Enhanced Eco-Friendly Concrete Nano-Change with Eggshell Powder

One of the unifying factors for all countries is the large consumption of chicken, and other, eggs in food and other types of economic activity. After using various types of eggs for their intended purpose, a large amount of waste accumulates in the form of eggshells. Currently, this problem exists and needs a non-trivial, original solution. The aim of the work was to fill the scientific gap in the direction of studying the microstructure formation of improved nano-modified environmentally-friendly concrete based on eggshell powder and obtaining a concrete composition for the manufacture of an industrial sample of such a material. An environmentally-friendly concrete was obtained, the characteristics of which were improved relative to standard concrete by modifying it with eggshell powder, for which the optimal dosage was determined. The most effective was the replacement of part of the cement with eggshell powder in the amount of 10%. The maximum increase in strength characteristics ranged from 8% to 11%. The modulus of elasticity increased by 4% compared to the control samples without eggshell powder. The maximum reduction in deformations under axial compression and tension in comparison with the control values ranged from 5% to 10%. The study of the composite’s microstructure nano-modified with eggshell powder, and an analysis of the changes occurring in this microstructure due to nano-modification, confirmed the improvement in characteristics and the optimal dosage of eggshell powder

Normal-Weight Concrete with Improved Stress–Strain Characteristics Reinforced with Dispersed Coconut Fibers

According to the sustainable development concept, it is necessary to solve the issue of replacing fiber from synthetic materials with natural, environmentally friendly, and cheap-to-manufacture renewable resources and agricultural waste. Concrete is the primary material for which fibers are intended. Therefore, the use of vegetable waste in concrete is an essential and urgent task. Coconut fiber has attracted attention in this matter, which is a by-product of the processing of coconuts and makes it relevant. This work aims to investigate the experimental base for the strength properties of dispersed fiber-reinforced concrete with coconut fibers, as well as the influence of the fiber percentage on the mechanical, physical, and deformation characteristics. The samples were made of concrete with a compressive strength at 28 days from 40 to 50 MPa. The main mechanical characteristics such as strength in compression (cubic and prismatic) and tension (axial and bending), as well as the material’s compressive and tensile strains, were investigated. The percentage of reinforcement with coconut fibers was taken in the range of 0% to 2.5% with an increment of 0.25 wt.%. Tests were carried out 28 days after the manufacture. The microstructure of the resulting compositions was investigating using the electron microscopy method. The most rational percentage of coconut fibers was obtained at 1.75%. The increase in mechanical indicators was 24% and 26% for compression and axial compression, respectively, and 42% and 43% for tensile bending and axial tension, respectively. The ultimate strains in compression were raised by 46% and in tension by 51%. The elastic modulus was increased by 16%

Increasing the Corrosion Resistance and Durability of Geopolymer Concrete Structures of Agricultural Buildings Operating in Specific Conditions of Aggressive Environments of Livestock Buildings

The problem of increasing the service life of buildings and structures for agricultural purposes operated in aggressive environments is relevant. The aim and scientific novelty of the work were to determine the relationship between the structure and properties of geopolymer concretes in aggressive environments. The properties of various concrete compositions under the influence of a solution of lactic, acetic, and oxalic acids were studied. With an exposure time of 90 days in an aggressive environment, samples of concrete based on a geopolymer binder had up to 6% less loss of strength and up to 10% less weight loss than concrete based on a cement binder. The effectiveness of the developed composition and technological solutions was confirmed, and it was quantitatively expressed in increased compressive strength and tensile strength in bending by 81.0% and 73.5%, respectively. It has been established that raising the heat treatment temperature to 80 °C leads to increased compressive strength for all compositions of geopolymer binders. The most favorable heat treatment conditions are created at 80 °C. The relations of the strength characteristics of geopolymer binders are revealed, which allow a detailed quantitative and qualitative assessment of the influence of the studied factors on the change in the system “composition—hardening conditions—properties” and can be used in the development of production compositions of binders and composites based on them, as well as their regulation—physical, mechanical, and operational characteristics

Improvement of Strength and Strain Characteristics of Lightweight Fiber Concrete by Electromagnetic Activation in a Vortex Layer Apparatus

The relevant problem of choosing effective materials for enclosing structures is compliance with the requirements of increased thermal resistance, reduced mass of buildings and structures, and reduced material consumption, labor intensity, and construction costs. These requirements are satisfied by structures made of lightweight fiber-reinforced concrete, which are the subject of attention of many scientists and engineers. One of the most rational requirements for industrial use is the activation of untreated components of the concrete mixture. This article is devoted to studying the influence of the activation of fiber-reinforced concrete elements in the vortex layer apparatus on concrete strength and structural characteristics. The effect of the raw component processing time of the concrete mixture on the strength and deformation characteristics of the lightweight fiber-reinforced concrete was studied. The optimal processing time for the cement–sand mortar in the VLA-75-85s was determined. It was shown that the activation of the vortex layer in the apparatus leads to an increase in strength from 27% to 61% and an improvement in the deformation characteristics of lightweight fiber-reinforced concrete by up to 12%. Furthermore, it was found that the use of activation in VLA leads to an increase in the coefficient of constructive quality for all experimentally determined strength characteristics of lightweight fiber-reinforced concrete by up to 27%

Special Issue “Reinforced Concrete: Materials, Physical Properties and Applications”

The Special Issue is devoted to reinforced concrete in terms of materials used, physical properties and application possibilities [...

Special Issue “Reinforced Concrete: Materials, Physical Properties and Applications”

The Special Issue is devoted to reinforced concrete in terms of materials used, physical properties and application possibilities [...

Special Issue “Reinforced Concrete: Materials, Physical Properties and Applications Volume II”

Concrete and reinforced concrete remain the most popular building materials for use in building structures in modern construction and production [...

Increasing the Corrosion Resistance and Durability of Geopolymer Concrete Structures of Agricultural Buildings Operating in Specific Conditions of Aggressive Environments of Livestock Buildings

The problem of increasing the service life of buildings and structures for agricultural purposes operated in aggressive environments is relevant. The aim and scientific novelty of the work were to determine the relationship between the structure and properties of geopolymer concretes in aggressive environments. The properties of various concrete compositions under the influence of a solution of lactic, acetic, and oxalic acids were studied. With an exposure time of 90 days in an aggressive environment, samples of concrete based on a geopolymer binder had up to 6% less loss of strength and up to 10% less weight loss than concrete based on a cement binder. The effectiveness of the developed composition and technological solutions was confirmed, and it was quantitatively expressed in increased compressive strength and tensile strength in bending by 81.0% and 73.5%, respectively. It has been established that raising the heat treatment temperature to 80 °C leads to increased compressive strength for all compositions of geopolymer binders. The most favorable heat treatment conditions are created at 80 °C. The relations of the strength characteristics of geopolymer binders are revealed, which allow a detailed quantitative and qualitative assessment of the influence of the studied factors on the change in the system “composition—hardening conditions—properties” and can be used in the development of production compositions of binders and composites based on them, as well as their regulation—physical, mechanical, and operational characteristics

Composition, Technological, and Microstructural Aspects of Concrete Modified with Finely Ground Mussel Shell Powder

Reducing the negative environmental impact of a widely spread building material such as concrete is possible by decreasing the amount of cement in this composite material, especially when specific waste is included as a substitution for the binder. Another important environmental issue is accumulated aquaculture waste. This work justifies the possibility of achieving modified concrete with improved properties based on sea mussel shell powder (MSP). An improved environmentally friendly concrete was obtained and modified with MSP as a result of experimental studies. The dosage of MSP in the amount of 6% instead of part of the cement turned out to be optimal and most effective. Because of the modification, it was possible to increase the strength properties: the increments were up to 12% for the compressive strength (CS), up to 13% for the axial CS, up to 14% for the tensile strength (TS) in bending, and up to 12% for the axial TS. The ultimate strains under axial compression and tension decreased to 9% and 12%, respectively, and the elastic modulus increased to 15%. SEM analysis showed a more integral microstructure without voids and cracks in this composite with a modifier content of 6% compared with the sample of the ordinary composition. Economic efficiency is expressed in reducing the total cost of new concrete compared to traditional ones by about 17% and the cost of building construction by up to 15% due to a decrease in the percentage of defects

Nanomodification of Lightweight Fiber Reinforced Concrete with Micro Silica and Its Influence on the Constructive Quality Coefficient

A hypothesis was put forward that a nano-modifying additive of micro silica, which had a beneficial effect on achieving a perfect structure of heavy concrete, can also be effectively used in lightweight fiber-reinforced concrete. The nano-modifying additives of micro silica application in manufacturing lightweight fiber reinforced concrete products and structures can significantly enchain their strength characteristics without increasing their mass and consequently improve their design characteristics. The purpose of the work was to increase the structural quality coefficients for all types of strengths of lightweight fiber-reinforced concrete due to its modification with micro silica. The effect of nano-modifying additives of micro silica on the strength characteristics of lightweight fiber reinforced concrete was studied. The optimal amount of micro silica addition was experimentally confirmed and established of 10% of the cement mass. The coefficients of constructive quality for all experimentally determined strength characteristics of lightweight fiber-reinforced concrete modified with micro silica additives were calculated. The coefficient of constructive quality for tensile strength in bending of lightweight fiber reinforced concrete with additives was two and a half times higher than that of heavy concrete without additives and up to 37% higher than that of lightweight fiber-reinforced concrete without additives