Construction Materials

More than 180 specialists from 33 regions of the Russian Federation took part in the XV International Scientific and Practical Conference «Innovations for Industrial Housing Construction: InterConPan-2025». The event was organized by Central Research and Design Institute of Residential and Public Buildings “TSNIIEP Zhilishcha” JSC (Moscow) and the joint editorial board of the magazines «Construction Materials»® and «Housing Construction» (Moscow) with support of the Chamber of Commerce and Industry Committee of the Russian Federation on business in the field of construction. The event was supported by the Ministry of Construction of Nizhny Novgorod Region and Nizhny Novgorod State University of Architecture and Civil Engineering, as well as leading enterprises of industrial housing construction in Nizhny Novgorod.

Privolzhsky (Volga Region) Center for Construction Technologies (PC ST) is a leading developer and manufacturer of universal, standardized and power thermal test benches. For almost 25 years, Privolzhsky Center for Construction Technologies has been professionally implementing industrial modernization projects and creating new turnkey enterprises in the precast concrete construction industry. Depending on the tasks that face the company employees, solutions of various scales and stages of implementation are offered.

Comparative long-term tests of high-strength self-compacting concretes of classes B70, B80, and B100 with the organomineral modifier MB10-50C were conducted to evaluate the effect of relative air humidity (20, 60, 90%) on their deformation and strength properties. The studies were carried out in accordance with GOST 24452–2023 and GOST 24544–2020. It was found that a decrease in relative air humidity from 90% to 20% slows down but does not stop the hardening processes of high-strength concretes from 28 to 268 days. This is explained by the specific structure of the cement paste, which can more effectively accommodate changes in relative air humidity. At the same time, the increase in compressive strength and elastic modulus of concretes of classes B70–B100 decreases from 7–12% to 4–5%. The experimentally obtained creep coefficients of high-strength self-compacting concretes of classes B70–B100, which determine the value of the concrete deformation modulus under prolonged load, fall within a narrow range at the same air humidity (0.32–0.38 at 90%, 0.41–0.50 at 60%, and 0.61–0.71 at 20%). These values are significantly lower-by a factor of 2 or more than the standardized values according to Eurocode EN 12390 (ranging from 0.71 to 1.41) and the set of rules SP 63.13330.2018 (ranging from 1.0 to 2.0).

The article examines the relevance of the analysis of concrete strength gain and carbonation in the context of judicial construction and technical expertise, due to stricter control over the safety of construction facilities and the need to protect the interests of participants in litigation. The opposite processes are considered: cement hydration, which provides long-term strength gain, and carbonation, which reduces the alkalinity of concrete and provokes corrosion of reinforcement. Special attention is paid to modern technologies (nanomodified compounds, 3D printing, accelerated hardening), which radically change the properties of concrete, requiring new approaches to assessing its characteristics. The methods of strength forecasting, including the calculation of concrete maturity and the chemical kinetics (Arrhenius) equations, as well as their limitations within the framework of regulatory standards, are analyzed. The importance of an integrated approach to carbonation assessment is emphasized, combining laboratory, field and mathematical methods to improve the accuracy of the EC.

The article addresses the issue of reducing energy and binder costs in the production of FSF birch plywood for construction purposes. Reducing production costs while ensuring the necessary performance standards is a competitive advantage of the material. One way to address this issue is by reducing the temperature of hot pressing (around 100°C) and the amount of phenol-formaldehyde binder (less than 100 g/m²). The experiment was conducted according to a second-order B-plan, and regression models were developed to determine the mechanical properties of plywood based on the pressing temperature, resin consumption, and the addition of modifiers such as copper acetate, resorcin, and copper resorcinate with acetic acid. The need for modifying the phenol-formaldehyde binder during low-temperature pressing is due to the low degree of polycondensation of the binder and the significant decrease in the peel strength of the plywood. The rational values of the factors in the plywood production process were obtained by analyzing the graphical dependencies and regression mathematical models of the mechanical properties of the plywood. When making plywood with a pressing temperature of 105°C, a resin consumption of 93 g/m², and a copper acetate additive content of 1%, the material has a static bending strength of 133 MPa and a peel strength of 2.2 MPa. When using 1% resorcin as a modifier and similar production processes, the static bending strength is 142 MPa and the peel strength is 2.1 MPa. Both proposed modification options (with an additive of 1% of the liquid resin mass) are cost-effective. When implemented in production, the obtained results will reduce costs and ensure the production of construction-grade plywood with the required mechanical properties.

By example of crushed stone-mastic asphalt concrete mixtures, it was found how various technological modes and parameters affect their properties. A modified technological scheme for the hot crushed stone-mastic asphalt-concrete mixtures preparation is proposed. It is shown that temperature and the asphalt-concrete mixture feeding sequence optimization have a significant impact on the physico-mechanical and operational characteristics: average track depth decrease, maximum relative tensile strain and Marshall deformation increase, tensile strength during bending and the destructive load according to Marshall lincrease. According to the experimental data obtained, the optimal temperature for the modified technology is 165±1.5°C. The tests performed showed the mixture complete mixing time to homogeneity was reduced by 20% relative to the mixture standard method preparation. It was found that increase of the asphalt concrete physico-mechanical and operational characteristics using the proposed mixture preparation is a result of the bitumen binder better distribution due to the filler and binder actual contact area increase, which significantly improves the coarse mineral aggregate grains surface wetting with bitumen.

Models of transport and filtration of small particles in porous media are used in the construction industry when designing foundations and underground structures. A liquid with particles moves through the channels of a porous soil. When particles are transported, some of them are locked in the pores and form a sediment. If the fluid flows slowly, the sedimented particles, retained on the walls of wide pores or in the throats of narrow pores, remain motionless. The liquid and suspension cannot tear the sedimented particles away from the sedimentation sites. When the flow rate of the suspension or colloid increases, part of the sediment is washed out by the carrier fluid and is transferred through the pores. A one-dimensional model of particle transport in a homogeneous porous medium is considered, taking into account the sedimentation of suspended particles on the framework and the erosion of the sediment. The model specifies the relationship between suspended and sedimented particles and the balance of sedimentation and erosion of the sediment. At low suspension concentration, the intensity of sediment formation and rise depends on the filtration function and the concentration of suspended particles; sediment erosion is determined by the number of particles deposited on the framework of the porous medium. Analytical solutions to the model and asymptotics in the form of a traveling wave are obtained. The maximum concentration of sediment with simultaneous action of particle retention and lifting is found.