Concrete pour - water cleanliness question

[otlski]

When pouring readimix concrete, how clean does the water have to be? I will be pouring a slab well away from access by truck. The water I hope to use is rain water collected off a roof and stored several months in an enclosed white poly 550 gal container. The water is relatively clear but has small amounts of algae in it. Otherwise there are some organics (leaf pieces) but no sediment. To give an idea, when transferred into a 5 gallon bucket, the water may be ever so slightly tinted with green specks and occasionally a wisp of algae the size of a 1/2 paper-matchstick. Will the fact that the water is not clean affect the strength of the concrete?

Dan

 

[crash325]

It should hve little or no meaningful effect. Use it with out worry;

 

[jaotguy]

ditto

 

[Cord]

The water needs to be "potable". In other words, it should be clean enough to drink. That's not say that it's bacteria free. If I saw that water being used on one of my jobs, I'd reject the pour.

 

[CalG]

The water needs to be "potable". In other words, it should be clean enough to drink. That's not say that it's bacteria free. If I saw that water being used on one of my jobs, I'd reject the pour.

For what reason?

Organic material is not wanted, but really? What difference does "green" make. I would use rain water and would accept large amounts of mineral sediment.

But, no leaves twigs, or frogs ;-)

(well, a frog or two would be cute.)(

 

[oosik]

I used rain water on a pour in 1967 and its still strong as ever. The water was stored in a whiskey barrel and DID have a little alcohol in it. Happiest concrete I ever worked with.

 

[Gary Fowler]

For what reason?QUOTE]

Well for one ACI (Code for concrete construction) states water for concrete is to be potable water. Now would rain water that was strained of all extraneous matter would be ok, most likely, although I don't know what the green algae would do. It may make the concrete off color or bleed white powder after curing like alkali water does but likely wont affect the strength.
Water that is slightly alkali will cause concrete to continually bleed white powdery residue for years when used on a wall, seen that many times in Saudi Arabia although I don't think it affects the strength. You can wash it off but it comes right back.

Why not use that barrel, clean it out and then fill with potable water and take that to the site for use.

 

[otlski]

Thanks guys. I found some info this morning. It was just a matter of finding the right Google keyword. http://www.engr.usask.ca/classes/CE/898/t2/b/notes/PCA/Chap.4/Water.pdf

http://pbadupws.nrc.gov/docs/ML1215/ML12153A326.pdf

It looks like I should switch over to tap water. I have no idea how to judge 1000 parts per million of algae. Testing it seems like it would only be valid the day you had it tested. I'll need to transport about 150 gallons up a rough trail about 1200 feet with a 350 foot elevation gain. All this will be 12 gallons at a time in my Bush Hog side-by-side.

Dan

 

[Texasmark]

I know "washed sand" vs straight deep pit sand makes a difference in the compressive strength of concrete. So I'd say that bad water would too; depending of course on amount of contamination and what.....anything that can come between the portland (glue) and the aggrigate.

While we are at it, ensure that your rebar is in the concrete, not under it which is easy for the contractor to let happen if you don't stay right there and supervise; especially when the mix has to be wheelbarrowed in and the crew is tired. The barrow pushes it down into the cushion sand and you have to stay on their .... to get it pulled back up.

I had to do that on my shop which has a 5" floating slab inside a pole barn; no perimeter beam. With our drought and all, and being heavy clay below the "select fill" brought in, packed and leveled for the slab, as the clay sub soil shrank, the slab cracked over about 40% of the surface. Had I not insisted on the rebar be inside the crete, I guarantee you the sections would be sliding apart leaving gaps. as it is, I just have a hairline crack and I don't have a problem with that, knowing that the soil is "unsuitable for dwellings and roadways" per the Civil Engineering report we got when we put in out community water well. On that we installed a 100' stand pipe on an 8' (that's foot) thick slab. Been there since '85 and no problems yet.

Mark

Mark

 

[k0ua]

Maybe make a filter out of a couple thickness of bed sheet stretched over another barrel? Transfer water from the first barrel to the second thru the sheets. The would get rid of any larger particulates, and a lot of the algae. I would give it a try.