I need to fasten a 2x4 to a slab. The slab is probably about 40 years old and sits in the open. I tried using cut nails but the concrete just crumbled. My battery powered drill isn't powerful enough to drill into the slab with a masonry bit. The slab is at least 200' from the nearest power outlet. So how can I fasten the 2x4? The slab is 8' wide and I just want a 2x4 across the width. This is for the end wall of a PVC pipe greenhouse. Can I glue it?