Old bags I've had here (in qld) often become rock hard over a few months, due to the humidity, unable to be broken up with anything but a sledge hammer. I'd imagine pills would soak up heaps and become really hard in no time. Believe it or not, concrete and mortars are my passion. I spend at least a day or two every week using it and doing experiments. Besides an ongoing beautification project, I'm working on using a particular high volume waste product that's not normally able to be mixed with concrete.anyone who uses concrete knows that an old bag thats been sitting there for a while goes hard but bashing it and it becomes a normal powder again.