That leaves you in an interesting situation. You should really talk to Scotty as he deals with tinted acrylics and we do not. If you use a clear acrylic the patch is going to be very visible. No matter what acrylic you use, you want to use a patch that will take the sealer.
Photo is tough. However, it is typical to see this area pop. Either due to freezing during cure process, de-icer salts, too much water in concrete, etc....
Patch with a quality product and can be coated with our tinted HD6600MMA, several coats or can use clear.
No not a vaccumm. Exterior concrete should by with air. Basically the producer uses air entraining cement or other admixtures in the concrete to allow the formation of millions of tiny air pockets. These air pockets give the water someplace to expand during freezing conditions. Air entailed concrete should not be steel troweled. The troweling action closes off the pores and will like
Y cause spalling see my picture above.