concrete questions

Discussion in 'Homesteading Questions' started by pcdreams, Jul 20, 2005.

  1. pcdreams

    pcdreams Well-Known Member

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    I'm looking for either an online calculator or the formulas to calculate how much concrete I need

    I'm pouring footings 24"x24" at 8" thick.

    I'm also pouring 8" piers that will be around 7' (max I hope)

    and I need to figure out how much concrete to get. :)

    how much water per 80lb bag should I figure on? We'll be hauling the water.

    does anyone know where I can find sonotubes that long? I've found them only in 4' lengths locally.
     
  2. Cabin Fever

    Cabin Fever Life NRA Member since 1976 Supporter

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    Footings
    2’ (length) x 2’ (width) x 0.67’ (depth) = 2.67 cubic feet

    Piers
    0.33’ (radius) x 0.33’ radius x 3.14 (pi) x 7’ length = 2.39 cubic feet

    One 80 pound bag of Sakrete Contractors mix yields 0.60 cubic feet of concrete. You'll need about 8.5 bags of Sacrete for each footing/pier combination.

    [​IMG]
     

  3. Nature_Lover

    Nature_Lover Well-Known Member

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    Here are two recent threads on the shop talk board:
    Concrete calculators:
    http://homesteadingtoday.com/showthread.php?t=90380

    costs of concrete:
    http://homesteadingtoday.com/showthread.php?t=90389

    I also read somewhere around these boards that there is a compression factor when converting dry cubic yards to wet, regarding compacting out the air space in the sand. I think s/he said something like you will need approx. 11% more than actual finished size.
    That's a new concept for me, but I've never done flatwork, either.
     
  4. pcdreams

    pcdreams Well-Known Member

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    Thanks CF.

    Wow Thats a lot of concrete :)

    I got 8 of these to do over vacation :)
     
  5. mysticokra

    mysticokra Well-Known Member

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    Estillfork, Alabama
    Pre-mixed Concrete is sold by the cubic yard and a truck will usually hold up to 13 yards.

    Cubic yard = 3' by3' by 3' = 27 cubic '
    1 Cubic ' = 1728 cubic " (12x12x12)

    Your footings 24"x24" at 8" thick. =4608 cu" or 2.66 cu'
    You didn't say how many you were pouring.
    Google has an on-line calculator for this.


    I'm also pouring 8" piers that will be around 7' (max I hope)
    and I need to figure out how much concrete to get.

    The volume of a cylinder equals the (area of the base)*height = π r2 h
    Pi times the radius squared(in other words the area of the base)
    times the height

    So, 3.12 * 16 (radius is 1/2 diameter, square it)* 96"=4792 cu" or 2.77 cu'
    each.

    You may find in considerably cheaper and easier to order the concrete pre-mixed than to buy the bags and mix your own.
    Sand cost at $20/ton
    Premixed contrete here was $54.00/yard.

    Don't take any crap off the delivery guy about how he has to get back.
    Just tell the concrete company this is going to be a slow pour and they will stay there all day, if they have to.

    By the way, for about $8.00/yard you can have them add a retardent that keeps the concrete from setting up too fast. Takes about 24 hours to set up with that added.

    how much water per 80lb bag should I figure on? We'll be hauling the water.

    does anyone know where I can find sonotubes that long? I've found them only in 4' lengths locally.
     
  6. ibcnya

    ibcnya Well-Known Member

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