Compression Resistance Research Articles

Effect of chemical treatment on the mechanical properties of intra-layer hybrid Alfa/Jute fabric composites

Bidirectional hybrid polymer-based composites are being introduced in many industrial applications. This is because the weaving patterns of woven composites have significant contributions to resulting composite performances. The main goal of this work was to study the effect of chemical treatments and the effect of hybridization on the mechanical properties of intra-layer hybrid Alfa/Jute fabric composites. Jute and Alfa fibers were used as natural fibers reinforcing the polyester matrix-based composites. First of all, the untreated, alkali and permanganate treated Alfa fibers were analyzed by using physical and mechanical tests (ATR-FTIR, XRD, and MEB). Weibull statistical analysis was employed to estimate the variability of untreated and treated Alfa fiber-resin interfacial shear strength. On the other hand, three plain-woven intra-ply hybrid fabrics were used as reinforcements for the polyester matrix. These three produced composite samples were subjected to mechanical, and physical tests such as three-point flexural strength, compressive strength, water absorption, and optical observation. The results were examined, analyzed, and compared to a jute-woven composite reinforced with the same resin. The results show that the chemical treatment can affect positively the fibers’ properties. In others hand, among the studied composites, the developed treated intra-ply woven fabric reinforced polyester resin have good mechanical properties in term of flexural and compression resistance. Weibull statistical analysis was conducted to evaluate and quantify the variability in the tensile strength of various intra-layer hybrid Alfa/Jute fabric composites.

Polycaprolactone for Hard Tissue Regeneration: Scaffold Design and In Vivo Implications.

In the last thirty years, tissue engineering (TI) has emerged as an alternative method to regenerate tissues and organs and restore their function by implanting specific lineage cells, growth factors, or biomolecules functionalizing a matrix scaffold. Recently, several pathologies have led to bone loss or damage, such as malformations, bone resorption associated with benign or malignant tumors, periodontal disease, traumas, and others in which a discontinuity in tissue integrity is observed. Bone tissue is characterized by different stiffness, mechanical traction, and compression resistance as a function of the different compartments, which can influence susceptibility to injury or destruction. For this reason, research into repairing bone defects began several years ago to find a scaffold to improve bone regeneration. Different techniques can be used to manufacture 3D scaffolds for bone tissue regeneration based on optimizing reproducible scaffolds with a controlled hierarchical porous structure like the extracellular matrix of bone. Additionally, the scaffolds synthesized can facilitate the inclusion of bone or mesenchymal stem cells with growth factors that improve bone osteogenesis, recruiting new cells for the neighborhood to generate an optimal environment for tissue regeneration. In this review, current state-of-the-art scaffold manufacturing based on the use of polycaprolactone (PCL) as a biomaterial for bone tissue regeneration will be described by reporting relevant studies focusing on processing techniques, from traditional-i.e., freeze casting, thermally induced phase separation, gas foaming, solvent casting, and particle leaching-to more recent approaches, such as 3D additive manufacturing (i.e., 3D printing/bioprinting, electrofluid dynamics/electrospinning), as well as integrated techniques. As a function of the used technique, this work aims to offer a comprehensive overview of the benefits/limitations of PCL-based scaffolds in order to establish a relationship between scaffold composition, namely integration of other biomaterial phases' structural properties (i.e., pore morphology and mechanical properties) and in vivo response.

Exploring the intricate studies on low-density polyethylene (LDPE) biodegradation by Bacillus cereus AP-01, isolated from the gut of Styrofoam-fed Tenebrio molitor larvae.

This study aims to investigate the biodegradation potential of a gut bacterial strain, Bacillus cereus AP-01, isolated from Tenebrio molitor larvae fed Styrofoam, focusing on its efficacy in degrading low-density polyethylene (LDPE). The biodegradation process was evaluated through a series of assays, including clear zone assays, biodegradation assays, and planktonic cell growth assessments in mineral salt medium (MSM) over a 28-day incubation period. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were employed to characterize the alterations in LDPE pellets, followed by molecular characterization. Over three months, sterile soil + LDPE pellets were treated with different concentrations of gut bacterial strain. The degradation capabilities were assessed by measuring pH, total microbial counts, carbon dioxide evolution, weight loss, and conducting phase contrast microscopy and mechanical strength tests. Results demonstrated that MSM containing LDPE as a carbon source with gut bacterial strain produced a clear zone and enhanced planktonic cell growth. FTIR analysis revealed the formation of new functional groups in the LDPE, while SEM images displayed surface erosion and cracking, providing visual evidence of biodegradation. Molecular characterization confirmed the strain as Bacillus cereus AP-01 (NCBI Accession Number: OR288218.1). A 10% inoculum concentration of Bacillus cereus AP-01 exhibited increased soil bacterial counts, carbon dioxide evolution, and pH levels, alongside a notable weight loss of 30.3% in LDPE pellets. Mechanical strength assessments indicated substantial reductions in tensile strength (7.81 ± 0.84 MPa), compression (4.92 ± 0.53 MPa), hardness (51.96 ± 5.62 shore D), flexibility (10.62 ± 1.15 MPa), and impact resistance (14.79 ± 0.94 J). These findings underscore the biodegradation potential of Bacillus cereus AP-01, presenting a promising strategy for addressing the global LDPE pollution crisis.

Combined compression and bending resistance of steel fibre reinforced concrete tower for wind turbine

Combined compression and bending resistance of steel fibre reinforced concrete tower for wind turbine

Application of machine learning models for the optimisation of compressive strength and water resistance of geopolymer stabilised compacted earth

Application of machine learning models for the optimisation of compressive strength and water resistance of geopolymer stabilised compacted earth

Highly compressible lamellar graphene/cellulose/sodium alginate aerogel via bidirectional freeze-drying for flexible pressure sensor.

Graphene exhibits exceptional electrical properties, and aerogels made from it demonstrate high sensitivity when used in sensors. However, traditional graphene aerogels have poor biocompatibility and sustainability, posing potential environmental and health risks. Moreover, the stacking of their internal structures results in low compressive strength and fatigue resistance, which limits their further applications. In this study, green and sustainable cellulose nanofibers/sodium alginate/reduced graphene oxide aerogels (BCSRA) were synthesized, featuring a well-defined lamellar structure and a fiber cross-linked network, employing techniques such as bidirectional freeze-drying, ionic cross-linking, and thermal annealing. The unique internal architecture of BCSRA results in a compressive strength of up to 64.55 kPa at 70 % compression deformation and an extremely low density of merely 7.21 mg/cm3. Furthermore, BCSRA displays outstanding fatigue resistance, maintaining 82.17 % of its stress after 100 compression cycles at 70 % compressive strain and 86.99 % after 1000 cycles at 50 % compressive strain. Remarkably, when utilized as a flexible pressure sensor, BCSRA achieves a sensitivity of 5.71 kPa-1 and endures over 2200 cycles at 40 % compression, all while ensuring consistent electrical signal output. These properties underscore its significant potential for application in wearable flexible pressure sensors, capable of detecting various human movements.

Enhancing Compressed Earth Block Performance: Effects of Gelatinized Starch and Fiber Reinforcement on Mechanical Properties

This study investigates the impact of starch stabilization and fiber reinforcement on the mechanical properties of Compressed Earth Blocks (CEBs). Various stabilization methods were tested to enhance the mechanical performance of CEBs, with a focus on starch as a natural binder and the incorporation of hemp as natural fibers. The research findings indicate that while starch slightly reduced internal cohesion by 13%, the addition of fibers alone significantly improved compression resistance by increasing strength by a factor of 3.57. When combined with starch, the effectiveness of fibers on compression resistance slightly decreased to a factor of 3.21. Cement stabilization, though providing the highest strength with a factor of 7, poses greater environmental challenges due to its high energy consumption and carbon emissions. In contrast, starch and natural fibers offer promising, eco-friendly alternatives that enhance CEB performance while reducing environmental impact. This study highlights the potential for integrating sustainable materials into construction practices to meet both structural and environmental objectives.

Evaluation of the relationships between compression resistance, point load and indirect traction of aggregates of the built heritage in San Francisco de Campeche

This research work analyzed the properties of stone aggregates, focusing on uniaxial compressive strength, point load strength tests and indirect tensile test.Seybaplaya, a port in Campeche, Mexico, was the site of sample collection from an active bank. The results showed that the compression varied between 8.6 - 84.7 MPa, the point load between 0.52 - 7.12 MPa, and the indirect tension between 0.672 - 10.839 MPa. These properties are essential for designers and builders, providing guidance on the importance of aggregates in structures.

Study of the relationship between uniaxial compressive strength and the indirect tensile test (BTS) in rocks from the bank in Seybaplaya Campeche Mexico

The present research focuses on analyzing the uniaxial compressive strength of rocks and its relationship with the indirect tensile test (the Brazilian method). It is important to note that Seybaplaya, located in Campeche, Mexico, is known for its fishing, industrial and commercial activities, and is home to a rock bank from which samples were obtained for this study. As a result, an equation was developed that allows predicting the simple uniaxial compressive strength from the values obtained in the indirect tensile test. It should be noted that this relationship is valid only for rocks with similar lithological characteristics of the samples analyzed. The results of the analysis and conclusions show the linearity of the relationship between the simple uniaxial compression resistance and the indirect tensile test.

First-Principles-Based Structural and Mechanical Properties of Al3Ni Under High Pressure

The structural, elastic, and thermal characteristics within the 0–30 GPa pressure range of Al3Ni intermetallic compounds were extensively studied using first-principles computational techniques. Using structural optimization, lattice parameters and the variation in volume variation under diverse pressures were determined, and the trends in their structural alteration with pressure were identified. The computed elastic constants validate the mechanical stability of Al3Ni within the applied pressure range and show that its compressive stiffness and shear resistance increase rapidly with increasing pressure. The Cauchy pressure variation implies that the metallic nature of Al3Ni increases gradually with increasing pressure. Moreover, through analysis of Poisson’s ratio, the anisotropy factor, and the sound velocity, we ascertained that pressure attenuates the anisotropic attributes of the material, and Al3Ni exhibits more pronounced isotropic characteristics and mechanical homogeneity under high-pressure conditions. The substantial increase in the Debye temperature further suggests that high pressure fortifies the lattice dynamic rigidity of the material. This current research systematically elucidated the stability of Al3Ni under high-pressure conditions and the law of the transformation of it mechanical behavior, providing a theoretical foundation for its application under extreme circumstances.

Materials and structures at cold‐region and Arctic low temperatures: A state‐of‐the‐art review

AbstractConstruction of infrastructures in cold regions and the Arctic has grown rapidly since the 2000s, including railways, platforms, bridges, roads, and pipelines. However, the harsh low temperatures significantly influence the mechanical behaviors of construction materials, and bring safety and durability challenges to these engineering structures. This study made a state‐of‐the‐art review on materials and structures exposed to low temperatures. This review started from constructional‐material mechanical properties, including concrete, steel reinforcement, mild/high‐strength steel plate, and steel strand at low temperatures. It reflected that low temperatures improved the strength of construction materials. However, the freeze–thaw cycles (FTCs) had a detrimental effect on the modulus and strength of concrete. Furthermore, it was revealed that low temperatures increased the interfacial bonding strength between the steel reinforcements (or shear connectors) and concrete. Moreover, low temperatures improved the bending, shear, and compression resistances of reinforced concrete (RC) or prestressed concrete structures, but reduced the ductility of RC columns under lateral cyclic loads. Finally, reviews also found that low temperatures improved the compression resistance of concrete‐filled steel tubes using mild, high‐strength, and stainless steels, whereas FTCs and erosion reduced their compression capacity. In addition, low temperatures increased the bending resistance of steel–concrete composite structures, but the FTCs reduced it. The low temperatures bring challenges to the safety and resilience of engineering constructions, which requires careful further studies. Continuous further studies may focus on the durability of materials and the resilience of structures under diverse hazards, including earthquakes, impacts, and even blasts.

Mechanical Characteristics of Sisal/Al<sub>2</sub>O<sub>3</sub>/Epoxy Hybrid Composites

This study examines the impact of Al2O3 particles on composites made of sisal and epoxy. A unique combination of hand lay-up and compression molding procedures are used to fabricate the Sisal/Al2O3/epoxy hybrid composites, with different weight percentages of Al2O3 particles of 0%, 1%, 2%, and 3%. The produced sisal/Al2O3/epoxy hybrid composites' flexural, tensile, and compressive properties are then correlated with water absorption studies. The sisal/epoxy composites have undoubtedly been affected by the Al2O3 particles, which have improved their mechanical and physical properties. Compared to other composite samples, the sisal/2wt.%Al2O3/epoxy hybrid composites show superior flexural, tensile, compressive, and water absorption resistances. Therefore, the optimal combination of hybrid sisal/Al2O3/epoxy composites can prominently improve the properties, making them a viable alternative for a variety of industrial applications.

Adobe Block Design with Addition of Fiberglass to Improve the Compression Resistance in the District of Saylla, Province and Department of Cusco

This article discusses improving the low compression resistance of adobe houses in Saylla, Cusco, by incorporating fiberglass. It reviews studies employing synthetic materials and suggests adobe blocks with varying proportions of fiberglass. These adobe blocks to be studied will be produced in a traditional, regulated manner, with the addition of fiberglass at 0.10%, 0.50%, and 1.00%. Three samples of each type will be tested for reliable results. Compression tests show that traditional adobe fails to meet standards, while regulated adobe with fiberglass significantly enhances resistance. Adding 1.00% fiberglass results in a 123.20% increase in compression strength, reaching 1.634 MPa. The study concludes that fiberglass effectively strengthens adobe, providing practical applications for sustainable construction in Saylla, Cusco.

Nonlinear deformation model in the analysis of eccentri-cally compressed concrete-filled steel tube elements

This paper discusses the applicability of a nonlinear deformation model for determining the parameters of the stress-strain state of eccentrically compressed concrete-filled steel tube elements. Adjustments to the deformation diagrams of the concrete core and the steel tube were introduced to account for the complex stress state of the materials. The cross-section of the concretefilled steel tube element is considered as a collection of elementary areas. As the criterion for calculating compressive resistance at the ultimate strength stage, it is proposed to use the maximum force calculated based on the compatibility condition of steel and concrete deformations. The advantage of this criterion is that it eliminates the need to normalize the ultimate compressibility of concrete and accounts for the high degree of force redistribution in cross-sections. The method was verified by comparing the calculated and experimentally obtained ultimate forces on a sample of experimental data. The applicability of the nonlinear deformation model based on deformation diagrams, considering the multiaxial stress state of concrete and the steel tube, was confirmed for the analysis of eccentrically compressed concrete-filled steel tube elements.

Axial and eccentric compressive behavior of partially encased channel–concrete composite columns with bolted connections in modular buildings

This paper introduces a novel partially encased channel–concrete composite (PECC) column for modular buildings, aiming to eliminate the need for cast-in-place concrete and facilitate rapid assembly. The PECC column consists of two prefabricated modules connected by high-strength bolts. To evaluate the column's viability, six slender specimens—one bare steel column and five composite columns—were tested under axial and eccentric compression. Variables considered included the presence of concrete, the type of transverse connections, bolt spacing, and load eccentricity ratio. The compression performance of the PECC columns was analyzed by examining their failure patterns, load–deformation responses, initial stiffness, compressive capacity, and ductility. Test results revealed that the PECC columns failed due to global buckling, concrete spalling, and crushing. The bolted connections effectively prevented module separation, enabling the PECC columns to exhibit favorable compressive behavior. The reinforced concrete encased in the channel delayed the column's buckling failure, increasing its initial stiffness and compressive capacity by 98% and 198%, respectively. Using perforated steel plates instead of transverse links between the concrete and the channel enhanced the column's initial stiffness by 20% but had little effect on its compressive capacity. Reducing the bolt spacing improved the column's initial stiffness and compression resistance by 50% and 5%, respectively. Additionally, a finite element model for the PECC columns was developed and validated against test results. Finally, simplified formulas derived from Eurocode 4 were proposed to estimate the resistance of PECC columns under axial and eccentric compression.

Behaviour and design of extruded high-strength aluminium alloy SHS beam-columns

An extensive study of beam-columns made from 7A04-T6 aluminum alloy in a square hollow section (SHS) configuration is presented in this paper, integrating both experimental and numerical work to study their flexural buckling behaviour. Eight pin-ended SHS specimens with two extruded SHS profiles - 80×5 and 120 × 10 (in mm), were tested under eccentric compression, along with tests of material coupons and measurements of initial geometric imperfections. The experimental data were employed in the investigation to assess the validity of the numerical model, which was subsequently subjected to a series of parametric analyses aimed at expanding the existing results across a wider spectrum of slenderness ratios, cross-section dimensions, and load combinations. Both experimental and simulated datasets were employed to verify the precision of resistance forecasts for SHS beam-columns by design approaches outlined in European, Chinese and American standards. Findings indicated that both the European and Chinese standards tended to provide relatively conservative predictions for buckling resistances, while the American standard sometimes produced predictions leading to higher risk. Finally, a modification strategy for the design of AA7A04-T6 SHS beam-columns, utilizing modified interaction buckling factors that account for non-dimensional member slenderness and compression resistances, was suggested to enhance the precision and reliability of resistance forecasts.

Study on sewage erosion resistance of nano titanium modified coral concrete

Sewage environments can significantly erode and degrade coral concrete, impacting its structural longevity. Moreover, the curing water environment greatly influences coral concrete's resistance to sewage erosion. This study investigated the modification of coral concrete with nano TiO2 to enhance its sewage erosion resistance. Concrete specimens with four different mass fractions of nano TiO2 were prepared and cured in three environments. Tests for compressive strength, flexural strength, and mass loss were conducted before and after 180 days of sewage exposure, and a corrosion coefficient was defined to evaluate resistance to sewage corrosion. While nano TiO2 significantly improved the mechanical properties and sewage erosion resistance of coral concrete, oxalic acid and seawater environments had adverse effects. Furthermore, increasing the nano TiO2 mass fraction initially enhanced and then reduced strength and resistance, while mass loss rates first decreased and then increased. The optimal nano TiO2 dosage of 4% resulted in a maximum increase of 22.2% in compressive strength, 33.2% in flexural strength, a 0.06 increase in the compressive corrosion resistance coefficient, and a 0.1 increase in the flexural corrosion resistance coefficient. At this dosage, compressive strengths of coral concrete cured in oxalic acid and seawater were 97.8% and 93.9% of those in freshwater, while flexural strengths were 97.8% and 94.4%, respectively, with slight decreases in corrosion resistance coefficients, accompanied by higher mass loss rates. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that nano TiO2 promotes cement hydration, forming a dense structure by filling matrix pores. However, oxalic acid reacts with Ca(OH)2 to form calcium oxalate, slowing cement hydration, while MgCl2 in seawater reacts with Ca(OH)2, forming expansive Mg(OH)2, which increases internal concrete pores.

Wettability and physical modification of coal under vacuum saturation invasion of SiO2 nanofluids

Coal seam water injection technology could improve the water content of coal seam, which is an effective technical measure to reduce dust generation in the mining process. Water-based silica nanofluids are a green wetting agent for coal seam water injection. To understand the wetting mode of nanofluids in coal, it is necessary to explore the physico-chemical properties of nanofluid-modified coals. First, a new idea of saturation and intrusion of nanofluid into coal was proposed by using vacuum pressurized saturation device. Then, the physical and chemical properties of the modified coal were studied by Fourier transform infrared spectrometer, low-temperature liquid nitrogen adsorption experiments, and uniaxial compression mechanics experiments. The results showed that the content of oxygen-containing functional groups in the modified coal increased, which was positively correlated with the concentration of nanofluids. The pore structure of the modified coal sample changed from complex to simple, and the nanoparticles blocked the micropores to make the coal surface smooth. The saturation invasion of SiO2 nanofluids changed the mechanical properties of coal samples, and the compressive resistance of coal was weakened, and the minimum strength of the coal invaded by 1.5 wt. % SiO2 nanofluid saturation was 13.68 MPa. The saturation intrusion of SiO2 nanofluids has a negative effect on the surface adsorption of coal samples and the blockage of microporous structures, and makes the coal seam easier to be wetted, which contributes to the application and development of nanofluids in the field of coal seam water injection.

Fracture Behavior of Engineered Cementitious Composites Concrete Under Center Point Bending Load

Abstract Fracture behavior is an important issue to consider when analysing and designing important concrete structures. Fracture behavior is dependent on the characteristics and materials percentage in concrete. Thus, due to the application of polyvinyl alcohol fiber, this type of concrete’s structure and fracture behavior will differ from normal concrete. This investigation aims to determine some mechanical properties, in addition to the fracture parameters corresponding to low and medium compressive resistance of engineering cementitious composite concrete reinforcing by fiber for notched and un-notched beams, using size effect model techniques in contrast to conventional concrete. The outcomes illustrate an increment in modulus of rupture; both fracture energy and fracture toughness, which were incremented. At the same time, the nominal stress reduction of the notched-beam is superior to un-notched beam. Five mixes for each strength grade were cast to test fresh and hardened properties; the optimum mixture that gave the higher modulus of rupture was chosen for fracture parameters investigations. Two engineering cementitious concrete mixtures containing 1.5% and 2% polyvinyl fiber for grades M25 and M65, respectively, obtained higher modulus of rupture. Geometrically, three (75×75×400) mm, (75×150×800) mm, and (75×200×1200) mm notched-beams were investigated by applying one central point load for testing their fracture toughness, fracture energy, and characteristics length, also the influence of tensile ductility of engineering cementitious concrete. The denser interfacial transition zone of engineering cementitious concrete had the highest fracture toughness and a ductile behavior of mode of failure with a flatter fracture plane than conventional concrete. The higher fracture toughness value was observed on (M25-BC3) and (M65-BC2). Outcomes indicate that conventional concrete exhibited greater sensitivity to size effect parameter due to its poorer tensile ductility than concrete incorporating polyvinyl alcohol fiber.

The Recycling Use of Concrete Waste as Aggregate to Produce Different Types of Concrete

The present study depends on two types of concrete: the first and second samples belong to Portland cement with a high strength of 52.5 R, and ordinary Portland cement with a normal strength of 42.5 N, respectively. The physical tests for these two samples according to Iraqi Standard Specification No. 5 of 2019 were conducted. Whereas the third and fourth samples of concrete waste were taken from Mosul City and Al-Anbar Governorate. The concrete waste samples were broken into different-size particles as a fine and coarse aggregate using a mechanical crusher (Los Angeles). According to the Iraqi Standard Specification No. 45 (1984, the Physical and chemical tests for both fine and coarse natural aggregate and recycled concrete waste were conducted. The physical and mechanical results of the recycled aggregate testing samples were found to be within the limits of specifications, in which a reference concrete was made from the standard cement samples with natural aggregate for comparison. The natural aggregate was replaced with 100% recycled aggregate, and its behavior was studied through mechanical properties tests, including compressive strength, flexural resistance, and direct tensile resistance within 7 and 28 days. The results show a decrease in the compressive, flexural, and direct tensile strength in the subjected samples compared to the reference specimens. The study concluded that a 100% replacement ratio of coarse and fine recycled aggregate can be used successfully with different types of cement to obtain a new type of concrete that can be used in several engineering fields. The mechanical properties of the new concrete depend mainly on the type, class and quality of the natural cement even on the properties of the recycled aggregate.