It might make you feel better, at least for a wile. Problem is, (if I visualize your plight correctly) there's a gap between the addition and the older concrete, right? It might be small, but water gets into this gap and in the winter it freezes and expands... who would ever think frozen water could exert that much pressure? This continues on each winter until, voila, complete destruction.
Actually you'd be better off to fill the gap with an all-weather latex sealant or caulking designed for the purpose. These come in cement colors so it shouldn't be all that obvious. It would keep the joint sealed for at least a while... maybe a few years. Eventually, it will need to be torn out and redone with pletny of rebar reinforcement to help it withstand any movement...
Best of luck!