Effect of superplasticizers on the hydration kinetic and mechanical properties of Portland cement pastes

Hydration of ordinary Portland cement in the presence of two different types of superplasticizers namely sodium lignosulfonate (LS) and naphthalene sulfonate-formaldehyde condensate (NSF) was studied using different experimental techniques. Superplasticized ordinary Portland cement pastes were prepared using the values of standard water of consistency with different additions of each type of superplasticizers used. Pastes were hydrated for different time intervals under normal curing conditions. The results reveal that both superplasticizers increase the workability and reduce the standard water of consistency. This results in an improvement in the mechanical properties of superplasticized cement pastes at all ages of the hydration–hardening process. Naphthalene sulfonate-formaldehyde condensate was found to have the higher efficiency in improving the mechanical properties of the hardened pastes than that of sodium lignosulfonate superplasticizer.