WTH is this stuff.....

[ADAduckhuntr]

Easy fix.
You need to pressure wash and apply a concrete "densifyer".

W. R. Meadows MED-CURE Concrete Curing Agent, Hardener and Dustproofer, 5 Gal. Pail - White Cap

 

[RSB]

Scrape it up then get some charcoal and make your own black powder. BOOM!!