Any of you ever use ice when mixing small batches of concrete on the job site? I’m going to have to mix a bunch of concrete for a footer. It will take about 3/4 yard, requiring at least 4 mixer loads. The temps will be 90degrees, plus, & my experience w/ those conditions SUCK! Like an entire ICF job that went partially south, requiring I chop rubble out of the top 3 ft of the wall & have it re-poured (at the contractor’s expense, BTW because he screwed up & let it happen.) I also had a bad time w/ a load of ready mix setting up so fast in a footer that we barely got it finished before it became unworkable. Amazingly, the first experience started w/ a pour beginning at 6AM & the second w/ a delivery at 5 PM.
I don’t want this to happen this time & I cannot control the weather & temps, but I can mix my crete using ice in the water. I’ve read the theory; understand the practice. Just wonder if any of you have ever resorted to this approach to ease of working the stuff between batches to preclude cold joints, etc.
Economics tell me I cannot buy that small a qty of ready mix. I have cheap slave labor to do the mixing. Here in Nawth Jawja, concrete runs about $120 per Yd. The premium for a small qty makes it unacceptable. I also live beyond the practical delivery time from the plants to get good concrete in the kinds of temps we are having.
Don
The Glass Masterworks
“If it scratches, I etch it!”
Replies
you can but the ice will act like an aggregate till its meld and then it will exceed the water cement ratio. it be easlier to figure how much water you need and then chilled the water on a 3/4 yard that be about a 120 gallons. that would need to be about 40 degrees. now you can do 1/2 and 1/2 but dont mix it by looks you got to mix by weight when the ice meld you have hell
Can you get retardant that you can add to your own crete the way you can get it in the mix from your batch plant?
Water weighs 8.35 pounds per gallon. Substitute that much ice by weight for each gallon of water you replace. Right?
yes but until the ice melts and go to liguid form, you will have no slump, then you will add extra water to control the slump. once the ice melt you have double water. The ice will act like an aggregate and once its melt will leave huge void in the concrete
How about crushed ice?http://www.quittintime.com/ View Image
I see in the JLC Field Guide I just bought, "shaved ice" can be ordered from some redimix firms when temps are an issue.
That just means they bring shaved ice treat to the job for the workers. You want blueberry or lemon?
If you get the shaved ice here in Florida its usually Pina Colada flavor.
But seriously, does anyone ever cover their new concrete with wet burlap or anything after the pour? If so does it help?
it helps a lot, about 300 psi, we use plain plastic with a soaker hose under it
Edited 6/22/2009 8:53 pm by brownbagg
Really? How far along afterwards do you cover it?
as soonas you can walk on it, keep it wet for seven days
The Ready Mix companies in the hot areas, usually have some system for chilling the water, and in areas that are really hot of weighing ice as a substitute for the water.
Marga crete a?Remodeling Contractor just on the other side of the Glass City
if you only pouring 3/4 of a yard. get couple people to mix and transport couple people to finish, start at daybreak 5:30 you can do it without ice, just normal. but plan on being done by 7
Brownbagg is our concrete expert. But in addition to what he said, how about doing the job before the sun comes up when it would be comfortable to work.
that what we do, 90% of our pours are before 3am
That's only because that's when your finishers get kicked out of the bars.
They gotta do something until 7Am when they open again.
now that's funny
That's only because that's when your finishers get kicked out of the bars. a concrete driver is a laberor with a driver license, when they get a DUI they become concrete finishers because they all show up in the same van.
In the California desert suburbs i heard they have the trucks form a circle around the pour with thier lights on because it is still dark."There are three kinds of men: The one that learns by reading, the few who learn by observation and the rest of them have to pee on the electric fence for themselves."Will Rogers
For many of the reasons you mentioned, I have used site-mixed batches lately on all my jobs. $99 per yard with a $50 truck delivery fee for as much as I want. They can mix and adjust ratio how I want it on site and travel time does not factor into pour time.
Served me well so far.
Seems to me like figuring the ice amount and having that much on site to work out would be too much of a chore.
Mike: How do you find a site mix outfit? If I could, at the rate you quote, it's worth it. $60 to rent a 9 cu ft mixer; cost of components; cost to pay slave laborers probably exceeds the cost you quoted. Not to mention the pure effort to do the job man (Teenager) handle all the massive amounts of heavy components in the heat. Sorry, Brownbagg, 3 AM is a bit early. Don't have the light to work at that time. Believe it or not, the earliest I can get ready mix is a 6 AM departure from the yard!DonDon Reinhard
The Glass Masterworks
"If it scratches, I etch it!"
I had pour that was site mixed. The only issue I had was he only had 3/4" rock and I wanted 3/8".
There were some places where it could have been mixed a little more. "There are three kinds of men: The one that learns by reading, the few who learn by observation and the rest of them have to pee on the electric fence for themselves."Will Rogers
Brownbagg is pouring a few hundred yards, they'll bring him concrete any time he wants it.
an average pour for us is 750 yards. concrete company love night times pour because it cool, no traffic, nice and quiet, by the time the sun comes up, they have their eight and heading to the house. a 700 yard pour takes us about five hours to get on the ground
Hey, Johnny,Didn't they use to use sugar to slow the cure ? I heard that the drivers used to keep a bag of sugar in the truck in case they were in a wreck, dump the sugar in and the load would stay liquid after the drum stopped.Is that an old wives tale ?You know what they call a guy that goes around spreading old wives tales, dontcha ?Dontcha ?A gynecologist !Greg
yes it will, some people will do expose aggregate slab using sugar. but sugar aint cheap, it take alot, 100 lbs.
Don,
There are a few in our area. Some are listed under "Site mix" in the phone book. I really like using them. They even will bring a pump for another $100 and run it.
I may never use ready mix again!
Mike
I would just pay for a short load. Trying to mix and place your own concrete in high heat is not worth the trouble.
David: Last time I checked, a short loads was a minimum of 5 yds at $120 per yd. I'll check on it, however. Just checked the Yellow Pages & no one in this part of GA advertises for site mixing. There are at least three RM Co's about 17 miles from here - all surrounding the same quarry!Thanks for the nudge. Worth trying - again.. Perhaps the lousy const mkt willl make them more willing to sell a partial load.DonDon Reinhard
The Glass Masterworks
"If it scratches, I etch it!"
I would talk to all of them. Someone could easily bring you 3/4 of a yard on their way to another pour. You should be able to unload it in a couple of minutes and get them out of there. I'm lucky, the one plant here will bring me any amount, no minimum.
chill the water with blocks of ice and keep the sun off the bags as the heat effects the setting time. And start early
I've done quite a bit of concrete with ice substituted for the water.
I used to work in Vegas, and in the late summer when the overnight lows, are in the nineties, the aggregate is hitting the scales at close to 90-degrees, even if you sprinkle it with chilled water 24/7.
So, ice and chilled water are the only alternatives to keeping the temps down.
I would recommend replacing at least a portion of the mix water with an equivalent weight of ice. Generally, by the time you get enough revolution on the drum to mix it thoroughly, the ice has melted.
You might also look into retarders. You might have to buy them from the batch plant, but if you are buying the aggregate from them, they will probably sell it to you.