Variation Of Tensile Strength Research Articles

Mechanical behaviour of structural concrete with ground recycled concrete cement and mixed recycled aggregate

This article analyses the combined effect of valorising ground recycled concrete (GRC) as 10% or 25% cement replacement and 0% or 50% mixed recycled construction and demolition waste aggregate (RA-CDW) in structural concrete. An exhaustive experimental programme was designed to assess the variation in compressive and tensile strength, modulus of elasticity and hardened concrete density. Non-destructive ultrasonic pulse velocity and electrical resistivity tests were also conducted. The concrete mixes prepared with GRC and RA-CDW exhibited lower mechanical performance than those manufactured with natural aggregate and cement only (although the difference was smaller than the respective replacement ratios). These findings were attributed to: a higher water/binder (cement + GRC) ratio, the dilution effect resulting from a lower cement content in the new mixes and the intrinsic properties (water absorption and abrasion resistance) of the new recycled components. The mixes with 10% GRC and 50% RA-CDW, however, showed similar mechanical performance and remained in the same strength class as those with 50% RA-CDW and 100% Portland cement. In terms of the electrical resistivity and ultrasonic pulse velocity tests, the effect of replacing OPC with GRC was below 14%, irrespective of whether natural or recycled aggregates were used. Such promising findings pave the way for more efficient and global C&DW management with a view to steering the construction industry toward the circular economy.

Impact of Sample Size and Maximum Aggregate Grain on the Representativeness of Concrete Samples

One of the basic criteria for the representativeness of composite material samples is the similarity of the quantitative and qualitative composition of the material in the sample to that of the material it represents. The article presents the results of experimental research concerning the impact of the ratio of the minimum size of cubic concrete samples (lmin) to the maximum size of aggregate grain (Dmax). The content of the basic components of concrete, i.e., coarse aggregate, mortar, sand and cement paste, was analysed. The content of these components in the concrete sample was identified by means of analysis of the sample cross-sectional image, and then, compared with the contents resulting from the concrete mixture proportion. Cases where lmin/Dmax was between 2.38 and 12.5 were analysed. The results of the study indicate a moderate correlation between these two parameters. The largest discrepancies between the component contents of the sample and the controlled concrete were usually recorded at the extreme values of the lmin/Dmax ratio. These discrepancies, depending on the component in question, range from approx. −15 to approx. +15%. Acceptable deviations (≤ ±5%) result in the value of this ratio within the estimated range between approximately 5.0 and approximately 10.0. In existing standards, the use of samples that meet the requirement lmin/Dmax ≥ 3.0 or 3.5 is recommended. In light of the presented test results, this requirement is sufficient for the material properties that are not sensitive to slight variation in concrete composition, i.e., compressive and tensile strength. The presented results are useful in the case of sample size selection for the study of concrete properties which are most sensitive to concrete composition changes. These properties include water absorption, permeability to liquids and gases, thermal properties, etc.

Evaluation of the processing quality of noodle dough containing a high Tartary buckwheat flour content through texture analysis.

A texture analysis method for evaluating the processing quality of noodle dough with a high Tartary buckwheat flour (BF) content was established. And then the improvement of wheat flour (WF), wheat gluten (WG), and pre-gelatinized Tartary buckwheat flour (PBF) for the processing quality of buckwheat noodle dough was compared quantitatively, and the mechanism was explored through the observation of gluten network in dough sheets. Texture results showed that the coefficients of variation of tensile strength and adhesiveness of dough sheets among 16 groups were 17.76% and 40.72%, respectively, and the intragroup variation coefficients were only 4.17% and 7.07%, respectively. The tensile strength of dough sheets was significantly positively correlated with gluten index of WF and WG. In addition, with the increase of WG and PBF addition, the tensile strength and adhesiveness of dough sheets showed a linearly increase trend. Furthermore, the gluten network in the dough sheets containing WF or WG with high gluten index distributed more evenly and compactly than that with low gluten index. The dough sheet with 9% PBF showed more uniform gluten network, compared with that without added PBF. Overall, texture analysis of dough sheet can be used to evaluate the processing quality of noodle dough containing 70% BF, and the WF and WG with high gluten index had better improvement than PBF.

Three‐dimensional discrete element simulation of indirect tensile behaviour of a transversely isotropic rock

SummaryThis paper presents the development of a three‐dimensional discrete element model using flat‐joint and smooth‐joint contact models to investigate the effect of anisotropy on the tensile behaviour of slate, a transversely isotropic rock, under Brazilian testing from both macro and microscales. The effect of anisotropy is further realised by exploring the influence of foliation orientations (β and ψ) on the tensile strength, fracture pattern, microcracking and stress distribution of the transversely isotropic rock. The variation of tensile strength with foliation orientation is presented. The cross‐weak‐plane fracture growth observed in laboratory is reproduced, and the criterion for which to form is also given from the aspect of foliation orientation. Furthermore, the proportional variations of microcracks well account for the effects of foliation orientation on the tensile strength and failure pattern. Finally, it is found that the existence of weak planes increases both the heterogeneity and the anisotropy of stress distributions within the transversely isotropic rock, with the degree of influence varying with the foliation orientation.

Functional characteristics improvement by structural modification of hydroxypropyl methylcellulose modified polyvinyl alcohol films incorporating roselle anthocyanins for shrimp freshness monitoring

A novel indicator film incorporating roselle anthocyanin extracts (RAE) was prepared to monitor shrimp freshness. Hydroxypropyl methylcellulose (HPMC) modified polyvinyl alcohol (PVA) was applied as film-forming substrates to obtain better functions. Structural characterization results suggested compositions were well dispersed and confirmed the structural modification. The addition of HPMC would improve film functions through generation of new interactions. The films with a ratio (HPMC-to-PVA) of 3:1 exhibited stronger tensile strength (91.88 ± 0.13 MPa), hydrophobic (moisture content of 10.44 ± 0.65%, water contact angle of 56.40 ± 3.11°), barrier properties and larger color variations in response to pH changes, demonstrating positive influences of physical functions on indication properties. Thus, a relationship among structural, physical and indication functions was proposed. Furthermore, the films were applied for shrimp freshness real-time monitoring. The film color changed from rose-red to light green at 4 d, corresponding to the onset of spoilage, and then turned into yellow at 8 d, when the shrimp was severely spoilage. The strong correlation between total color difference and chemical spoilage indexes (P < .05) was observed. Therefore, the incorporation of HPMC could improve film functional characteristics by structural modification of new interaction formation, and the PVA/HPMC/RAE films could be applied as intelligent packaging for real-time shrimp freshness monitoring.

Pembuatan film plastik biodegradable dari limbah kulit kopi dengan penambahan kitosan/gliserol

Biodegradable plastic production has been developed for a long time by researchers. Data from Ministry of Industry in 2017 stated Indonesia's plastic production reached 3.9 million tons/ year. In this study, the raw materials used came from untapped waste, namely coffee skin, biodiesel-waste glycerol and shrimp-shells chitosan. In this research, biodegradable plastic films have been produced with the addition of glycerol and coffee skin waste with chitosan concentration variations of 0, 2, 4, 6, and 8%. After the optimum conditions were obtained by comparing the elongation and tensile strength values, then the variations in coffee skin waste were added with a weight of 0, 2, 4, 6, and 8 g. Tensile strength and elongation values with variations of chitosan were 0.2-1.87 MPa and 0.22-0.15%, respectively. Whereas the variation of tensile strength and elongation coffee skins were 1.8-0.27 MPa and 0.14-0.2%, respectively. The optimum conditions for producing biodegradable plastic films were obtained with variations of chitosan 4% and 2 g coffee skin with tensile strength and elongation values of 0.98 MPa and 0.16%. The tensile strength and elongation data produced from biodegradable plastic was still below the standard value of commercial plastic or synthetic plastic (HDPE) with values of tensile strength and elongation of 28.64 MPa and 6.5186% respectively.

Interface bond strength of lightweight low-cement functionally layered concrete elements

Production of cement accounts for around 5% of human-made carbon emissions. When the selection of a cement-intensive mix with low porosity is driven by durability requirements, the resulting low permeability of the material is only fully exploited in peripheral regions of the element where the material acts as a physical barrier against the penetration of aggressive substances. This paper explores the potential of casting layered prismatic elements composed of an external durability layer and a lightweight core section as a means to achieve cement and weight savings. Layered elements are traditionally obtained by casting new concrete layers onto already hardened older concrete layers. A major problem with this technique is that planes of weakness are obtained at the interfaces between the layers. The bond between the layers can be improved by casting the materials at approximately the same time. However, research to date has not yet demonstrated the viability of producing elements with wet cast external layers. Furthermore, the effects of delays between successive pours on the mechanical tensile performance of the interfaces in layered elements have not been quantified. An original method is presented to form prismatic elements composed of an external durability layer and a lightweight core section by casting two concrete mixes at approximately the same time. The approach is validated by realising a proof-of-concept prototype layered element. A set of additional layered elements are cast with various pour delays and cored across the interface between their layers to characterize the interlayer bond strength by direct tension. To interpret the mechanisms affecting the bond, the variation of tensile bond strength with the location of the sample and the impact of roughness are also investigated. When the pour delay was minimal, failure did not occur at the interlayer. The relationship between pour delay and bond strength is markedly nonlinear, with bond strength reductions of more than 30% for pour delays of only three hours. It was also found that the bond strength of the interface varies significantly with the considered location and that up to 40% of the bond strength reduction due to a delay between the castings can be recovered by roughening the surface of the older concrete prior to casting the newer mix. The successful realisation of wet cast prismatic elements with an external durability layer is an important step towards the realisation of light-weight layered concrete elements with low embodied energy.

Internal friction study on precipitation/dissolution of Mn-Ni-Si phase in aged RPV model steel

The precipitation/re-dissolution of Mn-Ni-Si-based phase (MNPs) in Fe-1.6%Mn-1.0%Ni-0.2%Si (wt.%) RPV model steel under different aging temperatures was systematically studied using internal friction (IF) technique. It is clearly observed that the pinning/depinning effect of GB sliding results from the precipitation/re-dissolution of MNPs, which is also in favor of the corresponding variations in tensile strength and nanoindentation results.

Study on engineering properties of sand strengthened by mixed fibers and polyurethane organic polymer

A considerable number of engineering hazards are caused by loose internal structure of sands. Thus, many researchers have explored a variety of reinforcement methods. A new reinforcement technique was experimentally evaluated in this study. In particular, a hybrid method with a combination of fiber and polymer was studied. Three different types of fibers (sisal, polypropylene, and palm) in combination with varying concentrations of polymers were experimented to improve the internal structure and strength of sand samples reconstituted at different densities. Through a series of laboratory tests, the compressive and tensile strength variations of different combinations were obtained, and the interaction between fibers and polymer inside the sand was evaluated by scanning electron microscopy (SEM). The experimental results show that the tensile and compressive strength of the reinforced sand increases with the increase of the polymer concentration, sample density, and different fiber combinations. This provides some references for future practical engineering applications.

Process parameters and mechanical properties of SAPH440 steel in pulse arc welding with different heat inputs

Thermal cycling parameters of pulse arc welding for SAPH440 steel was experimentally determined for different heat inputs. The welding thermal cycle curves of the weld fusion and heat-affected zones were successfully constructed based on the thermocouple measurements through the back drilling hole. The hardness and tensile strength variations under different heat inputs were also analyzed. This provided a database for the determination and optimization of process parameters, improvement of microstructure and properties of weld fusion and heat affected zones, and overall quality of pulse arc welding of steels.

Analysis of Erosion Wear Behavior of LD Sludge Filled Polypropylene Composites Using RSM

In the current investigation, a large number of experimental data are created for a set of Linz-Donawitz (LD) sludge filled polypropylene composites by fabricating them through compression molding technique and by conducting different tests to find out their physical, mechanical and erosion wear behaviour under controlled laboratory conditions. The erosion wear trials are carried out on the fabricated polypropylene-LD sludge composite samples as per ASTM standard using response surface methodology (RSM). This study discloses that the impact velocity and the filler content are the most predominant factors influencing the erosion rate of the composite. Mechanical characterization of the composites under this investigation reveals that the trends observed in regard to the compressive strengths are quite different from those obtained in the case of tensile strength variations with the filler loading. It is also observed that these LD sludge filled composites show improved micro-hardness and low amount of porosity.

Thermomechanical and Morphological Properties of Poly(ethylene terephthalate)/Anhydrous Calcium Terephthalate Nanocomposites.

Calcium terephthalate anhydrous salts (CATAS), synthetized by reaction of terephthalic acid with metal (Ca) oxide were incorporated at different weight contents (0–30 wt. %) in recycled Poly(ethylene terephthalate) (rPET) by melt processing. Their structure, morphology, thermal and mechanical properties (tensile and flexural behavior) were investigated. Results of tensile strength of the different formulations showed that when the CATAS content increased from 0.1 to 0.4 wt. %, tangible changes were observed (variation of tensile strength from 65.5 to 69.4 MPa, increasing value for E from 2887 up to 3131 MPa, respectively for neat rPET and rPET_0.4CATAS). A threshold weight amount (0.4 wt. %) of CATAS was also found, by formation at low loading, of a rigid amorphous fraction at the rPET/CATAS interface, due to the aromatic interactions (π−π conjugation) between the matrix and the filler. Above the threshold, a restriction of rPET/CATAS molecular chains mobility was detected, due to the formation of hybrid mechanical percolation networks. Additionally, enhanced thermal stability of CATAS filled rPET was registered at high content (Tmax shift from 426 to 441 °C, respectively, for rPET and rPET_30CATAS), essentially due to chemical compatibility between terephthalate salts and polymer molecules, rich in stable aromatic rings. The singularity of a cold crystallization event, identified at the same loading level, confirmed the presence of an equilibrium state between nucleation and blocking effect of amorphous phase, basically related to the characteristic common terephthalate structure of synthetized Ca–Metal Organic Framework and the rPET matrix.

Effect of small ply angle variation in tensile and compressive strength of woven GFRP composite: Application of two parameter Weibull distribution

This paper demonstrates the effect of small ply angle variation in tensile and compressive strength of woven Glass Fiber Reinforced Polymer (GFRP) composites. Four different plies of (0/90)4, (±5°)4, (±10°)4, (±15°)4 manufactured by hand lay-up followed by the press molding machine. Samples for the tensile and compressive tests were prepared according to ASTM D3039 and ASTM D3410 standards. Three samples of each laminate were tested on a Universal Testing Machine (UTM) at a steady crosshead speed of 1 mm/min. A digital microscope was used for tracking the sample damage pattern. It was observed that fiber orientation in laminates affects the tensile and compressive strength. Fibers ruptured during tensile testing of specimens and in compressive testing, samples failed due to the separation of longitudinal fibers. The experimental results showed that (0/90)4 ply showed the maximum tensile strength and compressive strength followed by (±5°)4, (±10°)4, (±15°)4. Weibull distribution analysis was used for statistical estimation of the tensile and compressive life of specimens.

Influence of fused deposition modeling process parameters on the mechanical properties of PETG parts

This research work is aimed to provide insight on the dependency of mechanical properties on process parameters of the Fused Deposition Modeling (FDM) printed Polyethylene Terephthalate Glycol (PETG) parts. The experimental investigation is carried out on the PETG material to analyze the individual effect of process parameters such as layer thickness, infill density and infill pattern on the mechanical properties. Specimens were fabricated as per the ASTM standard for the various combination of the above mentioned process parameters. Tensile strength and surface roughness were performed on the Universal testing and surface roughness testing machine respectively. Among the process parameters selected for the fabrication, it is noted that the tensile strength decreases with increase in layer thickness and tensile strength increases with increase in infill density. The infill pattern combined with build orientation produces variations in tensile strength. Surface roughness value decreases with increase in infill density. From the experiment, suitable process parameters for an assuring tensile strength were inspected and studied to establish better end user functional parts.

Microstructural and mechanical behavior in dissimilar T91/T22 welded pipes

The aim of this work is to investigate the microstructural and mechanical behavior of T91/T22 steel welded pipes with iron based filler material/wires using Gas Tungsten Arc Welding (GTAW) process. By the fusion of two metal across the weld joint a variety of microstructural variation is observed as a result of solidification and solid state transformation. So, the evaluation of this welded joint formed with filler wires of different composition is based on microhardness variation, Tensile strength of the welded specimen and the microstructural arrangements. The deformation of dissimilar welded joints depends on the base metals i.e. T91, T22 and on the composition of filler materials as proved my microhardness variation and tensile strength and microstructural variation. In the following experiment two different kind of specimen were prepared using two filler wires E91T1-G C and ER80S D2 as specimen E1 and E2. It has been observed that the tensile strength of Specimen E1(593 MPa) is higher than Specimen E2 (474 MPa) also the microhardness of Specimen E2 around the HAZ of T22 and weld metal is quite high due to which the brittleness of material there will increase and the material fails while tensile testing.

Tensile strength of composite bonded scarf joint in various thermal environmental conditions

This study analyzed variations of tensile strength and the failure mode of composite bonded scarf joint in various thermal environments. A total of 70 scarf bonded joints were manufactured using secondary bonding and co-bonding methods, in which a number of 10 scarf joints were additionally attached to an external ply over the joint area to examine its effect. Six different environmental temperatures ranged from 25°C to 150°C were chosen and tested. A pure laminate having the same stacking sequence as the parent laminate was prepared and tested at the six temperatures for references. Experimental results revealed that tensile strengths of the secondary bonded (SB) and co-bonded (CB) joints at 75°C reduced by 9.3% and 10.5% in comparison with strengths of the corresponding joints at 25°C, respectively. Particularly, at 125°C, which is higher than the resin glass transition temperature, significant reductions of 57.1% and 53.6% in strength were found for SB and CB joints, respectively. In terms of the manufacturing methods, the strengths of the SB joints were higher than those of the CB at 25°C, 50°C, and 75°C by 6.5%, 7.6%, and 8.0%, respectively. However, at high temperatures (100°C, 125°C, and 150°C) these differences were negligible. Strengths of SB joints attached external ply increased by 5.9% and 37.5% compared to those of SB joints without the external ply at 25°C and 100°C, respectively.

The Influence of Temperature and High-Speed Heating on Tensile Strength of Granite and the Application of Digital Image Correlation on Tensile Failure Processes

Thermal induced cracks and the tensile strength variation of Eibenstock granite subjected to high-speed heating have been studied through lab testing. The Digital Image Correlation (DIC) technique was used for analysing the tensile behaviour of granite at high-speed heating rate and different temperatures. For samples heated to 800 °C with heating rates of 200 °C/min and 300 °C/min, thermal-induced macrocracks become visible to the naked eyes, while no obvious macrocracks are observed on samples heated according to ISO 834 curve. Compared to the influence of temperature, the selected heating rates only have a negligible impact on tensile strength and axial displacement. The DIC analysis shows the crack initiation and progressive crack propagation before the main crack is formed at failure. Compared to the samples heated up to 400 °C, the samples heated up to 800 °C show less brittle fracture behaviour, and the tensile strength is greatly reduced. The final failure patterns prove that different heating scenarios lead to different microcrack structures and consequently influence the failure mode at the macroscopic scale.

Strength Analysis on Natural Fibre Composite Banana and Sisal Fibres with Epoxy Resin

The tensile strength and bending strength variation on the basis of change in mass of HEMP and SISAL fiber content in the composite. The scope of work is constraint to hemp and sisal fibre composite with epoxy as resin. Study of the characteristics of hemp and sisal fiber, to fabricate the composite of hemp and sisal fiber with epoxy resin and increase the strength of hemp fibers composited with sisal fibers using epoxy to finding the variation of tensile strength of the natural fiber composite- Hemp &amp; Sisal with epoxy resin with different composition and finding the variation of bending strength of the natural fiber composite- Hemp and Sisal with epoxy resin with different composition and compare the mechanical properties of Hemp – Sisal composite with glass fiber.

Evaluation of the environmental aging of the glass fiber-reinforced polymer composite when in contact with the effluent of a treatment plant

This paper presents an evaluation of the mechanical and physical behavior of the type E glass fiber-reinforced polymeric composite when exposed to environmental aging agents in an effluent treatment plant. The composite was made by the hand layup process, and the test bodies were made according to the American Society for Testing and Materials standards D3039-14 and D790-10 for the uniaxial tensile and three-point bending tests, respectively, where they were exposed for a period of eight months, conditioned above and immersed in the effluent of the treatment plant. The physicochemical characterization of the effluent was evaluated considering the following parameters: pH, conductivity, sulfate, alkalinity, acidity, sulfide, and temperature, aiming to characterize the effluent conditions in direct and indirect contact with the composite. After the exposure period, tests were carried out for morphological evaluation, structural integrity evaluation, mechanical performance evaluation, and fracture characterization of the polymer composite, thereby leading to a comparison of the mechanical characteristics in the original state to that of the aged state (after exposure in the effluent treatment plant). The polymeric composite studied was stable after the aging period, with little mass variation, less than 0.5%, and slight changes in color. The mechanical properties evaluated also did not change significantly during the study period. Variations in uniaxial tensile strength were less than 1.4% and for three-point bending less than 10%, thus showing that the type E glass fiber-reinforced polymer composite has potential for use in harsh environments such as in effluent treatment plants.

Investigation of tensile strength and dimensional variation of T700 carbon fibres using an improved experimental setup

Knowledge of fibre strength is crucial for understanding the failure behaviour of fibre-reinforced composite materials and structures. Measuring the properties of technical fibres has been known to be very challenging, and the different challenges associated with single fibre characterisation are illustrated in this article. An improved and automated experimental methodology for tensile testing of single fibres is described. This process has been used to generate fibre strength data for T700 carbon fibres at three different gauge lengths of 4, 20 and 30 mm. The variability in strength and modulus of short fibres was found to be much larger than that of longer fibres. Statistical analysis of this large data set has also highlighted the limitations of the standard Weibull distribution for representing fibre strength behaviour. The need for a better statistical representation of the fibre strength data in order to provide a more accurate description of the fibre strength behaviour has been emphasized.