pouring Concrete in winter


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Old 12-17-14, 05:36 AM
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pouring Concrete in winter

Hi, I am making a 8" x 12" concrete wall to hold about 1000 lbs. The temps are going to be highs 45ish and lows 30ish..
1. Do I need to add something to the concrete?
2. How does this additive affect the long term strength?
3. How long do I need to wait to put the load on the wall?

Thanks
Mike
 
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Old 12-17-14, 06:44 AM
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i will be using quickcrete.. so if you know the best one to buy.. please let me know
 
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Old 12-17-14, 12:21 PM
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Is it a real wall or just a 12"x8" column?

With those mild temperatures, just use a quick-setting type of bagged mix. Heat the mixing water to no more than 140F, mix and place. Cover immediately and keep covered/protected (no insulation necessary) for 7 days or so. Strip the forms and clean up.

Dick
 
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Old 12-17-14, 12:43 PM
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Seems kinda small to hold 1/2 ton? And that's only 2 dimensions? I think more info might be needed?
 
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Old 12-17-14, 03:24 PM
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thanks for the replies, i forgot to say it will be sitting on a 5 inch slab
 
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Old 12-17-14, 04:19 PM
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Gunguy -

The 8"x12" of concrete is equivalent in area to a column made of more than 12-2x4s and has more strength and rigidity per square inch than wood.

Dick
 
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Old 12-17-14, 04:32 PM
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Oh I got that Dick...but we didn't know if it was a pad 8x12 rectangular in shape but only 2" thick or what. 1000lbs of point load on a 2" steel pipe or spread over the whole surface. Thats all I was trying to say.

It's that possible problem with terminology thing.

I'm also running on about 4 hrs sleep after an intruder around (not in) the house last night.
 
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Old 12-17-14, 06:57 PM
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Yeah - Not must information to give anything more than a shot in the dark. I was thinking it was a 28"x8" column carrying 1000#. 1000# on 224 sq. inches is under 5 psi.

A real tall column or a lateral load would be a different sort of animal.

Dick
 
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Old 12-18-14, 07:52 AM
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My bad.. The slab is 5" thick (this wall will sit on the slab) and the wall would be 8" tall 12" wide and 8' long.. Based on the previous answers, I am pretty sure it will hold
 

Last edited by Gunguy45; 12-18-14 at 08:04 AM. Reason: Typing error corrected
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Old 12-18-14, 10:17 AM
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When using any type of Quikrete, I would be wary about heating the mix water to 140 degrees F. (which is considerably hotter than usual hot water tap temperatures). That's likely to cause flash-set to occur, meaning the stuff will stiffen before you have a chance to completely consolidate and finish it. A better option would be to just store the unopened bags in a heated area instead of outside for a day or two before using. "Sweetening" each batch with a healthy shovel-full of Portland cement would also help, as doing so would both increase the mixed concrete's strength and promote a higher heat of hydration developing.
 
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Old 12-18-14, 10:29 AM
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I am amazed at all the knowledge you guys have.. Wish I were smart enough to learn all this. but hey, what else would I use message boards for? I so happen to have a bag of portlan cement and did not have a purpose for it, now I do..

BTW, my dad is building a deck and he asked me to look up how much weight a 16" long 4x6 post is rated for... Well I told him I knew the best place to ask.. So if any of you guys know, please let me know so I can pass it on to my pops
 
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Old 12-18-14, 10:45 AM
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how much weight a 16" long 4x6 post is rated for
Might get an answer here but there's a section for decks specifically if you do not.
 
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Old 12-18-14, 02:32 PM
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Without knowing the species of lumber, and its condition, it's difficult to determine a safe bearing load on any wooden member. A typical working compressive stress would be about 1200 PSI, meaning most 4 x 6 columns could support 23,000 pounds (almost 12 tons) each.

Since it's so short (16"), for sure your dad wouldn't have to worry about buckling. Allowable loads on longer members have to be decreased because of the buckling factor.
 
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Old 12-18-14, 03:05 PM
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My 140F temp was based on the maximum temperature acceptable for mortar for cold weather masonry construction. For small job, just draining a domestic hot water heater would still provide a good "kick" to start the chemical reaction between the cement and prepackaged mix that generates some more heat and protection will help contain the energy. They key is to get the action started to avoid long term durability problems. Concrete products will eventually continue to gain strength if moisture is available in the long run.

Keep the bags of mix at a reasonable temperature before mixing to get the benefits of the chemistry of concrete going as soon as possible.

You will be O.K. if you provide some short term protection, if necessary.

Dick
 
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Old 12-18-14, 03:11 PM
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Thanks.. Bridgeman, The wood is newly bought PT southern pine. He said he is gonna use strong ties and use 2x12 joists doubled.. He was hoping to overshoot.. He will be happy.. Thank you so much for your knowledge
 
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Old 12-18-14, 03:30 PM
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man, I did not know there were so many tricks to concrete...My dad is doing a project too and I gotta tel him about this site
 
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Old 12-20-14, 04:08 AM
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you're smart enough to learn ' all ' this stuff - you just haven't needed the info til now,,, short term protection = insulating blankets of some sort, straw, hay,,, if you're not comfortable w/temps, wait as once temps drop, so does the hydration process conc requires to cure ( get hard )
 
 

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