An experimental evaluation of the compatibility of NSF and PCE superplasticizers with different cement types

This paper deals with variability in the performances of seven different superplasticizers chosen among those of most common use belonging to the naphthalene (NSF) and polycarboxylate-based (PCE) families. In particular, compatibility of two naphthalene-based and five polycarboxylate-based admixtures with six different cements available on the Italian market was evaluated by measuring water reduction to manufacture mortars with the same workability at the end of mixing. Two different lots of the same cement (same plant) were used: lot 1 and 2 produced, respectively, on September 2005 and March 2006. Flow retention up to sixty minutes and tendency to entrap air in the mortars were measured. Results confirmed that the average water reduction and flow retention properties are better for PCE compared to NSF superplasticizers. However, experimental data confirm as performances of PCE admixtures are more strongly dependent on the cement type than those of NSF polymers. No differences were detected in terms of the air entrapped between the two superplasticizer families, except for the ACR5 superplasticizer.