Admixtures are those ingredients/materials that are added to
cement, water, and aggregate mixture during mixing in order to
modify or improve the properties of concrete for a required
application.
Q.
What major changes can be expected in the behavior of concrete
in which admixtures have been used?
Broadly the following five changes can be expected:
(i)
Air entertainment
(ii)
Water reduction for better quality
(iii)
Acceleration of strength development
(iv)
Improving the workability
(v)
Water retention
Q. How can you ensure that the admixture will perform as
required?
The best way to test the admixture is by making trial mixes
with the concrete materials to be used on the job and carefully
observing and measuring the change in the properties. This way
the compatibility of the admixture and the materials to be used,
as well a the effects of the admixture on the properties of
fresh and hardened concrete can be observed. The amount of
admixture recommended by the manufacturer or the optimum
quantity determined by laboratory tests should be used.
