Concrete strength

[yanmars]

I have a chance to get some concrete that is 1 foot square, with 4 pieces of 5/8 rebar in it. It would span 7 feet over a drive way to let water under. Any idea what those concrete pieces would carry in weight. There would be 9 of them but the tires would ride on just two of them.

 

[TnAndy]

How does a 'one foot square' hunk of concrete span 7 feet ?

 

[mcfarmall]

How does a 'one foot square' hunk of concrete span 7 feet ?

Perhaps the OP means a beam that is 12" x 12" x 84" (or more) long.

 

[Streetcar]

Is the rebar in each corner or is it all on one side

 

[Egon]

Placement of the rebar will be required to determine strength. Concrete strength is also required as well as maximum aggregate size.

 

[Streetcar]

Is there any rebar installed transverse in the beam
Unless the concrete Is homemade the strength should be 3000 PSI minimum
Aggregate size does not factor in beam strength

 

[ArlyA]

Maybe Egon was thinking of rocks being added as fill?? Aggregate size is standardized and should be appropriate for the PSI listed on the bag. We added plastic fiber to bridge abutments we poured.

 

[robstaples]

You could recess 3 on each side and pour a 4 inch cement cap to spread the weight over several "beams" . Or something like weight distribution over multiples.

 

[dadster4]

It would depend on what the concrete pillars were designed for...horizontal vs vertical load bearing, what is the source of the concrete?

 

[fried1765]

I have a chance to get some concrete that is 1 foot square, with 4 pieces of 5/8 rebar in it. It would span 7 feet over a drive way to let water under. Any idea what those concrete pieces would carry in weight. There would be 9 of them but the tires would ride on just two of them.

No enough information provided to make a determination.