this stage: grouting must remain flexible, but at the same time it should have "set" so that material doesn't "follow" the sponge.
At this stage it is allowed to finish correcting of joints, wait for grouting to dry out and remove its spills from the tile.
# For more flexible option, it's allowed to wrap a putty knife with fine sandpaper and carefully run it along the joint to remove roughness of dried joints.
# Once the grouting has dried out (it can be checked by running wet sponge along the joints - it shouldn't have any signs of the grouting) the tile must be washed from material residues and wiped dry.

See also

* Mortar
*Mortar joint
*Caulk
* Thinset
*Glue

References

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Building materials
Cement
Concrete
Masonry