How a concrete superplasticizer works
A superplasticizer is an admixture that improves the workability of cement without changing the water to cement ratio. This is a very important application of concrete admixtures, because it can result in easy placement, high strength concrete, and concrete mixes that contain less cement but are still strong enough to meet normal performance requirements.
Typical dosage is from 1 to 3 liters per cubic meter of concrete. This is a relatively low dosage, but it is sufficient for the majority of concrete applications and can be used with most commercial cements.
Dosage depends on many factors, such as the type of cement, the superplasticizer, the time of addition, water:cement ratio, nature of the aggregate and temperature. It can be added during batching, but more often it is added on site before casting.
Effect on Slump of Flowing Concrete
Superplasticizers increase the slump of flowing concrete but this will vary from concrete to concrete, depending on the type of superplasticizer, the dosage, time of addition, nature of the aggregate and other admixtures. It will also depend on the initial slump, temperature, humidity and other factors.
Durability of Flowing Concrete
The durability of concrete containing superplasticizers is very good. Studies indicate that despite the fact that the air-void spacing factor is higher, the concrete is as durable as concrete without the use of a superplasticizer.