Why Does Concrete Cure White And Portland Cement Cure Grey?

jgray152

This is something that has been bugging me and I think it may be due to the extra calcium in the redi-mixed concrete compared to the very little in portland cement??

Anyone know the reason? If I mix portland cement and sand together to get a grout mix which I use for my faux rock retainer walls, it will usually cure a dark grey or mild dark grey where as if I get it delivered from the concrete company it cures very white which is better for acid staining.

CJKarl

I have found it to vary from....Manufacturer of the cement, quarry that mined the sand and even how much water is added to the mix.

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jgray152

hmmm. Well thats a bummer. I usually mix my home made concrete mix real dry for strength. Is it possible if using a lot of sand or maybe a lot of silica or another fine filler to allow the cement to maybe not be so dense or turn it white or at least a light grey? I have got portland / sand to turn white after 3-4 days of curing but that is not always the case, I guess I got lucky on that mix.

6stringmason

Same here.

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user50444

slag mixes get really white. pretty much every redi-mix producer is either adding fly ash or slag, unless you tell them straight cement.

CaliDesigns

Your percentage of portland in concrete is a lot less than your slurry mix. That's why a lot of concrete guys add white portland to their slurry mix to wet face steps.

concretemasonry

Mortar color is highly influenced by the sand color, while ready-mix is not because of the difference in the cement content. The lightest mortar will be a traditional portland/lime mix that has more workability and long term healing from the weather.

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naptown CR

Portland cement comes in two colors white and gray. next time by white portaland.

jgray152

I know it comes in gray or white in bags but thats why it didn't make sence that portland in redi-mixed concrete trucks cured white or very very light gray where as portland in backs mixed roughly the same way cured gray or dark gray.

Its just something I will have to keep in mind thats all. White Concrete here is about $22 a bag verses $9.80 a bag of standard portland.

harpomason

thanks for asking as i have pondered over this same thing. I like my work to be consistant through out the job. Its one reason i try to avoid using dye or powdered color. when i can't talk them out of using it. I will measure very carefully every mix.
The man who schooled me on this trade told me that he remembers when a bag of masonry cement cost him 75cents and portland was $1-$1.25 per bag.

jgray152

Bringing this thread back as I want to find or make something that can be lighter in color other than spending $22 a bag on white cement. Home Depot does not carry it anymore so the only place I know I can get it is an hour away instead of 25 minutes away.

Masonry Cement I have read has more lime in it? Lime I read can make the cement whiter? So is masonry cement lighter in color than gray portland cement

I will be using Perlite in my lightweight mixes for now on which is white so that would help as well.

If I were to mix White cement and Grey Cement together...what proportions should I mix at? Anyone have experience with this?

Tscarborough

In my area it is, but only by a tiny amount. You can buy titanium dioxide to lighten it if you want, but it is not cheap either, about 10 bucks per bag of portland used.

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6stringmason

Save yourself the headache and go get the white portland. Then charge more for your products containing the white portland.

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superseal

White is what your looking for - buck up or cut it 50/50 25/75 if you a cheap azz

masonlifer

I've been using a mix with white portland to patch precast. Most of the time suppliers in this area don't keep it in stock unless someone places a large order. It's too expensive to sit in a warehouse waiting for someone to use it a bag or two at a time, and if not used soon enough it gets hard.
One source I have found is the local pool supplier. They keep some in stock for repairs on pools.

Tscarborough

Funny how very different areas are. We go through a couple of trucks a week of white portland and masonry, and we are slow. Plus our gray portland/masonry is very light.

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jgray152

Its aggravating... I think I'll start ordering portland from china, probably cheaper and lighter!

What brand of portland do you use Tscar?

Tscarborough

Lehigh, but I have sold imported white from Turkey. Not reliable enough for our volume though.

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stacker

i agree with six.bite the bullet and buy the white.when i manufactured stone,and when we had an order for white stone,thats all we used.white portland and haydite.altho my dad did experiment with puting a gallon of white paint in with regular portland once.i didnt work.

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Tscarborough

If he had used just the pigment KX, Titanium Dioxide, that made the paint white it would have worked but he would not have saved any money.

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