Grades of Concrete

See there is no fixed mix ratio. It depends on property of materials used in the mix. we have to perform a mix design based on standard procedures like ACI method, DoE method, BIS method and so on.

there is a process called sieving of sand. if the proportion of mixture is passed through the 4.75mm i.s. seive,the proportion passed out can be termed as sand the proportion that is retained on the sieve can be termed as gravel. this is valid if the proportion is the mixture of only sand and gravel.