Compressive Ductility Research Articles

Exploring the performance of steel fiber reinforced lightweight concrete: A case study review

This review paper aims to investigate the prior research on incorporating steel fibres into lightweight concrete (SF-LWC) to produce sustainable and environmentally friendly concrete. The objectives of the study are to analyse the chemical composition and physical characteristics of SF-LWC and examine its hardened properties such as compressive and flexural strengths. The research also focuses on the impact of steel fibres on the longevity of lightweight concrete and explores various properties such as the failure mode, stress-strain behaviour, ductility, and modulus of elasticity. A comprehensive literature review was conducted to evaluate the prior studies on the use of steel fibres in LWC. The findings of the previous studies were analysed and compared to determine the physical and durability properties of SF-LWC. The results of the literature review showed that steel fibres have a length range of 30–36 mm and a diameter range of 0.5–0.92 mm, with a smooth surface and high tensile strength of 1100–3000 MPa. The addition of steel fibres to LWC was found to improve compressive and flexural strengths and increase ductility. The review also highlights the impact of steel fibres on the durability and longevity of the concrete. The original contribution of this research lies in its comprehensive analysis of previous studies that have used steel fibres as a partial replacement for cement in lightweight concrete. The findings of this study provide valuable insights into the properties and performance of sustainable SF-LWC and offer suggestions for future research. By presenting a critical evaluation of prior research, this study advances the field and lays a solid foundation for further investigation. This paper offers recommendations for future studies and provides valuable insights into the properties and performance of SF-LWC, contributing to the advancement of sustainable and energy-efficient construction methods.

Mechanical behavior of CuZrAl metallic glass scaffolds fabricated by selective laser melting

Selective laser melting (SLM) was used to manufacture the CuZrAl metallic glass (MG) scaffolds containing body-centered cubic and face-centered cubic combined lattices (F2BCC) with straight and curved struts, and the effects of the lattice structures on the mechanical behavior were examined. The findings show that the curved struts significantly improve the compressive ductility by 122 % and the energy absorption by 106 %. The curved struts can effectively prevent catastrophic shear fracture and delay the fracture – mainly due to the relief of strain concentrations. The results from this work prove that it is possible to effectively improve the ductility and toughness of SLM MG components by designing a suitable lattice structure.

Axial compressive behavior of middle partially encased composite brace

To prevent the buckling and unbalanced tensile-compressive behavior of steel braces, a middle partially encased composite brace (MPEC) is proposed in this paper. In this composite brace, concrete is encased in the middle section of the H-shaped steel, and stiffeners are welded in the steel section for reinforcement. Axial compressive tests were implemented on four MPEC braces and one comparison specimen with considering the flange thickness, longitudinal reinforcement ratio, stirrup spacing and slenderness. The test results revealed that the failure of all composite braces was due to local buckling of the flange plates and separation from the concrete. The presence of concrete within the steel flange effectively limited the buckling of the H-shaped steel and improved the stiffness and compressive capacity. The compressive capacity of the composite braces was primarily influenced by the sectional dimension of the H-shaped steel, while the contribution of the reinforced concrete was limited. Additionally, a higher longitudinal reinforcement ratio improved the ductility of the composite braces, while larger stirrup spacing reduced both the compressive capacity and ductility. The specimen with large slenderness demonstrated poor mechanical properties and experienced a more abrupt failure. The axial compressive capacity of MPEC braces was calculated based on the critical buckling stress of steel plate and the confinement of concrete in partially encased composite columns (PEC). The calculated results showed good accuracy compared to the experimental data, and thus, the formula proposed in this study can be applied in design applications to predict the axial compressive capacity of MPEC braces.

A State-of-the-Art Review on Axial Compressive Behavior of Concrete-Filled Steel Tubes Incorporating Steel Fiber and GFRP Jacketing

Several types of fibers have enhanced the structural response of reinforced concrete-filled steel tubes (CFSTs). This article presents a state-of-the-art review of studies done on the axial compressive behavior of steel and glass fiber-reinforced CFSTs. The aim of using fibers is to improve the response of the CFSTs. This research indicates the findings of experimental programs and analytical evaluations of the effects of the fiber incorporation on the behavior of the CFSTs. The results of this research work demonstrate that steel fibers (SFs) have enough evident improving effects on the failure mode and load-carrying capacity of the CFSTs. The SFs greatly increase the ductility of the CFSTs. To enhance the compressive strength and ductility of the CFSTs, adding the SFs by 1% to the concrete mix is more effective than adding by 1.5%. The use of the SFs mixed with expansion agent considerably increases the yield and ultimate loads of the CFSTs. More glass fiber-reinforced polymer (GFRP) sheets reduce buckling and develop the compressive strength of the CFSTs. The implementation of the GFRP jackets not only enhances the load-carrying capacity of the CFSTs, but also increases their ductility. The GFRP reinforcement techniques for the CFSTs are also effective in improving their structural stiffness and energy absorption capacity.

Effect of Re and Al additions on the microstructure and mechanical properties of Nb-18Ti-12W alloy

Microstructure and mechanical properties at 25–1200 °C of new refractory alloys, Nb-18Ti-12W (NTW), Nb-18Ti-12W-5Re (NTW-R) and Nb-18Ti-12W-5Re-1Al (NTW-RA), all compositions are in atomic percent, are reported. The alloys are developed as an alternative to a denser, more expensive and difficult-to-process refractory alloy WC-3009. After production by arc melting and hot isostatic pressing at 1400 °C, 207 MPa for 3 h, the alloys have a BCC crystal structure with the average grain size of ∼150–200 μm and contain low volume fraction of (Ti,N)-rich precipitates near grain boundaries. NTW shows excellent malleability at all studied temperatures. Its yield stress at 25 °C, 1000 °C and 1200 °C is 874 MPa, 353 MPa and 202 MPa, respectively. The NTW-R and NTW-RA alloys are stronger at all the studied temperatures; however, they lack in compression ductility at 25 °C. Extensive deformation twinning and formation of intergranular voids precede the fracture of these two alloys at 25 °C.

Sustainable high-strength lightweight concrete with pumice stone and sugar molasses

AbstractThe building sector benefits from high-strength lightweight concrete (HSLWC) in various aspects, particularly in reducing the structure’s dead load. Incorporating waste materials into HSLWC encourages sustainable practices, reduces their environmental effect, and decreases product’s costs. This research focuses on producing sustainable HSLWC using a pumice stone and additive materials such as sugar molasses, silica fume, and high-range water reduction. The physical and mechanical properties and structural efficiency were investigated. The results demonstrate that the inclusion of additive material is the primary factor controlling the properties of the concrete. Also, using pumice stone instead of gravel in high-strength concrete significantly reduced weight and increased thermal insulation by 19.31 and 43.55%, respectively. Furthermore, the addition of steel fibers in HSLWC improved the compressive strength, tensile strength, ductility, and structural efficiency.

Size effect tests on axial compressive behavior of BFRP-reinforced concrete columns

To explore the compressive behavior and corresponding size effect of concrete columns internally reinforced with basalt fiber‐reinforced polymer (BFRP) bars and stirrups, twelve geometrically similar columns were tested under axial compression. The test parameters included cross-sectional shapes, cross-sectional diameters/widths and stirrup ratios. The test results indicated that both the circular and square BFRP reinforced concrete (RC) columns presented a notable size effect on nominal compressive strength and ductility. As the cross-sectional size varied from 200 mm to 600 mm, the nominal compressive strength of circular and square columns exhibited maximum decreases of 11.0 % and 19.1 %, respectively, while the maximum decreases of ductility index were 66.2 % and 16.7 %, respectively. Moreover, increasing the stirrup ratio could effectively improve the confinement efficiency and ductility as well as weaken the size effect on nominal compressive strength of BFRP RC circular columns. The accuracy of available design equations was significantly influenced by the confinement effect of BFRP spirals in circular columns, while for square columns the specimen size was the most important factor. Finally, new equations were derived by considering the confinement effect of stirrups or size effect of concrete, and these equations showed satisfactory accuracy in predicting the axial load-carrying capacity of BFRP RC columns.

Microstructure evolution and mechanical behavior of additively manufactured CoCrFeNi high-entropy alloy fabricated via cold spraying and post-annealing

In this work, equiatomic CoCrFeNi high-entropy alloy (HEA) was fabricated by solid-state cold spray additive manufacturing technology and then post-spray annealed at the temperature range of 500–1000 °C for 2 h. By adjusting the annealing temperature, four types of deposits (i.e., as-sprayed, recovered (500 °C), partially recrystallized (700 °C), and fully recrystallized (1000 °C) deposits) were obtained, and their microstructure, compressive and tensile properties were systematically explored. The as-sprayed deposit exhibited high compressive yield strength due to the dislocation strengthening and grain boundary strengthening effects but fractured within the elastic deformation regime in the tensile test. Such significant tension-compression asymmetry can be attributed to the difference in the sensitivity of the deposit to interior defects (i.e., pores and particle boundaries) under tensile and compressive loads. Only recover annealing hardly influenced the microstructure and mechanical properties of the deposits. While recrystallization annealing could trigger enhanced interface diffusion and the resultant metallurgical bonding, as evidenced by the improved deposit density and less visible interparticle interfaces. The partially recrystallized and fully recrystallized deposits exhibited an excellent combination of compressive strength and ductility. While the fully recrystallized deposit exhibited almost equal tensile and compressive yield strength and the best recovery of tensile ductility, indicating the weakened tension-compression asymmetry.

On the utilization of rice husk ash in high-performance fiber reinforced concrete (HPFRC) to reduce silica fume content

The HPFRC refers to a category of fiber-reinforced cement-based materials that have the remarkable capability to flex and strengthen prior to shattering. At present, research is being conducted with the intention of producing a worldwide guideline for the development of structures using HPFRC. However, due to its high initial price and constrained availability, its implementation is challenging, particularly in developing countries. In this study, the effects of fly ash (FA) and rice husk ash (RHA) were examined, with 10%, 20%, and 30% of the cement replaced with FA. Furthermore, the mix providing maximum compressive strength was then taken to replace the silica fume content at 10, 20, 30, and 40% by RHA, steel fiber was also added to optimize the compressive and flexural ductility performance of the specimens. An extensive evaluation of fresh, mechanical, microstructural, and durability of HPFRCs were carried out. In addition, the eco-mechanical properties of fiber-reinforced concrete are studied by taking into account the post-peak behavior of the manufactured specimens and associated CO2 emissions. Test results show that the maximum improvement in compressive, tensile, and flexural strengths was 6.49%, 12.85%, and 5.27%, respectively, at 10% RHA replacement. In addition, as the concentration of RHA increased, the flexural bending toughness increased between 7.4% and 9.2%, with good agreement between the analytical models and the experimental results of the uniaxial compressive stress–strain. Moreover, the gradual increase in RHA concentration improved the durability of the HPFRCs, as evidenced by a maximum reduction in sorptivity coefficient of up to 48 percent for 30% RHA replacement. Finally, the investigation shows how the eco-mechanical index (EMI) can be used to evaluate material design options for HPFRCs.

Effect of freezing soil temperatures on strength parameters of clayey sand soils stabilized by poly propylene and poly vinyl alcohol fibers

Applying synthetic fibers is one of the most effective physical methods for soil improvement and stabilization. In this paper, we determine the effects of polypropylene (PP) and poly vinyl alcohol (PVA) fibers contents (0.2, 0.5, 1.0 and 1.5%) at environment temperature (25 °C) and various freezing soil temperatures (0, −5, −10 and − 15 °C) on stabilization of the clayey sand soil (SC) samples. The results show that for both types of fibers, by simultaneous increasing of fiber content and lowering the temperature, the values of the unconfined compressive strength (UCS), elastic modulus (EM), ductility and California bearing ratio (CBR) increase, and they all reach their maximum values for 1.5% fiber content at −15 °C. Moreover, we show that PVA fibers perform better compared to PP fibers in increasing of UCS, EM, ductility and CBR values for different fiber contents and temperatures. This can be attributed to the fact that PVA has higher tensile and flexural strength compared to PP fiber.

Mechanical properties of steel reinforced coral aggregate concrete column under uniaxial compression

The production of coral aggregate concrete (CAC) from coral debris effectively addresses the lack of building materials in island construction. Due to the low compressive strength and visible brittleness of CAC, steel reinforcement with anti-rust treatment is adopted to improve the mechanical properties of CAC. This paper presents an experimental study on the mechanical behavior of 45 anti-rust coated steel reinforced coral aggregate concrete (RCAC) columns under uniaxial compression, designed with the consideration of concrete strength and configurations of the transverse reinforcement. The test results show that the volumetric ratio of lateral confinement can improve the compressive strength and ductility of RCAC effectively. The strengthening effect of diamond-shaped composite and spiral hoop is higher, while that of rectangular hoop is slightly weaker. The increase of concrete strength has a significant positive effect on the peak stress, but not on the peak strain. Based on the experiments, the formulae for the peak stress and peak strain of RCAC are given, and the constitutive model of RCAC is proposed. Moreover, the calculation method of the theoretical bearing capacity is arrived at, and the predicted values with a specific safety reserve are close to the measured values.

Experimental study and analysis-oriented model of PET FRP confined ECC cylinders under monotonic axial compression

Recently, several compressive yielding (CY) materials have been developed to improve the flexural ductility of FRP bar-reinforced concrete members, regarding the lack of ductility of FRP bars. However, the currently developed CY materials involving or using steel were not ideal for structures exposed to marine environments. It still needs to develop the non-metal material having CY behavior. This study investigated the failure modes and mechanical properties of large rupture strain (LRS) FRP confined ECC under monotonic axial compression intending to develop it to achieve the demand of CY properties. The results demonstrated that LRS FRP jackets could significantly enhance the compressive ductility (as high as 16.27) of ECC compared to the conventional FRP confined concrete or ECC with the same confinement stiffness of FRP jacket. Moreover, the ductility of LRS FRP confined ECC could reach the ductility of existing CY materials. After developing the dilation model and actively-confined ECC stress–strain model developed based on the database, the analysis-oriented model for LRS FRP confined ECC considering load-path dependence was developed to design the LRS FRP confined ECC as the CY material.

Influence of Microstructure on the Mechanical and Corrosion Response of a Friction Stir-Extruded WE43 Magnesium Rod

Friction stir extrusion (FSE) was used with WE43 Mg to create a rod with a hybrid microstructure. The rod’s electrochemical corrosion response was characterized in Hank’s balanced salt solution at 37 ± 1 °C. The rod showed refined grains near the edge, while coarse grains were observed at the rod center. A larger fraction of precipitates was observed near the edge possibly hindering grain growth. The refined grains and the presence of a larger fraction of precipitates in the edge regions resulted in higher hardness owing to a confluence of precipitate hardening and solid–solution strengthening. Texture analysis of the rod cross-section exhibited a basal texture, perpendicular to the extrusion direction and populating the rod’s outer surface. In compression, the rod showed a near-base material yield strength (225.6 MPa) and a good combination of compressive strength (357.5 MPa) and ductility (~17.7%). The rod’s electrochemical corrosion response was sensitive to variations in the grain size, texture, and precipitate distribution between the rod core and edge regions. Removal of the edge region resulted in the formation of a more stable and protective film with an increase in the immersion period. The results from the study establish the ability of the FSE process to tailor the rod microstructure thereby influencing the mechanical properties and corrosion rate of Mg alloy.

Behavior of ultra-high-performance concrete (UHPC) encased concrete-filled steel tubular (CFST) stub columns under axial compression

A total of seventeen ultra-high-performance concrete (UHPC) encased concrete-filled steel tubular (CFST) stub columns and one normal concrete encased CFST stub column were tested under axial compression. The influence of steel fiber content, diameter of steel tube, wall thickness of steel tube and strength of core concrete on the failure mode, axial load-axial strain curve, axial compression bearing capacity and ductility of the members was experimentally investigated. Furthermore, finite element model of UHPC encased CFST stub column subjected to axial compression was established. Based on the verified finite element model, typical axial load-axial strain curve, load distribution proportion, stress development and interaction between different components of the members were analyzed in depth. Parametric studies were performed to clarify the influence of steel fiber content of UHPC, CFST ratio, wall thickness of steel tube, steel yield strength, core concrete strength and stirrup spacing on the behavior of the members. At last, a simplified formula for calculating the axial compression bearing capacity of UHPC encased CFST stub columns was proposed, which could provide reference for practical engineering applications.

Analysis of Axial Compression Performance of Concrete Stub Column with CRB600H Stirrups

The CRB600H reinforcement is a new type of cold-rolled ribbed steel bar, which has the advantages of green and low carbon, stable quality, saving precious metal resources and so on. In order to study the axial compression performance of short concrete columns with CRB600H stirrups, the finite element analysis model of high-strength reinforced concrete stub columns was established by using ABAQUS, and the accuracy of the finite element model was verified by literature experiments. The effects of stirrup construction (Type A, B and C), stirrup spacing and concrete strength on the axial compressive bearing capacity and ductility of concrete columns with CRB600H stirrups were analyzed and compared with HRB400 stirrups columns. The results showed that the peak bearing capacity of the specimens with CRB600H stirrups was similar to that with HRB400 stirrups, and the ductility of the specimens was improved with CRB600H stirrup. Compared with the type A stirrup and type C stirrup, the type B stirrup had the best concrete restraining effect, and the ductility and peak bearing capacity of the specimens were higher. With a decrease in the stirrup spacing, the ductility and peak bearing capacity of the specimens increased. With an increase in concrete strength, the peak bearing capacity increases, but the ductility decreases. Through parameter analysis, a formula for calculating the axial bearing capacity of 600 MPa high-strength stirrup concrete stub columns based on the effective confinement index (keλt) was proposed. It is suggested that the equivalent volume of a HRB400 stirrup can be replaced by a CRB600H stirrup in the actual project. At the same time, when the high-strength stirrup was used, the restraining effect of the stirrup on concrete should be considered in the calculation of the axial compression bearing capacity.

Experimental Investigation on the Axial Compressive Behaviour of Cold-Formed Steel-Concrete Composite Columns Infilled with Various Types of Fibre-Reinforced Concrete

The exceptional structural strength and low cost of steel-concrete composite columns make them a popular choice for civil engineering structures. Numerous forms of composite columns, including steel tubes filled with concrete, have been produced recently in response to various construction situations. Cold-formed steel tubular columns with concrete filling have higher strength and ductility due to their capacity to withstand inner buckling and postpone outward buckling. The objective of this research is to determine the ductile and strength performance of composite columns containing various forms of fibre-reinforced concrete when subjected to axial compression. Several different kinds of fibre-reinforced concrete (FRC) are employed as additives in hollow steel columns, including steel FRC, carbon FRC, glass FRC, coir FRC, jute FRC, and sisal FRC. Axial compression tests were performed on 24 columns, including three hollow steel columns and 21 composite columns. Three distinct slenderness ratios were developed and used. Axial bearing capacity, compressive stress-strain curves, ductility, peak strain, axial shortening, and toughness were among the topics covered by the axial compression test. Experimental findings demonstrated that all conventional composite columns experienced failure through overall buckling, Local buckling and crushing of concrete infill, which was transformed into more ductile failure using fibre-reinforced concrete infills. The test results revealed that fibre-reinforced concrete-infilled steel columns outperformed conventional composite columns in terms of strength, ductility, and energy absorption capacity. The percentage increase in load-carrying capacity was observed as 203.88%, 193.48% and 190.03% when compared to hollow cold-formed steel tubular columns in medium, short and stub columns, respectively. Under assessment of stub, short, and medium columns, the load-strain plots demonstrated that the steel fibre-reinforced concrete in-filled columns performed well in terms of ductility. Localized buckling and crushing of the concrete infill caused the composite columns with low slenderness ratios to fail. In contrast, concrete-filled steel tube columns with higher slenderness ratios showed column failure through the overall buckling of the composite column.

Physical and mechanical properties of synthetic beams from high density polyethylene waste

Improper processing of plastic waste can cause several environmental problems, such as air pollution, soil damage, respiratory diseases, and others. This research utilizes high density polyethylene (HDPE) waste as a basic material for synthetic beams. The manufacture of synthetic beams goes through several stages, such as washing, drying, crushing, chopping, and melting HDPE waste, as well as moulding into a block. The physical properties examined in this study include compressive strength, flexural strength, density, and ductility which refer to SNI 03-3958-1995 and SNI 03-3959-1995 codes. From the test results, it was obtained that the average compressive strength and flexural strength of synthetic beams were 1.52 – 2.53 MPa and 0.61 – 0.95 MPa, respectively. Synthetic beams have an average modulus of elasticity of 109.4 MPa, and a density of 834.8 kg/m3. The test results from this study indicate that the strength of synthetic beams from HDPE is low and does not meet the requirements for use as a construction material. In further research, innovation is needed to obtain stronger synthetic beams.

Co47.5Fe28.•5Ni19Si3.3Al1.7 High-entropy Skeletons Fabricated by Selective Laser Melting and Properties tuned by pressure infiltration of Al

High saturation magnetization and low coercivity are required for soft magnetic materials. This study investigated the Co47.5Fe28.5Ni19Si3.3Al1.7 high-entropy soft magnetic skeleton was prepared by selective laser melting. Then Al was pressure infiltrated into skeletons to obtain a dense composite material. The high-entropy composite materials possessed favorable compressive ductility and moderate soft magnetic properties. The high-entropy composite materials were obtained with Ms being 97.1 emu/g, 79.8 emu/g, 33 emu/g and possessing 19 Oe, 15.8Oe and 17Oe of Hc, respectively. However, the magnetostriction coefficient remains low level, about 5ppm. These reported properties are attributed to the special structure of the material studied in present experiment. Nevertheless, a novel strategy of structural designing was proposed in this paper.

Rheological and microstructural properties of FA+GGBFS-based engineered geopolymer composites (EGCs) capable of comparing with M45-ECC as mechanical performance

In this study, it has been aimed to obtain the fly ash + ground granulated blast furnace slag (FA + GGBFS)-based engineered geopolymer composites (EGCs) having similar bearing strength and deformation capacity with the engineered cementitious composite (M45-ECC) known as M45. EGCs incorporating 70% FA and 30% GGBFS as binder were developed under three different groups in which the different ratios of alkali liquids/binder (AL/Bi) with the different content of AL + Bi. All of eight FA + GGBFS-based EGCs designed with 2.5 ratio of Na2SiO3/NaOH. FA + GGBFS-based EGCs, which were kept in the mold under laboratory conditions for 24 h immediately after production, were kept in water at 60 °C until the test age. The fresh, rheogical, mechanical and microstructural properties of FA + GGBFS-based EGCs were determined. Test results indicated that FA + GGBFS-based EGCs can be developed with similar or higher compressive strength and ductility than that of M45-ECC. However, the flexural strength of M45-ECC was higher than those of all other composites. In addition, TGA/DTA and FTIR analysis supported that the excessive amount of AL + Bi content would not improve the characteristics of FA + GGBFS-based EGCs after the optimal production of C–S–H and N-A-S-H gels which acquired in geopolymerization. However, ductility continued to improve significantly as the AL + Bi content increased. Moreover, reduction of AL/Bi ratio increased the total gel content and thus, the compressive strength of composites developed.

Microstructure and mechanical properties of medium-entropy TiNbZr alloy-based composites, reinforced with boride particles

The TiZrNb metal-matrix composites reinforced by in-situ formed borides were produced by vacuum arc melting using different amount of TiB2 (0.2, 2.0 and 4.4 wt%). Structure, mechanical properties and biocompatibility of the composites were studied. The initial microstructures of the composites were composed of the bcc TiZrNb matrix and needle-like (Ti, Nb) B particles the volume fraction of which was ∼ 1.0%, 6.8% and 13.2%, respectively. Besides a small amount of the ω phase particles measuring ∼ 10 nm were found in the matrix of all the composites. Compression test at room temperature showed that the minimum content of the borides did not have noticeable strengthening effect on mechanical properties of the composite. An increase in the amount of (Ti, Nb) B to 6.8 vol% resulted in an increase in the yield stress by 22% to ∼ 900 MPa without a visible decrease in ductility. The composite with 13.2 vol% of the borides showed the yield strength of 1010 MPa and compression ductility (deformation till fracture) of 9% that can be associated with a hypereutectic composition and appearance of coarse particles of primary (Ti, Nb) B. Evaluation of main strengthening mechanisms suggested that the load transfer strengthening contributed mainly to the overall strength of the composite. Analysis of biocompatibility suggests some decrease in the proliferation rate of mesenchymal stem cells with an increase in the borides amount.