Concrete/cement ratios

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shadow338

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Hello,

I bought a few 94-lb bags of portland cement. I read that these are 1 cubic feet each.
I also bought loose sand and gravel to make concrete.

How many 5 gallon buckets of sand do I need to mix for each 94lb bag of cement if the mix asks for 1 part cement and 2 parts sand?

I'm getting mixed answers on the internet that a 5gal bucket full of sand is either 0.68 cubic feet or 0.98 cubic feet.

It is safer to just fill a bucket with cement and then fill two with sand to get the correct ratio?

Thanks in advance.
 

Eddie_T

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You won't be must faster using a 5 gallon bucket! I wasn't trying to be smart, the contractor that built my chimney shoveled it into a concrete mixer.
 

Sparky617

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How are you mixing this? Lifting and pouring a 5 gallon bucket of sand into a mixer is no easy lift. I've only ever seen guys mixing mortar and concrete use a shovel to move the sand into the hopper, same with stone for concrete. The bags of cement are bad enough.
 

shadow338

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no mixer here. Gonna pour and mix on the ground. I just want to be sure I will end up with the correct mix ratio if I measure everything in buckets.
 

Sparky617

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For a quick comparison dump a bag of cement into your bucket and see how full it is, or if it is more than a 5 gallon bucket's worth. If it fills the bucket and you're shooting for a 1:2 cement/sand ratio dump in two buckets of sand.
 

shadow338

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For a quick comparison dump a bag of cement into your bucket and see how full it is, or if it is more than a 5 gallon bucket's worth. If it fills the bucket and you're shooting for a 1:2 cement/sand ratio dump in two buckets of sand.
thank you!
 

BuzzLOL

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For mortar we mix one shovel cement and 7 shovels sand in a mixing trough...

"The safest bet for any concrete mix is four-two-one: four parts crushed rock; two parts sand; and one part cement. The four-two-one mix, obviously, has seven parts. Conveniently, when mixing concrete, the ratio can be mixed on any range of scales." -bnproducts.com

Mixing it yourself can be a good idea as bags of 'premixed' often chintz out on the amount of cement...
 

tomtheelder2020

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There is no "right" mix for concrete - the mix to use depends on your purpose. For high compressive strength, use enough gravel to have continuous stone-to-stone contact. For concrete dams, each lift of concrete is rolled (and I assume vibrated) with a heavy compactor. The amount of water added is also important. Once the concrete is dry, the volume once occupied by water will be occupied by air. Also, see what Sparky said about a wheelbarrow.
 

bud16415

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Concrete actually doesn’t “dry out” it is a chemical reaction and the water is trapped inside the mixture. This is the reason concrete does not absorb water and makes it a great long lasting building material.



Here is a link.



Why Concrete Doesn't Actually Dry Out.
 

BuzzLOL

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Speaking of wheelbarrows, those ones with 'tires' that don't go flat can be impossible to push along as those 'tires' want to plow through and separate gravel and sand surfaces instead of gently floating over such surfaces like air tires do.
 

tomtheelder2020

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Bud, you are correct. For maximum strength, the water added to the mix should be no more than necessary for the chemical reaction - but that is a very "dry" mix and harder to work than a "wet" mix. Any water added beyond the chemically necessary amount results in excess void space. That space is water-filled if submerged and air filled if above water level. Either way, excess void space weakens the concrete.
 

Sparky617

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Speaking of wheelbarrows, those ones with 'tires' that don't go flat can be impossible to push along as those 'tires' want to plow through and separate gravel and sand surfaces instead of gently floating over such surfaces like air tires do.
I find if you really load up a wheelbarrow it can be a bear to handle across gravel or sand. I converted my wheelbarrow to a two wheeled one because my yard is hilly and I found if I didn't park the wheelbarrow in the right orientation to the hill I'd dump it over every time. On loading I find it better to make two trips than to over load.
 

Eddie_T

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When I built my house I used crusher run stone under my slab and to gravel my drive. I found a concrete recipe at the time using crusher run as the aggregate. I forget how many shovels of crusher run per shovel of cement powder was used. I used it to make a pad for my well tank and to anchor my postlight. I mixed in a wheelbarrow, I recall builders mixing and pouring footings from wheelbarrows long before I saw a concrete mixer truck in my small town. They kept busy pouring so they always poured to a wet edge. I have seen shovel tips worn thin in those days. The size of the shovel doesn't matter as long as one is consistent in loading it. When I bought sand at the builder supply they knew how many shovels equalled a yard³.
 
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bud16415

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When I built my house I used crusher run stone under my slab and to gravel my drive. I found a concrete recipe at the time using crusher run as the aggregate. I forget how many shovels of crusher run per shovel of cement powder was used. I used it to make a pad for my well tank and to anchor my postlight. I mixed in a wheelbarrow, I recall builders mixing and pouring footings from wheelbarrows long before I saw a concrete mixer truck in my small town. They kept busy pouring so they always poured to a wet edge. I have seen shovel tips worn thin in those days. The size of the shovel doesn't matter as long as one is consistent in loading it. When I bought sand at the builder supply they knew how many shovels equalled a yard³.
Those days are alive and well only now in places like Mexico. I helped my company put in a plant down there and we built a building roughly 200 yards x 100 yards and the floor was 10” thick. I could not believe my eyes the whole thing was done with a few hundred workers mixing it all by hand on the finished floor next to what was being poured. Not one mixer truck was used.



We then needed a machine foundation that required a continuous pour so they brought a truck in from a couple hundred miles away and it came empty and they formed a bucket brigade with 5 gallon buckets to fill it. Seemed crazy but when you don’t have the infrastructure and labor is less than a dollar per hour things change.

Like you I remember a time when people wore out a hoe or a shovel and had to replace it. now they break after a short time and you toss them and buy another. 🇺🇲
 

BuzzLOL

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I converted my wheelbarrow to a two wheeled one because my yard is hilly and I found if I didn't park the wheelbarrow in the right orientation to the hill I'd dump it over every time.
I think wheelbarrows usually have one wheel so a single plank can be used as a bridge or 'paved road' when needed...
 

Eddie_T

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A two wheeled wheelbarrow has more stability but is harder to turn as it will not pivot.
 

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