We’ve had sunny weather in the hi 40s and lo 50s for a week. Perfect for working outside building forms. I’ve got a foundation ready to go, 8″ walls about 2′ high on 16″ footings, all formed with 2x material. Trucks and pump scheduled for 8 AM tomorrow.
Problem is, they’re saying a cold front is coming tomorrow. Even my wife knows that cold is a problem for concrete. Forecast is for 30s during the day and as low as 25 at night, about a week’s worth.
What’s a guy to do? Proceed as planned? Will the concrete generate enough of its own heat to be all right? Buy a bunch of painters tarps and drape the whole thing? Buy a bunch of foamboard and line the whole thing? Build a tent and heat it? Cancel? Pour and forget it? This is an 800 SF footprint so anything I gotta do out there will be work and money.
I know a lot of you guys pour in colder weather than this, and yer probably laughin’ at me. Bein’ from down south I’m not used to this issue. Whaddya recommend?
Replies
Dave;
Surely the company knows the forecast! It should add the necessary chemicals to cure at temperature.
Why not call them at 6:00?
Quality repairs for your home.
AaronR Construction
Vancouver, Canada
Probably all you need to do is tarp it.
happy?
I'm with Dan, simply tarp it.
Beer was created so carpenters wouldn't rule the world.
Got poured this morning by noon, ate part of a pizza, and then picked up a handful of 'concrete blankets' from the batch plant. They're basically a heavy-duty version of R-foil with some grommets around the edges... "Space-Age Blanket, R-5.61". All buttoned up now and I don't care what the weather does. Tomorrow's a day off... maybe go look at some upcoming work and/or browse some tool catalogs.
The only stupid thing that happened today is that I forgot the half-yard that the boom pump wastes. I'm only ten minutes away so they sent out a truck with a half-yard in it. Won't forget that again.
Edited 2/14/2006 7:37 pm by davidmeiland
on pumps we always go extra 2 yards. cheaper to waste than wait.. 2+3=7
The cold weather has not been delivered as advertised. It went down to about 30 the first night and did not even freeze last night. Apparently it will actually start getting into the 20s tonight, maybe tomorrow.
How long do I need to try to keep things warm? Ideally I want to strip forms tomorrow, 72 hours after the pour. How long is the MC in the concrete going to be high enough to make for potential freeze problems?
On a side note, I talked to a mason I know and he was mixing antifreeze 1:20 with water into his mortar on Tuesday, and seemed quite concerned about the cold.
Did you vibrate the concrete?
Ha ha ha, of course I did, very easy when you OWN a concrete vibrator. Thing is, I'm still waiting for this other guy to send me $6 for a pair of pants... it's a long story.
I'm glad it worked out for you.[the vibrator]
I hope your trust wasn't misplaced on the pants deal. Six dollars is a lot of money. Threaten to mention his name.
:) [large grin]
if you can write your name in the concrete with your fingernail, leave it alone.. 2+3=7
I'm in Mass and no one around here worries about cold until it get to the low teens. Anything in the 20's at night is a decent winter night and the footing are stripped the day after they are poured, the wall forms (usually 8') are set that day, then usually the walls are poured the following day and stripped after day after. Concrete releases heat as it cures and it fairly strong after just 18 hours. Pour a 5" slab and you can walk on it no problem the next day. The only think that you need to wait on is backfilling. The pressure from the backfill could cause problems, so people usually give it more time.
After 24 hours, you can scratch the concrete but it is certainly very strong. Stripping forms for footings and walls, who cares if it gets scratched a bit. It's best to wait 3 or 4 days to start working on slabs, just so the surface gets harder and dropping a hammer won't hurt it.
on pumps we always go extra 2 yards. cheaper to waste than wait.
With the high hourly rate of pumps those 2 yards are pretty cheap insurance.
Beer was created so carpenters wouldn't rule the world.
Depends on your location. Here I pay about $145 per yard for a 6-sack mix. My 12 yard pour this week was almost $1800. Fortunately the pump only eats a little over 1/2 a yard.
>> I pay about $145 per yard for a 6-sack mix. << Wow! - that's really expensive. Are you paying extra for pea gravel so it will go through the pump better? We pay about $84 for 3000 PSI, regular aggregate, but I don't know how that relates to your "6 bag mix" - we don't use that terminology around here... We just order by the PSI, and then specify slump and admixes.
BTW - around here, when pouring public sidewalks the city inspector requires blankets if the temp is predicted to go below 34 for the next 3 nights. He drives by the next morning to make sure you really did it... The same kind of blankets you rented. We can't rent 'em from the concrete co though. Rental store is around $5 per day. They cost maybe $60 ea... Seems like your concrete co is doing that as a service so they can sell more concrete...
Also, re accelerators and freezing temps, I'm not sure how much sense that makes except that it ensures that all finishing will be done well before dark... I've always been told that you don't have to worry much about the first night as the hydration process keeps it warm for maybe 24 hours after the pour. I've been told that it's the 2nd and 3rd night that is more critical. Using calcium chloride for cold weather concreting is very common around here though...
I live on an island where almost everything comes by ferry. It can cost up to about $300 to bring a semi here. The concrete company has large loads of gravel brought into the harbor by barge, and then they run a caravan of 10-yard trucks up to their place, a few miles away. Sand and gravel are not produced locally anymore, although they were at one time (now the debate is what to do with the empty pit). The cement distributor comes over with a big hopper rig.
Ordering concrete according to how many 'sacks' of cement is common on the west coast, as far as I know. Same terminology when I lived in CA too. Six-sack is 3000 PSI. For the boom pump that works here I can order a concrete rock mix, which I think is up to 7/8" or 1". The line pump requires pea gravel.
Edited 2/18/2006 8:41 pm by davidmeiland
Depends on your location. Here I pay about $145 per yard for a 6-sack mix. My 12 yard pour this week was almost $1800. Fortunately the pump only eats a little over 1/2 a yard.
That is spendy. :-)
Beer was created so carpenters wouldn't rule the world.
Yeah, the batch plant is a monopoly. There was a guy here for a while who had some very expensive gear, a new Schwinge boom and a couple of 'SiteMix' rigs--small hoppers of gravel, sand, cement, etc., mixed by auger right on the truck on the way down the chute. He had some problems getting good concrete out of those and last I heard was having legal troubles too.
Something like this:
http://www.quickmix.net/
They're basically a heavy-duty version of R-foil with some grommets around the edges... "Space-Age Blanket, R-5.61".
Fancy!
Beer was created so carpenters wouldn't rule the world.
Yawn.
If ignorance is bliss why aren't more people
happy?
dave : ask you concrete company if they use hot water in the winter.. also how much to add calcium cholride
those two adds used to cost about $2/ cy each
25 overnight is not going to stop the heat of hydration.... but you can tarp the forms just for assurance..
the northern states pour under some very adverse cold conditions
If there is rebar in the pour then calcium chloride is not acceptable as an accelerant. The CaCl2 corrodes the rebar and may cause structural failure.
Locally the correct call now is for 'liquid sunshine" or NCA, non calcium accelerator, which is not reactive with iron.
There are also plasticizers that are available that will make the concrete flow like a slump of 6-7", but the actual water content is not increased, thus keeping the final concrete strength high. The load is slumped and sampled at site for correct mix, then the admixtures are poured in the truck and mixed.
On another note...addition of antifreeze to mortar is not advised (or allowed on spec jobs) as it diminishes the bond strength. Cold weather masonry calls for hot water, heated sand/stone/brick/cmu's, plus added heat from salamanders and then insulated blankets. Not much heat of hydration to prevent freeze compared to the mass of the masonry.
........................Iron Helix
I did not know that about Calcium Chloride. It's prevalent here, in fact a guy that works for the biggest outfit says they always use 1% in the footings and walls, and 2% in their slabs. It must make the day go faster and easier, and/or it looks good from the bank. I was at the batch plant the other day and noticed a very large plastic container of it, several hundred gallons.
For the upcoming slab I'm going to talk to them about the plasticizer. They have another large container of that, 'mid-range water-reducing plasticizer. Sounds like it would make the laydown go easier. Hot water ought to make it go off faster. We can get an 8 AM delivery and it gets dark at 6, probably will be between 40 and 50 degrees if the day is typical.
I helped a buddy pour his garage slab last year about this time. The building was already up, no sun hit us all day. We were in there at 9 PM with the power trowel.
Edited 2/18/2006 11:03 am by davidmeiland
Yeah, thanks Iron Helix. I didn't know that about calcium either. And we use enough rebar around here to tilt the earth off it's rotational axis.
I wonder if when I ask for calcium, they say "yeah, okay" then add the correct accellerator and don't bother trying to explain what you just said? I've worked around trades people enough to know the average old grouch doesn't often listen all that well to new terms and ideas. I can see how a dispatcher might just do it without trying to debate the finer points. TIPI,TIPI,TIPI!
calicum is corrosive, in large dose. 1 and 2% is perfectly safe. A concrete company is not gonna accept the liability for a product they sell if it can cost them money. A large building or structure fail due to calicum would put concrete company out of business everywhere. As long as the structure is not in a chemical area as in chemical plant, sea water etc. Its fine.If you still feel uneasy about calicum, they make uncorrosive accelerators. Like under say. I use superP which is a high range water reducer. Lower the water content and it will set up quicker. Place a three inch slump with super P and you got about a hour before you can walk on it.Any question about concrete ACI.org. 2+3=7
Well, we need more than an hour to finish. The local plant has something called Polar Set, which is an accelerator. I don't know if that can be used in the same mix as a plasticizer, but I'm going to talk to them about it.
This is only about 800 SF, so I think we can get it all out of the truck in about 45 minutes, fully screeded in another 20 or 30, and ideally hard enough to power trowel sometime in the afternoon.
What would you say is a typical application for super-plastizer? Sounds like a pour with little to no finishing would be a good application, but maybe not a pumped pour?
we use super p on everything but it great for thick pours like footing. so it will flow. I have even use it on sidewalks. I got about five gallon in my shed.. 2+3=7
Go get some straw and poly plastic. After the pour, wait several hours and cover with straw and then the poly. Depending on the size of the project, $50 or $75 is cheap insurance. You can get by with pretty thin plastic. It will take about an hour to apply. Leave it on for at least 4 days. Or for less mess, plastic, straw, and then plastic again. That way you can just roll the whole thing up for disposal. Sometimes though, the straw helps keep the mud down.
Edited 2/14/2006 7:24 am ET by Matt
Dave if you have a contractor rental store or sales store see if they have.Blankets for Concrete they are insulated and should help. Also ask your concrete suppler if they know where you might get some.
Edited 2/14/2006 9:17 am ET by mgard38
Edited 2/14/2006 2:17 pm ET by mgard38
Go ahead and pour, 25° won't hurt a footing or wall. If you were pouring a slab, then heat or some covering would be needed. If you pour in the morning the concrete will be set up by late afternoon anyway.
mike
Thanks for the advice, all. The batch plant is not recommending hot water or anything else for walls, but big surprise--they actually have concrete blankets, 6' x 25' each for $10/week. I think I'll take 5 of those, and I won't be surprised if I'm the first guy to ever use them but what the hey. That will cover the whole thing and I think by about two I'll be back inside with my boots off trying to see where my wife put the hot chocolate.
Wait a couple days before stripping those forms, too David. I've broken corners by stripping too soon in cold (for us) weather. TIPI,TIPI,TIPI!
come back and ask the question when it gets "cold", will ya?
Till then ... pour away and enjoy the heat wave.
btw ... if it's really too cold for U ... just sleep on top of the fresh concrete ... it'll be plenty warm!
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
I'm with many of the others here. Cover with visqueen/poly and then straw or hay.
I did a big pour like that once and it worked like a charm.
Of course I also had Calcium Chloride added to the mix. It is a cheap addition that generates more heat.
The difference between stupidity and genius is that genius has its limits. -Albert Einstein
http://www.peteforgovernor.com
Oh jeez, do I detect a note of envy, maybe for the fact that I've been working outside in the sun in a T-shirt. Well, you can take your Steelers (make that Stealers) and go pound sand.
Seriously, on the day I poured it was forecast to get into the low 20s that night. Never happened. Being a California wuss I figured I'd better get alarmed.
"Oh jeez, do I detect a note of envy,"
Nope!
real men work in all four seasons dammit.
plus ... when ya live thru all four ... or better yet ... "survive the winter" .... U really appreciate the warm stuff! Work hard enough and it can all be "jacket off" weather!
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
David,, I live in Washington also and concrete is my line of work, building and placing forms anyway. We usually are required to cover w/ the blankets you described, but before that we are supposed to cover w/ wet blankets or water cure and leave the forms on for typically three days. That's usually the requirement for state jobs, bridges, buildings, etc.anyway. Not sure about residential tho. Hope this helps
So how did it go?
Power always thinks it has a great soul and vast views beyond the
comprehension of the weak; and that it is doing God's service when it is
violating all his laws. -John Adams, 2nd US president (1735-1826)
Got the footings and walls in. I posted this pic elsewhere. The pour went fine, and the slab will be poured a week from Monday by someone else. I've been looking into the various chemicals you mentioned. It looks like Grace makes a lot of stuff. I think we'll do the slab with hot water and a plasticizer and/or water reducer (it looks like some of the products cover both bases).
Looks good. What a beautiful landscape.Is that a Kubota in the background?Power always thinks it has a great soul and vast views beyond the
comprehension of the weak; and that it is doing God's service when it is
violating all his laws. -John Adams, 2nd US president (1735-1826)
That's my excavator's machine, the Peanut. It's very quiet, and the tracks have done very little damage so far. It's been sitting there for about 10 days, and I tell ya', I could have made some money with it--people keep stopping in and asking if it's mine. Of course I'd need something more than my F-150 to move it.
Yea, those mini-excavators are very popular here too.
View ImageI
I looked at your web site and looked up your location too. Based on the location, I wouldn't think ~145/yard is that bad. Also, I'm guessing there is a lot of "out of town money" floating around there which is perfect to support the high end work you do...
Edited 2/19/2006 6:40 pm ET by Matt
The typical excavator here is about 3 times that size. I'd say there are 25 of those and about 4 of the small ones. Lots of guys have rock hammer heads for them. The typical excavation contractor here is a guy with a large Kobelco on a trailer behind his ten-yard dump, and a grading laser on the passenger seat. Average rate is about $90 per hour.
There's one guy who has gotten ambitious and started doing some new stuff. He bought a large tub grinder and can mulch wood waste. The entire barn I removed to build my shop went thru that grinder to become chips. If I'd had to take it to the transfer station it would have been 11 cents per pound, at least a couple grand. I know that less than half that is the typical disposal fee elsewhere. Some guys would have burned it.
I'm gonna start a thread about site work in the BT Photo Album folder in a few weeks. The idea will be more of a show and tell learning deal, rather than the typical - hey look what I built type of thing. I have a lot of stuff going on at work, and am collection some pics. For example, last Wednesday I (actually my company) had to rent a ~70K# hammer hoe - $7k for a week - to break out some rock... I told the operator I wanted him to put 40 hrs on it... or have the job complete.
I'm not sure what the specs on the tool are, but the typical hammerhead would run about $180 per hour here, same as you're paying. I looked at a job that involved removing some ledge, and no one would bid it, just pay by the hour and we'll start chipping it out. A couple of guys I know are doing a large custom that required weeks of rock hammering, and trucking out of the spoils. There may have been more than $50K in site prep alone on that house.
The specs on hammers are right up there with the HP specs on power tools for accuracy and informational value. Seems every manufacturer has their own idea about what markets well.I should be starting a rock job in a week, we'll get an 18,000# track hoe and a 2.25 CY articulated loader in there to clear everything out down to rock, then a 45,000# machine with a hammer that matches its capabilities and we'll start making noise.I figure we'll be there at least a month and a half breaking rock. We're going 3 feet below footings then putting it back together with engineered fill.The problem with hammers like that is they shake evreything so hard you feel them in your sleep.Power always thinks it has a great soul and vast views beyond the
comprehension of the weak; and that it is doing God's service when it is
violating all his laws. -John Adams, 2nd US president (1735-1826)
I was wondering about that last part. Seems like the operator would be heading for the porta-can about five minutes after the machine starts shaking him.