Analysis of structure-forming role of phosphogypsum in the production of nonfired cementless building composites

The working hypothesis is the development of the theory of disperse system aggregative stability considering the condensation processes of structure-forming of nonfired cementless building materials on the basis of phosphogypsum. The results of phisicomechanical and physicochemical analyses of Uvarovo chemical plant phosphogypsum are presented. To define the properties of phosphogypsum and phosphogypsum-based composite modern methods of analysis were applied with the use of the following equipment: the universal electromechanical test system Instron, the automatic diffractometer PANalytical EMPYREAN, the device for synchronic thermal analysis. The results of the research showed that the first endoeffects of Uvarovo chemical plant phosphogypsum have the dehydration energy of more than 200 joule/g, and they do not get lost within the time; this proves of the cementing properties of phosphogypsum. Due to the analysis of the differential scanning calorimetry results of phosphogypsum, pressed at 5 Mpa, it was found out that at the models compression the dehydration energy increases, and the correlation between the changes of water films’ thickness and dehydration energy can be observed. With the decrease of water films’ thickness we can observe the increase of dehydration energy with the simultaneous increase of the structure density and its transformation into a monolithic structure