AlfaBuild

RAR RUS 3001-3001 0000-0002-4515-6880 Liseitsev Yury Leonidovich yury.liseitsev@mail.ru Modified fiber-reinforced concrete for road and airfield pavements The article summarizes the author's research results over the past few years. The object of research is nanomodified fiber-reinforced concrete for road and airfield pavements. The work aims to develop a scientifically based technological solution that ensures the production of modified fiber-reinforced concrete for road and airfield construction and a comprehensive study of their operational characteristics. Method. The particle size distribution of the composite binder was studied using laser granulometry. The technological properties of the mixture were determined by examining the flow sediment. The average density was calculated by dividing the mass of the sample by its volume. Compressive strength was studied under static load on a press on samples with a rib of 70 mm at 3, 7, and 28 days of age. Results. A technological solution has been substantiated and experimentally confirmed to ensure the production of basalt fiber-reinforced concrete on a modified composite binder (MCB), which consists of creating an ultra-high-density package of hydrate formations at the nanolevel using new non-traditional raw materials (aluminosilicates obtained using the developed technology, as well as hydrothermal nanosilica). As a result, MCB, together with basalt microfiber selected following the law of similarity, ensures an increase in tensile strength during the bending of fiber-reinforced concrete four times and impact endurance up to 9 times. The ratio of tensile bending and compressive strengths of 0.25 confirms effective performance under dynamic and impact loads. This fact ensures the efficiency of structure formation in the early stages (tensile strength during bending in 1 day is 3.6 MPa). 10.57728/ALF.30.1 69 Concretes Composite Binder Superabsorbent Strength Polymer https://alfabuild.spbstu.ru/article/2024.30.1/ 3001.pdf

RAR RUS 3002-3002 57204505486 0000-0001-9132-7591 Moscow State University of Civil Engineering Ogidan Olamipe Timothy ogidano@gmail.com

26, Yaroslavskoye Shosse, Moscow, Russia

Linear programming for decision-making in construction management The object of research is to analyze the effectiveness of different linear programming (LP) methods in optimizing decision-making processes in construction project management. The aim of this research is to compare the effectiveness of different LP methods in optimizing construction quality control decisions, considering cost and duration constraints. Method. The study applies three LP methods: the Simplex Method, the Dual Simplex Method, and the Interior Point Method. Each method is applied to a case study scenario involving a development company facing a dilemma regarding the optimal method for conducting quality control during a construction project. The LP methods are used to evaluate the computational efficiency, accuracy, and practical implications of each approach. Results. Through the analysis of the case study scenario, it is observed that each LP method offers unique strengths and considerations. The Simplex Method demonstrates simplicity and relatively quick convergence, making it suitable for straightforward optimization problems. The Dual Simplex Method showcases robustness in handling complex scenarios, such as degeneracy and multiple optimal solutions. Meanwhile, the Interior Point Method proves highly efficient for large-scale problems with intricate variables and constraints, offering a precise and reliable solution. 10.57728/ALF.30.2 69 Linear programming Construction management Decision-making Technological processes Mathematical method Graphical method Simplex method https://alfabuild.spbstu.ru/article/2024.30.2/ 3002.pdf

RAR RUS 3003-3003 Gumenyuk Alexander Nikolaevich gumeniuk.an@gmail.com Polianskikh Irina Sergeevna irina_maeva@mail.ru Gordina Anastasia Fedorovna afspirit@rambler.ru Buryanov Aleksandr Fedorovich rga-service@mail.ru Impact of carbon fiber on electrical and thermal properties of fluoranhydrite based composites The object of research is the impact of carbon fiber on the electrical and thermophysical properties of a mineral matrix, as well as the possibility of the modifier being used as a micro-heating element. Method. Conventional test methods, combined with modern research methods, including differential thermal calorimetry, were used to study the development of mechanical, electrical, and thermophysical characteristics, as well as physicochemical properties of fluoranhydrite-based material. Results. The suggested approach to reduce the specific resistivity has proven to be effective. Mixes with low specific resistivity can be used to produce composites based on fluoranhydrite and carbon fiber. The analysis of thermophysical properties of large-size items based on the developed composition proved the possibility of using the items in resistive heating systems. 10.57728/ALF.30.3 69 Mechanical properties Binder Fluoroanhydrite Electrical conductivity By-product gypsum Resistive heating Carbon fiber https://alfabuild.spbstu.ru/article/2024.30.3/ 3003.pdf

RAR RUS 3004-3004 Nazinyan Levon Gaikovich nazinyan.lg@edu.spbstu.ru ABG-7557-2020 57218103892 0000-0001-5244-8024 Peter the Great St.Petersburg Polytechnic University Shevchenko Sergey Mikhailovich shef10b@yandex.ru

Saint-Petersburg, Russia

Roadblock made from plastic processing products The object of research is a polymer roadblock made from plastic processing products. The study is aimed at determining the optimal geometric and structural characteristics of the polymer block, which will provide the necessary strength when loaded by cars. Methods. Modeling of the main stresses of the block took place in the Simula Abacus software package. Results. Analysis of the distribution of compressive stresses in the initial cross-sectional area showed that peaks of compressive stresses are achieved in the internal corners of the block at the places where the load is applied. Stress concentration occurs when the cross section of the block changes abruptly. A smoother transition from one section to another made it possible to significantly reduce the resulting stress concentration. Rounding corners increases the material consumption of the block, which requires determining the optimal rounding radius. 10.57728/ALF.30.4 69 Plastic roads Simulation Abaqus Stress concentration analysis Stress distribution https://alfabuild.spbstu.ru/article/2024.30.4/ 3004.pdf

RAR RUS 3005-3005 Gutnikov Vladimir Anatolevich lomonosov25@rambler.ru Kavkazsky Vladimir Ivanovich кavkazskiy_vn@mail.ru E-6426-2019 56434340300 0000-0002-5694-1737 Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russian Federation Usanova Kseniia Yuryevna plml@mail.ru

St. Petersburg, Russian Federation

High performance polymer Zedex-100K based on polyethylene terephthalate: physical, mechanical and operational properties The object of research is a composite material, called ZEDEX-100K, based on polyethylene terephthalate with a complex of fillers made from mineral additives based on rare earth metals, when interacting with them in a special reactor, the structure of the polymer matrix and the physical and mechanical properties of the material change. The purpose of the work is to study the physical and mechanical characteristics of a composite material based on polyethylene terephthalate, used for the manufacture of wear-resistant sliding bearings, as well as to determine the performance characteristics of stern tube bushings made from this material. Method. The main physical and mechanical characteristics of the material under study were determined experimentally. Stern tube bushings made of ZEDEX-100K material passed a full-scale wear test. Results. The physical and mechanical characteristics of the ZEDEX-100K composite material were experimentally established: average density - 1327 kg/m3, water absorption by mass - 0.07%, Shore D hardness - 80 units, tensile strength and modulus of elasticity - 62 MPa and 2894 MPa , respectively, the tensile strength and modulus of elasticity in bending are 83 MPa and 2577 MPa, respectively, the compressive strength is 52 MPa, the compressive strength after exposure to diesel fuel for 30 days is 43 MPa and the compressive strength after exposure in sea water for 5 months - 31 MPa. The flexural strength is 34% and 60% higher than the tensile strength and compressive strength, respectively. The compressive strength decreased by 17% and 40% after exposure to diesel fuel for 30 days and exposure to seawater for 5 months, respectively. The maximum permissible wear of the 4.5 mm bow tube bushing and stern tube bushing installed on the Vagis tugboat will occur at 39000 hours of total operating time in the stern and 32500 hours in the bow of the vessel. 10.57728/ALF.30.5 69 Сomposite material Plastic Polymer Polyethylene terephthalate Strength Elastic modulus Water absorption https://alfabuild.spbstu.ru/article/2024.30.5/ 3005.pdf

RAR RUS 3006-3006 H-9967-2013 16412815600 0000-0002-8588-3871 Moscow Power Engineering Institute Kirsanov Mikhail Nikolaevich mpei2004@yandex.ru

Moscow, Russian Federation

Munitsyn Alexander Ivanovich munitsyn@rambler.ru Dependence of the fundamental vibration frequency of a semi-braced beam truss on the number of panels The object of research is a new scheme of a flat statically determinate regular beam truss with a semi-braced double lattice. An algorithm has been developed for deriving the analytical dependence of the first natural frequency of oscillations of a truss on its size, mass, and number of panels. The mass of the truss is concentrated in its nodes, the rods are elastic, and the nodes oscillate vertically. Method. To calculate the stiffness of the truss, the Maxwell-Mohr's formula is used. Generalization of solutions to the case of an arbitrary number of panels is performed by the induction method in the Maple computer mathematics systems. Results. The solution with coefficients of the type of polynomial in the number of panels is compared with the well-known Dunkerley solution and the numerical one obtained as the first frequency of the entire frequency spectrum. It is shown that the proposed method provides not only a more compact, but also a more accurate formula for calculating the frequency. As the number of panels increases, the accuracy of the analytical solution increases. 10.57728/ALF.30.6 69 Truss Natural oscillation frequency Induction Maple Semi-braced truss Dunkerley method https://alfabuild.spbstu.ru/article/2024.30.6/ 3006.pdf