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Several of my neighbors and I want to pour numerous small slabs of concrete (approx 3 ft x 6 ft x 4 inched deep) aound our homes this spring. I have done this in the past using bag pre mix and have rented a cement mixer for 24 hrs.. This time we want to go together and buy a small mixer so we are not constrained by time and can help each other one project at a time.. Two questions.. (1) What size of mixer should we buy? 2.5 cu ct? bigger or smaller?? We don't want to spend alot of $$$ but want something that will work.. Harbor Freight Mixer?? and (2) what is the minimum temperature that we should pour / work concrete in?
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For the relatively small amount of concrete you want to pour a 2.5 f3 mixer would do fine, something like a Husky (home depot) or a harbor Freight model would work fine. In the scheme of things your not mixing all that much concrete and not all that much at one time.
As your going to mix pre mix concrete I'd not pour unless you know the temperature is going to be above a min. of 40 F, this will give you a setting time of about 15 hours, 50F is around 11-12 hours setting time.
Concrete should not be exposed to freezing temps. for at least 24 hours after pour (well after setting time). When you mix concrete any temperature below 40F retards hydration (setting time) and will cause strength issues in the concrete unless other heat retention options are taken.
Basically if you pour concrete at say 50F make sure it's not going to drop below 40F for at least the following 24 hours. Insulated blankets can be used in colder temps. or if the temp. drops below 40F. For something small like your planning (6'x4') a good thick tarp doubled over would do the job as well.
If your needing "control joints" (slots in the concrete that encourages the crack to occur in the slot) make sure your groove the concrete 1/4 of it's thickness (4" slab has a 1" deep control joint).
Hope this helps.
Little about a lot and a lot about a little.
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Good Information..
Thanks a million for the info... exactly what I was looking for..Comment
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