Papers by Keyword: Strength

Abstract: Steel has been one of the most widely used materials in land and sea construction due to its advantageous properties, especially carbon steel. This study focuses on molecular dynamics simulation to demonstrate carbon steel’s mechanical behavior. A uniaxial tensile test was conducted for body-centered cubic (bcc) structured carbon steel and pure iron to learn the effect of carbon presence. Both simulation cells were simulated under temperature variation to reveal its effects. It was found that carbon steel is stronger than pure iron based on their value on yield and tensile strength, namely up to 2.434 GPa and 1.368 GPa respectively, which are stronger at room temperature. This study also revealed that carbon steel exhibits better elastic properties with a Young’s modulus of 285.749 GPa, compared to that of pure iron 230.117 GPa. Additionally, this molecular dynamic study also identified another phenomenon, such as brittle-to-ductile temperature of carbon steel at 340 K. Structural explanation is provided in the form of bcc structure fraction during the strain progression and under temperature variation. These findings provide a comprehensive molecular perspective to unveil mechanical properties of carbon steel.

Abstract: Temperature and steel fiber content have a great influence on the mechanical behavior of concrete, so it is urgent to study the mechanical properties of concrete at different temperatures and steel fiber content. The effects of temperature and steel fiber content on the mechanical properties of concrete are studied in this paper. Based on the uniaxial compression testing machine, the uniaxial compression tests of concrete under different temperatures (150°C, 300°C, 450°C) and different steel fiber content (0%, 1%, 2%, 3%) are carried out. With the increase of temperature, the compressive strength of concrete first increases and then decreases, which indicates that there is a critical temperature for the influence of temperature on the compressive strength of concrete. In addition, the addition of steel fiber content significantly improves the compressive strength of concrete. In addition, temperature and steel fiber content significantly affect the peak strain of concrete. Based on the SEM test results, the temperature effect of concrete was investigated from the microscopic perspective.

Abstract: Improper solid waste management in Lima, particularly glass, leads to severe environmental, social, and public health problems. The low recycling rate and waste accumulation contaminate soils and groundwater, impacting long-term quality of life. This research aims to evaluate the inclusion of residual glass powder (RGP) in concrete to enhance the sustainability of concrete design, focusing on San Juan de Lurigancho, where the highest amount of waste per person in Lima is generated. The proposed solution involves developing a waterproof concrete design by incorporating residual glass powder (RGP). This approach includes replacing 5%, 10%, and 15% of the cement in the mix to achieve a strength of 280 kg/cm², thereby reducing pollution from glass waste and CO₂ emissions. Fresh concrete properties were evaluated and found to improve flow and temperature. The slump of fresh concrete increased gradually with the percentage of residual glass powder (RGP), reaching up to 16.5%. Regarding the properties in the hardened state, in terms of strength, replacing 15% of the cement with RGP resulted in a 2.57% increase in compressive strength. The tensile strength at 28 days increased by 21.53% and 16.8% when replacing 10% and 15% of the cement, respectively. However, replacing 15% of the cement resulted in a 0.4% decrease in flexural strength, while a 10% replacement resulted in a 1.44% increase. On the other hand, replacing cement with 15% RGP reduced CO₂ emissions to 53.79 kg/m³. Additionally, a higher percentage of RGP in the concrete allows for cost savings of up to 12.2%, demonstrating a progressive reduction. From the analyses, it was found that the mix including 10% RGP stands out as the optimal option. It shows significant improvements in strength and profitability, reducing production costs by 3.4% and CO₂ emissions by 10.83%. This design achieves an ideal balance between performance, cost, and environmental sustainability.

Abstract: The aim of this study is to investigate the influence of temperature on the shear strength and elastic stiffness of sand under triaxial compression (TC) test. Air-dried Ottawa sand specimens were prepared to avoid pore pressure induced during shearing. Ottawa sand, widely used in geotechnical engineering research, was selected for these TC tests. The sample was first drained and then heated to different target temperatures (i.e., 30, 45 and 60°C), which were maintained constant during the tests. After heating, the sample was sheared under a constant cell pressure and temperature. Small strain-amplitude cyclic loading was applied successively at different shear stress levels to investigate the elastic Young’s modulus (E_eq) behaviour. The results revealed that the peak shear strength increased with increasing temperature. For E_eq values, a clear relationship with temperature was observed, indicating that elastic stiffness of Ottawa sand also increased with temperature. These findings are significant as they demonstrate that temperature variations can markedly affect the mechanical behaviour of sand, which is important for understanding and predicting the performance of geotechnical structures subjected to thermal effects. Moreover, a sudden drop of stress can be observed as a phenomenon commonly observed in round particle shapes.

Abstract: Doping high-zinc aluminium alloys with Ti builds in-situ composites reinforced with ternary aluminides Ti (Al,Zn)₃ with a significantly grain-refined matrix. In a series of studies, Ti was introduced with Al-6 wt% Ti (AlTi6) and Zn-4 wt% Ti (ZnTi4) master alloys in amount to contribute about 3 wt% Ti in the examined alloys. The alloy microstructure has been studied using light microscopy, SEM / EDS and XRD measurements. The observed significant refinement of the alloys matrix should lead to improvement in ductility, while the in-situ reinforcement should improve tensile strength and wear properties.

Abstract: In the study, pozzolanic materials serve as replacements for additives, namely Palm Shell Ash (PSA), Coal Fly Ash (CFA), and Rice Husk Ash (RHA). The purpose of the study is to determine the optimum proportion of additives used in high-performance concrete. The addition of 15% PSA resulted in a strength of 69.227 MPa over a test period of 56 days, while the addition of 15% CFA yielded a strength of 69.369 MPa, and the addition of 5% RHA resulted in a strength of 59.984 MPa. The maximum concrete strength is achieved by adding 15% PSA. Correlation analysis between stress-strain indicates that aggregates exhibit higher strength compared to cement paste, mortar, and concrete, highlighting the relationship between the aggregate, cement paste, mortar components, and concrete as a composite material. Aggregate strength values found to be the highest among concrete, cement paste, and mortar, indicating that cement paste contributes the least to the strength of concrete, followed by mortar as concrete reinforcement. The results suggest that aggregates remain the primary strength component supporting concrete. The finding indicates that the relationship between the basic substances in this study aligns closely with existing theory. Moreover, it suggests that all concrete materials with pozzolan variants can classified as high-quality concrete. The optimum percentage is obtained by adding 15% palm shell ash, resulting in the highest compressive strength compared to counterparts and test objects with other types of pozzolan additions. The relationships between the constituents of concrete demonstrate that aggregates continue to be important contributors to concrete strength, with the cement paste contributing the least. Concrete strength values fall between those of aggregates and those of cement and mortar pastes.

Abstract: This study analyse the effects of different wire drawing experimental tests on the die and product properties. Drawing load, temperature, and wear rate are main die factors, that concerned with the interaction effects of drawing speed variation, wire angle alignment and lubrication. For the product, two factors; tensile strength and hardness are taken. A copper wire is drawing from (4.3 mm) into (3.5 mm) diameter with an area reduction of 1.65, 34% ratio.Six dies were employed in various alignments at three different angles (0°, 1°, and 2°), each has two different drawing speeds of (20 mm/min and 40 mm/min). Results show, the highest drawing load and temperature values in die no.5. The effect of using grease on the die wear rate found that the die wear decreases compared to without. But, when using mixed gradients under the same working conditions, the wear rate changed into coating layer on the die surface. The interaction effect of wire alignment on the product strength showing very small when dealing with low or higher speed, but elongation and ductility are significantly reduced with increasing the angle. The wire produced from die no.1, gives the highest micro hardness.

Abstract: Pollution problems caused by industrial production of leather tanneries are an important environmental issue. In the present paper we propose to study effects of tannery sludge (TS) addition in manufactured clay bricks applying a mixture design formed by different proportions of four components: Clay, two types of sand and TS. The analysis leads to an optimal practical mixture of around 10% of TS, 20% of sand and 70% of clay and this to remain with an acceptable aspect, an admissible water absorption below 15%, an admissible total shrinkage (drying and after fire) lower than 8%, a tensile strength higher than 5MPa and a thermal conductivity of 0.93 Wm^-1K^-1, 15% lower than the reference mixture with 0% of TS. Experimental results indicate that a temperature cycle firing up to 950°C can lead to higher tensile strength and lower water absorption compared to a cycle that reaches only 850°C. Furthermore, incorporating (TS) in the fired brick manufacturing process can lead to significant energy saving. Additionally, it was observed that a moderate inclusion of TS can enhance evaporation process. Keywords : Mixture design, Tannery Sludge (TS); Clay bricks ; Evaporation ; Strength; Water absorption; Shrinkage; Leaching; Energy.

Abstract: Concrete mixtures with water-to-cement ratios (w/c) of 0.50, 0.40, and 0.30 were prepared. In the last mixture, 10% and 20% of aggregates were substituted with water-saturated expanded clay. This resulted in the creation of self-cured concrete mixtures. The mechanical properties and frost resistance of these mixtures were discussed concerning the results obtained for concrete without aggregate substitution. It was observed that self-curing can enhance the frost resistance of HPC, even though LWA reduces both flexural and compressive strength.

Abstract: Portland cement has been replaced with 50% ground, granulated blastfurnace slag (ggbs) of two types. The influence of 2 and 4% calcium nitrate accelerator on early hydration of such binders was investigated by isothermal calorimetry as well as X-ray diffraction and thermogravimetry. The strength development of mortar based on these binder blends has been followed up to 28 days and the influence of calcium nitrate discussed. One ggbs lower in SiO₂, A_l2O₃ and MgO yielded somewhat lower strength (about 90%) than the other. Addition of calcium nitrate led to lower strength at 1 day, but higher strength from 3 days on-wards. The blends with the two ggbs achieved similar strength at 7 and 28 days when blended with 4% calcium nitrate. Calcium nitrate led to more ettringite formation and AF_m phases (probably nitrate version) at 1-day sealed curing. However, the calcium hydroxide content was reduced. Potential explanations for calcium hydroxide reduction are discussed.