Heat damage to concrete and removal of reinforcement

[thedonblynd]

Hi, new here, I'd appreciate some help

My company has rented a bakery and we need to renovate it and open it under a new brandname. The previous owner installed an oven weighing in at 5 tonnes over a footprint of 3*4=12m^2. This was sitting on the edge of a reinforced concrete slab about 5.5*4.5m^2.We now to remove this oven.

The oven reached working temperatures of approximately 300 degrees Celsius. I am not aware the heat transfer index to the composite marble floor, through mortar down to the concrete slab, nor the daily operating time of the oven. I plan to have the flooring removed at that area to check for significant visible surface cracks, spalling and reinforcement degradation due to the heat. Should I perform any additional testing to check the quality of the concrete and reinforcement in depth? What would such test be? I am aware of the schmitt hammer but that only measures surface strength, and ultrasound testing, but it is near impossible to set up the apparatus correctly. Any thoughts?

Now comes the fun stuff. The owner propped the slab with an Ibeam frame in the basement at the middle to cope with the additional oven load (by guesswork), and ideally we want to remove this slab for space utilization. I need to be certain of the structural integrity of the slab before I sign off on this removal. There won't be any significant loads where the oven used to be, so I am only worried about strength degradation due to heat and excessive loading, as well as unforseen problems with removing the frame prop.

Any takers, guys? Thanks in advance

 

[Ron]

I would do a visual check on the concrete after the topping removal. Take several cores of the concrete and have petrographic examination done on the cores to check for carbonation and microcracking.

The temperatures you've noted are not excessive for concrete, even for long exposures.

 

[dik]

or for the rebar...

Dik

 

[dcarr82775]

May sound simple, but I often beat on the concrete with a 5lb hammer (a nice ring is a good thing for concrete). I also look for a pink color in the concrete which indicates it has gotten too hot in the past.

Look for cracks in the top and bottom of the slab in the area of the oven. Larger cracks that follow a yield line type of pattern over the steel beams would indicate the slab has seen higher loads, small cracks would tend to point to lower stresses.

 

[thedonblynd]

Sorry, I meant to say I need to have the I-beam frame removed, not the slab!

I inspected the bottom of the slab, it's deformed, and there's a part where the concrete cover (it's quite thick, for some reason) is sticking out like a huge peel...weird. At least there's no visible reinforcement. Can't wait to see what the compression side of the concrete looks like after I have the flooring removed.

 

[pwht1]

Could you post a photo?