The experience of operating livestock farms shows that periodic reorganization does not prevent biological corrosion of building structures. In this work, the possibility of using glutaraldehyde as a fungicide for volumetric administration in the preparation of biostable concrete was investigated. The study aims to minimize the adverse effects of the components of commercial biocidal products on the physical and mechanical characteristics of products. For research, we used an aqueous solution of glutaraldehyde with an active substance concentration of 0.5 and 1 %, which was introduced into Portland cement CEM I 42.5 N as mixing water. The degree of influence of the active substance on the properties of cement paste and mortar was estimated according to data on heat release during hydration, strength, and phase composition. The fungicidal activity evaluation of glutaraldehyde in cement systems and the degree of their growth with the Aspergillus niger test culture were evaluated. It was established by isothermal calorimetry that, in mixtures with glutaraldehyde, a delay in the achievement of the main hydration peak is observed – by 30 minutes for 0.5 %, by 1 hour for 1 %. After 72 hours of hydration, a lower total amount of released heat of hydration is observed – for 0.5 and 1% solutions by 6.8 and 5.8 %, respectively. According to X-ray phase and differential thermal analyzes, the phase composition of the initial and aldehyde-modified cement stone on day 28 does not differ and consists of the following phases: ettringite, portlandite, calcite and clinker minerals. Varying the phase composition leads to a change in strength: when using a 0.5 % solution of aldehyde, the power of the cement-sand mortar increases by 6.5 %, and a 1 % solution decreases by 6.7 %. The use of a 0.5 % solution of glutaraldehyde provides a decrease in the intensity of fungal development and the formation of a fungistatic effect. Based on the results, a 0.5 % solution of glutaraldehyde can be recommended for the development of cement composites with prolonged bio-resistance.