To answer your question, yes, playing on direct concrete is quite severe on your knees, and lesser known but actually worse, is the impact it has on your lower back. In your case it sounds like a good pair of shoes is the best solution. It also depends how often you train/play, but if you p[lay regularly, to avoid heel pain, invest in a pair of gel heels. As I train most days, I have these and have found it extremely beneficial in reducing heel and back pain.
The other most key thing, is lunging in a straight line as mentioned by @james. It is important to have an upright back and what on your quadriceps, rather than your back - should avoid falling forward when lunging to the net. This also significantly speeds up your recovery. Hope this helps and keep enjoying your badminton!