CIVL 1101 - Part 7 - Admixtures for Concrete- how to use concrete admixtures ,Part 7 - Admixtures for Concrete An admixture is "a material other than water, aggregate and hydraulic cement that is used as an ingredient of concrete or mortar and is added to the batch immediately before or during mixing."The Right Way to Use a Concrete Waterproofing Admixture ...The Right Way to Use a Concrete Waterproofing Admixture. If you’ve worked with concrete in the past, you know that this highly durable material can decrease in performance even …