What are the advantages of Selecting Ready Mix Concrete?

Unless you know what you're doing, mixing your own concrete is riddled with risks (proportions, age of the portland cement, how clean is the stone, etc).  If you only need a few cubic feet, it's a simple process to add the required water and stir.

Most things made out of concrete can only be made by having a continuous supply of concrete sufficient to do the work. 

No back ache.   

i used to be a batcher ..thats the guy who adds the ingredients to make ready mixed ....the biggest advantage is correct mix ..every item is weighed ..most people are not aware what makes a good mix ..a standard mix for foundations is 9-1 ..that sound  weak ?  not really ..6-3-1 ...6 pebbles ..3 sharp sand ..1 cement ..as the sand and cement only coats the pebbles ..its actually a 3-1 mix ...a strong mix with fat for troweling concrete would be 6-1 ..4-2-1 ...when you add labour time for mixing it not that more expensive overall ...

Much easier. Just add water. 

It's easy that's it.

Buying sand, aggregate, and cement and mixing it yourself is much cheaper

It's alot less work mixing and probably cheaper overall.If you have a large project rent a mixer or just have it delivered.

Seeing as I see one of their plants at every rock quarry I go to I would assume it's very plentiful and easy to find