Nº 6 (2025)

In civil buildings, double enclosing structures with layered elements are widely used as internal partitions. Partitions, having a small surface density, significantly reduce the load on the building’s supporting structures. Such structures are built in a short time and, consequently, construction costs are reduced. To comply with the regulatory requirements for sound insulation in partitions of this type, the number of layers of sheet sheeting is increased and the interior space is filled with sound-absorbing material. This significantly increases the thickness and surface density of the fence. The analysis of the currently proposed lightweight fences and the assessment of their acoustic efficiency show the possibility of improving their sound-insulating qualities by improving design solutions, and in particular, by using layered elements with vibration absorption in the structures of double fences. The acoustic efficiency of such structures increases due to internal losses in the layered elements. The paper presents the results of experimental studies of sound insulation of double fences made of layered elements with vibration absorption, made in large reverberation rooms of Vologda State University, and analyzes the influence of dynamic characteristics of vibration-absorbing materials on their sound insulation. It has been established that for the rational design of double soundproof structures made of layered elements, it is necessary to have a mechanism for regulating the characteristics of vibration-absorbing layers. This will make it possible to obtain effective soundproof structures and develop fences with specified parameters at the design stage.

The model of the enclosing structure, which is proposed to be used in non-stationary heat exchange between building premises and the external environment calculations is presented. The model is in representing of multilayer enclosing structure as single-layer with the same values of its heat transfer resistance and characteristic time of stationary heat transfer establishment. Various single-layer enclosing structures characteristic time calculations results are presented and basing on their statistical analysis, an analytical model for determining the volumetric heat capacity of the equivalent enclosing structure material with known enclosing thickness is proposed. The thermal conductivity coefficient of such an enclosing structure material is determined analytically from a given heat transfer resistance. Using the example of a massive wall insulated from the outside, it is shown that the proposed model of a single-layer structure gives a similar dynamics of the transition process as via calculating of the initial structure, with deviations much shorter than the characteristic time. Moreover, deviations occur only at the beginning of the transition process.

The results of the modern soundproofing materials used in floating floor structures dynamic characteristics experimental studies are presented. The work relevance is due to the need to update the soundproofing materials dynamic characteristics tabular values presented in SP 275.1325800.2016 “Enclosing structures of residential and public buildings. Sound insulation design rules”. The study examined the most common materials on the market: rock wool, polyethylene foam, needle-punched fiberglass mats and roll soundproofing materials. It is established that the maximum values of the elasticity dynamic modulus are demonstrated by rock wool materials, the minimum values are foamed polyethylene and fiberglass mats. The elasticity dynamic modulus dependences on thickness, density and load for different materials are revealed. For 30 mm thick rock wool under 10000 Pa load, the increase in density from 100 to 155 kg/m³ leads to an increase in modulus from 1.88 to 2.22 MPa. For needle-punched fiberglass mats with a load of 5000 Pa, an increase in thickness from 10 to 14 mm causes an increase in the modulus by 0.27 MPa. The study results allow to expand the possibilities of choosing soundproofing materials in the design and increase the impact noise reduced level index calculation accuracy.

Creation of safe thermal insulation materials and lightweight concrete involves the use of gypsum binder as a matrix of porous systems. The territories of the Russian Federation and Algeria (People’s Democratic Republic of Algeria) are rich in gypsum deposits, which makes it possible to use local raw material resources for the production of lightweight materials. The aim of the work was to develop the composition of porous gypsum material (modified foam gypsum) and study its properties. As a modifying component was used nanodiamond aqueous sol in the amount of 0.01–0.1 wt. %. The microstructure of samples of products made of foam gypsum mixture with and without the addition of nanodiamond aqueous sol was analyzed by scanning electron microscopy. As a result, the influence of gypsum binder crystals modified with nanodiamond additive on the performance properties of products was determined. The main characteristics of foamed gypsum mixture products were determined, including density, compressive strength, thermal conductivity, softening coefficient and sorption humidity. As a result, it was found that the nano-additive used in the form of nanodiamond aqueous sol modifies gypsum crystals, forming a denser pore wall structure of foamed gypsum products. This also forms a variotropic structure of the product, which is an important advantage for thermal insulation materials and lightweight concrete. The materials with sufficient strength, low thermal conductivity and sorption humidity are obtained.

The possibility of obtaining photocatalytic coatings by detonation spraying on a concrete substrate is considered. A study was conducted to select the optimal parameters for detonation spraying of titanium spherical powder on the surface of heavy concrete. The analysis of the results of experimental studies of a series of 25 concrete samples with coatings obtained at different spraying parameters was performed using X-ray phase analysis and evaluation of photocatalytic activity by the degree of degradation of methylene blue in the solution. The presence of four phases in the coatings was established: titanium, anatase, rutile and titanium monoxide. It was found that at spraying distances less than 100 mm and speeds less than 1000 mm/min, the process becomes unstable, causing destruction of the concrete surface layer due to dehydration of crystal hydrates. Increasing the spraying distance to more than 130 mm and speeds more than 1600 mm/min helps to reduce the content of anatase and rutile due to a decrease in the thermal effect of the detonation process. A correlation was found between the increase in the content of these phases and the enhancement of photocatalytic activity, which is consistent with the data on the effect of phase composition on the photocatalytic properties of materials. A rational spraying mode was established – the distance to the substrate is 120 mm, the spraying speed is 1500 mm/min.