Compatibility of Sulphate Resisting Cement with Super and Hyper-Plasticizer

Use of superplasticing chemical admixtures in concrete production is widespread all over the world and has become almost inevitable. Super-plasticizers (SPA), extend the setting time of concrete by adsorbing onto cement particles and provide concrete to preserve its fresh state workability properties. Hyper-plasticizers (HPA), as a special type of superplasticizer, provide the production of qualified concretes by increasing the workability properties of concrete, effectively. However, compatibility of cement with super and hyper-plasticizers is quite important for achieving efficient workability in order to produce qualified concretes. In 2011, the EN 197-1 standard is edited and cement classifications were updated. In this study, the compatibility of hyperplasticizer and CEM I SR0 type sulphate resisting cement (SRC) that firstly classified in EN 197-1 is investigated. Within the scope of the experimental studies, a reference cement mortar was designed with a water/cement ratio of 0.50 confirming to EN 196-1. Spread diameters (at 0, 60, 120 min after mix preparation) and setting time of reference mortar were determined with flow table and Vicat tests, respectively. Three mortars were re-prepared with using both super and hyper-plasticizer confirming to ASTM C494 by 0.25, 0.50 and 0.75% of cement weight. Spread diameters and setting times of super and hyper plasticizer added mortars were determined. The flow table and Vicat tests were repeated to these mortars and results were compared. In conclusion, Both SPA and HPA increased the workability of mortar initially and workability maintained after 60 min of mixing. To achieve a longer workability, higher dosages of SPA is needed (0.75%). In terms of HPA, much longer workability can be obtained even at the lowest admixture dosages.