Mobile concrete crushers.

[Oxbow]

Hi folks, here is my quandry:

A fellow that I do business with has been asked to submit a proposal to replace the floor (concrete) of an 80,000sf building. The existing floor is cracked and has settled in places, and is not satisfactory for the intended use. The following are some of the constraints that need to be considered:

1) This building is in a metropolitan area, trucking material in or out would be very difficult, so much so that a permit is required for traffic blockage in order to provide access for concrete trucks and pump truck.

2) The height to the ceiling is 13' from the existing floor.

3) I suspect that excessive noise and dust would not be acceptible.

4) The finished elevation of the new floor can be raised, but thresholds etc. would have to be blended to match.

My first thought is that it may be best to coat the existing floor with latex and pour over it. I am not a concrete contractor, but we are in the process of discussing this option with our concrete contractor. I am unsure of the structural integrity of the existing floor, or whether or not it would be a suitable substrate to pour over. Perhaps an engineers services might be required to ascertain this, or perhaps whatever settling is likely to occur has already done so.

We are considering breaking the concrete and processing within the building to create an aggregate that could be placed, and perhaps mixing with the aggregate that is beneath the existing concrete, in order to re-compact and pour on. I doubt that we could find a small enough concrete crusher to process within the building, and even if we did, the noise and dust issue may prohibit this. The dust could be mitigated with water perhaps, but the noise issue might be insurmountable.

The client specifically asked for a proposal that would not require hauling the existing concrete out.

I am very interested if any of you have experience dealing with this type of problem, and if so, would you be willing to share your insights?

Thank you, I appreciate your input and ideas.

 

[Scrub Puller]

Yair . . . Oxbow. This is way,way out of my area but when I was on a plantation in PNG a large peanut packing shed had the same problem . . . in this case it was a shoddy job originally, too thin and poor quality concrete set on inadequate foundations.

The old Pommy bloke who owned the place was a wheeler and dealer and "acquired" a heap of eight inch bore-pipe/casing. I made up a crude "pile-driver" run off the PTO and linkage of a Ford 5000 Ag tractor and we punched holes in the floor and belted them down in eight foot sections . . . I'd weld on sections as we went.

Some went down nearly sixteen feet mostly they were less. I think they were on about six foot centres. I cut them off to height and they filled them and poured a five inch slab across the top in sections. The tight old b*****d used an assortment of different steel reinforcement, rusty Marsden Matting, crane rope, you name it but it worked and, as far as I know, five years later it had never cracked or moved.

Cheers.

 

[Oxbow]

Thanks Scrub Puller, that approach may be more cost effective than dealing with trucking the old out! I suppose a structural engineers expertise may be warranted in this situation as liabilty would certainly be an issue. We could suggest that small holes are drilled in order to use a Nuc density tester in the worst spots to see if the substrate is now satisfactory. I will run this idea up the flag pole. I think if we can propose some possible solutions, along with the problems of using conventional methods, we may be able explore the costs associated with each idea and narrow it down.

We still do not have all the details, but rather were asked to provide some alternatives.

 

[Check Break]

You're going to need a lot more info. Have you determined the compressive strength of the existing floor. Do you know if it has sufficient reinforcement. As for the settling, it can be mud jacked. Hopefully the building didn't settle because something was buried underneath that rotted and settled. I remember a building addition that was built over an old landfill. The floor used to pop like a rifle shot and a whole pallet of drums would disappear from sight. If you have good subgrade that is now compacted over time you can mud jack the floor level. From there it depends upon what your customer needs. The cracks can be sealed and the floor ground smooth. I can't imagine demoing and replacing 1,600 yards of concrete unless the concrete won't make strength or is improperly reinforced.

 

[Oxbow]

As it stands now, we have suggested to the client that it will not be an inexpensive fix, and that we would need to look at it to move on with ideas. It is in a city about 600 miles away.

The building footings are evidently sound. Essentially we can put numbers to various scenarios, but a structural engineer will need to be hired unless we remove the existing concrete, repair the subgrade, and pour new concrete. I am not comfortable with the liability of guaranteeing any solution involving pouring over the existing, or raising and repairing the existing without an engineers approval.

Our suggestions are being floated up the chain of command and we are waiting to hear if they would like us to pursue this any further.