Admixture vs additive

• Admixture 

- SUbstqnces ( other than cement , water aggregates or rebar ) aded during or immediately before mixing to improve / alter the properties of concrete ( eg. accelerators ) 

Note : Doses are usually very small ( < 1 % ) 

   - Effect very sensitive tovariation in dose 

   - Side effect 

Additive 

 - Substance added by cement manufacturers to modify properties of cement ( eg. gypsum ) .