Residual Ratio Research Articles

Effective enhancement of ramie anaerobic continuous flow degumming by chitosan and its microbiological mechanism.

Based on a novel bio-degumming system, the effect of chitosan on the degumming effect of ramie was investigated. The degumming effect indexes before and after the addition of chitosan were assessed, and the enzyme activities (pectinase, xylanase, ligninase and cellulase) were detected. Meanwhile changes in microbial community structure were evaluated. Furthermore, the electron-donating effect of chitosan and cellulose was further simulated by Fukui function. Degumming effect indexes showed the addition of chitosan could effectively increase the breaking strength of degummed ramie (from 6.04 to 6.59 cN/dtex), reduce the fineness (from 10.06 to 8.039 dtex), so that more gums were removed (the residual gum ratio reduced from 16.55% to 12.09%) and more cellulose was retained in the degummed ramie (cellulose content increased from 78.01% to 80.96%). Enzyme activity measurements revealed that the addition of chitosan increased the activity of degumming enzymes (pectinase, xylanase and ligninase), while decreased cellulase activity. The addition of chitosan induced changes of the community structure, with an increase of degumming microorganisms and a decrease of cellulose-degrading microorganisms. According to Fukui function, chitosan has a stronger electron donating ability than cellulose, which might be one important reason for the changes in enzyme activities and community structures.

Age-Dependent Flexural Properties of Fiber Reinforced Concrete Used in Thin Overlays

This paper presents measured age-dependent flexural properties of fiber-reinforced concrete (FRC) as are used in the design of thin overlay pavements. A laboratory investigation was performed to quantify the pavement design properties, particularly residual strength ratio of FRC as a function of age. Four different types of structural macro-fibers, made of steel or polypropylene, and of different lengths or aspect ratios were investigated. Also different fiber volume contents from 0%, 0.5%, and 1.0% were studied for all fiber types and ages. The results confirmed that there is a significant agedependency to the residual strength ratio. The short steel FRC at high fiber volume content was the only mixture which showed constant residual strength ratio as a function of time. All other FRC mixtures exhibited a reduced residual strength ratio when tested at later ages.

Degradation of Interfacial Bond for FRPs Near-Surface Mounted to Concrete Under Fatigue: An Analytical Approach

In this study, an analytical model was developed for the local bond degradation behavior between a near-surface mounted (NSM) fiber-reinforced polymer (FRP) and concrete under fatigue loading. A trilinear local bond stress–slip relationship was adopted to characterize the fundamental bond behavior at the FRP-epoxy-concrete interface at different stages of elastic, softening and debonding. A series of post-fatigue direct pull-out tests (DPTs) of NSM FRP-bonded concrete blocks was conducted to provide the local bond degradation laws for the analytical model. The bond region was discretized into finite elements to include the effect of bond degradation to different extents, and a closed-form solution was derived by virtue of appropriate boundary conditions in each fatigue cycle. The model is capable of predicting the FRP strain distribution, local bond stress distribution and relative slip development at a targeted number of fatigue cycles. The reliability of the analytical model was confirmed by experimental data, and its sensitivity to various parameters such as local bond strength, the residual bond strength ratio and Young’s modulus of FRP reinforcement was also assessed in this study.

Effect of residual lung expansion on pulmonary function after lobectomy.

Pulmonary function after lobectomy is often higher than what is predicted. This occurrence could be related to postoperative expansion of the residual lung. The study aim was to determine if residual lung expansion affects pulmonary function after lobectomy. The participants in this retrospective study were 142 patients who had undergone lobectomy via video-assisted thoracic surgery. Computed tomography and pulmonary function tests were performed preoperatively and 1year postoperatively. Three-dimensional computed tomography volumetry was performed to assess lung volumes preoperatively and postoperatively, and the predicted postoperative forced expiratory volume in 1s was calculated. The residual lung expansion ratio was defined as the postoperative-to-preoperative residual lung volume ratio, and the postoperative forced expiratory volume in 1s ratio was defined as the measured-to-predicted postoperative forced expiratory volume in 1s ratio. The effect of the residual lung expansion ratio on the postoperative forced expiratory volume in 1s ratio as well as the factors affecting the postoperative forced expiratory volume in 1s ratio were evaluated. The median residual lung expansion ratio was 1.17 (interquartile range: 1.10-1.24), and the median postoperative forced expiratory volume in 1s ratio was 1.13 (interquartile range: 1.04-1.21). The residual lung expansion ratio significantly affected postoperative forced expiratory volume in 1s ratio (p < 0.001). After lobectomy, better residual lung expansion was associated with improved postoperative pulmonary function.

Enhancing electrochemical performance of lignin-based carbon fibrous aerogels via boron doping.

Self-supported hardwood kraft lignin (HKL)/graphene-based carbon fibrous aerogel (L/GCA) presents a fascinating prospect as the electrode of supercapacitor due to its impress rate capacity and cyclic stability. However, the hydrophobicity nature of L/GCA hampers the ion transfer between the electrode and electrolyte, thereby limiting its electrochemical performance. To address this, we enhanced the electrochemical performance of L/GCA through boron doping based on the improvement of hydrophilicity and the re-arrangement of electron density. The interaction between boron and L/GCA, as well as the effects of boron on the morphology, crystalline structure, wettability, and electrochemical performance were systematically investigated. Results indicate that boron doping increased the layer spacing of graphite lamella, reduced the degree of graphitization, and enhanced the hydrophilicity of L/GCA. These characteristics resulted in improved specific capacitance, rate capacity, and cyclic performance of boron doped L/GCA (B-L/GCA). The measured specific capacitance of the B-L/GCA-1.5-based electrode was 228 F g-1 at a current density of 0.5 A g-1, with a residual ratio of 113 % after 1000 cycles. The doping strategy presented in this study provides inspiration for enhancing the electrochemical properties of lignin-based carbon materials.

Comparison of three different scoring systems in predicting success of retrograde intrarenal surgery in kidney stones larger than 20 millimeters.

To evaluate stone free rate (SFR) predictivity of three different scoring systems in patients with kidney stones larger than 20 millimeters undergoing retrograde intrarenal surgery(RİRS). Digital records of a total of 166 patients were reviewed retrospectively. Epidemiological characteristics (age, gender, medical history) of the patients, stone and affected kidney characteristics (size, volume, location, density, opaque, presence of urinary system anomaly, presence of stones in different calyx, number of stones, lower pole stone, renal infundibulopelvic angle (IPA), renal infundibulopelvic length (RIL), hydronephrosis), and operative characteristics (preoperative ureteral stent, operation duration, postoperative residual fragments, hospitalization time and complications were recorded. Each patient was scored separately according to the Resorlu-Unsal Scoring System (RUSS), the modified Seoul National University Renal Stone Complexity (S-ReSC) and R.I.R.S scoring systems based on the stone characteristics seen on CT. All three methods had statistically acceptable sensitivity and specificity values. Sensitivity for R.I.R.S nomogram is 62.3%, specificity is 77.1% (cut-off: 7.5 points, area under the curve (AUC):0.735, p < 0.001), sensitivity for RUSS nomogram is 60.7%, specificity is 77.9% (cut off: 2.5, AUC = 0.749, p < 0.001), sensitivity for the Modified S-ReSC nomogram was determined as 65.6% and specificity as 71.2% (cut off: 2.5, AUC = 0.743, p < 0.001). The residual stone ratio was found to be higher in the presence of lower pole stone. While the cut-off value for IPA was 44.5°, this value was calculated as 24.5mm for RIL. Three scoring systems demonstrate accceptable sensitivity and specificity in predicting stone free rate(SFR) with stones ≥ 20mm. Multivariate analysis highlighted the superiority of the R.I.R.S. scoring system for SFR predictivity. In the presence of lower pole stones, IPA and RIL are important factors in predicting surgical success.

Quantitative Seismic Damage Assessment of Resilient Concrete Columns Using Drift Ratio-Based Fractal Dimension.

The objective of this paper is to develop assessment models to quantitatively evaluate the seismic damage caused to resilient concrete columns intended for buildings located in strong-earthquake-prone regions such as Japan and China. The proposed damage assessment models are based on the fractal analysis of crack patterns on the surface of damaged concrete columns and expressed in the form of a fractal dimension (FD) versus transient drift ratio relationship. To calibrate the proposed damage assessment models, a total of eighty images of crack patterns for eight concrete columns were utilized. All the columns were reinforced by weakly bonded ultra-high-strength (WBUHS) rebars and tested under reversed cyclic loading. The experimental variables covered the shear span ratio of the column, the concrete strength, the axial load ratio, and the amount of steel in the WBUHS rebars. A box-counting algorithm was adopted to calculate or derive the FD of the crack pattern corresponding to each transient drift ratio. The test results reveal that the FD is an efficient image-based quantitative indicator of seismic damage degree for resilient concrete columns and correlates strongly with the transient drift ratio and is subjected to the influence of the shear span ratio. The influence of the other experimental variables on the derived FDs is, if any, little. Based on the test results, a linear equation was developed to define the relationships between the FD and transient drift ratio, and a multi-linear equation was formulated to relate the transient drift ratio to the residual drift ratio, an important index adopted in current design guidelines to measure the repairability of damaged concrete structures. To further verify the efficiency of the drift ratio-based FD in seismic damage assessment, the correlation between the FD and relative stiffness loss (RSL), an indicator used to measure the overall damage degree of concrete structures, was also examined. The driven FD exhibited very strong correlation with RSL, and an empirical equation was developed to reliably assess the overall seismic damage degree of resilient concrete columns with an FD.

Biomass‐based crosslinked composite anion exchange membranes using bacterial cellulose template towards enhanced ionic conductivity and alkaline stability

AbstractA balanced relationship among ionic conductivity, mechanical properties and alkaline stability of anion exchange membranes (AEMs) is essential for their practical application in fuel cells. Herein, a porous substrate (BC@LDH) with hierarchical structure was constructed using natural bacterial cellulose (BC) as a template and then in situ grew inorganic hydroxide ion conductor (layered double hydroxide, LDH). The membrane was fabricated via a filling together with sol–gel crosslinking strategy after impregnating an ionomer containing both quaternary ammonium and hydroxyl groups into the porous substrate and then crosslinked by organosiloxane. Due to the synergistic enhancement effect of BC, LDH and cross‐linking, the obtained membrane exhibited a tensile strength of 47.48 MPa that was 88.3% higher than that of the pure ionomer membrane, and showed an ionic conductivity of 70.7 mS cm−1 (80°C) which benefited from the introduction of ionic conductor LDH. More importantly, its alkaline stability was significantly improved and the residual conductivity ratio was still as high as 81.5% even after hot alkali treatment for 580 h. The direct methanol fuel cell assembled with this membrane exhibited a peak power density of 13.6 mW cm−2 with an open‐circuit voltage of 0.72 V, indicating its potential application in biomass‐based AEMs for fuel cells.Highlights Hierarchical porous substrate comprising LDHs anchored BC fiber was prepared. LDH@BC served as a reinforcing substrate and an ion transport medium. The crosslinked membrane showed significantly improved alkaline stability. The membrane had high ionic conductivity and mechanical strength. Providing a new way to design biomass‐based AEMs with high performance.

Production and Forming of Deposition‐Welded Hybrid Multimaterial Shafts

The combination of several materials in one component can contribute to increased performance. Herein, three types of hybrid components are manufactured using two cladding processes and one joining process. The resulting workpieces are then formed and tested to determine the potential of the different material combinations. Two types of workpieces are produced to investigate multilayer claddings made of different materials, which serve to positively adjust the residual stress. The workpieces are tested using microstructural images and hardness measurements to characterize the microstructure and properties of the intermediate layers. In addition, residual stress measurements are carried out to determine the residual stress ratios. Compressive residual stresses are present in the subsurface of the welded and subsequently formed layer, which will improve the service life in case of rolling load conditions. The third type of workpiece is a combination of aluminum alloy and steel with a cladding layer that combines the performance of the cladding material in the bearing seat with the weight reduction of the aluminum alloy. Scanning Electron Microscopy (SEM) measurements are used to determine whether the application of the cladding has an influence on the intermetallic phase seam in the joining zone of aluminum alloy and steel.

Styrene-Butadiene-Styrene polymer modified bitumen: A review on compatibility and physico-chemical properties

Abstract The triblock elastomeric copolymer Styrene-Butadiene-Styrene (SBS) improves the engineering properties of bitumen and the performance parameters of flexible pavements. Although research investigations have been conducted worldwide, the literature lacks a comprehensive review to provide the up-to-date research status in this field. The current review summarizes the research findings on the compatibility, stability, physical properties, microscopic characterization, and chemical characterization of SBS modified bitumen. Quantitative analysis of physical test results concerning major pavement distresses shows improvement, particularly in high-temperature zones. The interlocked state of phase transition can be achieved at SBS content between 5-6% and the optimum SBS content has been reported to lie within this range. The blending temperature of SBS modified bitumen varies between 140℃-210℃ out of which 180℃ is the most frequently used by researchers. In addition, physical and chemical characteristics of aged binder have been reviewed. Aging indices (residual penetration ratio, change in softening point, viscosity aging ratio, residual ductility ratio) didn’t show any consistent trend, which establishes the need of exploring the co-additives to substantially improve the aging deterioration. Preliminary research on nano-additives showed the improved storage stability at high temperature and the performance of aged modified bitumen. This review has drawn essential conclusions and highlights existing research gaps for peer researchers and field engineers.

Effect of Processing Parameters on Recrystallization During Hot Isostatic Pressing of Stellite-6 Fabricated Using Laser Powder Bed Fusion Technique.

Crack-free Stellite-6 alloy was fabricated using the laser powder bed fusion technique equipped with a heating module as the first attempt. Single tracks were printed with a build plate heated to 400 °C to identify the processing window. Based on the melt pool dimensions, two combinations (sample A: 300 W/750 mm/s and sample B: 275 W/1000 mm/s) were identified to print the cubes. The as-printed microstructure comprised FCC-Co dendrites with M7C3 in the interdendritic region. W-rich M6C particles were found in the overlapping regions between the melt pools, matching the Scheil simulations. However, gas pores were observed due to the higher nitrogen and oxygen content of the feedstock requiring hot isostatic pressing (HIP) at 1250 °C and 150 MPa for 2 h. Sample A was partially recrystallized with slightly coarsened M7C3, while sample B underwent complete recrystallization followed by grain growth along with higher coarsening of the M7C3 after HIP. The varying recrystallization behavior can be attributed to the difference in residual stresses and grain aspect ratio in the as-built condition dictated by laser power and scanning speed. The microhardness after HIP was slightly higher than its wrought counterpart, indicating no severe impact of post-processing on the properties of Stellite-6 alloy.

Experimental characterization and numerical modeling of a frequency-independent viscoelastic damper

Conventional viscoelastic dampers (VED) exhibit significant frequency dependency, leading to variability in stiffness and damping properties at different excitation frequencies, which introduces uncertainties in their design and application in practical engineering. This study addresses this issue by developing a frequency-independent VED through comprehensive experimental characterization and numerical modeling. Four full-scale VEDs were designed and manufactured to explore its mechanical behavior. Cyclic loading tests were carried out under various loading conditions, including different strain amplitudes, loading frequencies, ambient temperatures, and low-cycle fatigue tests. Then, a frequency-independent mechanical model is proposed by combining an energy dissipation element with a nonlinear stiffness element in parallel. Finally, nonlinear dynamic time-history analyses were conducted on a steel frame with and without the VEDs at various ambient temperatures. The experimental results show that the developed VEDs maintain consistent hysteretic behavior across a range of frequencies, exhibit high mechanical stability under varying strain amplitudes and temperatures, and possess excellent recoverability after low-cycle fatigue test. The frequency-independent mechanical model developed in this study accurately simulates the hysteretic response of the developed VEDs, validating its applicability through experimental data. Seismic response analyses demonstrate considerable mitigations in inter-story drift ratios and residual inter-story drift ratios compared to the frame without dampers. These findings highlight the reliability and effectiveness of frequency-independent VEDs in structural vibration control, offering a promising solution for seismic performance enhancement.

Enhanced thermal shock resistance of Al2O3-MgO castables with MgAl2O4 interfacial layer between aggregate and matrix

MgAl2O4 coated corundum aggregates were prepared by impregnating tabular corundum aggregates with sizes of 1-6 mm in magnesium citrate solution followed by heat-treatment at 1500 oC, which were further used in Al2O3-MgO castables. The effects of the Mg2+ concentration in the solution on the characteristics of the MgAl2O4 coated corundum aggregates as well as the effects of the MgAl2O4 coating on the properties and microstructure of the castables were investigated. It is found that the MgAl2O4 coating exhibits optimal continuity and uniformity with a thickness of about 20 μm adjusting the mole concentration of 1.0 mol/L. The Al2O3-MgO castables exhibit the best thermal shock resistance at this concentration, where the residual strength value of 6.5 MPa and the residual strength ratio of 19.4 %. Furthermore, specific energy at micro scales of the aggregate/matrix interface was measured by nanoindentation method. The specific fracture energy of the aggregate/matrix interface region in S10 is 135.0 J·m-2, which is 80 % higher than S0 (243.5 J·m-2). The improvement in thermal shock resistance is mainly attributed to the MgAl2O4 interface layer causing multiple deviations in the crack path, reducing the occurrence of cracks across the aggregate.

Rapid and non-destructive determination of oil content in fuzzy cottonseeds via near-infrared reflectance spectroscopy

In China, enterprises specializing in cottonseed processing predominantly acquire fuzzy cottonseeds. However, the expeditious determination of oil content within these fuzzy cottonseeds remains a major challenge. This particular challenge considerably influences the economic efficiency of enterprises engaged in cottonseed processing. To address this concern, this research acquired near-infrared spectral (NIRS) information from fuzzy cottonseeds and applied the Standard Normal Variate (SNV) pretreatment to eliminate data noise. Subsequently, the Uninformative Variable Elimination (UVE) was employed to select feature wavelength points reflecting fuzzy cottonseed oil content. To further accurately extract the feature wavelengths of fuzzy cottonseeds, Competitive Adaptive Reweighted Sampling (CARS) and Random Frog (RF) were utilized for a second round of feature wavelength extraction. Finally, prediction models for fuzzy cottonseed oil content were established using partial least squares regression (PLSR), Support Vector Regression (SVR), and Least Squares Support Vector Machines (LSSVM). Results revealed that the LSSVM model constructed using the feature selected by the UVE-CARS had the best performance in predicting the oil content of fuzzy cottonseeds. The values of Coefficient of Determination (R2), Root Mean Square Error (RMSE), Residual Error Ratio (RER), and Residual Predictive Deviation (RPD) were 0.8605, 0.0075, 12.8116, and 3.8154, respectively. The LSSVM model built on the feature wavelength points selected by the UVE-RF demonstrated the second-best prediction performance with an R2 of 0.8329, an RMSE of 0.0091, an RER of 10.4861, and an RPD of 3.1228. The validation experiments corroborated these findings, it was found that the R2 was 0.8122, the RMSE was 0.0063, The RER was 7.6190, and the RPD was 2.9036. This underscores the effectiveness of the method employed in this study for detecting the oil content in fuzzy cottonseeds. The approach presented in this study serves as a crucial reference for the swift and accurate assessment of oil content in fuzzy cottonseeds, providing an impactful technical solution for cottonseed processing enterprises to enhance their economic outcomes.

Thermal stability and anti-ablation performance of plasma spray coated-YSZ on Al2TiO5 modified novel ablative carbon-phenolic composites

Abstract Despite ongoing challenges, ablative thermal protection systems are among the most promising methods for safeguarding spacecraft during re-entry thermal protection systems (TPS). A novel aluminium titanate (Al2TiO5/AT) and a highly efficient thermal barrier of coating (TB/TBCs) made from yttria-stabilized zirconia (YSZ), powder, but deposited using the plasma spray technique on polyacrylonitrile (PAN)-based carbon fiber fabric(C)-reinforced with resorcinol phenol formaldehyde resin (RF) composites (C-RF)) would be a potential candidate for TPS applications. This study investigates the composites with varying wt.% of AT that were developed, namely 0 wt.% (YSZ-C-RF), 1 wt.%, 3 wt.%, and 5 wt.% (YSZ-AT-C-RF) by utilizing a hot press moulding machine. Thermal stability and ablation performance of unmodified C-RF with modified YSZ-C-RF and YSZ-AT-C-RF composites are examined through thermogravimetric analysis (TGA) and oxyacetylene torch test/OAT (4.0 MW/m2 for 60 sec). Also, the phase composition and microstructure of the ablated surface are determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The TBC of YSZ has an obvious influence on the residual weight ratios at high temperatures in C-RF and also plays a positive role in increasing thermal stability under nitrogen atmosphere for enhancing ablation resistance concerning YSZ-C-RF. The mass and linear ablation rates (MAR and LAR) of the composites after modifying the surface by YSZ-coated particles are reduced by 82.98% and 15.65%, respectively. Similarly, the introduction of AT particles and TBC of YSZ results in evidence of improving the thermal stability and the ablation resistance in varying wt.% of YSZ-AT-C-RF composites. The primary optimum AT weight loading for enhancing ablation resistance in YSZ-C-RF composites is 1wt.%. The modification of 1wt.% AT particles and YSZ-Coated particles reduce MAR and LAR by 54.79% and 61.94%, respectively. This work offers a meaningful method to remarkably enhance the ablation performance of the modified C-RF and YSZ-AT-C-RF composites.&amp;#xD;

Bio-composites from barley, wheat, and cassava flours reinforced with oil palm residues: Characterization and tensile mechanical performance

This study explores the production of bio-composites from barley, wheat, and cassava flours, reinforced with varying ratios of oil palm residues. The research emphasizes principles of circular economy and sustainability. Both flours and reinforcements underwent characterization to elucidate how their physicochemical properties affect the mechanical behavior of the bio-composites. Barley flour exhibited significantly higher levels of protein (11.11 %), crude fiber (5.64 %), and ash (2.80 %) compared to wheat and cassava flours. Conversely, cassava flour stood out for its high carbohydrate concentration (approximately 97.8 % on a dry weight basis). Characterization highlighted enhanced adhesion between reinforcements in bio-composites with cassava flour, alongside morphological distinctions on fractured surfaces. Fourier-transform infrared (FTIR) analysis unveiled several functional groups in the bio-composites, while thermogravimetric analysis delineated five stages of thermal degradation. In terms of mechanical properties, bio-composites with barley flour showed higher elastic modulus values (970.5 MPa), while those with 12 % OPKS exhibited tensile strengths of 1.7–2.1 MPa. The interaction among components emerged as a fundamental factor influencing the mechanical properties of bio-composites, underscoring the necessity of considering reinforcement composition and distribution during fabrication.

Simplified calculation models for evaluating the post-earthquake axial load-carrying capacity of RC bridge piers

This study aims to develop simplified calculation models of the post-earthquake axial load-carrying capacity of reinforced concrete columns to determine the post-earthquake traffic flow capacity of the bridges for the evaluation and design process. To this end, the maximum and residual drift ratios are first determined as the engineering demand parameters for the simplified calculation model for the evaluation and design process, respectively. Then, the optimal models describing the relationships between the maximum/residual drift ratio and the post-earthquake axial load-carrying capacity are selected. The analysis results show the normal cumulative model in the coordinate system of ln(x)-y is the optimal relationship model. On this basis, the effects of high-sensitivity parameters (i.e. the axial compressive ratio and shear span ratio) on the post-earthquake axial load-carrying capacity are investigated. Results indicate that the axial compressive ratio negatively affects, while the shear span ratio positively affects the post-earthquake axial load-carrying capacity. Finally, the simplified calculation models of the post-earthquake axial load-carrying capacity are developed from the optimal model and the effects of the high-sensitivity parameters, and with validated high accuracy. The simplified calculation models provide engineers and policymakers with a tool to predict the post-earthquake traffic flow capacity of bridges.

Assessing suitability of surface water from Oued El Gourzi for irrigation east of Alger

The study was conducted to determine the suitability of surface water from Oued El Gourzi for irrigation in the Fesdis area, Algeria, during irrigation season of July 2022. The suitability was assessed by analysing eight water samples collected from various sites along the Oued. A range of physicochemical parameters were examined, including EC, pH, Mg2+, Na+, Ca2+, K+, HCO3– and Cl–, alongside other indices such as sodium absorption ratio (SAR), soluble sodium percentage (SSP), residual sodium carbonate (RSC), permeability index (PI) and magnesium adsorption ratio (MAR) using standard procedures. The Richards classification shows that these waters are characterised by high salinity and low alkalinity hazard (C3–S1). According to the Wilcox classification, the majority of these waters are of doubtful quality, with only 25% exhibiting good quality for irrigation. Based on the RSC and MAR, all water samples are deemed safe and suitable for irrigation. However, PI values suggest that all sampling sites are of marginal quality for irrigation (class II). In terms of sodium and chloride concentration, all water samples were deemed unsuitable for irrigation. Based on these results, the waters pose risks for irrigation, particularly due to salinity, necessitating the implementation of special management practices and the selection of salt-tolerant crops.

The effect of pre-dehydrated magnesium-silicate-hydrate on the properties of the castables bonded with hydrable magnesium carboxylate

This study investigates the effect of pre-dehydrated magnesium-silicate-hydrate (PMSH) on the properties of HMC-bonded castables (HMCC), aiming to enhance the medium-temperature mechanical performance of HMCC through the structural memory characteristics of PMSH. The results indicate that adding M-S-H-300 (PMSH treated at 300 °C) improves the mid-temperature mechanical properties of HMCC. Specifically, the cold modulus of rupture (CMOR) for the samples 300MSH increases by 605.9 % at 500 °C and 582.6 % at 800 °C compared to control samples due to the excellent thermal stability of M-S-H-300 and a 38.3 % improvement in castable sintering performance. Additionally, M-S-H-300 improves the thermal shock resistance and setting properties of HMCC, extending the castable's setting time by 19 %. The conductivity test results indicate that the addition of M-S-H-300 inhibits the ionization of HMC, thereby delaying its hydration process. Castables with M-S-H-300 demonstrate higher CMOR and residual strength ratio before and after thermal shock. Further testing reveals that adding M-S-H-300 increased the castable's elastic modulus by 482.6 % and fracture toughness by 35.6 % after sintering at 1500 °C, enhancing resistance to microcrack propagation during thermal shock. Furthermore, adding M-S-H-300 reduces the aspect ratio of HMC hydration products, optimizing microstructure and reducing porosity. However, this modification slightly decreases the mechanical properties of the green body.

Mode-I dynamic fracture evolution and energy dissipation of basalt fiber reinforced reactive powder concrete

Dynamic fracture experiments on basalt fiber reinforced reactive powder concrete (BFRRPC) were conducted using notched semi-circular bending (NSCB) specimens, aiming to investigate the Mode-I dynamic fracture characteristics. Based on the split Hopkinson pressure bar (SHPB) and digital image correlation (DIC) systems, this study focused on investigating the dynamic fracture toughness, fracture process zone (FPZ), crack propagation, fractal dimension of fracture path, and energy evolution of BFRRPC with different basalt fiber contents. The results show the basalt fiber break, pull-out and interface fracture in the matrix in the microscopic experiment results, which are the intrinsic reasons for the enhancement of fracture toughness in RPC due to the fiber presence. The increases in fracture toughness of BFRRPC range between 24.7 % and 42.7 %, with a notable enhancement observed when incorporating 1.0 % basalt fiber content. The crack and the FPZ tip of BFRRPC can be located effectively by the method of displacement-strain mixed calibration. The addition of 1.0 % basalt fiber content effectively delays the crack initiation in specimens, with crack initiation occurring earlier as the loading level increases. The CTOD and FPZ tip opening displacement have nothing to do with the loading level. Basalt fibers can lead to relatively lower and stable fractal dimensions of BFRRPC, effectively reducing the cracking degree and increasing the roughness of cracks. Basalt fiber effectively enhances the fracture energy of RPC. The dissipated energy is mainly composed of the energy consumed by the fracture (fracture energy) of BFRRPC, with the overall residual kinetic energy ratio (the ratio of residual kinetic energy to dissipated energy) generally below 1.90 %.