Papers by Keyword: Construction Materials

Abstract: With the acceleration of urbanization and the expansion of densely populated areas, the safety and durability of building structures in metropolitan areas have become increasingly significant issues. This trend has raised the requirements for building materials, particularly in the production of prefabricated building components, where the use of high-strength, high-toughness concrete has become the norm. Using high-toughness concrete reinforced with organic fibers can enhance the mechanical properties of concrete while ensuring good workability, and POM fibers are among the most widely used organic fibers. This study primarily investigates the mechanical properties of prefabricated hollow wall panels made from high-toughness concrete reinforced with POM (polyoxymethylene) fibers. The mechanical behavior of POM fiber-reinforced concrete was analyzed through laboratory tests, including assessments of compressive and tensile properties. The results indicate that the inclusion of POM fibers significantly improves the maximum elastic compressive strength and ultimate compressive strength of the concrete, as well as enhancing its tensile capabilities. Using the CDP model theory in finite element analysis, this study further calculated the structural response of high-toughness concrete prefabricated hollow wall panels under wind and seismic loads, demonstrating their practical feasibility in engineering applications. This research not only provides a scientific basis for the application of POM fiber-reinforced high-toughness concrete but also offers new directions for future research and application in building materials, particularly in urban constructions requiring high safety and durability.

Abstract: Carbon nanotubes (CNTs) have been studied as a reinforcement material for cementitious composites, with promising results. Incorporating CNTs into cement-based materials enhances the composites' mechanical, thermal, and electrical properties, as cementitious materials have limited applications due to their strain capacity and less tensile strength. CNTs have high tensile strength and modulus, along with excellent electrical conductivity. These features make them ideal for construction materials. Using CNTs in cement-based composites can improve the durability and sustainability of construction materials and provide new opportunities for advanced applications in the construction industry. The addition of CNTs to cement-based materials can improve mechanical performance, improve fire resistance and reduce carbon dioxide emissions. The incorporation of CNTs in cementitious composites is a promising area of research with significant potential for use in the construction industry. The current study's findings are expected to provide insight into the new material and its glamorous scopes for application as construction materials.

Abstract: Lime is used in a variety of industrial sectors (e.g. construction materials, iron and steel industry, flue gas cleaning, etc.) By the thermal decomposition of limestone (CaCO₃), known as calcination, two products are obtained: CO₂ and quicklime, i.e. calcium oxide (CaO). There is a growing interest in quantifying and improving the potential of CO₂ absorption of lime containing products during their operational life. The carbonation occurs during the lifetime of the lime application and it consists in the absorption of atmospheric CO₂ that closes the loop by forming calcium carbonate back. Thus, a portion of the CO₂ emitted during calcination is reabsorbed and stored in a permanent stable form. A literature review was carried out on the Carbonation Rate (CR) of lime used in three different construction materials: air-lime mortars, mixed air-lime mortars and hemplime. Out of 205 scientific publications reviewed, only 57 provide information about CR, specifically 21 for air-lime mortars, 27 for mixed air-lime mortars and 9 for hemplime. CR is 80-92% for pure air-lime mortars, 20-23% for mixed ones and 55% for hemplime. For all the materials, the CR trend over time was also assessed, according to the Fick’s law.

Abstract: Nowadays, FRCM (Fibre Reinforced Cementitious Matrix) systems are highly attractive for the building materials market; thus, their optimization and development cover an essential role. This work points out the chemical and physical parameters influencing the carbon-FRCM mechanical behaviour. Three different FRCMs composed of commercially available carbon fabric and different inorganic matrices are involved. Matrices are specifically developed to enhance the adhesion with the fabric and differ in organic additive used. Moreover, different fabric geometry (twisted and untwisted) and fibre coatings are considered: micro-silica, fine silica aggregate and medium-size silica aggregate. A new shear test setup is designed to obtain an inexpensive characterization method and employs traditional mechanical tests. Morphological and compositional analyses were performed on the surface fractures. On equal reinforcement typology, significant improvements in shear strength are promoted by organic additives and fabric coatings. Also, pull-out test displays that the twisted bundle promoted the fibre-to-matrix adhesion and remarkably modified the sample failure mechanism compared to the untwisted one. Finally, the FRCM mechanical performance is primarily influenced by mechanical adhesion contribution that might be increased by adopting simple geometrical choices or fabric surface treatments.

Abstract: In this paper, the thermal behavior of concrete blocks with different rubber ratios was examined experimentally. The rubber of 0%, 5%, 10%, 15%, and 20% used instead of fine aggregate in a concrete block raw materials. The size of the rubber granules used in this study is between 0-1 mm. The concrete approved mixing ratios are 1:2:1. The indoor solar simulator with 700 w/m² light intensity was applied on the external surface of each block and thermocouples were used to measure the temperature on the external and internal surfaces. The other block surfaces are insulated. The results indicated that the use of rubber aggregate with the concrete block reduced the inner surface temperature by increasing the thermal resistance of the heat flux. ​For 20% rubber added, produce 8.5% low-weighted construction materials and with high thermal resistance that works to save energy consumed in the building sector.

Abstract: The mechanorheological viscoelastic plastic model was used to study the effect of impact speed on the dynamics of mechanical interaction of a spherical body with the surface. An analysis of the impact process made it possible to draw some conclusions. The impact interaction time depends on the impact speed and mechanical properties of the material. The impact time decreases with an increase in the impact speed, a decrease in plasticity, and an increase in elasticity. With an increase in the impact speed, the impact time decreases. During the experiment, the initial impact speed increased 10 times. During the impact interaction, the body deformation increased 6-7 times. According to the calculations, the average body deformation speed also increased 10 times. As a result, the time for travelling a distance equal to the elastic and plastic deformation when loading bodies and the elastic deformation when unloading bodies decreased. The total deformation is composed of elastic and plastic components. With an increase in the impact speed, the plastic component increases, which decreases the unloading time due to a decrease in the elastic component. The impact time is an important characteristic of the dynamic process of interaction. Therefore, when identifying theoretical models to the real processes, these parameters should be congruent. To improve the modeling accuracy and reliability for various technological processes under dynamic loads, it is necessary to take into account various factors.

Abstract: The paper presents the results of analyzing the prospects of using clay raw materials in a composition with metallurgical slags for the production of ceramic products. The results of the analysis of the chemical and mineralogical properties of clay from the Khalilovsky deposit in the Orenburg region and nickel slags from the dumps of the South Ural Nickel Combine are presented. The studies were carried out using X-ray fluorescence and differential thermal analysis methods. The article presents the performed X-ray and derivatograms of slag and clay and the features of the experimental types of raw materials revealed during their analysis. The connection between the chemical and mineralogical compositions of the experimental clay and slags on the technological properties of finished ceramic products has been theoretically established. The use of XRF and DTA to study the characteristics of plastic and non-plastic raw materials made it possible at the first stages of the experiment to reject materials that were unsatisfactory in properties for the production of ceramic products, which contributes to the optimization of experiments, rational consumption of costs of newly mined clay raw materials.

Abstract: Restoration works for the cultural heritage in México have commonly used traditional materials, being the slake lime one of the main solutions employed. Nevertheless, other lime products have not been studied or applied in patrimonial works. The main objective of this research was to verify if high purity limes can be used as an alternative for restoration works, knowing that they have a higher powder surface area and consequently great efficiency. Compressive strength and ultrasonic pulse velocity tests, (UPV), were carried on specimens of slaked lime and high purity limes in pastes and mortars, to compare the values obtained and decide in which restoration works they could be employed. Results showed a better performance of the high purity lime in mortars and slightly better values of the slaked lime for pastes.

Abstract: This study was undertaken to investigate some specific problems that limit a safe design and construction of structures on problematic soils. An experimental study was carried out to examine the influence of loading rate and moisture content on shear strength of organic soil. Influece of moisture content on interface friction between organic soil and structural materials was also attempted. A commonly used soil in Iraq was prepared at varying moisture contents of 39%, 57% and 75%. The experimental results showed that the increase in water content will decrease the shear stress and the internal friction angle. An increase of the shearing rate was found to decrease the shear stress and internal friction angle for all percetanges of water contents. Further, direct shear tests were carried out to detect the interface shear stress behavior between organic soil and structural materials. The results revealed that the increase in water content was shown to have significant negetavie effects on the interface internal friction and angle shear strength.

Abstract: Limestone is one of the most ancient construction materials that exist, however it has become obsolete over the last decades, being replaced by industrial materials like cement. It must be considered that not only the construction lime can be used in works, but the limestone industry can provide other products like high purity lies The research about the surface area of high purity lime has verified that it exists an improvement in the adhesion and workability features of the material in comparison with construction lime, besides to be a more economical solution than masonry cement. It is proposed in this document the use of high purity lime in construction works to achieve the benefits previously mentioned. Various samples with different percentages of high purity limes were tested in the laboratory, analysing the surface area changes between them, considering its use for construction purposes and its performance.