During the past years, there has been an increase in the use of self compacting concrete (SCC) in many structural applications. This type of concrete does not require consolidation at the construction site and has better performance than conventional concrete. The rheological properties of this type of concrete depend on the interaction between cement and fly ash, slag, silica fume and other powders. This interaction is enhanced by using superplasticizers.

However, the problem with using a superplasticizer in SCC is that it destabilizes air entrainment system, which decreases the strength of concrete. Moreover, the mixing time increases due to the escape of air from the concrete slurry during high fluidity and segregation in the mixer. According to the research, SNF/SMF based super plasticizers destabilize the rheological properties of SCC, but MLS based superplasticizers do not destabilize them.

Another issue with SCC is the difficulty of determining the optimum dosage of superplasticizer to achieve good flowability and rheology. Some methods for SCC mix design use the determination of superplasticizer saturation dosage in mortar mixtures and then adjust it in concrete mix trials. This method has the advantage of being less expensive and material demanding than the one based solely on concrete batching.

In order to find the optimum dosage of superplasticizer, it is advisable to perform a Marsh Cone test. This test is performed by taking 2 kg of cement and adding 1-liter water to it. The slurry is then placed in a marsh cone and the time taken for the slurry to flow out is recorded. The superplasticizer dosage at which the marsh cone time is minimum is the optimum dosage for the chosen cement and w/c ratio.