Every substance in concrete having average particle size less than 125 microns in known as “powder”.
If we examine finely grounded powder when it comes in contact with water, we will see flocculation of particles which means that in the presence of water some kind of charge get induced on various clinker phases. They get activated and start attracting. In order to break this flocculation and make paste more workable we can add more water.
How Superplasticizer Work ?
In case of cement powder, positive charge gets activated on aluminate phases while negative charge gets activated on silicate phases. SP (superplasticizer) are essential negatively charged particles, Therefore upon addition of superplasticizers, aluminate phases will get negatively charged and negative charge of silicate phase will increase even further. Now as both phases become negatively charged they will start repelling each other instead of attracting causing cement particles to uniformly distribute in the mix.
It can be therefore stated that presence of SPs not only increases the fluidity of the mix but it also makes it more durable as cement particles are now well dispersed.