Papers by Keyword: Strength

Abstract: The usage of laterite is highly in the demand in all aspect of project. Assessing the index properties of lateritic soil from quarries in Kuje Area Council of FCT which can be used for construction needs. The characteristics of the laterite such as In-situ quality of laterite, color, Physical appearance, structure, and strength were examined by assessment. Quarried lateritic gravel from different quarry depths was enumerated for some index characteristics. Mechanical assessment of laterite from the location was performed to determine the amounts of the various characteristics, textures, and structures that were analysed by taking samples. The general characteristic including mechanical properties of laterite were however seen to be dependent on the soil in-situ profile characteristics, color, and general properties. The characteristics of laterite discovered to different totally concerning the area and depth of the quarry. There was an inquisition to understand the connection in between physical characteristics, and the general strength of the laterite. The results of the analyses are Atterberg Limit with Liquid limit 58% & 68% Plastic limits with 32% & 46% and plasticity index with 26% & 22%, other test are sieve analysis, with AASHTO A-7-5(5) & A-7-5(2) and Compaction test with O.M.C of 20.4% & 24.6%, M.D.D with 1.630 & 1.560, Soil specific gravity test with average 2.71 while permeability test has average 2.71 permeability. It is discovered that the samples needed to be stabilize so as to have strength to withstand imposed pressure or load after stabilization.

Abstract: The greening of cement industry has become a necessity and obligation in many countries and the Global Green Cement market is projected to grow at a Compound Annual Growth Rate of 9.9% in the 2024-2032 period. The race for more sustainable concretes includes a number of key strategies, such as the substitution of cement/clinker with other cementitious materials. In the current research a CEMI (complying with EN197-1:2011) based industrial mix of self-compacting concrete (SCC) is modified with an experimental mix based on CEMII/B-M(P-W-L)42.5N conforming to EN 197-1:2011. The experimental mix presents a dual reduction in CO2 footprint, since not only it is formulated with CEMII, instead of CEMI, but it also contains 320 kg of CEMII/m³ instead of 420 kg of CEMII/m³, by substituting the remaining mass of binder with emery powder. nanoparticles of silicon dioxide (nanosilica) and 12 mm polypropylene fibres were also added. The 7-day compressive strength reached 45 MPa and the 28-day strength reached 51 MPa, marginally lower than that of the industrial mix (60.3 MPa). The performance of nanosilica is discussed. Selected fresh properties in terms of density, slump-flow, air entrainment and strength testing, coupled with surface morphology observations with the use of stereo microscopy shed light into the potentials of such sustainable SCC mixes.

Abstract: The demand for environmentally sustainable methods to enhance the performance of low-carbon steel (LCS) has led to increased interest in organic waste-derived carburizing agents. This study explores the potential of using a blend of Shea Nut Shell (SNS) and Eggshell (ES) ash, mixed in a 1:3 ratio, as an eco-friendly carburizing medium for improving the mechanical and corrosion-resistant properties of LCS. Carburization was carried out at 900°C for 30 minutes, and the effects were assessed through comprehensive characterization. Mechanical properties such as hardness, tensile strength, and impact energy were evaluated alongside microstructural analysis using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), and wear rate testing. Corrosion resistance was investigated in H₂SO₄ and NaCl environments over a 21-day period. Results show that carburized LCS achieved significantly higher hardness (514.55 HB) compared to the uncarburized counterpart (399.05 HB), with improved toughness as indicated by increased impact energy absorption. However, un-carburized LCS maintained higher tensile strength. Microstructural examination revealed enhanced carbon diffusion and pearlite formation, contributing to reduced wear in carburized samples. EDS confirmed increased surface carbon content, while corrosion behavior varied: carburized LCS performed better in saline (NaCl) conditions, whereas uncarburized LCS offered better resistance in acidic (H₂SO₄) environments. In conclusion, the SNS-ES ash mixture presents a promising route for sustainable carburization of LCS, particularly for components exposed to saline environments such as agricultural tools and automotive parts. Future work will focus on optimizing treatment durations, expanding corrosion testing in simulated service environments, and scaling the process for industrial applications.

Abstract: At temperatures of 290 K and 77 K, the phase composition and mechanical properties ofnonequiatomic medium-entropy (MEA) alloys Fe40Mn40Co10Cr10 and Fe50Mn30Co10Cr10 werecompared in the coarse-grained (CG) and nanostructured (NS) states, in which additionaldeformation mechanisms are activated under load: phase transformations in the MEAFe50Mn30Co10Cr10 (MEA TRIP) and twinning in the MEA Fe40Mn40Co10Cr10 alloy (MEA TWIP). Itis shown that in the NS state in both alloys, in contrast to the CG state, a complete phase transitionfrom the fcc to the hcp phase is observed, the content of which weakly depends on the temperatureand the number of torsion revolutions during high-pressure torsion (HPT). The transition from theCG to the NS state leads to an increase in the microhardness (in the NS MEA TWIP by 3.7 and inthe NS MEA TRIP by 2.25). In the CG state, a thermally activated character of plastic deformationis observed for both alloys in the temperature range of 290 – 77 K. In the NS state, MEA TWIPremains plastic under active compression deformation at 290 K and 77 K, whereas in NS MEATRIP under similar conditions, macroscopic plasticity is absent. Tensile deformation up to 50 % at30 K in the CG state for both alloys leads to a significant decrease in the absolute values of Young'smodulus over the entire temperature range.

Abstract: The article investigates the influence of ultraviolet (UV) on polyurethane foams' structural and mechanical characteristics. To assess the impact of changes and degradation of foam properties, studies were conducted for two groups of samples: those without exposure to UV and those exposed to natural UV for 3 months. According to the analysis of IR spectra, insignificant chemical changes in the structure of the outer surface of the samples were established as a result of three months of UV influence on the foam. No noticeable chemical changes were found in the inner part of such samples. Compression tests of samples of different groups were carried out under static loading to study the change in mechanical characteristics. Based on experimental tests, changes in the values of mechanical, strength, and deformation characteristics were investigated: Young's modulus, elastic strength, yield strength, and degree of deformation recovery. A conclusion was made about the resistance of polyurethane foam to ultraviolet influence for a period of up to three months.

Abstract: The use of light concretes on porous aggregates in various areas of construction has an interest in many countries. The volume of concrete produced can be increased and the cost can be reduced by using a multicomponent binder, which includes Portland cement, quicklime, fly ash and chemical additives. Comprehensive consideration of the physical and technical properties of light concretes on porous aggregates makes it possible to reasonably identify rational areas of its application in products and structures. The selection of compositions and the study of the properties of structural light concretes was carried out by calculation and experimental method. The data were processed using experimental and statistical modeling, which made it possible to assess the degree of influence of the selected factors to the strength and deformation properties of light concretes.

Abstract: The emission of greenhouse gases during its production, and the poor performance of cementbased concrete in marine environments has raised the need for alternative eco-friendly materials. This study investigated the strength and durability of Geopolymer concrete cured in marine water. The Slag/Metakaolin-based geopolymer concrete was used in this study. Two curing regimes were adopted; a sample was cured in marine water while the control was air-cured and designated as GPCW and GPCD respectively. Geopolymer beams, cubes, and cylinders were used for flexural, compressive, and tensile tests, respectively, at 7, 28, 90, 180, 270, and 365 days. Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) were used to determine the microstructural and elemental compositions. Results showed an increase in compressive, flexural and tensile strengths between 7 to 180 days, with a gradual decrease at 365th days for the GPCD samples. The GPCW showed a 43% reduction in strength between the 7th and 28th days, with a further decrease of 11% from 28 to 365 days. The average strength of both samples was above C40 grade concrete. SEM revealed differences in GPCD and GPCW with the latter displaying less dense structures with larger voids, consistent with the reduction in compressive strength over time. The EDS analysis showed that there was <1% ingress of Sulphate into GPCW on average, this revealed its resistance to the deterioration-causing agent in cement-based concrete. This study concluded that GPC can be used for coastal marine concrete structures.

Abstract: The construction industry is facing increasing pressure to adopt sustainable and eco-friendly practices in response to the growing concerns over environmental degradation and climate change. Among the various innovative materials being explored, geopolymer mud blocks have emerged as a promising alternative to traditional construction materials such as cement and fired clay bricks. These blocks are characterized by their eco-friendly composition, which typically involves the use of industrial by-products like fly ash, metakaolin, and other aluminosilicate materials, activated through an alkaline solution. This process results in a material that not only exhibits superior structural integrity but also significantly reduces the carbon footprint associated with construction.This paper provides a comprehensive review of the material composition of geopolymer mud blocks, detailing the various raw materials used and the chemical reactions that confer strength and durability to the blocks. The review also delves into the structural properties of these blocks, including their compressive strength, thermal insulation capabilities, and resistance to environmental factors such as moisture and temperature fluctuations. Additionally, the paper explores the ecological impacts of geopolymer mud blocks, emphasizing their potential to reduce greenhouse gas emissions, minimize resource depletion, and promote the use of industrial waste, thus contributing to a more circular economy.Finally, the paper looks forward to the future prospects of geopolymer technology in the construction industry, suggesting potential pathways for overcoming the current limitations and further enhancing the sustainability of construction practices. By providing a holistic view of geopolymer mud blocks, this review aims to contribute to the growing body of knowledge on sustainable construction materials and to support the transition towards greener building practices on a global scale.

Abstract: In this paper the utilization of cashew nutshell ash as a partial replacement of fine aggregate in concrete. The aim was experimentally analyze the strength and durability properties of concrete with the incorporation cashew nutshell ash and comparing it with conventional concrete mix. In this cashew nutshell ash us added to 0%, 5%, 10%, 15%, 20%, 25% and 30% in M₂₅ grade of concrete with water cement ratio 0.45. The fresh and harden concrete properties was tested for slump test, compaction factor test, while the harden concrete for compressive strength, split tensile, rapid chloride permeability test and water absorption ,coefficient of water absorption and sorptivity for various replacement levels at the age 28 days, 180 days and 365 days determined. The experimental test results show that optimum replacement level of 25 % with weight of fine aggregate. Further then increasing replacement level of fine aggregate strength will be decreased.

Abstract: The assessment of bridge structures is not only relevant, but also an integral part of effective infrastructure management aimed at ensuring safety, convenience and comfort for citizens. Many bridges have been destroyed due to imperfect design, the use of low-quality materials, and inappropriate construction methods. Consideration of natural and human factors in the design, construction and operation of bridge structures is key to ensuring their safety, durability and long-term performance. Any defects require careful monitoring, assessment and timely repair to ensure the safety and reliability of bridges. Various methods are used to inspect bridge structures. Inspection methods can be used individually or in combination to obtain comprehensive information on the condition of bridge structures and take the necessary measures for their maintenance and repair. In work to determine the stresses in a bridge, we use the finite element method (LIRA 9.4 R3). The inspection of the bridge's structures revealed a number of defects resulting from corrosion processes, operational factors and certain structural deficiencies. To ensure the durability of the bridge structures, it is necessary to reconstruct the bridge.