The standard cement grout commonly found in most hardware stores and used in most residential homes takes around 48-72 hours to cure. But it is worth pointing out that you need to know how to mix grout the right way. If too much water is added it will obviously take longer to dry and won't do its job as well.
If grouted too early for instance of adhesive that takes 24 hrs to dry the white grout may discolour because of the moisture still in the adhesive and it cant get out due to the grout.. so will discolour... Small tiled area, there's nothing wrong with using rapid set and grouting the same day.
Wait 24 hours for the best results
Though contractors may tell you to wait at least 12 hours before using your new tile floors, household members should wait a full day before walking on or grouting newly-installed tiles for optimal results.
Once the grout has started to harden (20 to 30 minutes), begin sponging. Don't use just any sponge, especially one from the kitchen; choose a “hydrophilic” sponge. Make sure the sponge is damp, not wet, and sweep diagonally across the face of the tile and wipe the grout off the tile surface.
When you're searching for ideas on how to speed up grout drying time, lowering the room's humidity level can help. Removing any indoor plants and using a dehumidifier will decrease the moisture in the air, which can lower grout drying time.
Grout is everywhere. You can find it indoors and out, in and around swimming pools, and anywhere in a building where you see tile work or mosaics. Grout comes in many varieties, and it's generally considered to be safe once it has been applied and dries.
Walking on new grout- Once any grouting is completed, be sure to allow 24 to 72 hours of drying time. This is because, when a newly grouted surface is walked on before it has had time to completely dry, the grout can become uneven and dislodge itself from the joints.
How long does tile grout take to dry? The short answer is 24-72 hours of drying time. It's a big range because grout drying time depends on external factors like humidity and temperature and type of grout you're using.
Again, this will depend on your grout type. Floor grout, in general, usually dries completely after 24 hours, although humidity and other factors can extend this drying time to 48+ hours. Grout haze can sometimes be simply buffed out with a dry towel or cheesecloth, if done immediately within the first 48 hours.
Make sure your tile surface is completely dry before you attempt to remove any haze. This typically takes about 24 hours. Consult your installation professional—or, if you DIY-ed it, your grout's packaging—for the exact amount of time. But do not wait more than 10 days to remove grout haze.
The shortest time after laying tile that you can grout is 24 hours. However, it is much better to wait at least 48 hours before grouting.
He points out that he sees a “whitish” color on the edges of the grout. That is another very important clue. Grout almost always appears darker when wet than when dry. New grout can take 24 or even 48 hours before it dries completely.
Grout needs to be sealed. It's naturally porous and will stain easily. Most installers of tile floors do not seal them because grout has to cure first.
Let the grout dry for the length of time recommended by the manufacturer before applying sealer. Spread the sealer with a small paintbrush or a sealer applicator. Clean off any smears within the first five minutes. Let the grout dry for at least 24 hours.
Grout prevents shifting, not just acting as a buffer between the tiles but holding those tiles firmly in place and preventing movement in the first place. Grout is a very important part of your tile floor or backsplash.
Installation
With the use of cement surfacers after grouting the tiles, with the grout still fresh, any excess grout should be removed immediately with a sponge and plenty water. A few days after laying, clean thoroughly with buffered acids to completely remove and dissolve any residue.
High-traffic floor grout: Should be sealed every six months to one year. Guest bath and shower grout: Should be sealed every year or two, depending on frequency of use. Backsplash grout: Backsplashes in high-traffic areas should be sealed once yearly on average.
As we have mentioned already, grout dust contains silica in crystalline form. Therefore, if it is breathed, it can have harmful effects. For this reason, OSHA has published extensive information about respirable crystalline silica.
Mold growth can occur within the grout used in the spaces between the tiles. Like mold growth in the caulking, this is very difficult to clean. In its natural state, grout is highly porous and will absorb enough moisture to propagate mold growth.
Apply warm water and lemon juice to the grout and allow it to soak in. It should help to soften the area a little to make removal easier. For grout that has solidified on a surface it should not have, use steel wool to remove it as the water dissolves the grout.
Shrinkage. When cement-based, unsanded grout dries, it shrinks – and it can pull away from tiles. Adding sand to the grouting mix ensures that the material doesn't shrink as much. This is because the ratio of aggregate material to cement is much higher.
ANSWER. ANSWER - It is possible to grout over existing grout if there is enough depth to do so. 1/8 inch depth may or may not be adequate depending on the type of grout used. A latex modified grout may work, but you have to properly clean the existing grout to ensure the new grout adequately bonds.
Grout Must Set and Cure
That usually takes between 48 and 72 hours. If you can avoid walking on your floor for that amount of time, that would be ideal. Once the grout is fully cured, you can walk on your new tile flooring with no concerns about damaging it or causing tile pieces to shift.