Investigation of fresh and hardened properties of Calcium sulfoaluminate (CSA) cement blends

Calcium sulfoaluminate (CSA) is a comparatively new cementitious material that is mainly established in China where it is produced in a large scale. CSA cement is not covered by European standards. However, it provides different beneficial properties such as rapid hardening and high early strength development. Furthermore, the usage of CSA cement can save energy during production process in comparison to established cementitious materials. Therefore it is also more environmental friendly. Insufficient knowledge of this material behaviour restricts the possibilities and makes further research necessary. The research project applied a laboratory test program to elaborate the characterization of the materials. The obtained knowledge from these tests was then applied to further tests to determine application relevant key properties of CSA based pastes and mortars.The properties of pure CSA cement had been compared with the properties of CSA blends. The additions were PC, HAC, FA and GGBS with quantities of 10, 20 and 30%. The water to cement ratio was varying between 0.4, 0.5 and 0.6. General tests like fineness, XRD and XRF were used to define the present non-standardized material. Investigation of fresh pastes included measurement of setting time and calorimetry. Hardened mortar specimens of different ages were examined for compressive strength. The results showed that CSA itself hardens very rapidly and gives an early strength development. Possible ways of utilization of CSA based mortars and concretes were also emphasized in the paper.