PSI Rating?

Question

Today while I was driving in heavy traffic on the freeway I saw on the bed of a truck in front of me bags of concrete mix that were labeled "2500 PSI Concrete Mix." Why is concrete mix given a PSI rating?

Many thanks,
C.L.

Answer 1

It tells how much weight and/or stress the cured concrete can withstand before it fails (crumbles). So, if you have something weighing 10,000 pounds and its weight is supported evenly on four legs with 1 square inch feet, the surface of the concrete (if it's thick enough) can withstand that much pressure without crumbling under the weight.