Shear Strength Behavior Research Articles

Mechanical properties of reaction mediums in permeable reactive barriers

The mechanical properties of reaction media in permeable reactive barriers (PRB) is vital in geoenvironmental applications. Bentonite, activated carbon and zeolite, recognized for their excellent adsorption capabilities, are employed as the main reaction media in PRB for the treatment of contaminated underground water. The compaction test and the undrained and unconsolidated triaxial test were carried out to investigate the compression and shear strength of the activated carbon-zeolite mixture and activated carbon-bentonite mixture at various composition ratios. The impact of compaction degree on samples' shear strength was analyzed. The influence of different composition ratios on the mechanical properties and the permeability of each reaction medium were also evaluated. The results show that the mechanical performance of most activated carbon-zeolite (AZs) is not satisfactory compared to natural soil and activated carbon-bentonite mixtures. Activated carbon‑sodium bentonite (ANBs) and activated carbon‑calcium bentonite (ACBs) present similar compaction characteristics and shear properties. In ANBs and ACBs, the cohesion of mixes with a mass ratio of 1:2 (ANB2 and ACB2) was found lower than that of mixes with mass ratios of 1:1 (ANB1 and ACB1) and 1:3 (ANB3 and ACB3). And in most ANB and ACB mixes, 100 % compaction produced higher moisture content and higher friction angle, but lower cohesion, compared to 92 % compaction degree. And the shear strength behavior of ANBs is dominated by both bentonite and activated carbon. The permeability of ACB1, AZ3 and ACB1-sand are at 1.31 × 10−6 m/s, 1.37 × 10−6 m/s and 7.72 × 10−7 m/s, respectively. These results provide valuable insights into the selection and optimization of reaction media for PRBs in geoenvironmental engineering applications.

Shear Strength and Consolidation Behaviour of Kaolin Clay Reinforced with a Granular Column Backfilled with Crushed Waste Glass

Granular columns are commonly used for ground improvement. However, minimal research is presently available on the effect of backfill particle size on the geotechnical performance of granular column-reinforced soil. Geo-environmentally, using crushed waste glass (CWG) as a sustainable replacement for depleting traditional construction sands could offer a cleaner feedstock to backfill granular columns while helping recycle growing stockpiles of waste glass, potentially supporting the circular economy transition and decarbonisation of the construction industry. Given these multi-pronged motivations, this study investigated the shear strength and consolidation behaviour of kaolin reinforced with a CWG granular column. Three different particle size ranges (PSR) of CWG were discretely used to install a granular column in the kaolin bed, including fine (0.50–1.0 mm), medium (1.0–1.7 mm) and coarse (1.7–3.35 mm) particles with median particle sizes of 0.78 mm, 1.42 mm and 2.30 mm, respectively. The geocomposite containing a medium CWG column showed the highest increase in friction angle, increasing from 14.0° for kaolin only specimens to 20.7° for the geocomposites. Similarly, the consolidation behaviour of reinforced kaolin (geocomposites) was typically superior to that of kaolin only specimens. Notably, installing a coarse, medium or fine CWG column decreased the average compression index (Cc) of the geocomposites by almost 17%, 35% or 50%, respectively, compared to that of the kaolin only specimens. Given the promising results of this initial study, some suggestions are provided for future studies on assessing the application of CWG as an alternative backfill and sustainable geomaterial in granular column construction.Video abstractThis internationally-partnered Video highlights the findings of the research study, indicating that crushed waste glass (CWG) could potentially serve as a sustainable geomaterial and be used as a replacement for traditional construction sand to backfill granular columns in clayey soils for ground improvement, helping reduce the unsustainable exploitation of sand resources and increasing waste glass recycling, potentially supporting the paradigm shift to a circular economy and contributing to decarbonisation of the construction industry.EwdaqE4KyyTKvkX4_pnUt6Supplementary material 1 (MP4 3737519 kb)

The 6th Victor de Mello Goa Lecture: Development of large direct shear facility for geotechnical characterization and stability assessment of opencast mines dumps

As opencast coal production increases, a crucial challenge is safeguarding the stability and management of overburden dumps while prioritizing both safety and cost-efficiency. Determining the optimal stable dump slope dimensions during and after mining remains a key challenge for mining operations worldwide. Assessing the stability of overburden (OB) dumps is necessary to maintain them at the steepest possible angle without compromising stability. Understanding the shear strength, including cohesion and angle of internal friction, of the heterogeneous dump mass is crucial for this assessment. To evaluate the shear strength behaviour of OB materials, a large direct shear machine (LDSM) was designed and developed at Central Mine Planning and Design Institute, Ranchi. The LDSM features a shear box with dimensions of 1000 mm × 1000 mm × 1000 mm to facilitate testing materials with larger particle sizes. It can test large specimens with a thickness up to 500 mm and a maximum particle size (Dmax) of 80mm in accordance with ASTM D3080-98. Seven different OB materials from Magadh Coalfields, India were collected and tested for their shear strength. Using the obtained shear strength parameters, various slope profiles are assessed for stability using 2D limit equilibrium software such as Slide2 and GALENA. Probabilistic modelling is employed to generate a statistically distributed factor of safety (FoS) instead of a deterministic value, accounting for uncertainties related to input parameters. This paper aims to forecast the maximum safe height for OB dumps based on the determined shear strength parameters.

Deterministic and stochastic finite element modeling of reinforced concrete beams without stirrups containing plastic wastes

PurposeThe use of waste polyethylene terephthalate (PET) plastics derived from shredded bottles in concrete is not formalized yet, especially in reinforced members such as beams and columns. The disposal of plastic wastes in concrete is a viable alternative to manage those wastes while minimizing the environmental impacts associated to recycling, carbon dioxide emissions and energy consumption.Design/methodology/approachThis paper evaluates the suitability of 2D deterministic and stochastic finite element (FE) modeling to predict the shear strength behavior of reinforced concrete (RC) beams without stirrups. Different concrete mixtures prepared with 1.5%–4.5% PET additions, by volume, are investigated.FindingsTest results showed that the deterministic and stochastic FE approaches are accurate to assess the maximum load of RC beams at failure and corresponding midspan deflection. However, the crack patterns observed experimentally during the different stages of loading can only be reproduced using the stochastic FE approach. This later method accounts for the concrete heterogeneity due to PET additions, allowing a statistical simulation of the effect of mechanical properties (i.e. compressive strength, tensile strength and Young’s modulus) on the output FE parameters.Originality/valueData presented in this paper can be of interest to civil and structural engineers, aiming to predict the failure mechanisms of RC beams containing plastic wastes, while minimizing the experimental time and resources needed to estimate the variability effect of concrete properties on the performance of such structures.

Microstructure and mechanical behaviors of Gasar porous Cu/G4335V steel joint brazed by Ag-28Cu-0.75Ni alloy

Cu/steel composites have the advantages of low cost and high heat dissipation performance, which make them ideal materials for applications in the industrial heat dissipation field. Because of the unique pore structure, the Gasar porous Cu is more excellent in heat transfer performance. However, systematic research still needs to be done on the joining technologies of Gasar porous Cu/steel. In this paper, Gasar porous Cu was joined to G4335V steel using Ag-28Cu-0.75Ni. The microstructure, shear strength, and fracture behavior of the Gasar porous Cu/G4335V steel joint were investigated. The results show that a clear interface of the brazed joint and no brazing defects were found. The joint microstructure mainly comprises α-Cu (ss.), β-Ag (ss.), and Ag-Cu eutectic phase. As the pore diameter of Gasar porous Cu increased, the joining area of the Gasar porous Cu/G4335V steel joint became larger, thereby improving the shear strength of the joint. For the same pore diameter, the shear strength of the mode 1 joint (The load direction and the pore direction are parallel to each other. The pore direction refers to the growth direction of the pore.) was higher than that of the mode 2 joint (The pore direction and the load direction are perpendicular to each other). The fracture analysis indicated that the joint crack was initiated in α-Cu (ss.) and propagated along the banded α-Cu (ss.). The joint fracture was a mixed fracture mechanism that combined ductile-brittle fractures.

THEORETICAL FRAMEWORK FOR LARGE-STRAIN SHEAR RESISTANCE OF KAOLIN CLAYS UNDER CHEMO-MECHANICAL LOADINGS

The normal stress, strain rate, and pore-fluid chemistry significantly influence the large-strain shear response of clays and received great attention for engineering practice. The effect of inundation pressure, consolidation pressure, pH of aqueous solutions, and di-electric on the shear response of kaolin was experimentally investigated. The strain-softening behaviour was observed under normally consolidated (NC) conditions as observed in the past studies on different clays. However, this anomalous shear response with volumetric contraction is not understood. Thus, for the first time, the strain-softening behaviour of NC clays was addressed from an effective stress approach using physico-chemical analysis of kaolin. In this study, the drained shear strength response of NC kaolin was investigated under physico-chemical influence using ring shear tests. A theoretical framework was developed by including micro-mechanism of clay fabric evolution during shear and explicit expressions for electro-chemical forces. The proposed framework provides useful expressions for predicting the shear strength behaviour of kaolin clays, which were validated with experimental data from the present study and literature studies. The new conceptual framework satisfactorily explained the peak and residual shear strength variations under different chemo-mechanical loading for NC conditions. The proposed model adequately predicted the effective stress paths, peak, and residual envelopes in ring shear stress conditions for normally consolidated kaolin soils

Numerical Analysis of Geogrid-Axial Stiffness on Shear Strength Behavior of Fine Sand

Numerical Analysis of Geogrid-Axial Stiffness on Shear Strength Behavior of Fine Sand

Shear strength and compressibility of reconstituted Boom clay, a stiff clay from the Paleogene

Boom clay is a stiff marine clay from the Oligocene epoch of the Paleogene period. It outcrops along the rivers Rupel and Scheldt in Northern Belgium, nearby the city and the port of Antwerp. Most of the existing geotechnical investigation around the Antwerp area, where the clay is located at relatively shallow depths, consists of standard laboratory tests on undisturbed samples performed at stress levels around the estimated in situ stress. Although the geological preconsolidation pressure of this clay is relatively well known, the clay yields at much higher stresses in 1D compression. Moreover, due to the brittle behavior of the stiff clay, it is often difficult to evaluate its shear strength behavior beyond peak strength. To this end, evaluating intrinsic parameters of compressibility, critical state shear angle and residual strength is of great relevance. In the present research, the mechanical behavior of reconstituted normally consolidated Boom clay was examined in a series of oedometer, CRS, CU triaxial, and multi-reversal direct shear tests. The mechanical behavior of the reconstituted clay was compared to the behavior of undisturbed clay samples. The results allow for a better evaluation of the structure effects of the natural samples on their mechanical response.

Environmental implications of styrofoam waste and its utilization as lightweight fill material for embankment construction

This study investigates the adverse effects of styrofoam waste on the environment due to its non-biodegradable nature and persistence in natural ecosystems, encompassing issues such as visual pollution, habitat disruption, and potential health risks to flora and fauna. The research also delves into the feasibility of repurposing styrofoam waste as a lightweight fill material in embankment construction, aiming to improve the performance of such structures, with the primary objective of augmenting the structural performance of such constructions. The paper conducts an extensive assessment of the technical properties and engineering characteristics of a soil-styrofoam mixture. Key parameters under scrutiny encompass density, shear strength, and bearing capacity behaviors. Various proportions of styrofoam, specifically 0.0%, 0.2%, 0.4%, 0.6%, and 0.8% by weight, were systematically incorporated into the soil mixture. Based on this study, the use of styrofoam can reduce the maximum dry density of the soil mixture, but still has the desired bearing capacity. These results indicate that the reuse of Styrofoam waste as an additional material in embankment construction has great potential to improve the performance and sustainability of embankment projects.

Analysis of microstructures and fractures in Ag–In transient liquid phase bonded joints

Silver (Ag) and indium (In) are increasingly investigated as transient liquid phase (TLP) bonding materials for die attachment in next generation power modules. In this study, we systemically investigated the relationship between the microstructural evolution, shear strength, and fracture behavior of Ag–In TLP bonded joints. During bonding, Ag9In4 was the primary phase formed between the solid Ag and liquid In. The Ag9In4 joints exhibited brittle fractures with an intergranular fracture mechanism. The shear strength increased as bonding time and temperature increased (from 26.9 MPa to 53.0 MPa), attributed to the improved cohesiveness of grain boundaries. As the bonding process progressed, ζ (Ag3In) formed and developed between Ag and Ag9In4 owing to the solid–solid interdiffusion. The ζ (Ag3In) joints, obtained from the conditions of 250 °C and 40 min, exhibited the highest shear strength of 82.87 MPa. Here, the ductile fracture was characterized with an intergranular fracture mechanism. This ductility was partially attributed to the relatively low hardness of ζ (Ag3In) (2.1 GPa). The high strength and ductility of ζ (Ag3In) found in this study present differ from the conventional understanding of the inherently brittle intermetallic compounds. Therefore, the study findings form the basis for enhancing the reliability of power modules.

Retaining of dredging waste using geotextile tubes: analysis of the dewatering and undrained shear resistance of the sludge cake

The city of Rio Grande has its economy linked to coastal and port activities and has a port complex of high economic importance for the region. To maintain the depth of the port channels, periodic dredging operations are carried out, as occurred in the Port of Rio Grande between 2018 and 2020. Approximately 16 million m³ of sediments were removed from the channel and deposited in disposal zones. There has been an attempt to develop techniques that carry out the reuse and disposal of dredging waste more appropriately, seeking to minimize environmental impacts by avoiding inappropriate open-sea or onshore disposal. Within this context, this work aims to evaluate the potential of the retaining and dewatering process of dredging waste in geotextile tubs (linear geoforms, geobags e etc). This technique reduces the volume of dredged mud through desiccation and allows the geotextile tubs to be installed in sedimentation basins onshore or coastal protection structures. Thus, the present study evaluated the dewatering and filtration efficiency of these systems through tests of small bags. The advantages of adding flocculation polymer and the behavior of undrained shear strength over time of the retained cake were evaluated.

Suffusion in densely compacted Satozuka pumice sand and its impact on static loading undrained shear strength and dilation behaviour

Pumice sand of volcanic origin contains a high fraction of non-plastic fines (>40 % for Satozuka pumice sand in Sapporo, Japan). Suffusion in such soil can wash away a portion of the fine particles and alter the soil microstructure. The moisture content and degree of compaction can affect the suffusion characteristics of soil deposits, however their effect has not yet been evaluated. Future construction sites in growing Sapporo City, consisting of pumice sand, will require a high degree of compaction (over 90 % and preferably over 95 %) as this sand is prone to suffusion in spite of its dense state. The aim of this study is to assess the impact of suffusion on densely compacted pumice sand with a high proportion of fines, based on its mechanical properties, with an emphasis on shear strength and dilatancy. Firstly, the suffusion characteristics of Satozuka pumice sand were evaluated. Subsequently, undrained triaxial tests (CU¯ tests) under monotonic loading were conducted on high-density specimens, with suffusion and without suffusion, to study the impact of suffusion. It is seen in the results that the hydraulic conductivity, shear strength, stress paths, and dilatancy are all noticeably affected by suffusion. The specimens with suffusion exhibit an increase in residual shear strength and maximum deviator stress under shearing and experience an earlier occurrence of phase transformation from contraction to dilation during shearing. This tendency implies that suffusion has no significant negative impact on the deterioration of earth fill made from pumice sand and non-plastic fines, and that it persists at degrees of compaction between 80 % and 100 %.

Prediction of lap shear strength of GNP and TiO2/epoxy nanocomposite adhesives

Abstract In this study, graphene nanoplatelets (GNPs) and titanium dioxide nanofillers were added to epoxy resin P-5005 at five different weight percentages (wt%), viz., 1, 5, 10, 15, and 20 wt%. The tensile properties of the nanocomposites were experimentally tested following ASTM D638-14. Then, the above-mentioned nanocomposites were applied as adhesives for an overlap joint of two A5055 aluminum sheets. The apparent shear strength behavior of joints was tested following ASTM D1002-01. Moreover, experimentally obtained results were applied to train and test machine learning and deep learning models, i.e., adaptive neuro-fuzzy inference system, support vector machine, multiple linear regression, and artificial neural network (ANN). The peak tensile strength (TS) and joint failure load (FL) values were observed in epoxy/GNP samples. The ANN model exhibited the least error in predicting the TS and FL of the considered nanocomposites. The epoxy/GNP nanocomposites exhibited the highest TS of 28.49 MPa at 1 wt%, and the peak overlap joints exhibited an FL of 3.69 kN at 15 wt%.

Shear Strength Behavior for Reinforced Soil with Geosynthetic at Different Inclination Angles

Shear Strength Behavior for Reinforced Soil with Geosynthetic at Different Inclination Angles

Shear Strength Behavior of Soft Clay Reinforced with Ordinary and Geotextile-Encased Granular Columns

Shear Strength Behavior of Soft Clay Reinforced with Ordinary and Geotextile-Encased Granular Columns

Potential of carboxymethyl cellulose solution to increase the shale stability

Slope failures in Bangladesh's Chittagong division are a growing concern, with fatalities increasing from 19 in 2000 to 162 in 2017 and projected to rise further. This study aims to identify the most vulnerable rock formation and assess Carboxymethyl Cellulose (CMC) as a solution for enhancing shale strength and mitigating slope failures. The research began by evaluating weathering susceptibility and stability of different rock layers, revealing the high instability of shale in the Bhuban Formation. Slake durability tests measured cation concentration to understand shale instability mechanisms. Laboratory experiments, including immersion tests and grained-and-molded shale specimens, examined CMC's potential to improve shale stability. Results indicated that the shale of the Bhuban Formation had the highest hammer value variations, indicating increased weathering susceptibility. Shale instability was attributed to illite layer dissolution, releasing K+. Intact shale specimens treated with CMC showed enhanced penetration resistance, shear strength, and deformation behavior, suggesting CMC's potential in increasing shale stability. Grained-and-molded shale specimens treated with CMC demonstrated increased shear strength, critical shear displacement, and contraction deformational behavior. Optical microscopy and scanning electron microscopy revealed the formation of cross-links between shale grains, contributing to improved shale stability. Further research is needed to explore the application of CMC for enhancing in situ rock slope stability. This study emphasizes the importance of addressing slope failures in the Chittagong division and provides insights into mitigating the risks through CMC-based interventions.

An experimental study on the effect of particle size and non-homogeneity on the shear strength of soil

Soil deposits available in nature are often present as homogeneous mixtures of particles of different sizes and base minerals or as a combination of soils in different layers forming a non-homogeneous configuration. This variability in soil has great influence on the shear strength behaviour. In this study, different naturally occurring soil particle sizes and shapes (angular and flaky) have been utilized as reinforcements in the form of layers to determine their influence on the soil shear strength. Therefore, triaxial tests have been conducted on homogeneous sand (where particles are mixed proportionately), and on non-homogeneous sand (different layer combinations of different particle sizes as well as the inclusion of angular and flaky particles). It has been observed that there was a substantial increase in the shear strength for non-homogeneous arrangement compared to homogeneous sand sample. Furthermore, the addition of flaky particles from 10% to 30% by weight of fine grained sand increased the angle of internal friction (ϕ) and cohesion (c) values thereby increasing the shear strength. However, for angular-fine sand layer combination, the addition of 10-20% of angular particles by weight shows a significant increase in shear strength in comparison to 30-100% of angular particles.

Large area bare Cu-Cu interconnection using micro-Cu paste at different sintering temperatures and pressures

The microstructure evolution, shear strength, and fracture behavior of large area (10 mm × 10 mm) bare Cu-Cu interconnection sintered using micro-Cu paste at different sintering temperatures (180, 200, 250, and 300 °C) and assistant pressures (0, 2, 5, and 10 MPa) were investigated in this study. The results showed that, as sintering temperature and assistant pressure increased, the microstructure of the sintered joints became denser, and the bonding quality of both the Cu dummy chip/Cu paste and Cu paste/Cu substrate interfaces was elevated, while more small crack or blind hole generated at the former interface. Moreover, the shear strength of the sintered joints increased with increasing sintering temperature and assistant pressure, a robust joint could be obtained under an assistant pressure of 10 MPa regardless of the sintering temperature as well as under an assistant pressure of 5 MPa at 250 and 300 °C. The fracture preferred at the Cu dummy chip/Cu paste interface, and the ductility of the sintered joint increased with increasing sintering temperature and assistant pressure. Accordingly, the optimized sintering temperature and assistant pressure are 250 °C and 10 MPa, respectively.

Shear strength, wear, thermal conductivity, and hydrophobicity behavior of fox millet husk biosilica and Amaranthus dubius stem fiber–reinforced epoxy composite: a concept of biomass conversion

Shear strength, wear, thermal conductivity, and hydrophobicity behavior of fox millet husk biosilica and Amaranthus dubius stem fiber–reinforced epoxy composite: a concept of biomass conversion

Built-Up Fiber-Reinforced Polymers (FRP) Profiles with Improved Shear Performance for FRP–Concrete Hybrid Section

Fiber-reinforced polymer (FRP)–concrete hybrid sections, composed of FRP profiles and a concrete slab, have gathered attention in construction due to their lightweight, easy installation, and high durability. However, the low shear strength and brittle behavior of commercially available pultruded FRP profiles often leads to brittle shear failure at low load levels. To enhance the shear strength and ductility, this study proposes a novel H-shaped FRP profile that is built from two U-shaped pultruded FRP profiles and a hand lay-up sandwiched core of multi-directional fibers. Direct shear tests showed that the built-up FRP profiles failed in pseudo-ductile mode while the U-shaped pultruded FRP profiles failed in brittle mode. Built-up FRP had 1.5 times the capacity and 2.8 times the ultimate redundancy compared to pultruded FRP. Additionally, flexural tests of FRP–concrete hybrid beams revealed that the webs of the built-up FRP profiles failed in a higher shear capacity with smeared cracks.