j-how

New Concrete on Old concrete

I'm pouring new concrete over old. It's a small slab. 4' x 5' x 4". I was planning on mixing liquid bonding adhesive into the concrete to help the new and old stick together. Do I need to use the adhesive in all 10-11 bags or can I use it in the first 3-4 that will be in contact with the old concrete? Thanks.

stadry

for best results on a bonded overlay, you 1st need to prep the old conc,,, acid etch & neutralize OR diamond grind,,, prewet the old, apply bond enhancer, & place new conc,,, not a bad idea to insert some topcons into the existing to promote stability