New concrete patio over existing concrete patio

My patio is lower than my yard which results in flooding. Two contractors have said they could raise my patio about 5" (1 inch of sand over the old, then 4" of new concrete). One said they would cut out the edges about 4-6", lay 1" of sand, pour the new concrete over some wire.  The edges that were cut out would be filled in completely to keep the sand in, etc. have you ever heard of this? Is it feasable and will it work? It sounds legitimate since two contractors both said the same thing. I am getting ready to spend a lot of money so I just want to make sure the patio will last. I also haven't been able to find anything on-line to suggest this particular procedure. Any help would be greatly appreciate. Thanks!