Shear Strength Tests Research Articles

Strong and Environmental-Friendly Adhesive Glass Based on Chitin Nanoparticles

Chitin is a biopolymer that can be used as a candidate material for a strong and environmentally friendly glass adhesive. In the form of nanoparticles with needle-like morphology and attractive functional groups in the form of amide and hydroxyl, Chitin Nanoparticle (ChNP) shows a strong Van der Walls adhesive force against glass. In the study, ChNP was successfully isolated from crab shells from the sea of Lombok. The isolated ChNP has a characteristic size around 351 nm with -chitin conformation and needle-shaped morphology. Based on the results of shear strength testing, 0.42 mg of ChNP can withstand a load of 21 kg and the addition of Gum Arabic (GA) and Hen Egg White lysozyme (HEWL) in a ratio of 1: 1 to ChNP succeeded in increasing adhesion by 72%.

Bulk adhesion of ice to concrete–strength

This paper presents the results of a laboratory test program designed to investigate the adhesive effects of large-scale (bulk) ice on concrete. Medium-strength concrete cylinders were sawn into discs, and attached to a sample table. Freshwater ice samples, frozen using smaller, standard-sized concrete cylinders, were adhered to the concrete with both varying bond times and added weight during bonding. Shear strength tests were conducted at a set displacement rate, under a number of temperatures. The effect of these variables on the adhesive strength of ice to concrete was examined, as well as whether there was any noticeable removal of concrete cement paste or aggregate during testing. The tests indicate that the adhesive strength is negligible when the method of adhesion is “dry” (no liquid layer at the onset of adhesion). Tests with “wet” adhesion indicated a significantly higher strength. The nominal versus the apparent contact area had significant implications for the determination of the adhesive strength of the bond between the ice and the concrete. Removal of cement paste was evident in a number of tests, however the amount was not significant. The results have relevance for design of structures in a marine environment, such as revetement dams or rubblemound breakwaters, as well as for the standardization of adhesion tests with ice and concrete.

Contribution to the design of prestressed hollow core purlins without transverse reinforcement

AbstractThe hollow core purlin is a structural element resulting from the sectioning of hollow core slabs into two ribs. This component can be classified as a prestressed hollow core beam without transverse reinforcement. Although this solution offers potential for increasing the productivity of precast concrete element factories, it currently lacks normative guidelines due to the high risk of shear failure. The aim of this study is to highlight an equation to underpin the design of hollow core purlins based on experimental verification. To achieve this objective, six samples of hollow core purlins were analyzed. Initially, the manufacturing characteristics and cross‐sectional geometry of each piece were observed to gather data on the production process. Subsequently, positive bending tests were conducted to characterize stiffness and determine the effective mean tensile strength. Later, shear strength tests were performed to identify the failure mechanisms of the elements. In parallel, the prestressing forces, stiffness, tensile strength, cracking moment, calculated shear strength using the flexural‐shear mechanism, and verification of shear strength due to diagonal tension were computed based on concrete compressive strength values and data provided by the manufacturer. Finally, the experimental values obtained were compared with the theoretical calculated values to establish a correlation that highlights the calculation procedure that best represents the behavior of the studied elements.

Effect of granite powder on the strength, durability and sustainability of soil treated using steel slag or cement

Granite powder, a byproduct of granite quarrying, enhances the long-term strength of cement-treated soil due to its pozzolanic reactivity. However, its effects on early strength and seawater durability, as well as its influence on slag-treated soils, remain unexplored. We studied cement-treated and slag-treated soil composites with 0% and 30% granite powder, using 8% cement or 30% steel slag per dry soil mass. We performed vane shear and unconfined compressive strength (UCS) tests at 1, 3, 6, 12hours, and 1, 3, 7, 28, 63, 91, 119 days. After 28 days of air curing, samples endured seawater exposure at 30°C for 0, 28, 63, and 91 days, followed by UCS and XRF calcium composition tests. Seawater samples were also analyzed for calcium and magnesium concentrations using a photometer. Despite similar dry unit weights, slag-treated soil initially exhibited lower strength than cement-treated soil. However, granite powder enabled slag-treated samples to reach comparable strength levels to those of cement-treated soil. Its pozzolanic reactivity facilitated self-repair in samples affected by seawater-induced calcium depletion, while also reducing emissions, resource consumption, and construction costs associated with treated soil materials.

Experimental Study on Mechanical Properties and Stability of Marine Dredged Mud with Improvement by Waste Steel Slag

As marine-dredged mud and waste steel slag in coastal port cities continue to soar, the traditional treatment method of land stockpiling has caused ecological problems. Thus, it is necessary to find a large-scale resource-comprehensive utilization method for dredged mud and waste steel slag. This study uses waste steel slag and composite solidifying agents (cement, lime, fly ash) to physically and chemically improve marine-dredged mud. The physical improvement effect of the particle size and dosage of waste steel slag was studied by the shear strength test under the effect of freeze–thaw cycle. Then, based on the Box–Behnken design of the response surface method, the interaction effects of the solidifying agent components on the unconfined compressive strength were studied. Then, the water stability under dry–wet cycles and a microscopic mechanism were analyzed by XRD and SEM tests. The results show that the waste steel slag with a dosage of 30% and a particle size of 1.18~2.36 mm has the best improvement. The interaction between cement and lime and lime and fly ash has a significant effect on the linear effect and surface effect of 7d unconfined compressive strength, and the strength increases first and then decreases with the increase in its dosage. For the 14d unconfined compressive strength, only the interaction between cement and lime is still significant. The unconfined compressive strength prediction model is established to optimize the mix ratio of the composite solidifying agent. In the water stability, the water stability coefficients of the 7d and 14d tests are 0.68 and 0.95, respectively, and the volume and mass loss rates are all below 1.5%, showing a good performance in dry–wet resistance and durability. Microscopic mechanism analysis shows that waste steel slag provides an ‘anchoring surface’ as a skeleton, which improves the pore structure of dredged mud, and the hydration products generated by the solidifying agent play a role in filling and cementation. The results of the study can provide an experimental and technical basis for the resource engineering of marine-dredged mud and waste steel slag, helping the construction of green low-carbon and resource-saving ports.

Microstructure evolution, elemental diffusion behavior, and bonding strength of TA1/AZ31B laminated composite fabricated by hot pressing

Ti/Mg composites can combine the benefits of Ti and Mg in terms of mechanical properties, cost, and other factors, making them highly valuable for various applications. In this study, Ti/Mg laminate composites were prepared by vacuum hot pressing at temperatures of 350 °C, 400 °C, and 450 °C for 6 h, 8 h, and 10 h, respectively. The study aimed to examine the effect of the diffusion behavior of elements and microstructure on the bonding strength of Ti/Mg laminate composites. The shear strength test results indicated that the laminated composites displayed a strong bonding strength at 400 °C, while a significant decrease in bonding strength was noted at 350 °C and 450 °C. Results of TEM analysis show that when the temperature is 350 °C, the intermetallic compound is not observed at the interface; when the temperature increased to 400 °C, a transition region along the interface is observed, and there is a Ti3Al compound in the region, the compound is uniformly distributed along the interface; when the preparation temperature is 450 °C, intermetallic compounds were observed at the interface, and the compounds were TiAl, TiAl was not uniformly distributed along the interface. EBSD analysis showed that in the Mg matrix of the composites, the distribution of coarse crystals and fine crystals was obvious due to the dynamic recrystallization, and such a distribution of grain size was also conducive to the further enhancement of the bonding strength of the composites. It can be concluded that the formation of intermetallic compounds with a continuous distribution of the transition region caused by elemental diffusion and the enhancement of the mechanical properties at the matrix are both effective in improving the bond strength of composites.

Development of Double Frame Method to improve the seismic performance of low-rise reinforced concrete buildings

ABSTRACT The current paper proposes a seismic reinforcement method that uses a double frame and is called the Double Frame Method (DFM). Performance tests are conducted to assess the material suitability of a post-installed anchor that directly connects the existing frame to the double frame, while a shear performance test is conducted to examine the vertical connector. The performance of column members with and without DFM reinforcement was compared and evaluated. Ultimately, we have fabricated a two-story, one-span reinforced concrete existing frame test specimen and a DFM reinforced frame test specimen that we can use to examine the effect of improving seismic performance through repeated loading tests. The result of the anchor’s pull-out test show that the average tensile strength is 27.9 kN, exceeding the average design strength of 21.7 kN suggested by the manufacturer. The shear strength test results of the anchor show an average value of 28.7 kN. Meanwhile, the vertical connector test show that the internal force per anchor is 46.83 kN, which is approximately 163% more than the single anchor design shear strength of 28.7 kN. As a result of the DFM-reinforced column test, in the actuator direction, the yield strength is improved by about 120%, while the maximum strength is improved by about 150–180%. As a result of the two-story frame experiment, the double frame reinforced specimen shows a maximum strength of about 4.0 to 4.5 times that of the non-seismic specimen.

The influence of tannin on the improvement of adhesive properties of urea-formaldehyde resin

This study aimed to examine the properties of urea-formaldehyde (UF) adhesive with the addition of tannin, to determine whether it is possible to obtain so-called, bio-adhesives for wood with better mechanical properties compared to commercial UF. Tannin-based UF resins, with four different concentrations of tannin (5, 10, 15, and 20%), were prepared, and adhesive properties were tested and compared with properties of pure UF. Testing of tensile shear strength showed that the addition of tannin in UF adhesive formulation significantly increases its performance compared to pure UF adhesive. It was found that tensile shear strength increased with increasing concentration of tannin, while UF-tannin adhesives with tannin concentrations of 15% and 20% showed higher tensile shear strength than the corresponding pure UF adhesive. Therefore, it can be concluded that tannin-based UF adhesive can be a good candidate for application as an environmentally-friendly wood adhesive due to improvement in terms of adhesive and mechanical properties.

3D-Printed high performance PEEK/CF-PEEK polymer composites—An investigation on microstructural characteristics and mechanical performance

This study investigates the microstructural characteristics and mechanical properties of 3D-printed polyether ether ketone (PEEK) and carbon fiber-reinforced PEEK (PEEK CF20) composites. Using a specifically optimized 3D printing process parametric condition, samples of pure PEEK and PEEK CF20 (containing 20% carbon fiber) were fabricated. Mechanical properties were estimated by tensile, flexural, and interlaminar shear strength (ILSS) tests, performed as per ISO and DIN standards. Results indicated that PEEK CF20 exhibits significantly enhanced mechanical properties compared to pure PEEK. The tensile strength of PEEK CF20 was 81.069 MPa, compared to 76.070 MPa for pure PEEK. Maximum load values were 1456.608 N for PEEK CF20 and 1286.137 N for pure PEEK, while ILSS values were 15.76 MPa for PEEK CF20 and 11.82 MPa for pure PEEK. Microstructural analysis through field emission scanning electron microscopy (FESEM) revealed that PEEK CF20 had better fiber-matrix bonding and fewer defects compared to pure PEEK.

Апробация методики сдвиговых испытаний геосинтетического композита «КАПЛАМ»

Purpose: to investigate the effect of different test methods on the shear properties of geomaterials and to determine the test method that provides the most consistent shear strength results. Demonstrate the need to include shear test methods for geosynthetic materials in state standards. Determination of interaction properties of geosynthetic composite “KAPLAM” with soil. Methods: a 300×375 mm shear machine was used to perform shear tests at the soil-geomaterial interface with normal loads ranging from 100 to 500 kPa. These tests were performed according to the American standard ASTM D5321. Results: the relationships obtained from the tests allow the identification of the test methodology that produces the most significant shear strength results and an understanding of the fundamental mechanisms underlying the observed shear strength. The need for further investigation of this methodology on other geosynthetics is identified. Practical relevance: overall, these results have important implications for the design of railway embankment slopes, ISDS lining systems and shear strength testing. The tests provide better modelling of field conditions and a more accurate representation of the shear strength of composite materials.

Dynamic Mechanical Performance of Glass Microsphere-Loaded Carbon Fabric–Epoxy Composites Subjected to Accelerated UV Ageing

This study investigates the effects of incorporating glass microspheres (GMSs) as fillers in carbon fabric–epoxy composites (CFECs) on their degradation behavior under environmental conditions such as moisture and ultraviolet rays. The GMS-filled composites were subjected to accelerated ageing and evaluated using dynamic mechanical analysis (DMA), the Charpy impact test, and inter-laminar shear strength (ILSS) tests. The results indicate that the addition of GMS fillers significantly improves the stiffness and viscoelastic behavior of the composites. However, the impact strength of the composites decreases with the addition of GMS fillers and accelerated ageing. The ILSS results demonstrate that the addition of GMS fillers improved the interfacial bonding between the carbon–epoxy matrix and fillers. This study provides insights into the mechanical properties of GMS-filled carbon–epoxy composites.

Influence of incorporating beta-cyclodextrin/essential oil-based wood preservative on the bonding strength of wood composite products

The introduction of additives during the production of wood composites may disrupt the development of bonding strength between wood and adhesive, potentially compromising the structural performance of wood composites. This study investigates the impact of incorporating a natural wood preservative into 3-ply southern yellow pine (SYP) plywood on its bonding strength. The formation of β-cyclodextrin and trans-cinnamaldehyde (βCD-tCN) inclusion complex as a natural wood preservative was confirmed by Fourier transform infrared and X-ray diffraction analyses, with an inclusion yield ranging 78 % to 120 %. The differential scanning calorimetry analysis found the curing of pMDI with wood was not significantly affected by the βCD-based additives. The influence of βCD-tCN addition on the bonding strength of a wood composite was assessed by a shear strength test of the 3-ply plywood, following ASTM D906-20. The average shear strength of all panels ranged 1.53 N/mm2 to 2.07 N/mm2, exceeding the minimum requirement of 1.00 N/mm2 for cross-layer bond lines according to EN 16351-2015. Statistical analysis indicated no significant differences between the bonding strength of pristine pMDI and pMDI containing βCD-tCN complex. The combined results suggest that βCD-tCN could be effectively implemented in the manufacturing of wood composite products.

Investigation of Wetting Behavior and Brazing Reliability of Zn-15Al-xGa Filler Metals in Cu/Al Joints

Ga elements with different contents (0.1-1.5wt.%) were melted into the Zn-15Al filler metal to change the microstructure and thus improve the properties of the Cu/Al joints. The results showed that the addition of Ga element reduced the solidus and liquidus temperatures as well as the surface tension of the Zn-15Al filler alloy. Low concentrations of Ga (≤0.5wt%) can effectively increase the wettability of the filler metal. With increasing Ga addition amount, the size and proportion of the CuAl2 phase within the Cu/Zn-Al/Al brazed joint microstructure were increased, and also guided the transformation of the interfacial constituent phases on the Cu side interface from Al4.2Cu3.2Zn0.7/Al3Cu5Zn2 to Al4.2Cu3.2Zn0.7/CuAl2/Al3Cu5Zn2, which effectively adjusted the crack propagation path and increased the shear strength during the fracture process of the shear strength test on the brazed joint. The shear strength test results indicated the Cu/Zn-Al-0.5Ga/Al joint have the highest shear strength (85.8MPa, 15% improvement over the Cu/Zn-Al/Al joint). Consequently, appropriate Ga addition (0.5wt%) enhanced both the meltability and wettability of Zn-15Al filler metal, which was suitable for obtaining high-quality Cu/Al brazed joints.

Impact of graphene oxide lateral sizes on the mechanical and thermal properties of carbon fiber composites

AbstractThe impact of carbon fiber (CF) composites sizing with graphene oxide (GO) to form brick‐and‐mortar structures on their mechanical properties and thermal conductivity has not been closely examined. This study systematically investigates the effect of GO sheet size on the interfacial properties and thermal conductivity of CF composites. Three sizes of GO—small (0.11 μm), medium (0.33 μm), and large (0.97 μm)—were used to modify CF surfaces via layer‐by‐layer self‐assembly, forming the brick‐and‐mortar structures. The mechanical properties were assessed through flexural tests, interlaminar shear strength (ILSS) tests and tensile tests, while thermal conductivity was measured using a thermal constant analyzer. The results revealed that medium‐sized GO (GO‐M) significantly enhanced the interfacial strength and toughness of the composites. This improvement is attributed to the orderly arrangement of GO‐M on the CF surface, which enhances stress transfer between the fiber and the matrix. In contrast, small‐sized GO (GO‐S) tended to scatter, resulting in less effective reinforcement, while large‐sized GO (GO‐L) exhibited stacking and agglomeration, limiting its reinforcement effectiveness. However, GO‐L provided the highest thermal conductivity due to the formation of continuous heat conduction pathways. These findings suggest that GO‐M offers a balanced improvement in mechanical properties, whereas GO‐L is more suitable for applications requiring high thermal conductivity. This work underscores the importance of selecting the appropriate GO sheet size to optimize the interfacial properties and thermal conductivity of CF composites, which is crucial for enhancing their performance in high‐end engineering applications, such as aerospace, automotive, and marine industries.Highlights Modification of CF composites by GO‐M sheets significantly improved toughness and strength. GO‐L sheets formed an effective heat transfer channel with the highest thermal conductivity. The study emphasized the critical role of selecting the appropriate GO sheet size to optimize the mechanical and thermal properties of CF composites.

Effect of polypropylene fibres on the shear strength of fine-grained soil

This paper presents the results of shear strength tests of fine-grained soil reinforced by randomly oriented fibres. The tests were carried out in a direct shear apparatus on samples with a diameter of 100 mm and a height of 20 mm. The samples were formed directly in the apparatus box at a natural moisture content and two values of the degree of compaction (IS = 0:79 and 0.90). The studies were carried out for samples of natural moisture content and for soaked ones. The two types of polypropylene fibres were used: monofilament and fibrillated (of traded names Fibermesh 300-e3 and SikaCem Fiber-12, respectively). The fibre content was 0.25; 0.50 and 1.00% by the weight of the dry soil. The results showed that the presence of fibre within the soil increased its the shear strength. The improvement of the shear strength was related to the type of reinforcement, its content and the soil parameters. The maximum increase in shear strength was 47% compared to the shear strength of the unreinforced soil. The increase in shear strength values were related mainly to the increase in the angle of internal friction of the soil. It was found that as the degree of compaction of the soil increases, the higher enhance of the shear strength of reinforced soil occurs. It was also found that the improvement of shear strength of reinforced soaked samples was more significant than for un-soaked ones.

A ceramizable adhesive with high temperature resistance at 1400°C: Bonding strength and bonding mechanism

In this study, two types of high-temperature adhesives were prepared using molybdenum-modified phenolic resin (MoPF) as the matrix and TiB2 or TiB2/ZrSi2 particles as active fillers for bonding Al2O3 ceramic substrates. Shear strength testing, thermo gravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were employed to investigate the bonding properties, thermal properties, microstructure, compositional evolution, and bonding mechanism of the adhesives. The results demonstrate that MoPF-TiB2/ZrSi2 adhesive exhibits superior bonding properties than MoPF-TiB2 adhesive. It is noteworthy that the incorporation of ZrSi2 can mitigate the internal stress induced by rapid volume expansion of the adhesive, and ensuring high density and mechanical strength through the generation of ZrB2 and ZrTiO4, which effectively prevents the sudden decline in bonding performance beyond 1200℃. The mechanical strength of the adhesive can still be maintained at 31.5 MPa after treatment at 1400℃.

Bio-Epoxy Resins Based on Lignin and Tannic Acids as Wood Adhesives-Characterization and Bonding Properties.

The possibility of producing and designing bio-epoxides based on the natural polyphenol lignin/epoxidized lignin and tannic acids for application as wood adhesives is presented in this work. Lignin and tannic acids contain numerous reactive hydroxyl phenolic moieties capable of being efficiently involved in the reaction with commercial epoxy resins as a substitute for commercial, non-environmentally friendly, toxic amine-based hardeners. Furthermore, lignin was epoxidized in order to obtain an epoxy lignin that can be a replacement for diglycidyl ether bisphenol A (DGEBA). Cross-linking of bio-epoxy epoxides was investigated via FTIR spectroscopy and their prospects for wood adhesive application were evaluated. This study determined that the curing reaction of epoxy resin can be conducted using lignin/epoxy lignin or tannic acid. Tensile shear strength testing results showed that lignin and tannic acid can effectively replace amine hardeners in epoxy resins. Examination of the failure of the samples showed that all samples had a 100% fracture through the wood. All samples of bio-epoxy adhesives displayed significant tensile shear strength in the range of 5.84-10.87 MPa. This study presents an innovative approach to creating novel cross-linked networks of eco-friendly and high-performance wood bio-adhesives.

Study on the epoxy bonding properties of polyphenylene sulfide matrix composites reinforced by montmorillonite and basalt fiber

To improve the epoxy bonding properties of polyphenylene sulfide (PPS) matrix composites, CK-MMT and K-BF were prepared by modifying montmorillonite (MMT) and basalt fiber (BF) with cetyl trimethyl ammonium bromide (CTAB) and 3-Glycidyloxypropyltrimethoxysilane (KH-560) as the modifiers. CK-MMT/BF/TPU/PPS composites were prepared by injection moulding. The surface properties of the composites were tested and characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), etc. The epoxy bonding and mechanical properties were studied by combining the single-lap-joint tensile shear strength test and notched impact test. The results demonstrated the successful preparation of the modified MMT and BF. With the addition of CK-MMT and K-BF in different ratios, the surface roughness and the contents of polar groups of the composites increased, which could effectively improve the epoxy bonding properties of PPS matrix composites. When the additions of CK-MMT and K-BF were 10 and 25 wt%, respectively, the composites had the best overall properties. It demonstrated a single-lap-joint tensile shear strength was 7.56 MPa, representing a 220.34% increase over that of thermoplastic polyurethane/polyphenylene sulfide (TPU/PPS) and a 477.10% increase over that of pure PPS.

Fire-Resistant and Thermal Stability Properties of Fluorosilicone Adhesives by Incorporation of Surface-Modified Aluminum Trihydrate.

Fluorosilicone was combined with aluminum trihydrate (ATH) to induce synergistic flame-retardant and thermal-resistant properties. The surface of ATH was modified with four different silane coupling agents. The flammability and mechanical properties of the fluorosilicone/ATH composites were assessed using an UL94 vertical test and a die shear strength test. The change in shear strength was investigated under aging for 1000 h at -55 °C and 150 °C. Pure fluorosilicone had inherent fire resistance and thus achieved a V-0 rating even at 20 wt.% ATH loading. Upon addition of ATH treated with 3-glycidoxypropyl trimethoxysilane, the composites exhibited the highest shear strength of 3.9 MPa at 23 °C because of the additional crosslinking reaction of fluorosilicone resin with the epoxide functional group of the coupling agent. Regardless of the types of coupling agents, the composites exhibited similar flame retardancy at the same ATH content, with a slight reduction in shear strength at 180 °C and 250 °C. The shear strength of the adhesives gradually decreased with aging time at -55 °C, but increased noticeably from 3.9 MPa to 11.5 MPa when aged at 150 °C due to the occurrence of the additional crosslinking reaction of fluorosilicone.

Comparison of the Adhesive Remnant Index and Shear Bond Strength of Different Metal Bracket Bases on Artificially Aged Human Teeth: An In vitro Study

Abstract Aim: Bond failure can compromise the clinical efficacy and duration of orthodontic treatment. A decemented bracket can lengthen the course of treatment by about 0.6 months. This study aimed to compare the adhesive remnant index (ARI) and shear bond strength of different metal bracket bases on artificially aged human teeth. Materials and Methods: In this experimental in vitro, prospective, cross-sectional study, thirty-six human premolars were cemented with three types of metal bracket base designs: Group 1 had a laser-structured base, Group 2 had a mesh base, and Group 3 had a base with retention grooves. All groups were bonded with Transbond XT light-curing resin. Shear strength testing was performed, and the ARI was evaluated. The parametric one-factor analysis of variance test and Tukey’s post hoc test were used for the comparison of shear bond strength, and the effect size was also evaluated with eta squared. In addition, the Kruskal–Wallis test was used to compare the ARI of the three groups on an ordinal scale. All statistics were set at a significance of P < 0.05. Results: The ARI scores did not exhibit any statistically significant differences (P = 0.163). Nevertheless, the three groups exhibited statistically significant differences in shear bond strength, with an effect size of 69% (P < 0.001). The mesh base bracket had the lowest average (9.9 ± 2.6 MPa) (P < 0.001), while the laser-structured base bracket had the greatest average (19.1 ± 3.0 MPa) (P = 0.006). Conclusion: The variation in shear bond strength was influenced by 69% due to the type of the metal bracket base used. Laser-structured and mesh-based brackets had the highest and lowest shear strength, respectively. All bases left a similar ARI on the tooth enamel.