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Concrete odor

user-831496 | Posted in Green Products and Materials on

A new concrete floor was poured in the basement of my home that is under construction. After 8 weeks there is still a strong odor.

I am chemically sensitive and afraid that this may be a problem for me when I move in. I was told that this is a normal cement odor.

What could be causing this odor and will it off gas over time? We will be pouring another layer of cement for radiant heating. Will this help contain the odor? And what kind of cement should I ask for?

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  1. Christopher Briley | | #1

    I love that smell. It's the smell of construction progress. I don't think it's a harmful smell (unlike just about every other smell in the construction world). I'm no chemist and I'm not sure which part of the chemistry process you are smelling, but concrete is basically made thusly: Limestone is heated to enormous temperatures to burn out the carbon (which is vaulted into the air in massive amounts) it then crumbles into a powder (lime). Silica (very, very fine sand) is added. Now all you need to do is add water to it and the lime will brake the water (throwing off heat) and use the hydrogen to bond the silica (SiO2 is close a relative to CO2 in the periodic table) and will start to form a solid anound and between the rocks (or aggregate) in the mix. Ta da. Man-made rock. As the concrete cures the chemistry will slow and the odor will go away until it is undetectable.

    Now, sometimes adatives or pigments are thrown in, but I don't think what you are smelling is any kind of petro-chemical smell. You are probably smelling something akin to wet mud.

    Chris Briley, Architect

  2. dankolbert | | #2

    Or the flatwork crew sealed it - some of that stuff is indeed nasty.

  3. Dayton | | #3

    Ok, so it was over 20 years ago so my recollection is hazy, but I remember concrete curing compound having a sharp and lasting odor. Ask if the crew sprayed curing compound after the pour.

  4. bdrfab | | #4

    Or Calcium Chloride to get it to dry faster. They do this sometimes if it is cold or if pouring on top of poly vapor barrier. To my nose the smell goes away quickly, but I'm not chemically sensitive.

  5. jklingel | | #5

    Have you called the installation crew chief or your local concrete ready-mix place? They've likely heard this question before and can give you a straight answer.

  6. Dayna | | #6

    I know this is a longshot because your post is 12 years old but I’m just wondering if you could share how everything ended up for you since you said you were chemically sensitive and reacting to Concrete smell? I’m building a concrete house and concerned about the same thing so I would love to hear how your experience has been? Thank you so much.

  7. onslow | | #7


    I am not the original poster, but one thing not addressed in the earlier postings was the possible use of diesel fuel for forms release. What with diesel still being nearly $5 a gallon it may not be the "cheap" alternative it apparently was 8 yrs ago when I was having a foundation poured. I had to mop up diesel runoff from one of my multi level slab pours and the stink is strong and very persistent. I made the crew get "real" forms agents and to date have not sensed the diesel smell in the two levels where it got used. I am pretty sensitive to the smell after an industrial accident in my teens. Be sure to write into the specifications that low VOC/biodegradable release agents are used if you are chemically sensitive.

    There are biodegradable form release agents available. They should be research-able with Google or whatever. I did not think to gauge the smell in direct comparison when the new type was used on my slabs. However, I would suggest that you look more closely at any post pour treatments that you might have in mind. If you plan to stain a slab or coat walls with paint or plaster, it will be important to know if the surfaces need to be cleansed of the release agent first. You might end up with splotchy stain or poorly adhering finishes if residual release agent is present. Maybe some release agents will specify their compatibility with various finishes.

    The concrete sealants used on my slab work were different because one was a much heavier duty coating intended for garages. I can safely say that neither has resulted in any persistent or even noticeable odors that stand out above the normal "cement-y" smell one gets if the concrete gets wet from the cars. They certainly smelled when applied, but the smell faded quickly. I actually get bothered more by floor waxes and countertop coatings.

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