Résumé
This work aims to develop new formulations based on OPC/CSA/Anhydrite blends, incorporating at least two admixtures: a retarder (citric acid) and a superplasticizer (PCE) for applications such as self-leveling screeds. These two additions are necessary in order to control rheological property and setting time; for the targeted application, a workability of 3 hours to facilitate on-site use is recommended. The aim of this work is to investigate the competitive interactions between the retarder and the superplasticizer through their effects on hydration (isothermal calorimetry, in-situ XRD) and rheology. Vicat setting time measurements were used to determine the optimal citric acid content. The results show that the PC–CSA–C$ system without admixtures sets very rapidly and is unsuitable for practical applications. PCE alone improves initial fluidity but does not maintain workability over time. Citric acid strongly delays hydration by chelating calcium ions. The combination of PCE and citric acid stabilizes paste rheology, with initial competition slightly reducing fluidity but maintaining PCE efficiency over several hours.