Chemical, physical, fresh and mechanical properties of modified biocidal cements

Despite the large amount of research in cement materials, the research gap addresses many issues related to the development of biocidal binders. In particular, this applies to modified biocidal cements and composites based on them, which have increased biostability, environmental friendliness, improved physical and mechanical characteristics and low cost. The novelty lies in the development of production technology and optimization of the compositions of biocidal Portland cements with active mineral additives for the production of building composites with biocidal properties that have increased resistance in biological environments, as well as improved physical and mechanical properties. Compositions of biocidal cements have been developed, including in different proportions (wt%): clinker - 100, gypsum - 6, Na2SO4 - 3.5, NaF - 6, and fly ash - 20. Chemical, physical, fresh and mechanical properties of MBC were determined in accordance with current standards (X-ray diffraction (XRD) and thermogravimetric (TG) analyses, differential thermogravimetry (DTG), calorimetry, etc.). During the research, the features of phase transformations in cement paste were revealed depending on the type and content of biocidal preparations, active mineral additives and hydration time. Curves TG and DTG for hydrated biocidal cement with the addition of fly ash and sodium sulfate are identical to the curves of hydrated ordinary cement. According to the results of the study of normal density, setting time, compressive and flexural strength, regression equations were obtained, graphical dependencies were plotted, and optimal compositions of biocidal cements were determined. Compositions of biocidal cements have been obtained that are superior in physical and mechanical properties to ordinary Portland cements, which are recommended for the manufacture of biostable building products. © 2024 Institution of Structural Engineers