Plasticizers or high range water reducers, or simply water reducers, as the name suggests, serve the basic purpose of reducing the water requirement of concrete. Thus, the purpose is to improve workability without compensation or even an increase of strength. The concrete strength is inversely proportional to the w/c (water-cement ratio). But a certain amount of water has to be provided to ensure the complete hydration of cement and proper workability of concrete. What plasticizers do, us that they reduce this certain required amount. Hence, strength increases. On the contrary, if you don’t reduce water, with the addition of plasticizers, you get bonus workability!
The uses are :
- Concreting in weather conditions when maintaining workability for a while is tough.
- High strength concreting.
- Reduction in cement content.
- Mass concreting (workability needs to be maintained for quite a while).
- Pumping concrete.
- Pozzolan concrete (substitution of cement with pozzolans calls for lower w/c to compensate the reduction in strength)
- Reduction of shrinkage in concrete (shrinkage directly depends on the water content).
- Pre-stressed concrete (shrinkage is significantly undesirable)
- Corrosion resistance.
- Permeability reduction.
- Durability enhancement.
- Pile foundation construction (concrete needs to be workable and strong to be poured into the bore)
- Underwater concreting (low w/c is desired underwater. Also, concrete is generally poured into the sea and not cast on the land and then installed)