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Rennes, France

Aranda B.,CNRS Chemistry Institute of Rennes | Aranda B.,I KR SAS | Guillou O.,CNRS Chemistry Institute of Rennes | Lanos C.,CNRS Civil and Mechanical Engineering Laboratory | And 5 more authors.
Construction and Building Materials

An innovative industrial process based on heating the gypsum at high temperature during few seconds leads to the production of a reactive binder characterized by a multiphasic structure of the plaster grains. Such structure induces changes on plaster hydration kinetic and final gypsum product performances. Therefore, the setting and mechanical properties of this material have been compared to those of a classical β-plaster. Both binders have been synthesized with the same quantity of water and the same quantity of setting agents. The same rheology of mixes is obtained by adjusting the amount of superplasticizer. Reactivity of the two plasters has been evaluated by XRD and thermal analyses during setting and hardening. After molding prismatic specimens, weight and hardness have been measured and flexural and compressive strengths are measured at different dates. Results show that the new binder leads to improved mechanical strengths. © 2015 Elsevier Ltd. Source

Berenger A.,European University of Brittany | Berenger A.,CNRS Chemistry Institute of Rennes | Berenger A.,I KR SAS | Olivier G.,European University of Brittany | And 14 more authors.
Materials and Structures/Materiaux et Constructions

Flash-calcination of gypsum by a new patented process produces a particular type of plaster. This particular plaster has been characterized and compared to a classical β-plaster. It appears as a stable mixture of hemihydrate and of γ-anhydrite. Because of its composition, this new plaster presents several stable states depending on the storage conditions. A study of its reactivity followed by XRD and thermal analyses has been realized. It reveals that even after several months of exposition under moist atmosphere, γ-anhydrite is still present in the sample. A model of composite particle of plaster is proposed for explaining this unusual behavior. © 2014, RILEM. Source

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