Flexural Concrete Paving

[eatapeach]

We are having areas in our paving that is cracking around bollard and manhole blockouts. The engineer did not indicate any reinforcing for the flexural 650 psi concrete in the paving. The owner is now asking that we remove all panels that have full depth cracking. The contractor doesn't feel obligated to replace the panels since their was no reference in the specifications that require it. The specifications only reference ACI 301 and no where in ACI 301 states you must replace the concrete panels. The owner has also stated he doesn't think you can use epoxy in unreinforced concrete. Does anyone have any input on my situation?

 

[oldestguy]

Yes. Concrete shrinks and cracks and points of crack initiation and propagation are those discontinuities. Tell the owner to get used to it.

 

[Ron]

OG is correct. Each of the bollards and blockouts becomes a point of restraint for the concrete. The concrete will shrink in all directions, so it will pull away from these penetrations and crack. There are some construction techniques that can prevent a lot of the cracking, but not all cracking.

As for epoxy repair, that can be done. It makes no difference if the concrete is reinforced or not...epoxy will still work.

A sketch of the cracking patterns (and penetrations) would be helpful for our continued input.

 

[hokie66]

It is usual and appropriate practice to provide reinforcement at blockouts to control (not prevent) cracking. The re-entrant corners create stress risers as the concrete shrinks. Whether or not these panels are replaced, presumably with a different jointing pattern, is at the owner's discretion, and I think at his cost.