Browse Forums Building A New House 1 Aug 24, 2021 6:31 pm Can anyone tell me what these white patches on our slab are from? It was laid almost two months ago and now that we have finally had enough time to see it dry, these are really noticeable. Thanks Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: White patches on slab 2Aug 24, 2021 8:07 pm Looks like efflorescence to me, it can occur with any product containing cement. As moisture migrates up to the surface of the concrete, it carries along with it calcium salts from the concrete. When the salts reach the surface, they react with carbon dioxide in the air and form insoluble calcium carbonate. It won't affect the strength. The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: White patches on slab 3Aug 24, 2021 9:10 pm bashworth Looks like efflorescence to me, it can occur with any product containing cement. As moisture migrates up to the surface of the concrete, it carries along with it calcium salts from the concrete. When the salts reach the surface, they react with carbon dioxide in the air and form insoluble calcium carbonate. It won't affect the strength. Thank you. Is this polishable? We paid a lot extra to upgrade our Concrete and have it laid ready for polishing. Re: White patches on slab 4Aug 24, 2021 10:11 pm Once the slab is cured and dry there ahould be no more efforvecence, and whats there should be removed during the initial grind. The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: White patches on slab 5Aug 24, 2021 10:12 pm bashworth Once the slab is cured and dry there ahould be no more efforvecence, and whats there should be removed during the initial grind. Thank you, a Google search wasn’t making it look good. Re: White patches on slab 6Aug 24, 2021 10:30 pm Its more of a problem when there is issues of water getting into the slab, for instance I had ongoing issues at the front edge of my garage slab, but only the first 50mm from the door. Well inside and sealed, problems are much less likely. The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Looking for advice on whether this variation in tile colour is acceptable. The large tile on the left was used in my main bathroom renovation 1 year ago. My ensuite… 0 8488 Dover white or surfmist garage door. I am having trouble choosing a garage door. The outside of house will be tranquel retreat. I want it to all blend nicely however I… 0 6801 Thankyou for your advice. We do have Caesar coming out and hopefully resolve the issue for us. 4 18740 |