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what is the formula for cement btu's compared to water btu's

Ron Schroeder
Ron Schroeder Member Posts: 998
in THE MAIN WALL
as a cu ft of concrete is denser than a cu ft of water, more lbs to the cu ft.

Another question for you Brad I bought a box of 18 fish sticks, brand name and prices left out due to common courtesy, now I have 3 rows of 7 fish sticks each is this dicrepency due to where I went to school or does someone still believe in a bakers dozen and a half??

Comments

  • Sun Energy , Mora MN
    Sun Energy , Mora MN Member Posts: 5
    formula's

    I can't seem to find the formula to get how many btu's it takes to raise a cubit foot or yard of cement one degree.... I have 180 yards of cement in the upper floor of my new house/shop complex- in floor heat of course
  • Brad White_46
    Brad White_46 Member Posts: 11
    With water as the identity number

    of 1.00 (BTU's per lb.) concrete is 0.788

    You may also find this helpful if in metric units:

    http://www.projects.ex.ac.uk/trol/scol/ccshcapm.htm


  • Sun Energy , Mora MN
    Sun Energy , Mora MN Member Posts: 5


    Thank you very much, now in the know
  • Boilerpro_3
    Boilerpro_3 Member Posts: 1,231
    Are you sure, Brad

    that sounds really high. I don't have the specific heat for concrete, but marble is only .21, steel and iron .11

    Boilerpro
  • Eugene Silberstein 3
    Eugene Silberstein 3 Member Posts: 1,380
    Concrete

    The specific heat of concrete is 0.156.

    So, it takes 0.156 btu to raise the temperature of 1 pound of concrete 1 degree F.
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Depends if it is Metric maybe?

    Not sure about the metric units, BP (Joules per kg. per degree C. versus BTU's per lb. per degree F.)

    Might as well be furlongs per fortnight for all that I use that system.

    Then again, as an engineer, I cannot count to 21 if barefoot but with my pants on...

    :)

    In your standard is water at 1.00? And in what units?

    Check out the link for the calculator I posted. I checked my textbook against that and it came out ok.

    I will always defer to greater minds though. Thanks Prof. Silberstein and BoilerPro. Back to school for me. Gotta check those units...
  • Boilerpro_3
    Boilerpro_3 Member Posts: 1,231
    1.0 is the standard

    so all specific heat numbers are proportional to that. From Mr. Silberstein's post, that would put concrete at 15.6 % of the capacity of water. Marble 21% steel and iron 11%. Water is a pretty amazing material, isn't it! Carries nearly ten times the amount of heat per pound when compared to steel. And converting it to steam makes it even more powerful!

    BTW... 6 years in a Architecture School and can't draw a straight line.....I know your feeling!

    Boilerpro
  • Eugene Silberstein 3
    Eugene Silberstein 3 Member Posts: 1,380
    That's why...

    That's why water is the best refrigerant!

  • Boilerpro_3
    Boilerpro_3 Member Posts: 1,231
    Brad may be right....

    I was thinking pounds, the question was stated in cu ft or yards.....Word Problems!!!!

    Boilerpro
  • Weezbo
    Weezbo Member Posts: 6,232
    So , Basically you are saying....

    You have no idea :)

    Is that Portland cement of Jamacia or just closer by bus as usual?

    I love it *~/:)
  • Hugh Mason
    Hugh Mason Member Posts: 24


    All of my sources list the specific heat for concrete at ~.19 BTUs per pound. That jives nicely with the typical specfic heat of most rocks being ~ .19 to .21 BTUs per pound. Since concrete weighs ~ 150 lb per cubic feet or 4000 lb per yard it would take ~ 30 BTUs to warm one cubic foot of concrete 1 degree F or 810 BTUs per degree per cubic yard.

    But all of the Pros on this site already knew that;)

    SciGuy
  • hr
    hr Member Posts: 6,106
    a yard

    of typical redi mi is 1800 lbs stone, 1400 lbs sand, 500 lbs cement and 250 lbs water @ 30 gallons.= 3950 lbs.

    But doesn't most or all of that water come out? So somewhere in the 3700 lbs per yard.

    hot rod

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  • Hugh Mason
    Hugh Mason Member Posts: 24


    Most the water is chemically bound with the concrete. Concrete doesn't dry it "sets". Yes there certainly is some amount of excess water that does evaporate but not the majority of it.

    I do believe that most concrete does run a bit less than 4000 lbs per yard but that is a nice round number for back of envelope quick calculations.

    Hugh
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