I installed 3/4" PVC in cement for load levellers. Mortar got into the PVC when they were building the structure. The Mortar hardened int the 90 degree fittings. How do I get it out? Is there some type of acid or something?

Muriatic acid will dissolve the calcium oxide and then flush with water. If you can get to it, carefully drill some holes in the concrete. If this is a lot of concrete, it will take time.