We all know the general constituents of concrete. Other than aggregate, water and important cement, some materials, called admixtures are added during or before mixing of concrete to change its properties like setting time, workability, water proofing and many other properties. In this post we will discuss retarding admixtures. From the name we can easily realize that it retards concrete to set early.
It is interesting to know that some retarders in most cases reduce the water requirements of concrete mix. So the retarders are frequently termed as water reducing retarder. According to ASTM C494 retarders are type B chemical admixture but they also found in type D which deals both with water reducing and retarding chemical admixture.
a. Better workability
b. Higher strength
c. Better durability
As an example, Lignosulfonate retarder has influence in the early development of strength with its main purpose of retarding. The cement slurry containing lignosulfonate retarder is successfully used in oil industry with the above extra advantages.