Basic Facts on Admixtures

M N Ramesh
M N Ramesh, Director, Talrak Construction Chemicals Pvt. Ltd., Bangalore
Chemical admixtures are the forth ingredient of the concrete which is inevitable for the modern concretes. The properties of the concrete can be modified either in the plastic or the hardened state as required. Chemical admixtures play a very important role in doing the same.

High Performance Concrete (HPC)
Concrete has renewed its definition from just being a mixture of cement, sand, and aggregate along with water. Advancement in Concrete Technology has revolutionized this "mixture" of above mentioned various conventional ingredients in the fulfillment of several desired properties.

Concrete nowadays has become much more worker-friendly, stronger & more durable than ever before with various other desirable properties. Concrete with such advanced diversified properties is referred to as HPC which signifies superior concrete performance during wet stage (mixing & placing process); with higher strength in hardened stage along with a greater durability in long-term with respect to Normal concrete.

Use of Admixtures
Admixtures refer to those materials in concrete, in addition to its basic constituents: Cement, Sand, Aggregate & Water; usually added during mixing process. Admixtures alter the concrete properties in various positive ways like:
  1. Increase in Workability
  2. Increase in Homogeneity & Cohesiveness
  3. Increase in Strength
  4. Increase in Durability
  5. Increase or Decrease in Setting Time
  6. Increase in Water proofing Property
  7. Increase in Corrosion Resistance of Steel
  8. Increase in Soundness
Admixtures are mainly of two types viz. mineral and chemical admixtures.

NBM&CW September 2016