Grvl+PrtlndCmnt+H20=(x)cubic yds ?

[Jstpssng]

Has anyone mixed enough concrete to know how much gravel to estimate?
I'm pouring a 16x24 ft slab, 7" deep. Total concrete required; 8.297 yds. I bought a 14yd load of screened road gravel (<1"), which includes a lot of sand. Because of the fine agregate, I'm using about a 5 1/2 bag mix. Even allowing for compaction; Is there any chance this won't be enough? I 'm pouring 3, 5+ft strips. Just finished the first & wanted to pour the second tomorrow, then fill in the middle next weekend. Trouble is, I only have about 4-5 yards left in the pile. Before I go talk to my supplier, I would like to know. Is there any way that 8-9 yards of gravel can be compressed into <3yards?

Thanks

R

 

[SimS]

R;

Seems to me maybe you did not receive 14 yards. Maybe they delivered 14 tons? If that's the case you probably started with about 10 yards in volume. With your estimate of 4-5 yards remaining; it sounds like that is the case. Good luck.

Sims

 

[JB4310]

I would like to know. Is there any way that 8-9 yards of gravel can be compressed into <3yards?

Thanks
R

No.
You can add all kinds of finer materials into the voids of the larger aggregate, like a yard of 3/4" stone a 1/2 yard of coarse sand and a few bags of portland cement, seperatly they equal more than a yard but mixed together they may only equal a yard.
But you can't compress the gravel enough to be noticed, It's pretty compressed in that giant truck that delivered it. It would have to be a very large triax dump if it was brought in one load, gravel is normally sold by the ton, around here anyway. so maybe it wasn't 14 yards.

 

[bugstruck]

It's impossible for the volume of mixed concrete to be less than the volume of the aggregate you bought. The aggregate is somewhat more separated in a concrete mix than it is clean in a pile. So aggregate fluffs slightly for volume when converted into concrete and certainly can't compress. I do think you bought 14 tons though or got seriously shorted on the yardage order. Stone that size is roughly 105 lbs. per CF dry. That would be 4.93 CY of aggregate at 14 tons. Keep in mind that fines in the aggregate and moisture add to the weight so reduce volume. Something isn't adding up but your CY calc for the concrete is dead on.