Grouting Overhead Penetration Through Concrete Slab 1

[RaptorEIT]

Have an existing, elevated 9" thick concrete slab with several penetrations through it that have been requested to be filled to eliminate tripping hazards. Each penetration is void and has a grout ring and steel cover plate installed over them (see attached picture). It appears each penetration was core drilled.

My initial plan is to chip away the existing grout ring, roughen up the penetration surface within the slab, chip out a "lip" near the middle of the penetration, and fill with epoxy grout. The lip is to support the grout so it doesn't fall through. Does this approach sound acceptable? Instead of chipping a lip I could specify dowel into the existing slab. I don't need the grout to work compositely with the slab, just need to fill it up and prevent it from falling out.

The biggest issue though is some of these penetrations are too small to fit a drill or hammer inside them to roughen up, chip, or dowel into. Is simply placing an epoxy grout within a core drilled hole through a concrete slab enough to adequately bond the grout to the slab to prevent it from falling through? From what I understand, core drilling doesn't allow proper bonding. The only perceived load on the grout patches will be from personnel live loading.

Thank you

 

[jayrod12]

What's the diameter of the holes to be filled, and what's the intended use of the floor? I'd be tempted to try and chip an angled ledge from the top of the slab sloping inward to allow gravity to hold the infill piece.

 

[RaptorEIT]

Jayrod: The diameters vary from around 4" up to around 16". The floor supports operating equipment and receives light foot traffic from operations. It also occasionally is used lift loads from lower stories.

Your idea sounds far better than what I came up with. Thank you for sharing that thought.

 

[MotorCity]

I would saw cut a larger hole at each location such that you could install dowels. I would not rely on the craftsmanship (or lack thereof) of a worker to create an angled ledge. Another idea might be to sawcut a square opening, attach ledge angles, place form deck and pour.