What Concrete Mix for Slabs?

38mm are too thin for anything but light traffic ...thats people ..not cars ..if you do make them then use chippings .not pebbles ..10mm max ..3-1 is a daft mix ...6-1 by weight is a good strong mix ..most concretes are 9-1 ...but to be honest you are better off buying new ...im a builder and can buy them for �1 each