Cement weight lifting related

[Slik]

If I poured an 80 pound bag of cement would it weigh 80 pounds after it formed and dried?

[B_B_C]

If I poured an 80 pound bag of cement would it weigh 80 pounds after it formed and dried?

without water ?
depends on the air poisture content
 the density of dry cement is roughtly half the density of normal concrete (cement, aggregate & water)
eg a Litre of dry cement is about 1.2kg (1200g)
a litre of concrete is about 2.4 kg
and for comparison
a litre of steel is about 7kg

If you are making up a mix to make weigths (as I suspect you are) then ask me more as you could be very disapointed with the results

[Slik]

Well yes. I was planning on making a form with the bottom consisting of a metal tray with the sides of the tray about 2 inches high. Then inserting lag bolts into the sides. Building the rest of the form out of pine board. Pouring cement w no gravel or agg into the form. As it begins to set put a large steel handle in the top.
I just wanted to create a challenging big block of cement like atlas stones but this would again be a rectangle and have a handle to try to lift it. 

So I wanted to know, if I used 4- 80 pound bags of cement would it weigh approx 320 after it dries and sets.  Common sense says it would be close because on e the water is gone u r left with just the powder now in solid form. Correct?

[BILL ANVIL]

mpa

[Slik]

mpa

i had to urban dictionary that one
I'm either part of the music publishers association, a massage parlor attendant, or a mass produced asshole. Hmmm. Out of those choices ill go w the asshole.

[BILL ANVIL]

i had to urban dictionary that one
I'm either part of the music publishers association, a massage parlor attendant, or a mass produced asshole. Hmmm. Out of those choices ill go w the asshole.

  those all look fun to me.

should have said mega pascals sorry.

[B_B_C]

says it would be close because on e the water is gone u r left with just the powder now in solid form. Correct?
NO

not intending to be rude but you seem to know enough about concreting to waste the cement.
a homemade cement mix is weaker than concrete and in both cases water becomes part of the hardened material (its a chemical reaction and heat is generated - even more so with high cement content and consequent cracking.
I suggest the following:
decide the weight you want to make,
divide it by 2.3 to get a volumn and then either make up a box (form) or find a close approximate size
either paint the inside with shuttering oil (or any old engin oil) or find a plastic bag big enough to size and shape you want.
Then make up a Concrete mix (1:2: 4 cement: sand: gravel )
mix
and
add water deally half the weight of the cement -
The greater the ratio of cement: water the weaker the final concrete will be.
You have about 2 hours from first adding water before the concrete starts setting (not the same as hardening - that takes days weeks, years )
Have what ever you want to insert in to the mix ready, clean of dust, oil etc but maybe rinse in water before inserting.
Any movement of the mix after it starts setting weakens it, once placed protect from the sun if hot..  
 

[Slik]

not intending to be rude but you seem to know enough about concreting to waste the cement.
a homemade cement mix is weaker than concrete and in both cases water becomes part of the hardened material (its a chemical reaction and heat is generated - even more so with high cement content and consequent cracking.
I suggest the following:
decide the weight you want to make,
divide it by 2.3 to get a volumn and then either make up a box (form) or find a close approximate size
either paint the inside with shuttering oil (or any old engin oil) or find a plastic bag big enough to size and shape you want.
Then make up a Concrete mix (1:2: 4 cement: sand: gravel )
mix
and
add water deally half the weight of the cement -
The greater the ratio of cement: water the weaker the final concrete will be.
You have about 2 hours from first adding water before the concrete starts setting (not the same as hardening - that takes days weeks, years )
Have what ever you want to insert in to the mix ready, clean of dust, oil etc but maybe rinse in water before inserting.
Any movement of the mix after it starts setting weakens it, once placed protect from the sun if hot..  
 

great answer thanks. I do all my own work and yes have worked with concrete cement but don't know the tech aspects of it.

[B_B_C]

great answer thanks. I do all my own work and yes have worked with concrete cement but don't know the tech aspects of it.

its got many similarities with baking
 you could get extra weight for less space by mixing in scrap iron - nails, screws , bolts etc  but make sure there is a 50mm (2") concrete cover if you are in a damp environment or leave the weight outside. it would be trickier to figure out the final weight when finished.

when a teenager I mand up some concrete discs in a washing up bowl . I intended to use an old horse cart axel as the bar and chairs as props - however I found out the attic floor was a bit dodgy in parts when I put a foot through the plasterboard ceiling below - luckely before I'd loaded up the  "bar"

dont forget to compact / tamp the mix into the form (but not so much as for the mix to seperate:). strike the forms  about 4 - 7 days after casting,  no mixing or placing if temperature in that time will go below 5C

[Slik]

Great. Again. Thanks!

[Tapeworm]

Careful.  Masonry in general doesn't accommodate shock loads well.  I predict your blocks will develop cracks and fail over time if you're putting them down on a hard surface, and I'd guess any metal you include (such as the handle) will weaken the block with microcracking as heat expands it.  Concrete is strong compressively but is brittle.  I forsee a busted toe sooner or later.

Also you're going to be dealing with a much larger object than a heavier material would give you for the same weight.  If I understand you, you want deadlift/ farmers walk weights?  I'd just use plates stacked with a threaded rod/pipe through the bore and a nut or cap beneath.  You could weld a handle on or rig something with pipe fittings.

To answer the question, I would guess mostly yes except for water weight contributed by humidity and water consumed in the hydration reaction which becomes an integral part of the concrete and isn't evaporable water.  I don't know how much that is, if any, but I'd guess it would be negligible.  Idk.  You'd have to use aggregate which is dimensionally stable in water such as rock and concrete sand (with low clay content) or else the concrete will shrinkage crack severely as it dries.  All concrete shrinkage cracks to some degree.  The mpa above is megapascals and refers to the compressive strength of the mix.  

[BigCyp]

Why are you making rocks?

Just go and find some

[The True Adonis]

Why are you making rocks?

Just go and find some

Exactly.  Or just fill a garbage can full of clay, dirt and mud and pick that up. 

[cart@@n]

Homemade gym, all the weights are made from concrete.

 

Pulldown cable machine made with wood, and concrete weights:

All the plates are concrete blocks:

[BigCyp]

Exactly.  Or just fill a garbage can full of clay, dirt and mud and pick that up. 

If only all people were as sensible.

[Natural Man]

Homemade gym, all the weights are made from concrete.

 

Pulldown cable machine made with wood, and concrete weights:

All the plates are concrete blocks:

retarded... all these materials will deteriorate, plus it s completely unsafe..there s a reason serious people use metal to build gym equipment... Using wood and cement might sound like a great and economic idea at first, but when it deteriorates you re good to throw the whole stuff and buy something more solid.

[Mr Nobody]

If I poured an 80 pound bag of cement would it weigh 80 pounds after it formed and dried?

Falcon could probably answer this best.

[LATS]

I would venture to guess that those plates are not "true" or accurate in weight.. So having plates on the bench press that are uneven can lead to injuries ect

[BILL ANVIL]

dipped in epoxy those weights might preserve better and be safer.

[HTexan]

Find/make a mold. Like a bucket with a pvc pipe down the middle are something .  As long as the weigh the same, you should be find.
IMO, I would just used Craigslist or yard sales and find sone metal weights. People sell them for nothing. Sometimes you can even get them for free. 

[Tapeworm]

Keene's cement, which is an alum treated gypsum, sets harder (in terms of scratch resistance) than portland cement and apparently can be tooled (lathed, etc) when set which might indicate it can take knocks without cracking better than portland based concrete.  I think it's what they pour for self leveling floors, and I remember seeing pictures of it being poured over electric floor heating grids.

Concrete sand would be a sufficient aggregate, no need for stones, and glass or nylon fiber reinforcement would take well.  It would be set enough to remove the form in a couple hours.  You could pour different colors and swirl them a little if you want a tie-die weight set.

You couldn't leave them out in the rain like concrete though.

[B_B_C]

You couldn't leave them out in the rain like concrete though.

[Tapeworm]

... cause it took so long to bake it!  LMAO!

That's going on the kitchen tunes mix.