there are a lot of different types of binders for construction purpose, a strong interest is focused on free-of-cement binders of new generation, which are characterized by unique and/or improved performance properties. Among them there is composite nanostructured gypsum binder (CNGB) as a quite new binding system. In the framework of this study the hypothesis of synergetic effect in hardened binding system was proposed and approved. The hypothesis is realized when interaction of two binding systems with different structure formation mechanism such as followings: polymerization-polycondensation and hydration. A number of experiments were carried out and the results were obtained, which demonstrate a resistance of CNGB under high-temperature effect (up to 1000ºC) vs. ordinary gypsum binder. It was determined that a heat-resistance of CNGB is associated with joint crystallization of sulphate-based component (gypsum binder) and highly-reactive silica-based component (in nanostructured binder). Normally, nanostructuted binder is stable under high-temperature exposure. The indicator of synergetic effect is formation of new crystalline phase – hydroxyellestadite Ca5(SiO4)3(SO4)3(OH)2. This phase has unit cell size which is stable under temperature gradient. This characteristic allows saving structure framework in CNGB under high temperature.
The subject of this study was an experimental confirmation of stability of composite nanostructured gypsum silicate binder (CNGSB) system under high-temperature exposure (up to 1000 °C). The hypothesis of the heat-resistance performance of gypsum-based binder was crystallization process in CNGSB system involving a silicate constituent as a reactive component in NB. XRD and DTA analyses demonstrated that thermal exposure of CNGSB to wide range of temperatures of 20–1000 °C leads to α-quartz to β-quartz phase transformation in the binder; amorphous alkali-aluminosilicate (gel) changes to crystal phase of Са-albite. The calculation of cell volumes characteristics for low-temperature (before thermal exposure) and high-temperature (after thermal exposure) phases was performed. The calculated ratios of unit cell volumes were close to 1 which ensures a structural stability of the GNB under thermal exposure and confirms its heat-resistant performance.
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