Cylindrical Specimens Research Articles

Residual Bond Strength of Highly Corroded Reinforced Concrete

Corrosion of reinforcement due to chloride attacks in the marine environment is a natural phenomenon. Corrosion of reinforcement produces corrosion products of high volume, which deteriorates the structural integrity of reinforced concrete structures due to loss of bond, cracking, and spalling of the concrete. Existing literature has documented tests investigating the bond behavior of uncorroded and corroded specimens, but there is a dearth of data pertaining to a more advanced stage (higher mass loss) of corrosion. In the current study, an accelerated corrosion test was conducted on cylindrical (lollypop) specimens, which involved utilizing an impressed current laboratory technique to induce three distinct levels of corrosion (10%, 20%, and 40% mass loss). Moreover, to assess bond strength, the pull-out tests were performed on both corroded and uncorroded specimens. The present study deals with the residual bond strength at three different corrosion levels, as a function of different parameters such as clear cover (CC), water-cement (W/C) ratio, and two different reinforcement diameters. Experimental data reveals that the mass loss achieved is lesser than the target mass loss for all specimens. It is observed that at higher corrosion levels, where the mass loss exceeds 10% or cracks appear on the surface of the reinforced structure, both an increase in mass loss and a decrease in residual bond strength is consistently observed. These effects remain consistent regardless of whether the parameters such as bar diameter, W/C ratio, and CC are increased or decreased. The statistical analysis was performed on the experimental data to develop predictive models for estimating the residual bond strength and mass loss. For higher mass loss of 30% to 35%, the corresponding bond strength for all of the specimens falls within the range of 4 Mpa to 6 MPa.

Estimating Young’s moduli based on ultrasound and full-waveform inversion

Ultrasound is commonly utilized to determine the dynamic Young’s moduli for estimating material deterioration or quantifying material parameters. This is either done with a resonance frequency analysis or ultrasound for rock or concrete specimens in geophysics or civil engineering. For ultrasound, these are typically cylindrical specimens measured in a through-transmission arrangement. However, this method presents some challenges, such as the need to accurately determine the onset of each wave mode and to calibrate system latency. To overcome these challenges, this study introduces a novel method that utilizes wavefield simulation and full-waveform inversion to estimate p- and s-wave, also called compression and shear wave, velocities. Where the traditional method requires two measurements, this innovative approach requires only one measurement with a single p-wave transducer. The s-wave velocity is estimated considering mode conversions within the specimen. High-fidelity ultrasound simulations are necessary for this approach. For that reason, the spatially distributed excitation of the ultrasound transducer is characterized by a laser Doppler vibrometer measurement. This led to a good estimate of the directivity pattern of the ultrasound transducer. The inverse problem for determining p- and s-wave velocity was solved successfully using a suitable misfit or cost function, the so-called graph-optimal-transport misfit. The specimens for the proof of concept study include six different metals. The precision of the estimated velocities using full-waveform inversion was compared with manual picking. As the simulated and measured waveforms matched well, this study can be seen as a starting point for material parameter determination for more complex geometries and heterogeneous materials using full-waveform inversion.

Behaviour of carbon or glass FRP-confined rubberised concrete under monotonic compression

This paper presents a comparative assessment of the compressive behaviour of rubberised concrete (RuC) confined with FRP jackets. In total, three RuC mixes were investigated with rubber content of 6%, 12% and 18% of the total aggregate volume, as well as a conventional concrete mix as a reference. A total of 100 cylindrical concrete specimens (Ø100 × 200 mm) subjected to monotonic axial compression were tested. Confinement scheme comprised 1 or 2 FRP layers of either carbon or glass uniaxial fabric. The mechanical properties, stress–strain behaviour, and confinement effectiveness ratios were assessed. The discussion includes a comparative assessment of the influence of rubber content, confinement and the type of fibre of the fabrics used on the aforementioned properties. The efficiency of analytical models in predicting the experimental results was also investigated. The results revealed a significant reduction of the compressive strength when crumb rubber was used as mineral aggregate replacement in concrete. FRP confinement of RuC was able to mitigate the reduction in compressive strength. Confinement of RuC with glass or carbon FRP jackets having similar axial rigidity resulted in similar stress–strain behaviour, which was mostly affected by the rubber content. Existing analytical models were able to predict the experimental results with moderate accuracy.

A Laboratory Study of the Effect of pH on Solubility of Bulk-Fill and Conventional Composites

Aim: Factors such as the low pH of acidic foods and beverages can affect long-term clinical success of restorative materials in the oral cavity. The aim of this study was to compare the solubility of Bulk-fill and Conventional Nano-Hybrid Resin Based Composites (RBCs) in different solutions. Material and Methods: A total of 60 cylindrical specimens were prepared from two RBCs (Tetric N-Ceram, Tetric N-Ceram Bulk-fill) and their constant weight was measured. The specimens were divided into six groups ( N = 10) in accordance with RBC type and pH solution (solution 1, 2, 3 with pH = 2.5, 5, 7, respectively), and were immersed in desired solutions for 30 days. Then they were weighed again and solubility levels of the specimens were calculated according to ISO 4049. Data were analysed by two-way ANOVA. The test power was considered at 80%. Results: The type of RBC had no significant effect on solubility; while the effect of PH was significant. Solution 1 caused significantly the highest solubility. No statistically significant differences were found among other groups. Conclusions: Considering the limitations of the laboratory investigations, it was concluded that solubility rate of Bulk-fill and Conventional RBCs was higher in solutions with lower pH. There was no difference among the RBCs. However, the solubility rates of all groups are within the clinically normal range.

Combined rate-temperature effects in postnecking plasticity of A2-70 stainless steel

In this paper, a comprehensive study that integrates theoretical, experimental and FE analyses, elucidates the combined effect of strain, strain rate, and temperature on the mechanical response of A2-70 stainless steel. A wide series of tensile experiments on cylindrical specimens is presented, including low to high temperatures and quasi-static to dynamic rates. Opportune combinations of temperatures and strain rates are imposed in order to possibly separate and identify their respective effects on the flow curve of the material. The adopted experimental procedures based on neck-related measurements revealed the onset of secondary phenomena affecting dynamic tensile tests. Classical material models were found not suitable to correctly predict the complex elastoplastic deformation of this material. Thus, a new general material model is presented and used to account for the complex interplay between strain, temperature, and rate-dependent effects. Finite element simulations are conducted using both the proposed constitutive model and another classical model of dynamic hardening, to investigate and compare their predictive capability over the entire experimental campaign.

Experimental and analytical model of CFRP-confined spontaneous combustion coal gangue aggregate concrete

In this study, carbon fiber reinforced polymer (CFRP) confined cylindrical concrete specimens were tested under monotonic axial loading. The effects of the replacement ratio of the spontaneous combustion coal gangue aggregate (SCGA) and stiffness of the CFRP confinement on the mechanical properties of concrete were mainly considered. The results showed that the confinement efficiency of CFRP on the concrete decreases with increasing SCGA content. Despite the increase in the confinement stiffness, the confinement efficiency of the CFRP confinement on high-content SCGA concrete (SCGAC) will also be significantly reduced. Evidently, the influence of aggregate properties on confined concrete cannot be ignored. A CFRP-confined analysis model considering the SCGA replacement ratio was established. Through the verification of existing test data, its accuracy meets the requirements.

Characterization of concrete behavior under cyclic loading using 2D digital image correlation

The development of plastic deformations of concrete during loading-unloading cycles and post-cracking behavior must be carefully controlled for accurate modeling of concrete structures. This study aims to validate the use of digital image correlation (DIC) for characterizing concrete behavior under loading-unloading conditions. Experimental tests were conducted on cubic and cylindrical concrete specimens, employing strain gauges and DIC methods. Uniaxial compressive static and loading-unloading tests were performed on two series of concrete with different compressive strengths to establish stress-strain relationships.The experimental results demonstrated good agreement between strain gauges and DIC measurements in the elastic range for both cylindrical and cubic specimens. Analytical and numerical modeling further confirmed the accuracy of permanent strains obtained through DIC for the cubic specimens subjected to cyclic loading beyond the elastic domain. Based on these findings, it can be concluded that the DIC technique is reliable for tracking strain evolution up to the point of material failure under uniaxial loading-unloading compression.

Processing condition dependency of increased layer thickness on surface quality during electron beam powder bed fusion

The energy beam and powder layer interaction influences the dynamic melt behavior and determines the surface quality in electron beam powder bed fusion (PBF-EB). It is generally believed that increasing the powder layer thickness favors production efficiency but is contradictory to improving the forming quality. How variations in the powder layer thickness affect the interaction between the electron beam and the powder bed, which influences the melt behavior and resultant surface quality, has not been well understood. In this study, cylindrical specimens with increased nominal layer thicknesses from 80 to 140 μm were prepared using PBF-EB. The study verified the processing feasibility of ensuring the forming quality under a high layer thickness. Within the processing regime of this study, a relatively large powder layer thickness expanded the processing window. According to the thermophysical-property analysis of the powder bed, the emissivity and thermal conductivity exhibited upward and downward trends, respectively, with increased powder layer thickness. The increased thickness reduced the fusion efficiency, restricting the height difference within the overall sample surface caused by overheating. The numerical simulation clarified the dependence of the layer thickness-effect on the processing conditions. The proportion of incomplete melted powder in the electron beam irradiating area increased at a high scan speed. Subsequently, the hindering effect on heat absorption and transfer caused by the powder layer and its increased thickness was fully manifested. That is, the evolution trend of melt behavior and surface morphology resulting from increased layer thickness is remarkable at high scan speeds.

Qualification Approach Detailed for Offshore Hydrogen Pipeline Systems

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 32158, “Offshore Hydrogen Pipeline System Qualification: Design and Materials/Welds Testing in Hydrogen Environment,” by Angelo Santicchia, Elvira Aloigi, and Salvatore Terracina, Saipem, et al. The paper has not been peer reviewed. Copyright 2023 Offshore Technology Conference. Reproduced by permission. _ The qualification of a pipeline system for hydrogen transport, important in the transition to a decarbonized energy system even if strictly related to offshore pipelines, is a broad field that requires a systematic approach from basic material knowledge to complex physical models and fracture and fatigue assessments. The authors’ analysis of qualification requirements, including available test types and testing protocols, led to a matrix of potential tests, detailed in the complete paper, to be conducted in hydrogen and air environments for the steel base material, seam weld, and girth weld of offshore pipelines. Offshore Pipeline Materials Requirements vs. Hydrogen Transportation The authors’ work outlines many challenges, including the following: - Although hydrogen pipelines installed and operating onshore are common, at the time of writing, none exist in the offshore environment. - The blending percentage of hydrogen into natural gas in the future-transport scenario is still under discussion. - Small amounts of hydrogen can have a substantial effect on fatigue and fracture on high-strength materials. - The effect of hydrogen on pipe-material fatigue and fracture properties correlates directly to the specificity of the offshore environment, which will be very demanding in terms of longitudinal stress and fatigue. Another important aspect to consider is the effect of hydrogen on weldments both longitudinal and circumferential that are part of pipe-material fabrication and pipeline fabrication. A dedicated engineering team analyzed key standards and the available literature in terms of theoretical studies and experimental tests of materials in hydrogen environments. This activity indicated that, in addition to theoretical and design considerations, characterization of primary material and welding properties in hydrogen environments that will affect the failure modes of offshore pipeline design is a critical step. Testing Protocols and Equipment Slow Strain Rate Test (SSRT). Smooth cylindrical specimens were tested in inert gas (nitrogen), pure hydrogen, and a hydrogen/natural gas mixture for comparative purposes. This testing was aimed at evaluating the susceptibility of the pipeline materials (base material and weld metals) to hydrogen embrittlement when subjected to typical conditions envisaged for future hydrogen service. Tensile cylindrical specimens were tested at room temperature (24°C) in a high-pressure gaseous atmosphere. Tests were carried out in displacement control mode. In the initial part of the tensile test, in the plastic regime, after attainment of material yielding but before reaching the maximum tensile strength of the specimen, the strain distribution along the specimen was approximately uniform.

Effects of thermo-chemical treatment and grinding process of external cylindrical surfaces on residual stresses in 13CrMo4-5 steel

This paper presents a study aimed at determining the effect of the carburizing treatment process and the subsequent grinding process on the residual stresses occurring in ring-shaped specimens made of 13CrMo4-5 steel.During the tests, vacuum carburizing was used, achieving an effective case depth ECD = 0.5 mm. Subsequently, the cylindrical outer surfaces of the samples were ground by conventional plunge grinding and with innovative kinematics using a test stand based on a conventional flat-surface grinding machine. As part of the study, microhardness and residual stresses were measured before and after grinding. Measurements were carried out to a depth of 1 mm. The main component of the stand is an original special device that allows the cylindrical specimen to be clamped. Then the angle between its axis of rotation and the axis of rotation of the grinding wheel is set with respect to the plane of the grinding machine’s magnetic table. In the described tests, the axis of rotation of the cylindrical specimen was deviated from its original position by 15 and set at an angle of 75 to the axis of rotation of the grinding wheel. The specimens were ground with a grinding wheel of noble electro-corundum marked 38A60K8V. In both kinematic cases of the grinding process, a machining allowance of 0.01 mm was removed.Grinding using innovative kinematics did not cause any significant changes in the microhardness distribution, either for vacuum or conventional carburizing. In addition, residual stress measurements using the Dawidenkov-Sachs method showed that innovative grinding enables a more favourable distribution than those obtained after conventional plunge grinding.Further research will focus on, among others, selecting the angular settings of the workpiece axes relative to the grinding wheel axes depending on their dimensions. Grinding guidelines should include coverage ratio, infeed value, grinding time, and peripheral speeds. In addition, the plan for future research includes measuring the components of the grinding force and the geometric structure of the surface.Grinding process is a crucial stage of steel treatment in almost every industrial branch. In sustainable manufacturing, it is extremely important to produce high-quality items while reducing the cost of manufacturing and taking care of the environment and workers’ health.The proposed test stand, together with the authors’ device, makes it possible to conduct machining of the external surfaces of cylindrical workpieces on a flat surface grinder. In this case, the innovation of the grinding process consists of the non-parallel alignment of the cylindrical rotational axis of the specimen and the rotational axis of the grinding wheel with respect to the plane of the magnetic grinding table.

Experiment‐based statistical distribution of buckling loads of cylindrical shells

AbstractA silo structure is usually constructed in the form of a cylindrical steel shell. It has the advantages of being lightweight, having a short construction period, and possessing a large storage space. It has been widely used in many fields of industry. Thin‐walled cylindrical shells often exhibit buckling failure and the experimental buckling load is usually lower than calculation results from classical theory and simulation without geometrical imperfection. Besides, test results with carefully conducted similar specimens still have substantial scatter due to imperfection sensitivity. The nonlinear analysis with FEM can obtain a high‐precision result comparing the experiment if the geometric parameters of the shell are fully known. However, this is almost impossible in practical engineering. The initial geometric imperfections and shell thickness of cylindrical shells are complex and random properties. Theoretically, these geometric imperfections can be described using a random field. This paper presents the experimental investigation of buckling analysis of cylindrical shells under axial compression considering the randomness of geometric imperfections and thickness. A total of 12 cylindrical shell specimens were fabricated and tested. Based on the test results, the optimal statistical distribution is obtained by the maximum entropy fitting method and the obtained results were compared with geometric imperfections based on laser scan measurements.

Pull-out tests to evaluate the effects of crack healing on the steel-to-concrete bond on concretes exposed to chloride-rich environments

This paper presents an experimental methodology to evaluate the effects of the self-healing of cracks on the steel-to-concrete bond. Overall, 80 cylindrical concrete specimens with a coaxial steel bar were cast and subjected to pull-out tests. To this purpose, the experimental methodology envisaged the casting of two types of concrete specimens: one made with a reference concrete and the other type to investigate the effects of a crystalline admixture as a self-healing promoter. Through pull-out tests, the specimens were precracked and subjected, together with uncracked companion specimens, to wet/dry cycles in tap water or saltwater. To facilitate the evaluation of the self-healing of the specimens, indices relating to the physical-mechanical characteristics have been defined. The results show a better behavior of both, surface crack sealing and recovery of the bond performance, when specimens were subjected to wet/dry cycles in saltwater. Moreover, crystalline admixtures promoted a continuous recovery of the steel-to-concrete bond performance due the continuous generation of healing products inside the crack.

Effect of a Diode Laser (445 nm) on Polymerization Efficiency of a Preheated Resin Composite Used for Luting of Indirect Composite Restorations.

The aim of this study was to evaluate the polymerization efficiency of a preheated resin composite used as a luting agent for indirect restorations light-cured by a blue diode laser (445 nm). Bronze molds were used to prepare cylindrical specimens of a laboratory composite (Ceramage) with dimensions 2, 3, and 4 mm in height and 8 mm in diameter. The molds had additional height of 120 μm for the placement of the preheated resin composite. A nanohybrid resin composite (Enamel Plus HRi) was preheated at 55°C to use as a luting agent. Photopolymerization was followed for 20 seconds using three light sources: a diode laser emitting at 445 nm (SiroLaser Blue) and two light-emitting diode (LED) units (Bluephase Style and Valo). Degree of conversion (DC) of the preheated resin composite was evaluated using Fourier transform infrared spectroscopy. The results indicated that the main effects of the analysis were significant for both material thickness (p<0.001) and polymerization method (p<0.001). The preheated resin composite was not polymerized under 4-mm-thick specimens, independent of the light-curing unit. For 2-mm material thickness, there was no difference among the three light-curing units (p=0.383), while 3-mm Bluephase Style presented very low DC. Diode laser (445 nm) achieved better polymerization efficiency at the same fluence compared to the LED unit at 3-mm depth, implying a better mechanical behavior and potential improved adhesion of the luting material to dentin.

Unit Weight and Elastic Modulus of Concrete utilizing Volcanic Stone Waste as Coarse Aggregate

Unit weight and elastic modulus of concrete utilizing volcanic stone waste (VSW) as coarse aggregate have been studied at 28 days of hydration. The origin of VSW was the residual of volcanic stone processing for making the handmade ornaments of traditional Balinese buildings. Three types of concrete mixture compositions were made by varying the proportion of cement, fine aggregate and coarse aggregate in concrete. Each mixture composition stirred using four variations of water/cement (w/c) ratio. For each variation in w/c, five cylindrical specimens with a diameter of 150 mm and a height of 300 mm were made to measure the unit weight and modulus of elasticity of concrete specimens after 28 days of hydration. The result shows that the unit weight and the elastic modulus of concrete decrease with increasing w/c at fixed proportions of cement and aggregates and increase with increasing proportion of aggregates at fixed w/c. The increase in elastic modulus with an increase in the a/c ratio for a fixed w/c ratio is more noticeable for a w/c ratio of more than 0.6. Moreover, the elastic modulus increases correspondingly with an increase in unit weight for a given a/c ratio.

A Comparative Evaluation of Dissolution Rate of Three Different Posterior Restorative Materials used in Pediatric Dentistry: An In Vitro Study.

The study aimed to compare and assess the dissolution rate, color stability, and other mechanical parameters, such as compressive and flexural strength, of three distinct posterior restorative materials used in pediatric dentistry. The three posterior restorative materials used in pediatric dentistry are divided into group I-Zirconomer, group II-Composite, and group III-Cention N. Around 111 cylindrical specimens were grouped into three groups of 37 each. According to the manufacturer's standards, all materials were proportioned and handled. The materials were thermocycler in a chewing simulator and were subjected to various tests to estimate the dissolution rate, compressive strength, flexural strength, and color stability of the three individual groups. The dissolution rate was highest in Zirconomer, followed by Cention N and Composite, which were highly significant (p = 0.05). Compressive strength was highest with Cention N, followed by Composite and Zirconomer, which was highly important (p = 0.05). Cention N had the greatest flexural strength, followed by Composite and Zirconomer, which were highly significant (p = 0.05). Finally, the Composite had the highest color stability, followed by Cention N and Zirconomer among the three groups. It is concluded that resin-based restorative materials outperform glass ionomer-based Zirconomer cement in terms of dissolution rate, compressive strength, flexural strength, and color stability. Because of the widespread improvement in dental materials, many dental restorative types of cement have emerged on the market. The features of good restorative materials are mechanical strength, fluid dissolution rate, and retention. Raman V, Srinivasan D, AR SE, et al. A Comparative Evaluation of Dissolution Rate of Three Different Posterior Restorative Materials used in Pediatric Dentistry: An In Vitro Study. Int J Clin Pediatr Dent 2023;16(S-1):S20-S26.

In Vitro Evaluation of Candida albicans Adhesion on Heat-Cured Resin-Based Dental Composites.

Microbial adhesion on dental restorative materials may jeopardize the restorative treatment long-term outcome. The goal of this in vitro study was to assess Candida albicans capability to adhere and form a biofilm on the surface of heat-cured dental composites having different formulations but subjected to identical surface treatments and polymerization protocols. Three commercially available composites were evaluated: GrandioSO (GR), Venus Diamond (VD) and Enamel Plus HRi Biofunction (BF). Cylindrical specimens were prepared for quantitative determination of C. albicans S5 planktonic CFU count, sessile cells CFU count and biomass optical density (OD570 nm). Qualitative Concanavalin-A assays (for extracellular polymeric substances of a biofilm matrix) and Scanning Electron Microscope (SEM) analyses (for the morphology of sessile colonies) were also performed. Focusing on planktonic CFU count, a slight but not significant reduction was observed with VD as compared to GR. Regarding sessile cells CFU count and biomass OD570 nm, a significant increase was observed for VD compared to GR and BF. Concanavalin-A assays and SEM analyses confirmed the quantitative results. Different formulations of commercially available resin composites may differently interact with C. albicans. The present results showed a relatively more pronounced antiadhesive effect for BF and GR, with a reduction in sessile cells CFU count and biomass quantification.

Effect of Contents, Tensile Strengths and Aspect Ratios of Hooked-End Steel Fibers (SFs) on Compressive and Flexural Performance of Normal Strength Concrete

This study is a part of the study to simplify the reinforcing details of reinforced concrete (RC) structural members by substituting the conventional reinforcement with hooked-end steel fibers (SFs). This paper investigates the effects of SF strength, dosage and aspect (l/d) ratio on the compressive and flexural behaviors of normal strength concrete with specified compressive strength of 30 MPa. In this study, hooked-end SFs of high strength (2000–2400 MPa) and normal strength (1100–1200 MPa) were used with three l/d ratios of 64, 67 and 80. Hooked-end SFs were incorporated with three dosages of 20 kg/m3 (0.25 vol.%), 40 kg/m3 (0.50 vol.%) and 60 kg/m3 (0.75 vol.%). Eighteen steel fiber reinforced concrete (SFRC) mixes were mixed. To evaluate the compressive and flexural performance of each SFRC mixture, three SFRC cylindrical and prismatic specimens for each mixture were manufactured and tested, respectively. The test results that the inclusion of hooked-end SFs had little effect on the compressive strength, while it improved the toughness of concrete. Hooked-end SFs were also found to be effective in enhancing the flexural performance of concrete. The dosage and properties (strength and l/d ratio) of SFs significantly affect the residual flexural tensile strength (fR1 and fR3) at serviceability (SLS) and ultimate limit state (ULS) defined in fib Model Code 2010 (MC2010).

The scale factor effect on Young’s modulus of steel specimens determined by tensile tests

The modulus elasticity (or Young’s modulus) is considered to be a rather stable physical and mechanical characteristic of metallic materials being a weak function of the chemical composition and structure. However, the temperature and anisotropy can be referred as the main factors affecting the Young modulus. Scanty data on the scale factor effect on Young’s modulus are sometime even contradictory. We present the results of studying the impact of the scale factor on Young’s modulus of steel 45 determined by the tension of cylindrical tensile specimens with different initial diameters on an Instron 8801 machine with a movable traverse speed of 0.1 mm/min at room temperature. An extensometer and a digital image correlation (DIC) method were used to measure elastic deformations. Both methods showed fairly close results during tensile testing of specimens with equal diameters. DIC method made it possible to measure elastic deformations on small-size specimens on which it was impossible to fix the extensometer. A decrease in the Young modulus with an increase in the specimen diameter has been revealed. Graphical dependences of the Young modulus on the specimen diameter and cross-sectional area have been obtained. Possible reasons for the decrease in the Young modulus under the influence of the scale factor have been indicated. A decrease in the specific surface area and specific surface energy, an increase in the deformable volume, and a decrease in the strain rate at a constant movable traverse speed are among the main reasons. The decrease in Young’s modulus under the influence of the scale factor must be taken into account in strength calculations and in assessing the residual life of large-scale parts and structures with relatively large cross sections and wall thicknesses.

Creep behavior of sintered nano-silver at high temperature: Experimental and theoretical analysis

Creep experiments were conducted on self-designed cylindrical specimens of sintered nano-silver at temperatures ranging from 298 K to 523 K. The creep behavior of sintered nano-silver at different temperatures was investigated. It was observed that an increase in temperature led to significant softening, accompanied by an increase in the maximum strain from 0.26 to 0.889. Additionally, the creep rate showed accelerated decay, with the rate rapidly approaching zero for temperatures exceeding 373 K, indicating a strong temperature dependence. Based on material microstructure characterization techniques and finite element analysis, it shows that the high temperature sensitivity of sintered nano-silver creep is primarily attributed to void formation. A new theoretical model has been developed based on the theory of entropy increment, which can accurately predict the creep strain of sintered nano-silver compared with the experimental data, the key factors influencing the creep behavior has been analyzed. The current study presents a more accurate description strategy regarding the high-temperature creep behavior of sintered nano-silver. Compared with the conventional creep models, the proposed model can accurately capture the softening properties of sintered nano-silver.

The use of sugarcane bagasse ashes (sba) in the confection of concrete’s traces and precast, replacing and adding to cement

Concrete is one of the most used construction materials in the world, with cement being one of its main ingredients. The incorporation of Sugarcane Bagasse Ash (SBC) in the production of concrete can present solutions for the use of this agro-industrial by-product and minimize environmental impacts arising from the removal of limestone in the production of cement, in addition to contributing to the reduction of emission of carbon dioxide and preserve natural deposits for cement production. This study aimed to use sugarcane bagasse ash in the addition and partial replacement of cement in the production of concrete. The specimens (TBs) were manufactured following the NBRs 7223 and 5738, in which a ratio was adopted: (1:1.98:3.23:0.61) as primary proposal (T1), and the replacement (T2) and addition (T3) of 5% of Portland cement by mass was performed. The ruptures of the specimens were performed by the compressive strength test of concrete cylindrical specimens at 7, 14, 21 and 28 days of age, after rectification. The results obtained show that it is feasible to use SBA, since the water/cement ratio and the percentage of mass to be replaced or added are appropriate, because both in the addition and the replacement of 5% cement by SBA obtained a gain in strength of concrete.