Jake's In Mass (Started July 3, 2011)

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

Good luck.

[PizzaIdiot]

Re: Jake's In Mass (Started July 3, 2011)

Leigh - Since Density = Mass / Volume, I thought if I had the mass and the density, I could calculate the volume. Seemed simple enough when I bought the cement - LOL.

Well I'm off to create the forms for the perlcrete and if all goes well, I'll get that poured today too.

[rodeair]

Re: Jake's In Mass (Started July 3, 2011)

Jeff, not to beat a dead horse, density is not necessarily the same as weight. If you use the homebrew, you'll find hydrated lime is very light compared to sand. A cubic foot of each would be very different as far as weight. Your mix will turn out to be a 6:1 ratio. You'll find it's easier to moisten the perlite before you add the premixed slurry of portland, at least it was for me. Good luck!
Leigh

[PizzaIdiot]

Re: Jake's In Mass (Started July 3, 2011)

Thanks Hank and Jake. I did some googling too. It's not that I don't believe people here, I just try to understand the differences I'm finding.

I found this at Concrete Technology | Frequently Asked Questions (FAQs): Unit Weights | Portland Cement Association (PCA)and this http://www.adhf.co.uk/portland.pdf and they addressed all the concerns I've run up against. It covers the range of density values I've found and what people are saying here.

Q: What are the unit weights (densities) of cement and concrete?

A: Cement: Cement (finely ground gray or white powder used to bind concrete mixtures) weighs between 830 kg/m3 and 1650 kg/m3 (52 lbs/ft3 and 103 lbs/ft3) depending on its handling. The weight of cement that has been pneumatically loaded into a cement silo may be as low as 830 kg/m3 (52 lbs/ft3), while cement that has been stored for a period of time exposed to vibration may be as heavy as 1650 kg/m3 (103 lbs/ft3). It is standard practice to consider a 94 lb bag of cement to be one cubic foot when freshly packed.

Why can't they just put 1 cu ft on the bag ? ! ? UPDATE: They did - I just didn't see it -ARG

I've spent the past week trying to make sure I get my next step right. So with everyone's input I can finally feel good about mixing my 12 cf of perlite with 2 93# bags of cement (in 4 batches!).

Thanks for y'all's patience.

-jeff

[Hank10746]

Re: Jake's In Mass (Started July 3, 2011)

HI
Found this at Portland Cement Association.

Example: Assume that the proportions will be made based on one part being a cubic foot (this is convenient since a 94 lb. bag of cement is 1 cubic foot of bulk material). For a 3/4" maximum coarse aggregate, the mixture would be 1 part Portland cement, 2 1/2 parts sand, 2 1/2 parts coarse aggregate, and 1/2 part water. The sum of the parts is 6 ?. In general the final volume of concrete produced will be approximately 2/3 of the sum of all the volumes included in the mixture. Therefore the approximate volume of this concrete mixture is 4.3 cubic feet. There are 27 cubic feet in a cubic yard so we divide 27 by 4.3 giving 6.2 batches for a cubic yard. Plan on making 7 batches to assure that you will have more than enough material at the start of the job.

Hope it helps in your calculations.

One thing they are not talking weight but volume. So I know that I can get more volume of cement on a shovel than I can get aggregate depending on how wet it is sand can be equal or more than the first two. So it would probably be best to use a small bucket to mix equal parts especially the water as I can get very little on the shovel. In my case it will probably be a measuring cup.

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

Also googling around, Dan the brick Man says....
"a bag of portland cement is exactly 1 cu. ft. ...to this you would add 2 cu. ft. of sand and 3 cu. ft. of gravel... a six bag mix of concrete (3500 psi mix) would contain 6 bags of portland...so roughly 1/6th of a cu yd..."

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

So, I also took a 94# bag of portland to be 1 cuft. A 80lb bag of ready mix is .66cuft, the 94 lb bag is slightly larger.

So, for each 20# bag of vermiculite, about 4.4 CUFT each, I use a little less than 1 bag of portland cement. That gave me somewhere between 4:1 and 5:1 at 5" thick.

Overall the mix looked just about right, it is strong, but airy.

[PizzaIdiot]

Re: Jake's In Mass (Started July 3, 2011)

Leigh
Thanks for the timely input. Maybe I'm being too technical in my thinking, but I would have thought yours was a 10:1 (assuming 1 94# bag is 0.5 cubic feet).
-jeff

[rodeair]

Re: Jake's In Mass (Started July 3, 2011)

I did an insulation layer of vermicrete 4.5 inches thick. The calculations showed I would need 8.5 cuft. I ended up needing 10 cuft of vermiculite and (2) 94# bags of portland which gave me a 5:1 mix.

Leigh

[PizzaIdiot]

Re: Jake's In Mass (Started July 3, 2011)

When I checked the density, it's about 198#/cubic foot.
The bags are also about the same size the 80# concrete mix, which is about 0.59 cubic feet.

So how many bags of cement did you wind up using?
In any case, it looks great.

I hope a few other people will weigh in on this.

-jeff

[rodeair]

Re: Jake's In Mass (Started July 3, 2011)

Jeff - Be careful of the portland, 1 94# bag is 1 cubic foot the way I understand it.

Leigh

[PizzaIdiot]

Re: Jake's In Mass (Started July 3, 2011)

Glad you got the new phone. Keep the pictures coming!

So you used 18 cf of vermiculite and at 5:1 that means you used 3.6 cf of portland cement. By my calculations that's about 7 94# bags.
Is that right?

I'm not trying to challenging you on this, it's just that this is my next step and I have 12 cf of perlite ready to go (hopefully this weekend) with 1.5 cf of cement (3 94# bags) to fill 9 cf. Sounds like I need to plan to mix it all together and use as much as I can - and hope I have enough. Worst case is I'll leave a 'hole' in the middle and fill it in when I get more perlite and cement.

Thanks,
-jeff

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

One last note for tonight:

I ended up using 4 1/2 bags of vermiculite for the hearth That's about 18 cuft of material and my form was about 11 cuft. That is about a 60% yield/40% compaction. Not too bad I guess. I hand mixed some and machine mixed some, compaction was the same.

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

Next, to nerd it up. This is a picture of my lates thermocouple reader. This uses an analog/digital MUX in order to cut down on the number of very expensive MAX6675 ICs for temperature sensing.

I also dropped from an Arduino Pro to a PICAXE 14M2. This wend from about a $20 part to about a $4 part. There are definitely cheaper ways to go, but I am not an "embedded" programmer so I need at least a little hand holding and both Arduino and PICAXE are very hobbyist friendly.

I am working on redoing my schematic and board layout and will post those if anyone is interested.

What you don't see in the picture is the Bluetooth modem and the LiPo battery supply, but they are both part of the design.

[jatsrt]

Re: Jake's In Mass (Started July 3, 2011)

Oh, and that was all mixed about 5:1 vermiculite to portland.