Real rookie question this, Building 101 stuff. I bought a few bags of Mastercrete last summer (2020) to lay some limestone slabs in a section at the back of my garden. Not really load bearing or anything, mainly cosmetic. Anyway, I know cement has a fairly short shelf life, but the bags have been kept under cover and are visually still like new. What could I expect if I attempt to use them? Will they not mix well, not cure well, produce weaker cement? Just wondering if it's possible to get away with using them or if I need fresh bags? Thanks