I have to replace a 45 degree bend in my concrete sewer line that was damaged by roots. Can I do this with ABS? I know I can make the connection to one (non flared end) with a rubber adapter boot, but how do I make the connection to the other side on the which is flared? Also I want to put in a clean out at ground level. What's the best way to do this with parts available at a home center... (It's the weekend, plumping supply houses are closed).

I know I can make the connection to one (non flared end) with a rubber adapter boot, but how do I make the connection to the other side on the which is flared?
OK! You're going to hafta be a little more descriptive. Your ABS 45 has a bell and a spicik . ( a flared and a straight end) What are the endings on the concrete pipe?

Also I want to put in a clean out at ground level. Connecting to what? The concrete pipe? Cast iron? Both? What?
You will need to cut in a combination wye and eight bend and bring it to grade with a clean out fitting.
Back to you, Tom

Fernco makes couplings that will connect ABS to other materials. Go to Fernco Couplings, Flexible Couplings, Flexible Pipe Connectors, Fernco Fitting, Shielded Couplings, Fernco Donut, Pro-Flex Coupling, Large Diameter Couplings, Sewer, Drain, Waste, Plumbing Flexible Couplings, Plumbing Pipe Leak Repair | Fernco (http://www.Fernco.com) and pick the size you need. I suggest that you use Shielded Coupling underground.