ASSESSMENT OF THE EFFECT OF THE USE OF LIME AS AN ADDITIVE ON THE STRENGTH CHARACTERISTICS OF WOOD-GYPSUM MATERIAL THROUGH THE PRISM OF AN ANALYSIS OF CHANGES IN ITS STRUCTURE

The study focuses on improving the strength characteristics of wood-gypsum composite material by adding lime as a modifying additive. Data on determining strength parameters, such as compressive strength and tensile strength in transverse bending, were obtained in accordance with GOST 23789-2018 "Gypsum Binders. Test Methods" for six beam samples measuring 4×4×16 cm made from wood-gypsum material and wood-gypsum material with lime as a modifying additive. The analysis of the results determined the optimal amount of lime to be added. It was found that the maximum tensile strength in bending is 1.93 MPa, corresponding to a lime content of 17.5%. Additionally, the main reactions occurring during the setting of the gypsum binder with lime in an aqueous medium, leading to structural changes in the material, were identified. To assess structural changes, an analysis was performed using mercury porosimetry, based on measuring the pressure required to force non-wetting mercury liquid into the sample's pores. Key data on pore diameters and their quantitative distribution in the material structure were obtained. The main porosity values of the material were also presented and analyzed. The study concludes the impact of lime as a modifying additive on the strength characteristics and structural changes of wood-gypsum composite material. The findings define the application scope for products made from wood-gypsum composite material with lime as a modifying additive.