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1

Study on the mechanical performance of sustainable earth blocks from sandy granite saprolite and marble waste

Hamideche Rahima, Mezhoud Samy, Toumi Youcef

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2025

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Vol. 34, No. 4

327--347

EN

In the pursuit of sustainable and energy-efficient construction materials, earth-based technologies such as compressed earth blocks (CEBs) offer a promising alternative to conventional fired bricks. This study investigates the physico-mechanical performance of CEBs formulated with 85% sandy granite saprolite from Chétaïbi and 15% marble waste, stabilized with varying cement contents (6%, 9%, and 12% by weight) and subjected to different compaction pressures. The produced blocks were evaluated in terms of dry density, total water absorption, compressive strength, and flexural strength. Results indicate that increasing the cement content significantly improves the mechanical properties while reducing water absorption. All formulations exceeded the minimum compressive strength of 2 MPa required by the French standard XP P 13-901, and water absorption values remained below the 15% threshold established by the Indian standard IS 1725. These findings confirm the potential of these blocks as a viable, low-impact alternative to traditional masonry units, supporting the development of more environmentally responsible construction practices.

2

Comparative assessment of the physico-mechanical properties of crumb rubber concretes developed with natural and dune sands

Mezidi Amar, Merabti Salem

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2025

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Vol. 34, No. 4

417--435

EN

This paper investigates the incorporation of crumb rubber from recycled tires into ordinary concrete (OCCR) and dune sand concrete (SCCR), analyzing the effect of incorporation rates ranging from 1% to 5% relative to the sand mass. A comparative study was conducted focusing mainly on apparent density, compactness, mechanical strengths, and the elastic modulus in the linear regime. The results show that the addition of crumb rubber in concrete leads to a reduction in both compressive strength and flexural tensile strength. For an incorporation rate of 3%, Young’s modulus decreases significantly in SCCR compared to OCCR. Specifically, the elastic modulus is E = 24.7 GPa for OCCR and E = 14.23 GPa for SCCR, representing a reduction of approximately 42%.

3

Microstructure and Mechanical Properties of Modified AISI 4140 Steel with Addition of Cr and W Elements

Lee Gang Ho, Park Minha, Noh Sanghoon, Kim Byoungkoo, Kim Byung Jun

Archives of Metallurgy and Materials

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2025

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Vol. 70, iss. 3

1133--1137

EN

High-temperature environments require materials with exceptional properties, including strength, oxidation resistance, and wear resistance. Quenched and tempered (QT) AISI 4140 steel, a chromium-molybdenum low-alloy steel, is known for its superior strength and toughness, making it widely used in industries such as automotive, aerospace, and oil & gas. The outstanding characteristics of 4140 steel stem from its alloying elements: chromium (Cr), molybdenum (Mo), and manganese (Mn), along with the quenching and tempering treatment temperature. These alloying elements facilitate carbide formation with carbon (C), resulting in finer grains and improved mechanical properties. This study aimed to enhance high-temperature performance by adjusting the chromium content, a key element influencing high-temperature properties. Modified AISI 4140 steel was produced using various QT treatment conditions. Tensile tests conducted at room temperature and at 400℃, 500℃, and 600℃ revealed that increasing the tempering temperature generally decreased tensile strength while increasing elongation. At 600℃, the tensile strength decreased for all specimens; however, higher chromium content and lower tempering temperatures improved the high-temperature strength of the modified 4140 steel.

4

Polyoxymethylene copolymer matrix nanocomposites with enhanced ability to dissipation of mechanical energy

Kaczor Paulina, Kuciel Stanisław, Rusin-Żurek Karina, Bazan Patrycja

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 12

156--172

EN

The objective of this study is to examine the mechanical properties and surface characteristics of composites with antibacterial potential, specifically those based on structural polyoxymethylene and titanium oxide. The nanocomposite was modified through the incorporation of commercially available impact modifiers derived from high-molecular weight silicones, as well as aramid fibers with a compatibilizer of ethylene-n-octene grafted with maleic anhydride (EOC-g_MAH). Fundamental strength and low-cycle tests were conducted to ascertain the dissipation energy of the material, and assessments of surface tension and contact angle were performed. The inclusion of silicone was found to diminish the strength properties, yet it positively influenced the release and surface tension of the material. In contrast, aramid fibers enhanced impact strength while reducing the contact angle of the surface by approximately 6%.

5

Badania wpływu minerałów hunterytu/hydromagnezytu oraz kalcytu pod kątem niepalności i właściwości mechanicznych kompozytów drzewnych

Atay Gül Yilmaz, Loboichenko Valentyna, Wilk-Jakubowski Jacek Łukasz

Cement Wapno Beton

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2024

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R. 29, nr 1

40--53

PL

W pracy zbadano właściwości dodatków mineralnych w kompozytach drzewnych, które wpływają na palność materiału, a jednocześnie są przyjazne dla środowiska. W artykule poddano analizie wyniki pomiarów kompozytów drewnianych, będących naturalnym materiałem budowlanym wielu domów, a także elementów ich wyposażenia. Jako matrycę zastosowano trociny drzewne. W pracy zbadano wpływ współobecności kalcytu i minerału mieszanego huntyt/hydromagnezyt. Kalcyt zastosowano jako minerał pomocniczy oprócz huntytu/hydromagnezytu, w celu uzyskania lepszego środka zmniejszającego palność zgodnie z normą UL94 i właściwości mechanicznych kompozytu drzewnego, takich jak wytrzymałość na zginanie i moduł sprężystości przy zginaniu. Uzyskane wyniki oceniano w zależności od zawartości składników mineralnych w kompozytach. Wyniki wykazały, że próbka 40S/50H/10C jest optymalna pod względem stosunku modułu sprężystości do niepalności. Materiały ognioodporne można stosować w budownictwie, a także w elektrotechnice, np. w gaśnicach akustycznych [np. do budowy falowodu].

EN

This work examines the characteristics of mineral additives in wood composites that affect the fire retardant properties of the material, and at the same time are environmentally friendly. The paper analyzes the results of measurements for wood composites, which is the natural building material of many houses, as well as elements of their furnishings. Sawdust waste was applied as a matrix. In the paper, a co-presence effect of calcite and huntite/hydromagnesite mineral was investigated. The calcite mineral was used as auxiliary minerals in addition to the huntite/hydromagnesite mineral to obtain a better flame retardant according to the UL94 standard and mechanical properties in the wood composite, such as flexural strength and flexural modulus. The results obtained were measured and evaluated depending on the mineral content of the composites. The results indicated that sample 40S/50H/10C is the most optimal in terms of the ratio of the modulus of flexibility and fire retardant characteristics. Fire retardant materials can be used in the construction industry, as well as in the electrical engineering applications, such as for acoustic fire extinguishers [e.g. for waveguide construction].

6

Mechanical Alloying Synthesis and Spark Plasma Sintering Consolidation of Al-Ti-Si-W Alloys

Park Bum-Soon, Park Jae-Cheol, Park Hyun-Kuk, Lee Jeong-Han

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 1

25--28

EN

Al-Ti-Si-W quaternary powders were mechanically synthesized by planetary ball milling; and further consolidated by spark plasma sintering. The nominal compositions of the quaternary alloys were designed to be Al60Ti30Si5W5 and Al45Ti40Si10W5(wt.%). The microstructural evolution of intermetallic compounds in Al-Ti-Si-W alloys included titanium aluminide, titanium silicide, and ternary alloys (AlxTiy, TixSiy, and TixAly,Siz), whereas W was embedded in the Al-Ti matrix as a single phase. The phase composition and grain size distribution were investigated using electron backscatter diffraction analysis, in which refined and uniform microstructures (less than 0.3 μm) were attributed to severe plastic deformation and rapid densification of the pre-alloyed powders. The mechanical properties were correlated with the Al content in the quaternary alloys; a high hardness of 1014.6 ±73.5 kg/mm2 was observed.

7

Improvement of Strength and Oxidation Resistance at High Temperature in AISI 4140 Steel by Micro-Alloying Chromium and Tungsten for Automotive Engine Applications

Kim Hyo-Seong, Kang Moonseok, Park Minha, Kim Byung Jun, Kim Byoungkoo, Ahn Yong-Sik

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 1

61--65

EN

Increasing the operating temperature and pressure of an automotive engine and reducing its weight can improve fuel efficiency and lower carbon dioxide emissions. These can be achieved by changing the engine piston material from conventional aluminum alloy to high-strength heat-resistant steel. American Iron and Steel Institute 4140 modified steels (AISI 4140 Mod.s), which have improved strength, oxidation resistance, and wear resistance at high temperature were developed by adjusting the AISI 4140 alloy compositions and optimizing the heat treatment process for automotive engine applications. In this study, the effects of modifying alloy compositions on the microstructure, mechanical properties (both at room and high temperatures), and oxidation of AISI 4140 Mod.s were investigated. Effective grain refinement occurred due to the influence of high-temperature stable carbide forming elements such as Mo, and V. The bainite structure changed to martensite structure under the influence Cr and Ni. As the Cr and W contents increased, the oxidation resistance was improved, and the oxide layer thickness decreased after 10 hours exposure at 500°C. The AISI 4140 Mod. exhibited a 35% improvement in room temperature strength, 70% improvement in high-temperature strength, and 40% improvement in high-temperature oxidation resistance compared to conventional AISI 4140.

8

Enhanced Mechanical Properties of Mg-8Li Dual-Phase Alloy Processed by Friction Stirring Versus Hot-Extrusion

Zhang Li, Li Nan

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 4

1473--1480

EN

The microstructure evolution, texture and tensile properties of the Mg-8Li dual-phase alloys processed by hot-extrusion and friction stir processing were investigated. It was found that the friction stir processing was more advantageous when compared with hot-extrusion in achieving the superior mechanical properties. The tensile strength, yield strength and elongation of the as-FSPed alloy reached 235.4 MPa, 185.3 MPa and 35.6%, respectively. The outstanding strength-ductility combination of the as-FSPed Mg-8Li alloy was ascribed to refined grains, weakened texture and formation of high-fraction high angle grain boundaries.

9

Effect of Cooling Rate on Microstructure and Mechanical Properties According to Heat Treatment Temperature of Inconel 625

Park Minha, Lee Gang Ho, Kim Hyo-Seong, Kim Byoungkoo, Noh Sanghoon, Kim Byung Jun

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 1

95--98

EN

Inconel 625 is typically used in extreme environments due to excellent mechanical properties such as high strength, corrosion resistance, abrasion resistance and low-temperature toughness. When manufacturing a hot forged flange with a thick and complex shape, the cooling rate varies depending on the location due to the difference in thermal gradient during the cooling process after hot forging. In this study, to evaluate the microstructure and mechanical properties of Inconel 625 according to the cooling rate, we performed heat treatment at 950°C, 1050°C, and 1150°C for 4 hours followed by water cooling. Additionally, temperature data for each location on the flange were obtained using finite element method (FEM) simulation for each heat treatment temperature, revealing a discrepancy in the cooling rate between the surface and the center. Therefore, the correlation between microstructure and mechanical properties according to cooling rate was investigated.

10

Study on preparation and mechanical properties of a new type of high-temperature resistant ultra-high performance concrete

Wang Xingchen, Zhang Wenhua, Chen Ruixing, Chen Yuan, Zhang Yunsheng, Liu Yanjun

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 2

art. no. e115, 2024

EN

Ultra-high performance concrete (UHPC) tends to crack and flake at high temperature, which causes the structure to lose its overall stability and collapse, posing a serious threat to people’s lives and property safety. In this study, by selecting the cementitious material and the high-temperature resistant aggregate, a new type of high-temperature resistant ultra-high performance concrete (HTR-UHPC) was successfully developed. The high temperature resistance tests of HTR-UHPC were systematically carried out at 5 different temperatures (20 ℃, 250 ℃, 500 ℃, 750 ℃, 1000 ℃). The compressive and axial tensile properties of the specimens were investigated after high temperatures, and the compressive and tensile stress-strain curves were obtained. High-temperature products and internal structures were tested by scanning electron microscopy (SEM) and X-ray diffractometry (XRD), respectively, and the microscopic mechanisms were revealed. The results showed that the mechanical properties of the HTR-UHPC had been significantly improved after heating at 500 ℃, 750 ℃, and 1000 ℃. When heated to 500 ℃, the compressive and tensile strength of HTR-UHPC retained 106 and 88% of the unheated status, respectively. While the structure of traditional UHPC was damaged, the compressive and tensile strength retained only 90 and 76%. Moreover, when heated to 750 ℃, the HTR-UHPC still maintained structural integrity. The residual compressive and tensile strength could still reach 115.83 and 6.17 MPa. During the hydration process, the HTR-UHPC did not generate calcium hydroxide, and the failure stress caused by high-temperature dehydration was small. At the same time, the ability of late crystal transition to reduce strength was suppressed by the addition of mineral admixtures, which enabled the formation of cracks and pores to be effectively suppressed. The stability and mechanical properties of the structure were maintained. Overall, these findings offer valuable insights into the influence of cementitious material system and high-temperature resistant aggregate on the mechanical properties of HTR-UHPC.

11

Optimization of porthole extrusion die for 6063 aluminum alloy profile with thin‑walled multi‑cavity complex section and analysis of profile performance

Ma Zheng, Shu Xuedao, Xu Haijie, Wang Guobiao, Tong Fei, Li Zixuan, Chen Kai, Li Guoping, Li Bo

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 2

art. no. e85, 2024

EN

In the porthole extrusion of complex profiles, the die structure plays a significant role in the formability of the profile. In this study, numerical simulation was conducted to optimize the porthole extrusion die for a complex cross-sectional profile, with the standard deviation of velocity (SDV) as the evaluation criterion. The optimization involved the introduction of pseudo-mandrels, adjustments to the shape of the 2nd-step welding chamber, and modification of the bearing height. The rationality of the optimized die structure was verified through porthole extrusion experiments, and the microstructure and mechanical properties of the profile at different locations were investigated. The results show that the optimized die effectively controlled the metal flow velocity. The actual profiles obtained from the experiments exhibited improved surface quality and avoided defects such as distortion and dimensional errors. The grain size is uniform at different positions of the profile, and the mechanical properties are comparable. The profile meets the performance requirements. This research provides guidance for the practical production of the profiles.

12

Mechanical properties and energy of sandstone under cyclic loading in evolutionary pattern experimental studies

Xu Daqiang, Zhang Peisen, Yan Wei, Zhang Xiaole, Dong Yuhang, Niu Hui

Archives of Mining Sciences

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2023

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Vol. 68, no. 2

351--370

EN

In order to explore the mining failure law of deep coal seam floor and clarify the mechanical behavior and energy change in the floor strata during mining, the mechanical properties and energy evolution law of sandstone under cyclic loading with different confining pressures (20, 30, 40 MPa) were studied using the Rock Top multi-field coupling tester. The results are as follows: (1) the hysteresis phenomenon of a rock stress-strain curve under cyclic loading is evident. Moreover, the hysteresis loop migrates to the direction of strain increase, and the fatigue damage caused by cyclic loading has a certain weakening effect on the peak strength of rock; (2) both the number of cycles and the axial strain show a nonlinear change characteristic that satisfies the quadratic function relationship. Among them, the stress level of the rock is the main factor affecting the fitting effect; (3) under the same confining pressure, with an increase in cycle level, the macroscopic deformation of the rock increases, the accumulation of fatigue damage in the sample increases, and the irreversible deformation of the rock increases, which leads to an increase in energy input and dissipation; (4) in terms of elastic energy and dissipation energy, elastic energy plays a dominant role. In the initial cycle, the rock is destroyed, and the rock energy loss is great. After the second cycle, the input energy is mainly stored in the rock in the form of elastic energy, and only a small part of the input energy is released in the form of dissipation energy; (5) the confining pressure can improve the efficiency of rock absorption and energy storage, enhance the energy storage limit of rock, and limit the dissipation and release of partial energy of rock. The greater the confining pressure, the more evident the limiting effect, and the more significant the dominant position of elastic energy; and (6) the change in the energy dissipation ratio can be divided into three stages: rapid decline stage, stable development stage and rapid rise stage. The greater the increase in dissipation energy, the greater the degree of rock damage. The evolution process of the energy dissipation ratio can reflect the internal damage accumulation process of rock well, which can be used as the criterion of rock instability.

13

Parameter optimization and compressive property of the TC31 titanium alloy X‑type lattice structure by the superplastic forming/diffusion bonding process

Wu Dipeng, Chen Minghe, Fan Ronglei, Xiao Wenchao, Wu Yong

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 2

art. no. e137, 2023

EN

The superplastic forming and diffusion bonding (SPF/DB) process was investigated for the manufacture of the TC31 titanium alloy X-type lattice structure. The finite element (FE) model was used to simulate the SPF process and compression behavior of the X-type lattice structure, and the deformation and compression failure modes were analyzed. A theoretical model was revised to predict the structural compressive strength. The results showed that the material processed by heat treatment still had great plasticity with the maximum elongation of 142.5% at 920 °C. The bonding rate, thinning rate and shear strength of the TC31 alloy joint bonded at 920 °C/3 MPa/60 min were 97.1%, 5.56% and 364 MPa, respectively, which indicated it was suitable for the X-type lattice truss structure to formed in the process parameter. Based on the result of the fundamental test and FE simulation, the X-type lattice structure could be fabricated by DB at 920 °C/3 MPa/60 min and SPF at 920 °C with a target strain rate of 0.001 s-1. Thickness measurements indicated that the area with a maximum thinning rate of 32.9% was located at the transition filet between the bonding areas and the ribs. The surface compressive strength of the X-type lattice structure was 1.51 MPa with a relative density of 0.015 when rib width was 5 mm, and the rib plastic buckling was considered as the failure mode of the TC31 titanium alloy lattice structure formed by SPF/DB. The surface compressive strength of the simulation results is 1.59 MPa with an error of 5.3%. The decrease of material properties and rib local thinning affect the accuracy of the theoretical predictions, and the revised theoretical result is 1.52 MPa with an error of 0.7%.

14

Feasibility of preparing self‑compacting mortar via municipal solid waste incineration bottom ash: an experimental study

Wang Qun, Chu Hongyan, Shi Wenfran, Jiang Jinyang, Wang Fengjuan

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 4

art. e251, 1--16

EN

To date, incineration is the main method of municipal solid waste (MSW) disposal. Fly ash and bottom ash (BA) are generated in large amounts from municipal solid waste incineration (MSWI), but the disposal of incineration residues poses a significant challenge to large cities with limited landfill space. The feasibility of using MSWI-BA to replace natural sand in the preparation of self-compacting mortar (SCM) was investigated to realize the resource utilization of MSWI-BA. The changes in SCM regarding durability, mechanical properties and workability when MSWI-BA was added at varying ratios were explored in this study. In addition, the changes in SCM microstructure, dynamic modulus of elasticity (DME) and ultrasonic pulse velocity (UPV) under the impacts of MSWI-BA were investigated. Eventually, the environmental and economic effects of SCM were weighed via the material sustainability index. It was found that (1) there was a drop of 23.79-44.69% in the compressive strength of SCM and a drop of 12.22-30.99% in the flexural strength, due to the incorporation of MSWI-BA; (2) the drying shrinkage of SCM increased from 2.9 to 11.76%, and the chloride migration coefficient increased from 4.66 to 46.06%, due to the incorporation of MSWI-BA; (3) the production costs, carbon footprint and energy consumption of SCM could be reduced, due to the addition of MSWI-BA; and (4) SCM could satisfy the engineering requirements of durability, mechanical properties and workability. Therefore, MSWI-BA was found to be a feasible method for the production of SCM.

15

A cost-effective approach to manufacturing ultra-high-performance lightweight concrete via air-entraining

Chu Hongyan, Qin Jianjian, Gao Li, Jiang Jinyang, Wang Fengjuan, Wang Liguo

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e210, 2023

EN

Ultra-high-performance concrete (UHPC) has attracted wide interests in civil engineering but it has large deadweight, which limits its application in lightweight structures and rehabilitation. Compromising the merits of UHPC and lightweight concrete, ultra-high-performance lightweight concrete (UHPLC) is a potential solution to solve the drawback of high self-weight. Based on particle densely packing theory, this study proposed a UHPLC manufacturing approach using shale ceramic sand and air-entraining agent (AEA). An experimental study was conducted to systematically examine the effects of the types and contents of AEA on various performances of UHPLC, including its workability, mechanical properties, durability and microstructure. The results show the following: (1) The addition of AEA resulted in the decrease of UHPLC in elastic modulus, compressive strength and flexural strength but bring UHPLC higher specific strength; (2) A void system that is featured with homogeneous distribution of pores and an appropriate size and could be formed by adding a suitable amount of AEA; (3) The optimum proportion of AEA in UHPLC was 0.01% in consideration of its influence on UHPLC from the perspectives of microstructure, durability and mechanical properties.

16

Mechanical Property Comparison of Al11Si Wheels Grain Refined by Ti, Nb and MTS

Aydogan F., Dizdar Kerem Can, Sahin Hayati, Mentese E., Dispinar Derya

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 4

14--18

EN

In this work, 25 wheels were cast with three different grain refiners: Al5Ti1B, Al3Nb1B and MTS 1582. Samples were machined from the wheels to check the mechanical properties. It was found that Nb grain refinement had the lowest grain size (260 mm) and highest tensile properties (yield strength of 119-124 MPa and ultimate tensile strength of 190-209 MPa). Al5Ti1B and MTS 1582 revealed quite similar results (110 MPa yield and 198 MPa ultimate tensile strength). The fading of the grain refining effect of Al5TiB1 master alloy was observed in both Nb and Ti added castings whereas during the investigated time interval, the fading was not observed when MTS 1582 was used.

17

Effects of SiC Coating of Carbon Fiber on Mechanical Properties in Short Carbon Fiber Reinforced Al Matrix Composite

Jang Jin Man, Ko Se-Hyun, Lee Wonsik

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 4

941--946

EN

A356 Al composites reinforced by short carbon fiber were prepared through the 2-step process: fabrication of a composite precursor and ultrasonication of the precursor melt. The short carbon fibers were coated with 0.15~1.5 μm thick SiC layer by a car-bothermal reaction, and an amount of the carbon fiber reinforcement was determined to be 1.5 vol.% and 4.0 vol.%, respectively. The addition of the carbon fiber increased the hardness of A356 alloy. However, tensile strength did not increase in the as-cast composites regardless of the SiC coating and volume fraction of the carbon fiber, due to the debonding which reduced load transfer efficiency from matrix to fiber at the interface. After T6-treatment of the composites, a significant increase in strength occurred only in the composite reinforced by the SiC-coated short carbon fiber, which was considered to result from the formation of a precipitate improving the Al/SiC interfacial strength.

18

Consolidation and Oxidation of Ultra Fine WC-Co-HfB2 Hard Materials by Spark Plasma Sintering

Park Hyun-Kuk, Oh Ik-Hyun, Kim Ju-Hun, Hong Sung-Kil, Lee Jeong-Han

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 4

997--1000

EN

In this study, a novel composite was fabricated by adding the Hafnium diboride (HfB2) to conventional WC-Co cemented carbides to enhance the high-temperature properties while retaining the intrinsic high hardness. Using spark plasma sintering, high density (up to 99.4%) WC-6Co-(1, 2.5, 4, and 5.5 wt. %) HfB2 composites were consolidated at 1300°C (100°C/min) under 60 MPa pressure. The microstructural evolution, oxidation layer, and phase constitution of WC-Co-HfB2 were investigated in the distribution of WC grain and solid solution phases by X-ray diffraction and FE-SEM. The WC-Co-HfB2 composite exhibited improved mechanical properties (approximately 2,180.7 kg/mm2) than those of conventional WC-Co cemented carbides. The high strength of the fabricated composites was caused by the fine-grade HfB2 precipitate and the solid solution, which enabled the tailoring of mechanical properties.

19

Investigation of steel wire mesh reinforcement method for 3D concrete printing

Liu Miao, Zhang Qiyun, Tan Zhendong, Wang Li, Li Zhijian, Ma Guowei

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 1

406--423

EN

3D concrete printing has received widespread attention and been developed for an increasing number of applications. However, a major challenge facing this technology is an effective way to introduce reinforcement into continuously deposited cementitious material. In this study, different layers of steel wire meshes (SWM) are employed to reinforce the 3D printed structures to improve mechanical capacities. Both destructive (bending, compression and splitting) and non-destructive (using electro-mechanical impedance) tests are employed to characterize the impact of this reinforcement method. The damage accumulation process is measured through the smart PZT patches based on the electro-mechanical impedance method. The results indicate that reinforced 3D-printed components with SWM change their failure modes from brittle to ductile. The peak loads are increased by 59.2–173.3% and the deflection capacity can be increased by more than 11 times than the non-reinforced one. Different mechanical responses of print and cast samples under compression are studied. The splitting tensile strength of wire mesh reinforced concrete is also measured, which is 43.7% higher than the non-reinforced sample. The calculating methods of the cracking moment and ultimate moment of steel wire mesh reinforced 3D printed concrete are presented. Comparison between the calculated and the experimental results verifies the effectiveness in predicting the ultimate moment. Experimental results show that it is feasible and effective to employ steel wire mesh for strength and toughness enhancement of 3D printed structures.

20

Thermally stable biopolymer composites based on poly(3-hydroxybutyrate) modified with linear aliphatic polyurethanes– preparation and properties

Zarzyka Iwona, Czerniecka-Kubicka Anna, Hęclik Karol, Dobrowolski Lucjan, Pyda Marek, Leś Karolina, Walczak Małgorzata, Białkowska Anita, Bakar Mohamed

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 2

91--105

EN

Purpose: Poly(3-hydroxybutyrate) (P3HB) is a biopolymer, but storing products from P3HB causes the deterioration of their properties leading to their brittleness. P3HB has also low thermal stability. Its melting point almost equals its degradation temperature. To obtain biodegradable and biocompatible materials characterized by higher thermal stability and better strength parameters than the unfilled P3HB, composites with the addition of polyurethanes were produced. Methods: The morphology, thermal, and mechanical property parameters of the biocomposites were examined using scanning electron microscopy, thermogravimetric analysis, standard differential scanning calorimetry, and typical strength machines. Results: Aliphatic polyurethanes, obtained by the reaction of 1,6-hexamethylene diisocyanate and polyethylene glycols, were used as modifiers. To check the influence of the glycol molar mass on the properties of the biocomposites, glycols with a molecular weight of 400 and 1000 g/mol were used. New biocomposites based on P3HB were produced with 5, 10, 15, and 20 wt. % content of polyurethane by direct mixing using a twin-screw extruder. The following property parameters of the prepared biocomposites were tested: degradation temperature, glass transition temperature, tensile strength, impact strength, and Brinell hardness. Conclusions: Improvement of the processing property parameters of P3HB-biocomposites with the addition of aliphatic polyurethanes was achieved by increasing the degradation temperature in relation to the degradation temperature of the unfilled P3HB by over 30 C. The performance property parameters have also been improved by reducing the brittleness compared to the P3HB, as evidenced by the increase in impact strength and the decrease in hardness with an increase in the amount of polyurethane obtained by the reaction of 1,6-hexamethylene diisocyanate and polyethylene glycol with a molecular weight of 400 g/mol (PU400) as modifier.