Let me describe what I have then I can tell you what I want to do.
Our back door has a small concrete slab in front of it attached to the house. In front of that is a larger slab that isn't attached. There is (well, was) a small gap between the detached slab and the house. I recently filled that gap with concrete so now is it attached to the house as well as the other slab. Here's a photo http://www.vertigofx.com/public/phon...-12-02_831.jpg. After I filled the gap, I started to consider doing more.
I have a raised gravel area around our back door, mostly retained by old railroad ties I found. I call that our "patio". I want to make it concrete, but I can't afford to have it all done at once. I can get a few bags of concrete now and then, so I wondered if I could do it sections at a time. In the photo you can see a small square area at the end of the slab where I'm preparing to put the next section. To get that section done, I plan to only buy a couple bags of concrete (under 10 bucks) and nothing else. When I have some more money, I'll get a few more bags and add another section.
Here's the thing. I'm on an extremely low budget. I can't afford any expensive tools or materials. Fortunately my neighbor has a seemingly endless supply of tools (he's going to let me use a light-duty cement mixer), so that helps, but this still has to be a really low budget project.
I realize that getting freshly poured concrete to adhere to existing solid concrete is tricky business. Aside from perhaps detaching at the seam, are there other problems that I could run into?
I don't really care about it looking pretty. I just want to be... solid.
As I'm typing this, I'm getting ideas for myself. I've never priced rebar, but getting a few short lengths of it with my concrete from time to time shouldn't be too expensive. How about each time I poured a section, I could lay rebar in it that sticks out into the section I plan to do the next time. That way, each of the sections are attached by rebar. That may not keep it from cracking at the seams over time, but it would at least keep it level on the surface, right?
My neighbor suggested putting some kind of treated wood in between each section rather than actually trying to 'bond' the sections together. I guess the idea there is that it would seal up nicely. I know there are products and stuff used for this purpose, but remember, I'm on a super low budget, so I have to use stuff that I already have or can get for super cheap.