I'm not sure as I'm not a builder or plasterer and it does depend on the use case.
However I do know that some grout and some paints that say they are anti-mold contain Lime or calcium hydroxide as their primary anti-mold ingredient. I think pure Lime putty can be used as pointing material between bricks in humid basements. Lime plaster (lime mixed with sand) can also be used in bathrooms (with some considerations I am not familiar with). So, my best guess is that some mix of Lime can be used as grout. But I can't say for sure.
Something I plan on doing before this winter is to use Lime Wash. Take Lime (CaOH2 in powder form) and mix with water until it has milk like consistency and brush it on grout or on (white) bathroom walls. If it works, I expect it to be a yearly or quarterly ritual and not a one time solution.
EDIT: A fascinating historical material I recently learned about used in bathrooms is called Tadelakt [1] which uses Lime as one of its ingredients.
I like the idea of treating limewash as maintenance rather than a permanent cure. That is probably closer to how these materials were historically used anyway
I just restored an 1800’s house and we redid the paint in limewash as part of that process. (Effectively zero VOCs but pretty caustic when wet.)
Historically (for interior paint) you would use regular limewash in dry spaces and add casein/milk in high traffic/wet spaces. It works in a bathroom but wouldn’t hold up in a shower (for that you would want to use “tadelakt“ - especially if you’re going for that Aman spa look).
The contemporary solution with modern limewashing is to use “mineral shield” - it uses silicone instead of casein - it makes water droplets bead up but still lets water vapor breath through.
It also doesn’t flatten out the nice velvet texture one gets with limewash paint from the calcite crystals.
That said, it’s extremely obvious if one touches up a patch of wall with limewash. No two batches are the same color unless you’re going pure white and even then…
This is why you pay the premium for epoxy grout. When we redid our house we used only epoxy grout and cleaning it as as simple as using a foaming tile spray.
This is not always a great idea. Especially if you have a water proofing membrane that allows drying out. You never want to trap moisture in a cavity. You want to be able to dry into the wet side.
It is not lime as in the fruit, it is lime as in the material (CaOH2). Lime the material is the binding agent in lime plasters. It is not likely to get washed away.
caoh2 is water soluble (slightly). the question was about anti-mold properties and it is commonly used for these properties in paint for example in cellars but it will lose these properties when too wet. so it's not used in bathrooms.
Sure but lime plaster can be used in bathrooms on the non shower walls as there's no running water but lots of moisture/humidity which leads to mold growth. As far as using it in the grout behind tiles, you may have a point.
I'm considering applying lime wash between the tiles regularly but not sure what the results will be.
However I do know that some grout and some paints that say they are anti-mold contain Lime or calcium hydroxide as their primary anti-mold ingredient. I think pure Lime putty can be used as pointing material between bricks in humid basements. Lime plaster (lime mixed with sand) can also be used in bathrooms (with some considerations I am not familiar with). So, my best guess is that some mix of Lime can be used as grout. But I can't say for sure.
Something I plan on doing before this winter is to use Lime Wash. Take Lime (CaOH2 in powder form) and mix with water until it has milk like consistency and brush it on grout or on (white) bathroom walls. If it works, I expect it to be a yearly or quarterly ritual and not a one time solution.
EDIT: A fascinating historical material I recently learned about used in bathrooms is called Tadelakt [1] which uses Lime as one of its ingredients.
[1] https://en.wikipedia.org/wiki/Tadelakt