Natural marine clays exhibit distinct dynamic behavior compared to remolded counterparts due to their inherent structural properties. Dynamic and static triaxial tests were conducted on both marine clay types to evaluate stress-strain behavior, double amplitude strains, pore water pressure, and dynamic elastic modulus, as well as post-cyclic strength attenuation. The results indicate that due to the structural properties, the effective stress path of undisturbed samples is more ductile than that of remolded samples. Also, there is a clear inflection point in the strain development curve of undisturbed samples. The structure exerts a certain degree of restraint on the strain development of the undisturbed samples, and has a distinct impact on the variation of pore water pressure at varying dynamic stress levels. Both marine clay types exhibited gradual reductions in dynamic elastic modulus and marked undrained strength attenuation. Critically, the attenuation of dynamic elastic modulus in undisturbed samples aligned with post-cyclic strength loss, while remolded samples exhibited greater dynamic elastic modulus loss relative to strength degradation. These findings clarify the role of soil structure in cyclic response and strength degradation, offering insights for the long-term stability assessment of structures and disaster mitigation in marine clay engineering.

Earth-building materials offer a low-carbon option for construction, but their poor water resistance limits their adoption by the construction industry. Adding biopolymers to earth materials can improve mechanical strength and water resistance but also promote mold mycelium growth that reduces indoor air quality. However, for other applications such as insulation or packaging, the controlled growth of specific mycelium is seen as a promising option for producing natural waterproof materials. These application require heat-inactivation to kill the mycelium and preserve air quality. It is currently unknown if heat-inactivated mold mycelium could improve the water resistance of earth materials. This study explores a new design by promoting the natural growth of molds on biostabilized earth materials and studying the effect on earth material properties after heat inactivation. Earth mortars were prepared by mixing soil, water, and biopolymers (2 % of soil mass) to a consistent texture. Twenty formulations, using two soils and four biopolymers, were subjected to two different 21-day cures, under dry (oven at 50 degrees C) or humid (30 degrees C, 98 % RH) conditions. Mortar properties were investigated after a 48-h 80 degrees C heat treatment to inactivate mold. We found that the humid cure consistently prompted mold growth on biostabilized mortars, which was associated with significantly higher water resistance compared to unexposed mortars. Specifically, capillary water absorption and mass loss after water spray was reduced by 28 % and 64 % respectively. These improvements were achieved with minimal impact on shrinkage, density, and mechanical strength. The amelioration in water resistance was attributed to the hydrophobic mold mycelium filling the earth mortar pore as observed by UV microscopy. Together, this study demonstrates that mycelium could dramatically improve the water resistance of biostabilized earth materials.

Undrained residual strength, s(ur), often termed remolded or postcyclic strength, is a critical input into embankment dam numerical deformation analyses. There are multiple methods available to assess s(ur) for fine-grained soils, each with advantages and disadvantages. Field tests, such as the vane shear test and the cone penetration test, can provide reliable in situ measurements of s(ur). In the laboratory, s(ur) can be estimated by measuring the shear stress mobilized at high strains in monotonic tests such as direct simple shear or triaxial shear. s(ur) is also frequently determined from postcyclic monotonic testing; however, the postcyclic stress-strain curves can be difficult to interpret because of high excess pore water pressure existing at the start of monotonic shear due to the sample being previously subjected to cyclic loading. Such analyses often have a significant amount of uncertainty. The work described here presents two new methods developed to quantify s(ur) through lab testing, namely, analysis of stress paths from postcyclic monotonic tests and iterative strain-controlled cyclic loading. This paper introduces the new approaches and presents results from testing performed on five fine-grained soils from the foundations of embankment dams. Values of s(ur) from the new approaches are compared with those from VST and monotonic and postcyclic monotonic direct simple shear testing. The paper details the new approaches and presents results and conclusions from five fine-grained soils from various sites across the western United States.

In this work, environmentally friendly materials based on zein, glycerol, and xanthan gum (XG) are developed through the innovative use of extrusion and injection-molding methodologies for this type of bioplastic materials. This methodology has never been applied to thermoplastic zein materials and this approach represents a significant advancement over traditional cast film methods, enabling enhanced control over properties and expanding potential applications thanks to the possibility of producing new geometries. Mechanical properties show that XG increases the stiffness and hardness of the materials, achieving elastic modulus of 1294 MPa and tensile strengths of 21 MPa. The thermal stability of the formulations is also enhanced by the addition of XG, which considerably increases the maximum degradation rate temperature from 259 up to 340 degrees C. The wettability of the materials is assessed by contact angle measurements, which show a very high hydrophilicity (29 degrees), nonetheless, it was decreased to not so extremely low contact angle values thanks to the addition of XG (50 degrees), which is very positive from the point of view of food packaging applications. Finally, all materials proved to be completely disintegrated under controlled compost conditions after 9 weeks of incubation in controlled compost soil conditions, verifying the great environmentally friendly value of these formulations.

Polylactic acid (PLA) and tapioca starch biocomposites offer a sustainable alternative to petroleum-based plastics for single-use packaging. This study focused on optimizing injection molding parameters for a novel PLA/tapioca starch blend using response surface methodology (RSM). Injection temperature had the most significant impact on tensile strength. The optimal parameters identified were injection temperature of 181 degrees C, pressure of 40 MPa, and speed of 300 mm/s, achieving a tensile strength of 25.34 MPa without defects. Morphological analysis revealed smoother fracture surfaces and presence of microfibrils denoting increased ductility. Mechanical properties, including 16 % elongation, 24.5 MPa flexural strength, and 9.32 kJ/m2 impact strength, were comparable to conventional plastics. Enhanced biodegradation in ambient soil conditions was observed, while migration tests showed no leaching in most stimulants, supporting its potential for sustainable packaging applications.

In recent years, geological disasters on loess fill slopes have occurred from time to time, which has attracted widespread attention. In order to deeply understand its deformation and failure laws and promote the disaster prevention and mitigation work, this paper takes remolded loess as the research object, systematically explores the effects of three different stress paths (conventional triaxial compression test (CTC), triaxial compression test with constant average principal stress (TC), and triaxial compression test with reduced confining pressure (RTC)) on its mechanical properties, and observes and analyzes its microstructural characteristics by scanning electron microscopy (SEM). The results show that the soil is strain hardening under the CTC path, while it is strain weak hardening under the TC and RTC paths. In the order of CTC, TC, and RTC paths, the shear strength and volume shrinkage of the soil are reduced in turn, and its deformation has both shear reduction and shear expansion plastic deformation. In the order of CTC, TC, and RTC paths, the degree of particle crushing decreases in turn and the pore content increases in turn. It is inferred that in the initial deformation of loess under loading, the soil is compressed and compacted, and its strength is improved to a certain extent. As the loading continues to increase, the deformation rate increases steadily, and the soil deformation develops gradually, which is mainly axial compression deformation, while the lateral bulging deformation is small until it is destroyed. For the deformation behavior in the form of lateral unloading, the soil is maintained in a relatively stable state at the beginning, and the deformation is very small. When the lateral constraint is reduced to a critical state, the structure is completely unstable, and the deformation develops rapidly in a short time until it is destroyed. This study is of great significance for reducing the occurrence of geological disasters on fill slopes in loess areas.

Variations in excavation construction periods for fissured soil transportation engineering lead to differing unloading rates, which affect the soil's mechanical properties. This study utilizes a triaxial testing system to conduct monotonic and cyclic loading undrained shear tests on undisturbed fissured samples as well as remolded samples subjected to three distinct unloading rates. The K0 consolidated samples are regarded as soil mass that undergoes no unloading during testing. The findings indicated that the initial unloading rate influences the reloading shear mechanical properties of undisturbed and remolded specimens. The effects of unloading rates differ between undisturbed and remolded soil, a discrepancy attributed to inherent fissures. Specifically, undisturbed soil exhibits significant damage at low unloading rates due to fissures, while remolded soil experiences strength augmentation due to compaction with decreased unloading rates. Similarly, unloading will cause a loss of strength. Structural disparities result in the monotonic loading strength of undisturbed specimens being higher than that of remolded ones. In contrast, remolded specimens demonstrate greater dynamic strength under cyclic loading, likely because fissures deform, diminishing overall dynamic strength. Subsequent microscopic analysis, utilizing SEM images, along with a discussion of macroscopic inherent fissures, elucidated the impact of unloading rate on soil damage mechanisms, advancing the understanding of fissured soil behavior post- unloading. The study of mechanical properties of fissured soil following varying unloading rates is crucial for comprehending its damage mechanism and determining post-unloading soil strength parameters, providing valuable insights for practical applications in soil engineering.

Although poly (lactic acid) (PLA) is a good environmentally-friendly bio-degradable polymer which is used to substitute traditional petrochemical-based polymer packaging films, the barrier properties of PLA films are still insufficient for high-barrier packaging applications. In this study, oxygen scavenger hydroxyl-terminated polybutadiene (HTPB) and cobalt salt catalyst were incorporated into the PLA/poly (butylene adipate-co-terephthalate) (PLA/PBAT), followed by melting extrusion and three-layer co-extrusion blown film process to prepare the composite films. The oxygen permeability coefficient of the composite film combined with 6 wt% oxygen scavenger and 0.4 wt% catalyst was decreased significantly from 377.00 cc mil m-2 day-1 0.1 MPa-1 to 0.98 cc mil m-2 day-1 0.1 MPa-1, showing a remarkable enhancement of 384.69 times compared with the PLA/PBAT composite film. Meanwhile, the degradation behavior of the composite film was also accelerated, exhibiting a mass loss of nearly 60% of the original mass after seven days of degradation in an alkaline environment, whereas PLA/PBAT composite film only showed a mass loss of 32%. This work has successfully prepared PLA/PBAT composite films with simultaneously improved oxygen barrier property and degradation behavior, which has great potential for high-demanding green chemistry packaging industries, including food, agricultural, and military packaging. (c) 2024 Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Giant reed (Arundo donax L.) is a plant species with a high growth rate and low requirements, which makes it particularly interesting for the production of different bioproducts, including natural fibers. This work assesses the use of fibers obtained from reed culms as reinforcement for a high-density polyethylene (HDPE) matrix. Two different lignocellulosic materials were used: i) shredded culms and ii) fibers obtained by culms processing, which have not been reported yet in literature as fillers for thermoplastic materials. A good stress transfer for the fibrous composites was observed, with significant increases in mechanical properties; composites with 20% fiber provided a tensile elastic modulus of almost 1900 MPa (78% increase versus neat HDPE) and a flexural one of 1500 MPa (100% increase), with an improvement of 15% in impact strength. On the other hand, composites with 20% shredded biomass increased by 50% the tensile elastic modulus (reaching 1560 MPa) and the flexural one (up to 1500 MPa), without significant changes in impact strength. The type of filler is more than its ratio; composites containing fibers resulted in a higher performance than the ones with shredded materials due to the higher aspect ratio of fibers.

The effect of polyphenylene sulfide binder content on the properties of injection molding polyphenylene sulfide/NdFeB magnets were investigated. The maximum filling amount of NdFeB magnetic powder was 87.6 wt.-%, and the mixing process and subsequent injection molding of the polyphenylene sulfide/NdFeB were in good condition. The melt mass-flow rate of the polyphenylene sulfide/NdFeB granular materials reached 121.7 g/10 min, the compressive strength of the polyphenylene sulfide/NdFeB magnet was 92.18 MPa, and its maximum magnetic energy product reached 5.59 MGOe. The structure and morphology characteristics of polyphenylene sulfide/NdFeB magnets were investigated using scanning electron microscopy and atomic force microscopy. The corrosion behavior of polyphenylene sulfide/NdFeB magnets was also studied using potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results indicated that the injection molding process facilitated the uniform coating of polyphenylene sulfide particles on NdFeB powder, which directly enhanced the corrosion resistance of polyphenylene sulfide/NdFeB magnets. With an increase in polyphenylene sulfide content, the surface of polyphenylene sulfide/NdFeB magnets became more uniform. The corrosion current density of 13 wt.-% polyphenylene sulfide/NdFeB magnet was approximately one order of magnitude lower than that of 9 wt.-% polyphenylene sulfide/NdFeB magnet, indicating an improved corrosion resistance of polyphenylene sulfide/NdFeB magnet.