• # Thread: How to calc amount of concrete to fill cinder blocks?

1. ## How to calc amount of concrete to fill cinder blocks?

I know this has probably been stated somewhere, but I can't seem to find it. How many cinder block cores can you fill with an 80# bag of concrete?

2. that I do not know but do a google search for concrete block fill calculator and it will tell you what you need to know in yards. Then just divide it by the amount in one 80# bag.

Zac

3. a lot

seriously- you can always fit more. lol

you are so correct though...ya think you have enough bags of it....and voilah! you need more!

5. Use duct tape to seal one side of the block. Then fill with water, and empty into a bucket. Determine the gallons & convert to Cu Ft & there you go!!

6. Originally Posted by Popfish
Use duct tape to seal one side of the block. Then fill with water, and empty into a bucket. Determine the gallons & convert to Cu Ft & there you go!!
That would work if you didn't use any beam bond blocks!

7. I asked a simiar question a few months ago with several really good responses.

http://www.koiphen.com/forums/showth...hlight=fill%2A

I believe 80lb bags produce something like .66ft2 of concrete. So for 8x8x16 blocks, it would be .66ft2/bag divided by .25ft/block or about 2.6 blocks filled with each 80lb bag.
Last edited by mpageler; 10-23-2008 at 12:38 PM.

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As "John" mentioned above, the www.concrete.com is a good source for information. There is also a quick tool (there are many others too) at http://www.964-rock.com/calculat/calcconc.htm to calculate exactly how much is needed to fill in a cinder-block wall.

As far as how many bags one would need, you may want to check out manufacturer's site to be sure. I used TXi manufactured "Maximizer" for my puddle and they (=TXi) claim that each 80lbs bag equals to 1 Cu.ft. per bag ( http://www.lowes.com/lowes/lkn?actio...050&lpage=none ).

Hope this helps,

Kari

9. Originally Posted by kah1010
As far as how many bags one would need, you may want to check out manufacturer's site to be sure. I used TXi manufactured "Maximizer" for my puddle and they (=TXi) claim that each 80lbs bag equals to 1 Cu.ft. per bag ( http://www.lowes.com/lowes/lkn?actio...050&lpage=none ).

Hope this helps,

Kari
I don't know what kind of lightweight concrete they have in the bags at Lowes, but cement has a specific gravity of 3.15 which means it weighs 196 pounds per cubic foot solid volume, and most of the sand and gravel that they would use is mostly silica with a specific gravity of 2.65 which means it weighs 165 pounds per cubic foot solid volume, and the only other ingredient is water which has a weight of 62.4 pounds per cubic foot. Putting these together in the form of concrete, will give a weight of about 140 to 150 pounds per cubic foot mixed. What may be referenced on the bag to 80 pounds equals 1 cubic foot is dry measure in the bag with all the air between particles. Bag cement used to be sold in 94 pound bags, which were defined as one cubic foot dry measure. When it comes time to fill the voids, the concrete must be a thick liquid, which means 80 pounds is about 0.55 cubic foot mixed.

The reference to lightweight is that concrete can be made with rock similar to lava rock that makes the concrete light weight due to all the voids in the rock, and that concrete can be made to weigh as little as 80 pounds per cubic foot, but would be very expensive and very tricky to work due to the high absorbsion of that type of rock. I have made concrete using vermiculite for crash cushions that weighed about 40 pounds per cubic foot, but I could seriously dent it with my hand.

10. On my last pond I used 80lb. bags it equaled out to 1.3 yards.
This new pond will take almost 7 yards. There's no way I'm going to go the bag route.
Calling a pumper tomorrow.

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