The influence of plasticizers on the properties of gypsum binders activated in vortex layer apparatus

Introduction. The article presents the results of a study to determine the influence of introduction method, type and concentration of plasticizing additives on the structure parameters and properties of gypsum stone obtained using gypsum cement treated in a vortex layer apparatus. Materials and methods. The G-5 BII gypsum cement was used for the investigation. The physicomechanical properties of the gypsum stone were determined in accordance with standard procedures, specific surface area was determined by air permeability, X-ray patterns were taken by means of the D2 Phaser diffractometer. Results. The data were obtained from 11 compositions of gypsum binder processed in the vortex layer apparatus and compared with a reference composition in the sense of the specific surface of the binder, mineralogical composition and physicomechanical characteristics of the gypsum stone. Conclusions. As a result of the investigation, it was revealed that the processing of the gypsum binder in the vortex layer apparatus leads to an increase in the specific surface up to 2 times. Modification of gypsum with MF superplasticizer significantly increases the ultimate compression strength (by 323 %) and bending strength (by 218 %) of the gypsum stone, as compared with the initial composition. Meanwhile the combined activation of gypsum with superplasticizers leads to a sharp decrease in strength and a significant slowdown in hydration. The greatest increase in the strength of the gypsum stone is observed when modifying activated gypsum. So, depending on the type of superplasticizer, the compression strength increases by 100 to 302 %, and bending strength by 86 to 218 %. Also this significantly reduces the gypsum stone overall porosity (down to 23 %) and softening coefficient (down to 51%).