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Effect of alumina fillers on physical and mechanical properties of luffa/groundnut shell natural fiber reinforced polymer composites

AbstractThis study aims to investigate the physical and mechanical properties of epoxy composites reinforced with hybrid luffa waste and groundnut shell waste natural fibers and to evaluate the effect of different filler loadings of alumina on the mechanical behavior of the hybrid composites. The luffa fibers were made to undergo mercerization in 10% NaOH solution. All the treated fibers and the alumina fillers were characterized using X‐ray diffraction analysis (XRD). The study used three different filler loadings of alumina (Al2O3) (5%, 10%, and 15% by volume) and three different fractions of treated luffa‐waste groundnut shell hybrid fibers (10%, 30%, and 50% by volume). The composites were fabricated using the hand layup technique, and the prepared test specimens were subjected to mechanical and physical properties testing as per ASTM standards. The experimental findings indicated that the inclusion of Al2O3 filler improved the physical and mechanical characteristics of the natural fiber‐reinforced hybrid composites. The results showed that the composites with 30 vol. % fibers (1:1 luffa fiber: groundnut shell fiber) and 10 vol. % Al2O3 content showed enhanced tensile, flexural, shear, and impact strength and hardness. Besides, a good synergy between the alumina fillers, natural fibers, and the polymer matrix was observed in the surface morphology of the composite specimen. The developed composites can be used in low and medium‐load‐bearing structural and non‐structural applications.Highlights Development of hybrid polymer composites with luffa and novel groundnut shell fibers Hybridization of alumina ceramic particles with natural fiber hybrid composites Assessment of physical and mechanical properties of the polymer composites

Aviation fuel hydrocarbons from camphorwood and low-density polyethylene: Cascade catalytic approach with CaO and Zn/HBeta

In this study, the co-pyrolysis of camphorwood and low-density polyethylene employing a cascade catalyst system consisting of CaO and Zn-modified HBeta in a fixed-bed reactor was investigated for the production of aviation fuel hydrocarbons (C8–C16). The effect of Zn loading on HBeta, CaO to Zn/HBeta mass ratio, and the feedstock to catalyst mass ratio on both oil yield and composition was investigated. Results revealed that loading Zn onto HBeta led to ZnO cluster and oxygen-bridged Zn dimers ([ZnOZn]2+) formation, which affects HBeta's acid properties and aromatization capacity. The 10 wt%Zn/HBeta catalyst with more ZnO content exhibited weak acid sites, and moderate aromatization capacity, increasing oil yield from 32.06 to 44.25 wt% compared to 3 wt%Zn/HBeta and favoring presence of straight-chain components in oil products. CaO also enhanced straight-chain alkane formation. The highest oil yield, reaching 48.44 wt%, was obtained when CaO and 10 wt%Zn/HBeta cascade by a 1:1 mass ratio was adopted, producing oil with aviation fuel with a maximum yield of 18.45 wt%, and selectivity of 38.09 area%, of which 26.54 area% being aromatics and 11.55 area% being alkanes. Furthermore, the feedstock-to-catalyst ratio influenced the products significantly, with lower feedstock-to-catalyst ratio enhanced aromatization and the ratio of 2:1 recommended. Therefore, this cascade catalytic approach, which combines cost-effective CaO and 10 wt%Zn/HBeta catalysts shows significant potential for enhancing bio-aviation fuel production from solid wastes. Moreover, it provides a viable and promising solution for addressing concerns related to low oil yield and excessive aromatization.

Effects of compressive cyclic loading on the fatigue properties of oil-well cement slurries serving in deep downhole environments

With the increasing demand for energy from deep oil and gas reservoirs, oil-well cement slurries are subjected to complex compressive cyclic loading in high-temperature and high-pressure (HTHP) environments. Currently, no standard to guide the evaluation of the fatigue performance of cement slurries under cyclic loading or a systematic investigation to help understand it exists. To fill this gap, this study used a set of innovative HTHP curing and testing devices to mimic the actual operating conditions of deep wells. Cement slurries were cast, cured, and subjected to quasi-static and cyclic loading tests at four downhole temperatures (25, 90, 115, and 140 °C). In the cyclic-loading tests, three loading levels (30%, 50%, and 70%) under 20 MPa confining pressure were applied to study the fatigue performance, and nuclear magnetic resonance (NMR) was employed to identify internal microcrack damage. When the downhole temperature increased from 25 to 140 °C and the cyclic loading level increased from 30% to 70%, the accumulated plastic strain of samples increased by 13.8 times. A large increase in the plastic strain of oil-well cement slurries can significantly reduce the fatigue resistance and service life of oil and gas wells. Based on this research, the authors propose the addition of compressive cyclic loading tests (particularly under HTHP testing conditions) to the current oil-well cement slurry testing standards, which will be very significant for the fatigue performance evaluation of cement slurries used in HTHP environments in deep wells.

Structural, Optical and Dielectric Properties of Some Nanocomposites Derived from Copper Oxide Nanoparticles Embedded in Poly(vinylpyrrolidone) Matrix.

Polymer nanocomposite films based on poly(vinyl pyrrolidone) incorporated with different amounts of copper oxide (CuO) nanoparticles were prepared by the solution casting technique. The PVP/CuO nanocomposites were analyzed by X-ray diffractometry (XRD), scanning electron microscopy, UV-Visible absorption spectroscopy and dielectric spectroscopy. The XRD analysis showed that the monoclinic structure of cupric oxide was maintained in the PVP host matrix. The key optical parameters, such as optical energy gap Eg, Urbach energy EU, absorption coefficient and refractive index, were estimated based on the UV-Vis data. The optical characteristics of the nanocomposite films revealed that their transmittance and absorption were influenced by the addition of CuO nanoparticles in the PVP matrix. Incorporation of CuO nanoparticles into the PVP matrix led to a significant decrease in band gap energy and an increase in the refractive index. The dielectric and electrical behaviors of the PVP/CuO nanocomposites were analyzed over a frequency range between 10 Hz and 1 MHz. The effect of CuO loading on the dielectric parameters (dielectric constant and dielectric loss) of the metal oxide nanocomposites was also discussed.

ISSLS prize in clinical/bioengineering science 2024: How standing and supine positions influence nutrient transport in human lumbar discs?-A serial post-contrast MRI study evaluating interplay between convection and diffusion.

The intervertebral disc being avascular depends on diffusion and load-based convection for essential nutrient supply and waste removal. There are no reliable methods to simultaneously investigate them in humans under natural loads. For the first time, present study aims to investigate this by strategically employing positional MRI and post-contrast studies in three physiological positions: supine, standing and post-standing recovery. A total of 100 healthy intervertebral discs from 20 volunteers were subjected to a serial post-contrast MR study after injecting 0.3mmol/kg gadodiamide and T1-weighted MR images were obtained at 0, 2, 6, 12 and 24h. At each time interval, images were obtained in three positions, i.e. supine, standing and post-standing recovery supine. The signal intensity values at endplate zone and nucleus pulposus were measured. Enhancement percentages were calculated and analysed comparing three positions. During unloaded supine position, there was slow gradual increase in enhancement reaching peak at 6h. When the subjects assumed standing position, there was immediate loss of enhancement at nucleus pulposus which resulted in reciprocal increase in enhancement at endplate zone (washout phenomenon). Interestingly, when subjects assumed the post-standing recovery position, the nucleus pulposus regained the enhancement and endplate zone showed reciprocal loss (pumping-in phenomenon). For the first time, present study documented acute effects of physiological loading and unloading on nutrition of human discs in vivo. While during rest, solutes diffused gradually into disc, the diurnal short loading and unloading redistribute small solutes by convection. Standing caused rapid solute depletion but promptly regained by assuming resting supine position.

Investigating the Significance of Fluid Load Effects on Wet Surfaces in Concrete Dam Analysis: An Examination of Structural Behavior and Performance using the Pine Flat Dam as a Case Study

Investigating the Significance of Fluid Load Effects on Wet Surfaces in Concrete Dam Analysis: An Examination of Structural Behavior and Performance using the Pine Flat Dam as a Case Study

Effect of loading and pyrolysis of carbon-supported cobalt phthalocyanine on the electrocatalytic reduction of CO2

Understanding the structure-activity relationship of materials that are active for the CO2 electrochemical reduction reaction (CO2ERR) is crucial for developing stable, high-performance catalysts. In this research, it is first shown that ball-milling is a highly efficient way to disperse cobalt phthalocyanine (CoPC) onto carbon black without influencing the CO2 electroreduction performance of the resulting materials. Then, the link between the loadings of the CoPC precursor on the carbon support and the CO2ERR activity of the pyrolyzed materials is demonstrated. With CO current efficiencies higher than 45% and CO current densities as high as -20 mA cm−2 at -0.77 V vs. RHE, the materials with CoPC loadings of 7.9 wt% and higher were still surprisingly active after pyrolysis at 800 and 900 °C. On the other hand, the CO2ERR activity of the materials containing less than 6.1 wt% CoPC was drastically reduced after pyrolysis at these temperatures, with CO current efficiencies lower than 10 %. X-ray powder diffraction revealed that only the materials containing crystalline CoPC before pyrolysis showed good CO2ERR activity after pyrolysis at 800 and 900 °C. Furthermore, X-ray absorption spectroscopy showed that the loading of the CoPC precursor influenced the structure of the active sites in the pyrolyzed CoPC/C materials. Overall, this study highlights the importance of the dispersion of CoPC when forming a material that is catalytically active for CO2ERR after pyrolysis.

Tribo-Dynamic analysis of nano-enhanced palm blend lubricant for roller bearing application

Abstract Environmental concerns have led to an increase in the development of bio-lubricants during the last ten years. Many tribological studies address the findings of various types of bio-based lubricant performance derived from plant-based edible and non-edible oils in different operating conditions. However, those tribological tests were limited to workbench tribometers. In the present work, experimental investigations were carried out to evaluate the lubrication performance of functionalized multiwall carbon nanotubes (FMWCNTs) blended palm oil compared to mineral oil. The steel bearings are commonly used to minimize the effect of dynamic loads coming from the driven end in sliding / rolling conditions of the bearing. The wear severity on the bearing surfaces was examined using a Scanning electron microscope coupled with energy-dispersive X-ray spectroscopy (EDX), 3D-optical profilometer results provided detailed information on surface profiles and roughness created on bearing surfaces under machine operating conditions. FFT-bearing vibration results were correlated with the surface degradation study of SEM analysis. Zeta-potential values reveal that the nanomaterial showed stable performance in the lubricant for 80 % of the total machine operating duration. Overall, experimental studies indicate that the tribological and vibration response of nanomaterial blended bio-oil lubricated bearing exhibited better results than that of mineral oil-lubricated bearing results.

Effect of Normal Load on the Nanofriction Behavior of Graphene on Stainless-Steel Substrate: Implication for Nanoscale Lubrication

Effect of Normal Load on the Nanofriction Behavior of Graphene on Stainless-Steel Substrate: Implication for Nanoscale Lubrication

Ionic Cross-Linked MOF-Polymer Mixed-Matrix Membranes for Suppressing Interfacial Defects and Plasticization Behavior.

To address the plasticization phenomenon and MOF-polymer interfacial defects, we report the synthesis of ionic cross-linked MOF MMMs from a dual brominated polymer and MOF components by using N,N'-dimethylpiperazine as the cross-linker. We synthesized brominated MIL-101(Cr) nanoparticles by using mixed linkers and prepared brominated polyimide (6FDA-DAM-Br) to form ionic cross-linked MMMs. The gas permeation properties of the polyimide, ionic cross-linked MOF-polymer MMMs, and non-cross-linked MOF-polymer MMMs with various MOF weight loadings were investigated systematically to effectively understand the effects of MOF weight loading and ionic cross-linking. The ionic cross-linked 40 wt % MOF-polymer MMM exhibited significantly enhanced gas permeability with an H2 permeability of 1640 Barrer and CO2 permeability of 1981 Barrer and slightly decreased H2/CH4, H2/N2, CO2/CH4 and CO2/N2 selectivities of 16.9, 15.4, 20.5, and 18.6, respectively. The H2 and CO2 permeabilities are approximately 2-3 fold higher than those of the pure polyimide (6FDA-DAM) membrane. Moreover, the ionic cross-linked 40 wt % MOF-polymer MMM exhibited significantly increased resistance to plasticization. This is because the brominated MOF incorporation boosted molecular transport and polymer chain rigidity, and ionic cross-linking further reduced the number of interfacial defects and polymer chain mobility.

An essentially radiation-transparent body coil integrated with a patient rotation system for MR-guided particle therapy.

The pursuit of adaptive radiotherapy using MR imaging for better precision in patient positioning puts stringent demands on the hardware components of the MR scanner. Particularly in particle therapy, the dose distribution and thus the efficacy of the treatment is susceptible to beam attenuation from interfering materials in the irradiation path. This severely limits the usefulness of conventional imaging coils, which contain highly attenuating parts such as capacitors and preamplifiers in an unknown position, and requires development of a dedicated radiofrequency (RF) coil with close consideration of the materials and components used. In MR-guided radiation therapy in the human torso, imaging coils with a large FOV and homogeneous B1 field distribution are required for reliable tissue classification. In this work, an imaging coil for MR-guided particle therapy was developed with minimal ion attenuation while maintaining flexibility in treatment. A birdcage coil consisting of nearly radiation-transparent materials was designed and constructed for a closed-bore 1.5 T MR system. Additionally, the coil was mounted on a rotatable patient capsule for flexible positioning of the patient relative to the beam. The ion attenuation of the RF coil was investigated in theory and via measurements of the Bragg peak position. To characterize the imaging quality of the RF coil, transmit and receive field distributions were simulated and measured inside a homogeneous tissue-simulating phantom for various rotation angles of the patient capsule ranging from 0° to 345° in steps of 15°. Furthermore, simulations with a heterogeneous human voxel model were performed to better estimate the effect of real patient loading, and the RF coil was compared to the internal body coil in terms of SNR for a full rotation of the patient capsule. The RF coil (total water equivalent thickness (WET) ≈ 420µm, WET of conductor ≈ 210µm) can be considered to be radiation-transparent, and a measured transmit power efficiency (B1 +/ ) between 0.17 µT/ and 0.26 µT/ could be achieved in a volume (Δz=216mm, complete x and y range) for the 24 investigated rotation angles of the patient capsule. Furthermore, homogeneous transmit and receive field distributions were measured and simulated in the transverse, coronal and sagittal planes in a homogeneous phantom and a human voxel model. In addition, the SNR of the radiation-transparent RF coil varied between 103 and 150, in the volume (Δz=216mm) of a homogeneous phantom and surpasses the SNR of the internal body coil for all rotation angles of the patient capsule. A radiation-transparent RF coil was developed and built that enables flexible patient to beam positioning via full rotation capability of the RF coil and patient relative to the beam, with results providing promising potential for adaptive MR-guided particle therapy.

Bond performance of freeze-thaw damaged concrete and reinforcing bars subjected to high-cycle fatigue loading

Concrete bridges are susceptible to the detrimental effects of freeze-thaw cycles (FTCs) and dynamic vehicle loading in cold regions, compromising the bond between reinforcing bars and concrete. After high-cycle fatigue loading using eccentric pull-out tests, an experiment on the bond performance of freeze-thaw damage specimens was carried out. The investigation focused on the impact of FTCs, fatigue load cycles (FLCs), and concrete strengths on the bond behaviour. The test results showed that eccentric pull-out specimens of reinforced concrete with freeze-thaw damage under high-cycle fatigue loading were more susceptible to experiencing splitting failure. As the number of FTCs increased, the peak and the residual bond strength decreased continuously. Fatigue loading had a slight improvement effect on the peak bond strength, but it significantly reduced the residual bond strength when the specimens suffered from higher fatigue damage. The peak slip initially increased and subsequently decreased with FTCs, showing minimal sensitivity to the number of FLCs. Considering the stiffness degradation of the ascending section, a bond-slip model for freeze-thaw damaged concrete and reinforcing bars under high-cycle fatigue loading was established, and verified through experimental results.

An overview of the NEMO modelling for the BaySys project

This article is intended as an introduction to discuss the development of a modelling framework to examine simulated climate change and river discharge regulation and their combined impact on marine conditions in the Hudson Bay Complex as a contribution to BaySys, a collaborative project between Manitoba Hydro, Hydro-Quebec, the University of Manitoba, the University of Alberta, Université Laval and Ouranos. In support of this work, a sea ice and oceanographic model was improved and then used to further study the effects of freshwater loading and ice cover on the circulation of Hudson Bay. This modelling perspective is based on the Nucleus for European Modelling of the Ocean (NEMO) ocean general circulation model coupled to version 2 of the Louvain-la-Neuve sea ice model (LIM2). The goal of the modelling was to provide a framework and tool for simulating projected changes in marine state and dynamic variables, while also enabling an integration of observations and numerical analyses. A key aspect of this work was the climate-hydrologic-ocean model integration aspect. The inclusion of a biogeochemical model and explicit tidal forcing to examine the evolution of a Canadian marginal sea with century-long integrations was also a novel aspect of the work. Overall, this work examines the NEMO modelling configuration used in BaySys, how it is set up and the experiments carried out. A broader picture evaluation of the model output is made including the BaySys mooring observations, showing that the modelling framework is suitable to examine the posed questions on the role of climate change and river regulation.

Enhanced paracetamol photodegradation over synthesized TiO2/g-C3N4 nanocomposites: Effect of g-C3N4 loading on the properties and performance

Water pollution has been a consistent issue faced by mankind worldwide. With the increase in world population and rapid urbanization, it has become even more concerning, especially with the detection of new pollutants such as pharmaceutical and personal care products. These compounds must be removed to minimize the adverse effects on all living beings, and one effective method for their elimination is through photocatalytic degradation. In this study, titanium dioxide nanoparticles (TiO2 NPs) was synthesized and nanocomposites were formed with addition of graphitic carbon nitride (GCN) where its loading was varied. These materials were then characterized and used as catalysts to degrade paracetamol, a pharmaceutical product. Structural analysis showed that GCN is present in the nanocomposites indicating the successful modification. Nanocomposites exhibited excellent photocatalytic activity with the highest degradation rate of 0.0364 min−1 was obtained using 2 wt% GCN loading with experimental conditions of an initial paracetamol concentration of 10 ppm, a catalyst dosage of 0.2 g and a pH 5. The synergistic effect that occurred between the two components in the nanocomposites contributed to the high photocatalytic activity, compared to its singular component which is lacking this factor. Overall, nanocomposites have good potential to be used to remove pharmaceutical products from wastewater.

Combined Effect of Dietary Acid Load and Cardiometabolic Syndrome on Bone Resorption Marker among Post-Menopausal Women in Malaysia.

This study aimed to investigate factors associated with bone resorption status and determine the independent and interactive effects of dietary acid load (DAL) and cardiometabolic syndrome (CMS) on bone resorption in post-menopausal women. Overall, 211 community-dwelling post-menopausal women were recruited from the National Council of Senior Citizens Organization, Malaysia. DAL was estimated using the potential renal acid load from the food frequency questionnaire. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) and smoking behaviour was assessed using the Global Adult Tobacco Survey 2011. Serum 25(OH) vitamin D levels were determined using the ADVIA Centaur vitamin D assay and serum C-terminal telopeptides of type I collagen (CTX1) were used as surrogate markers to assess bone resorption. CMS was determined based on the harmonised criteria. Age (β = -0.145, t = -2.002, P < 0.05) was negatively associated while DAL (β = 0.142, t = 2.096, P < 0.05) and sleep quality (β = 0.147, t = 2.162, P < 0.05) were positively associated with CTX1. Height was positively correlated with CTX1 (r = 0.136, P <0.05). Conversely, other variables (CMS traits, CMS, serum 25(OH) vitamin D level, years of menopause, years of education and physical activity) were not significantly associated with CTX1 levels. There was no significant interaction between DAL and CMS on bone resorption. Our findings propose that high DAL, but not CMS, is a potential risk factor for bone resorption. The analysis did not demonstrate the combined effects of DAL and CMS on bone resorption.

Green Energy from Palm Kernel Shell Gasification – dual fuel engine performance analysis

&lt;span lang="EN-US"&gt;Electricity generation in Indonesia is mainly generated from non-renewable fuels. Based on these problems, this research utilizes palm kernel shells to be converted into producer gas as secondary fuel for a 5 kW diesel engine. Through a gasification process equipped with a cooling and gas cleaning system, low tar gas is fed to the diesel engine with variations of gas flow rate ratio to combustion air. A dummy load is installed to investigate the effect of load on diesel consumption. The diesel engine vibration increases due to using two fuel types was measured by installing a vibration meter. The research results show that the higher the load and the greater the ratio of producer gas injected, the less diesel consumption. At a gas ratio of 4:1 and an increase of load from 1 to 5 kW, the diesel fuel flow rate reduces by 25 - 31%. The most significant reduction in diesel consumption occurred at a load of 5 kW, valued at 38.49%. On the other hand, increasing the gas ratio causes an increase in diesel engine vibration. The research results showed an increase in engine vibration of 5.84% - 10.25%. The largest vibration was recorded at a load of 5 kW with a value of 92.4 m/s&lt;sup&gt;2 &lt;/sup&gt; &lt;/span&gt;

Evaluating the effect of unidirectional loading on the piezoresistive characteristics of carbon nanoparticles

The piezoresistive effect of materials can be adopted for a plethora of sensing applications, including force sensors, structural health monitoring, motion detection in fabrics and wearable, etc. Although metals are the most widely adopted material for sensors due to their reliability and affordability, they are significantly affected by temperature. This work examines the piezoresistive performance of carbon nanoparticle (CNP) bulk powders and discusses their potential applications based on strain-induced changes in their resistance and displacement. The experimental results are correlated with the characteristics of the nanoparticles, namely, dimensionality and structure. This report comprehensively characterizes the piezoresistive behavior of carbon black (CB), onion-like carbon (OLC), carbon nanohorns (CNH), carbon nanotubes (CNT), dispersed carbon nanotubes (CNT-D), graphite flakes (GF), and graphene nanoplatelets (GNP). The characterization includes assessment of the ohmic range, load-dependent electrical resistance and displacement tracking, a modified gauge factor for bulk powders, and morphological evaluation of the CNP. Two-dimensional nanostructures exhibit promising results for low loads due to their constant compression-to-displacement relationship. Additionally, GF could also be used for high load applications. OLC’s compression-to-displacement relationship fluctuates, however, for high load it tends to stabilize. CNH could be applicable for both low and high loading conditions since its compression-to-displacement relationship fluctuates in the mid-load range. CB and CNT show the most promising results, as demonstrated by their linear load-resistance curves (logarithmic scale) and constant compression-to-displacement relationship. The dispersion process for CNT is unnecessary, as smaller agglomerates cause fluctuations in their compression-to-displacement relationship with negligible influence on its electrical performance.

An investigation of a process for selective biogas desulfurization and autotrophic denitrification in a membrane supported reactor

A lab-scale dense polydimethylsiloxane (PDMS) membrane bioscrubber (MBS) was used for selective removal of highly toxic H2S from biogas under autotrophic conditions for the first time. The performance of MBS was evaluated under the effects of sulfide loadings, pH, and hydraulic retention time (HRT). The results showed that gradual increase in sulfide loading rate from 131 to 316 g/m3.d boost S/N ratios 1.9–4.0, on average sulfide oxidation efficiencies higher than 95% were achieved. The S/N ratios were determinant on the formation of oxidation products, but not on the H2S gas removal efficiency. The transition of HRT significantly affected the denitrification rather than the sulfide oxidation, when HRT reduced from 24 to 12 h the nitrate removal efficiency suddenly dropped from 98% to 70%. Increasing the pH values from 7.0 to 9.0 also decreased the sulfide oxidation efficiency from 97±0.5–92±1.1%. Denitrification efficiency > 96% was observed between pH value of 7.0 and 8.0, whereas at pH 9.0 dropped rapidly to 82%. In the whole experiment time there was no membrane-induced problem that adversely affected the system performance. Over-all the developed anoxic dense MBS successfully employed for selective removal of 10,000 ppm H2S and nitrate concurrently with low chemical consumption, possibility for recovery of elemental sulfur, enhanced CH4 calorific value and eliminating the risks of explosion and dilution of biogas. The current work showed the PDMS MBS system is a promising alternative way in biological nitrogen removal and biogas desulfurization under anoxic conditions. Its application in real scale would have high economic importance.

Mode-I failure and mechanical behavior of sandstone under cyclic loading: Laboratory testing and DEM simulation

To study the mode-I failure and mechanical behavior of rock under cyclic loading, the cracked chevron notched Brazilian disc (CCNBD) of sandstone was employed in this paper, and thus three different upper-limit loads cyclic tests were carried out, including 95 %SUL(static ultimate load) ∼ 35 %SUL, 85 %SUL ∼ 25 %SUL, 75 %SUL ∼ 15 %SUL. The 3D discrete element model of CCNBD specimen was built to study mechanical properties and cracking behavior at a meso-scale. Meanwhile, the effect of cyclic loading on microstructure characteristics and fracture process zone (FPZ) was discussed. The results show that cyclic loading has a weakening effect on fracture toughness, and a modified fracture toughness calculation method was proposed considering the effect of irreversible plastic deformation under cyclic loading. There are obvious stages of microcracking behavior under cyclic loading, specific for the condition of 85 %SUL ∼ 25 %SUL, and the microcrack density is positively correlated with the number of cycles. Meanwhile, the effect of cyclic load on sandstone microstructure contains weak-structure fracture effect and compaction effect, and they exist simultaneously and work together. In addition, cyclic loading has a great influence on the length of FPZ, and the length of FPZ under cyclic loading is greater than that under monotonic loading.

Sustainable solutions for railway using recycled rubber

This paper introduces four innovative applications of waste rubber from scrapped tyres or conveyor belts in railway tracks. They include (a) a synthetic energy-absorbing layer of coalwash, steel furnace slag and rubber crumbs (SFS + CW + RC) for railway subballast, (b) a rubber inter-mixed ballast system (RIBS), (c) energy-absorbing rubber geogrids, and (d) a hybrid track incorporating tyre cells and elements of off-the-road truck tyres. Comprehensive laboratory and field tests have been conducted to investigate the geotechnical properties of these applications. Specifically, an empirical model was developed to predict the permanent deformation response of SFS + CW + RC mixtures that incorporate the effect of granular rubber and axial loads based on cyclic triaxial tests. Large-scale triaxial tests and field trials proved that RIBS exhibited improved energy-absorbing properties, sufficient shear strength and the promising ability to mitigate ballast breakage and stress distribution. A rubber geogrid with an optimal rib thickness of 10.6 mm was selected based on drop-hammer impact tests. The performance of the hybrid track was investigated using the National Testing Facility for High-speed Rail (NTFHR), from which it was found that the reinforced track had significantly less settlement, lateral deformation and ballast breakage than the traditional track.