wrote in message
...
I have a section of concrete floor (1-1/2" thick x 60 square feet)
that is fragmented and deflects slightly when I walk on it because the
5/8" plywood subfloor was inadequately fastened to the joists.
To stabilize the concrete, I'm thinking about applying a topping on
it, ideally no more than 3/8" but thicker if necessary.
Can anyone recommend a topping that's trowleable, thin,
crack-resistant/crack-proof and rigid enough to resist deflection from
foot traffic?
Thanks...

There is none. Can you support the weak section from underneath? Fasten
through the existing concrete?