I recently bought a house that has a fairly large concrete patio, and I know next to nothing about maintaining it. It looks as if it had some kind of sealant that made it look wet (lacquer?) but about half of it has rubbed off. In some places it looks like it was put on with a roller but they didn't cover everything. The end result is the entire patio looks mottled, with some parts looking wet and fresh, and other parts looking looking dry, chalky, and worn (see pictures below.) Is the sealant something I can buy and put on by myself? If so, do I need to clean off the old sealant first? Are there preferred brands, or brands to stay away from? Also, there are quite a few small and hairline cracks running through it. I live in an area that gets below freezing quite often in the winter, so I'm assuming these should be sealed up to prevent further damage. Will any polyurethane type caulk work, or is there a specific product for this? Again, are there any brands that are known to be better or worse? For what it's worth, we plan on putting some patio furniture out here and a grill/smoker that should get quite a bit of use for three seasons out of the year. Here you can see the mottled surface colors Areas where the current sealant/lacquer ends One of the areas where it looks like it was rolled on, but for whatever reason they didn't finish or it's been rubbed off. One of the larger cracks.