UPSC Civil Service Exam Questions - Engineering

Q1:

The role of superplasticizer in a cement paste is to

A disperse the particles

B disperse the particles and to remove air bubbles

C disperse the particles, remove air bubbles and to retard setting

D retard setting

ANS:C - disperse the particles, remove air bubbles and to retard setting

Superplasticizer increases setting time through deflocculation by adsorption of negative charges on the cement particles so that they repel each other due to electrostatic force.

And it also increase workability of cement paste and remove air bubbles.