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J Harp
04-08-2018, 02:12 PM
Re some recent discussions of exact measurements and different systems of weights and measures, I have a head-scratcher.

A bag of mortar mix has these instructions. Add approximately 3 quarts of clean water per 25 pounds of powder to a bucket, then add the powder and mix to a workable consistency. There is more to it not having anything to do with measurements.

My scale weighs in pounds and ounces, also in grams and kilograms. My measuring cups are marked in quarts, cups and fractions of cups, and tablespoons. They are also marked in milliliters.

I don't need to mix 25 pounds, I think 4 or 4.5 pounds will do the job. I did it mostly by guess and by gosh. If I had to do it again I would use the metric system. If the metric measurements were not available, how could I come pretty close by using pounds, ounces, cups and tablespoons? That part of the job is done, this is just to "stir up" some more discussion, and I just might learn something.

Baz
04-08-2018, 02:37 PM
Well you obviously need to think about this over a cup of tea. So buy a pint of milk and then you have a sensible sized building site friendly container to measure your water in. If you ditch the quarts in favour of pints it is a much more obvious rough calculation.

danlb
04-08-2018, 02:42 PM
Should be fairly easy since a liquid ounce of water weighs approximately 1 ounce. Convert 3 quarts to ounces = 96 oz. You are using 4.5 / 25th of the powder, so use 4.5/25th of the 96 oz. and that tells you to use 17.28 oz of water. You don't need to use a measuring cup. Just weigh it.

Dan
P.S. My math skills are failing. Please excuse any mistakes. The concept is to use the same ratio of water as the ratio of the powder.

Mark Rand
04-08-2018, 02:51 PM
"A pint of pure water weighs a pound and a quarter"

Unless you're in some of the colonies, where it don't :p

lakeside53
04-08-2018, 02:52 PM
You should also eyeball the mix consistency and adjust as required. A tiny amount of extra or less water make a huge difference. One unknown is how much moisture has already been adsorbed from the air by mix powder.,

Jim Stewart
04-08-2018, 03:02 PM
"A pint of pure water weighs a pound and a quarter"

Unless you're in some of the colonies, where it don't :p

In these colonies the saying goes "a pint is a pound the world around". Except in Olde Blighty and posessions, I guess.

-js

MattiJ
04-08-2018, 03:04 PM
Well you obviously need to think about this over a cup of tea. So buy a pint of milk and then you have a sensible sized building site friendly container to measure your water in. If you ditch the quarts in favour of pints it is a much more obvious rough calculation.

Nah, I think you better buy a keg or two (UK or US, both units work) of beer, drink some of it and start adding water to the cement mixture. Drink more beer and add water until the mix look like "workable consistency" ;)

LKeithR
04-08-2018, 03:18 PM
...add water until the mix look like "workable consistency" ;)

Exactly. It's only mortar mix. Get it close by measuring and then fine tune as you go. Too dry? Add water. Too wet? Add
some more powder. That's the way "backyard" concrete has been mixed as long as I've been around. It's not rocket science...

J Tiers
04-08-2018, 04:38 PM
Exactly. It's only mortar mix. Get it close by measuring and then fine tune as you go. Too dry? Add water. Too wet? Add
some more powder. That's the way "backyard" concrete has been mixed as long as I've been around. It's not rocket science...

Yes.... but you watch someone who does that all day and they know just what the right ratio is.... you don't often see them dripping in just a bit more, or another handful of mix.... In go a couple bags, and some water, and out comes just right mortar.

Concrete may be different... slump ratio and all that, I leave that stuff to the folks who know. For small concrete jobs, I know that a bit dryer is better than too wet, and just do as you say.

J Harp
04-08-2018, 04:38 PM
Thanks for the replies, weighing the water sounds workable. One site I looked at said to mix it to the consistency of mashed potatoes, another said mix to the consistency of creamy peanut butter, I mixed it a little stiffer than Jif. That seemed to work, had a good grab.

J Harp
04-08-2018, 05:00 PM
Keith, I hope your sig line doesn't apply to me. Last week I mentioned the projects I'm into to a fellow I was talking with. As we parted he said, "I hope you get all your projects finished", I said "there's no way I'll ever have them all finished. How am I going to live to be a hundred if I don't have a project to keep me going?"

Juergenwt
04-08-2018, 06:59 PM
Let's say you want to use only 5 Lbs of your 25 Lbs. That is 1/5th.
You need 3 quarts for the whole 25 Lbs.
That is 3.0 liters (approx).
Divide 3 liters by 5.
3/5 =0.6 liters or 600ml or just over 1/2 liter beer stein. If you have a German Stein with a 0.5 liter mark on the side (all German Steins made in Germany have it) - than just fill it to the top.
The space just over the 0.5 liter mark is for the foam.
3000ml : 5 = 600 ml = 0.6 liter

Now you know why you should use metric!

J Harp
04-08-2018, 08:50 PM
In this sort of thing I suppose metric would be less confusing. Generally I am unfamiliar with metric measurements, I know about what 5 gallons looks like, but I have no idea what 20 liters looks like. I suppose most people would be just as lost about the imperial system.

Too bad the digital scale doesn't have a decimal pounds option in addition to the pounds and decimal ounces option.

tlfamm
04-08-2018, 10:44 PM
I never quite trust in complete uniformity of mixture in bagged mortar mix - especially since they aren't giving you even a minute amount of "extra" masonry cement in the bag. If I'm not doing a full-bag mix, then I add a small amount of extra masonry cement to my fractional mix.

I use Home Depot's mortar-mix product - 15 or 20 years ago it had a poor reputation, but the current offering (Mason's Mix) is better received. For pure masonry cement, I use Iron-Clad, an excellent product available in New England (at least).

flylo
04-08-2018, 10:55 PM
With any of the premix it's good to have a bag of real mortar or portland cement to richen the mix a bit IMHO.

andywander
04-08-2018, 11:50 PM
There is absolutely no need to weigh the water.

Your ratio is 25lbs of mix to 3 quarts of water.

So figure out how many lbs of mix you re actually using, call it Xlbs.

X/25*3 is the number of quarts of water you need to use.

J Tiers
04-09-2018, 12:04 AM
I never quite trust in complete uniformity of mixture in bagged mortar mix - especially since they aren't giving you even a minute amount of "extra" masonry cement in the bag. ,,,,



Totally correct. IMO.... the stuff settles unevenly and may not even be mixed up evenly when bagged. Neither mortar nor concrete.

If I were doing the process, I would put a measured amount of aggregate/sand and a measured amount of cement in. That would ensure a constant mix, fewer complaints, and a more economical system overall. That might likely not be mixed up when bagged, but even if it were, it will get messed up later.

Alistair Hosie
04-09-2018, 06:55 AM
When I want to mix these things I just put in the water first and add powder until it is about enough to absorb all the water assuming this is not just cement but a ready mixed mortar mix. I when mixing it seems either too dry or too wet then add either more water or mix. I won't insult your intelligence by explaining that any more. I short it is not some highly explosive chemical formula it is just plain old mortar mix if you mix it incorrectly for a small mix like this by eye when mixing you can bump it out and start over or doing it as I describe all by eye and general feel if it is too sloppy or as dry as talcum then as I suggested just add or subtract it is not rocket science. And of course either way it will set eventually anyway so go out and have some fun. Alistair p s how do you grow and make tobacco can it be done in a small batch at home or not. Also I need to ask is it legal as if it was anyone else's business what I make to smoke or eat or apply to the outside of my broken window ledge, or doorstep ,or concrete false teeth , in my own home anyway.

cameron
04-09-2018, 09:03 AM
Let's say you want to use only 5 Lbs of your 25 Lbs. That is 1/5th.
You need 3 quarts for the whole 25 Lbs.
That is 3.0 liters (approx).
Divide 3 liters by 5.
3/5 =0.6 liters or 600ml or just over 1/2 liter beer stein. If you have a German Stein with a 0.5 liter mark on the side (all German Steins made in Germany have it) - than just fill it to the top.
The space just over the 0.5 liter mark is for the foam.
3000ml : 5 = 600 ml = 0.6 liter

Now you know why you should use metric!

A good illustration of why children in early grade school should be taught to add, subtract, multiply, divide and work with fractions so they don't have a nervous breakdown or cower with fear every time someone mentions inches, gallons, poles or surveyors' chains of 66 feet. Not sure what your excuse is, though, since you do seem capable of handling rudimentary arithmetical tasks, and could probably handle this one without having to resort to the metric system if you put your mind to it.

tlfamm
04-09-2018, 12:49 PM
If I were doing the process, I would put a measured amount of aggregate/sand and a measured amount of cement in. That would ensure a constant mix, fewer complaints, and a more economical system overall. That might likely not be mixed up when bagged, but even if it were, it will get messed up later.

Which is exactly how I did it for years until my local sand & gravel dealer closed up shop about 5 years ago. Now I buy the pre-mixed stuff mostly to get the sand and some unverified quantity of cement - to which I add more. But if you want absolute control over quality, it should be done as you describe.

gambler
04-09-2018, 02:48 PM
jeeze louise, just mix the whole bag, use what you need throw the rest out. the alternative, 5 years from now when you go to use the remaining amount it will be hard in the bag! if you can even find it.

J Tiers
04-09-2018, 03:35 PM
jeeze louise, just mix the whole bag, use what you need throw the rest out. the alternative, 5 years from now when you go to use the remaining amount it will be hard in the bag! if you can even find it.

VERY TRUE.

What is it.... 3 bucks a bag or so? Pretty cheap, anyhow. The worst problem is getting rid of the excess.

danlb
04-09-2018, 04:39 PM
I think I'd rather mix just what I need and throw the excess in the garbage can while still in the bag.

I don't have a mixer, so mixing it by hand can be quite tiring. Mixing 25 pounds of it in a wheel barrow is a lot of stirring. Then dumping it somewhere and cleaning the barrow is a hassle. Then breaking the hardened mass to a size that I am allowed to throw in the can... and so on. Mix 4 lbs in an old 5 gallon bucket. Pour it. Toss the bucket. Done.

J Tiers
04-09-2018, 04:50 PM
The original issue is that getting 4 or 5 lb out is very unlikely to get you an even mix of aggregate and cement powder. It's ofthen easier to mix the bag and get what you want.

Rather than letting the rest harden, it is also possible to just wash out the cement, which is usually a smallish part of the mix anyhow. The rest is sand and gravel that can actually be used for something, so you can, if you want, recover some value, and you have to wash out the container anyhow so you already doing much of the work.

Your choice

danlb
04-09-2018, 06:20 PM
The original issue is that getting 4 or 5 lb out is very unlikely to get you an even mix of aggregate and cement powder.

Yep. I guess that's the original issue, since it was brought out at post 14.

The OP was more concerned with using the imperial measures to divide a big bag of mix and it's water proportionally, even though none of it's decimal. He got his answer in several ways.

Dan Dubeau
04-09-2018, 06:30 PM
Mix it all and pour the rest in 5gal buckets. Always handy to have weights around for tarps, awnings, dead body disposal, ez-up canopies, etc :)

J Harp
04-09-2018, 08:21 PM
Thanks for the replies. I'll be printing some of them after I have a chance to review them.

I didn't state the question very well, I shouldn't have even mentioned mortar mix, but that was the example I'd just been working with. BTW the stone is up, cleaned and ready for sealing and grouting.

What I'm really after is quick, easy, or better ways of doing the math in such situations. Such problems come up frequently, and some, such as mixing pesticides and herbicides, need rather precise answers. Someone always has a better idea, and I like to hear those better ideas.

I am very poor at math, but I usually manage to muddle through to a workable answer. Thanks again, I'm enjoying the discussion.

rzbill
04-09-2018, 08:40 PM
"A pint of pure water weighs a pound and a quarter"

Unless you're in some of the colonies, where it don't :p

And we don't have the handy line at the top of the glass that keeps the beertender honest.

16 oz and we get gypped on top of that. Darn it. :mad:

danlb
04-09-2018, 09:39 PM
I didn't state the question very well,

What I'm really after is quick, easy, or better ways of doing the math in such situations. Such problems come up frequently, and some, such as mixing pesticides and herbicides, need rather precise answers. Someone always has a better idea, and I like to hear those better ideas.

I am very poor at math, but I usually manage to muddle through to a workable answer. Thanks again, I'm enjoying the discussion.

Jim, my understanding is that it comes back to those infernal lessons about how many XYZ there are in a ABC. We learned that a pound was 16 oz (dry) and a wet quart was 32 fl oz and foot was 12 inches. They taught us all these thing because they are the basis of doing most of the "word problems" that we now find we need to do as adults.

MY TRICK; I just reduce things to the oz, inches or feet that I'll be rounding to. If the given measurement is 1 quart, 3 OZ I make it (32 + 3) which is 35 oz and then do the math as if it's decimal.
Same for 3 lbs, 7 oz. That's 3+7/16 = 3.4375 pounds or 3x12 + 7 = 43 oz
The result is 35 fl oz for every 43 oz gives a ratio of 35:45.


Dan

J Harp
04-09-2018, 10:53 PM
Thanks Dan,

That's the same as what I came up with after thinking about it for a while. If I don't do something like that for a while I will forget how, and have to work it out again. This time I'm cheating, I printed out conversion charts for pounds to ounces today, now if I can just remember where I stashed them when I need them!

danlb
04-09-2018, 11:15 PM
On the other hand... Imperial liquids are almost easy, as mentioned on another thread. From cups to gallon, just double it each time.
cup = 8 oz
pint = 16
quart = 32
half gallon = 64
gallon = 128

But I must admit I cheat. "Ok Google. how many ounces in 3 gallons plus 1 quart?" works quite well on my cell phone.

J Harp
04-10-2018, 09:13 AM
Computers and cell phones certainly make getting info much easier than spending hours in a library looking up something. They don't make the math mistakes I would make either, long division is always iffy with me without electronic aids, extracting roots near impossible, and algebra a bear. I use the computer, calculators, and cell phones, but I can still get lost if I don't get the entries correct.

I can learn to do one or two math operations for a solving a problem, but I don't get the big picture, and I'll forget the procedure if I don't use it frequently. Math just doesn't come naturally for me.

danlb
04-10-2018, 11:13 AM
Yeah Jim, I'm having the same problem. Math has never come easily to me. That's why I went into computer science. Let the computer do the work! :) Oddly, even though I have problems with basic math I can often spot an incorrect answer to an equation.

I envy those who can easily remember all the formulas and when they apply. Thank goodness for cell phones.

Dan