Concrete Floor Loading

I'm not exactly sure if you are asking about surface damage or structural, but I'll assume you mean surface.

Increasing the density of the concrete (see densicrete ) will certainly help, and there are also coatings ( see ) that will help a lot. I think that increasing the total density is better, since this also will improve the structural characteristics. In a perfect world you would do both.

Please note that I am not a structural engineer, and this is an opinion based on research and personal experience with concrete building materials while working with a qualified structural engineer to make sure I didn't kill myself.

Apologies in advance if I answered the wrong question.

Is this a slab on grade or a suspended slab? What is the 5500 kg load supported on? skids?, wheels? It's a little difficult to drag a 5500 kg (12K) 'box' across the floor.

I assume it's a slab on grade. If on grade, what is the sub-base like, how thick is the slab, any reinforcing, strength of concrete, age, and what is the overall construction of it?

If a suspended slab... need a lot more information, bay spacing, thickness, design loading, etc.