This study investigates the microhardness and geometric degradation mechanisms of interfacial transition zones (ITZs) in recycled aggregate concrete (RAC) exposed to saline soil attack, focusing on the influence of supplementary cementitious materials (SCMs). Ten RAC mixtures incorporating fly ash (FA), granulated blast furnace slag (GBFS), silica fume (SF), and metakaolin (MK) at 10 %, 15 %, and 20 % replacement ratios were subjected to 180 dry-wet cycles in a 7.5 %MgSO4-7.5 %Na2SO4-5 %NaCl solution. Key results reveal that ITZ's microhardness and geometric degradation decreases with exposure depth but intensifies with prolonged dry-wet cycles. The FAGBFS synergistically enhances ITZ microhardness while minimizing geometric deterioration, with ITZ's width and porosity reduced to 67.6-69.0 mu m and 25.83 %, respectively. In contrast, FA-SF and FA-MK exacerbate microhardness degradation, increasing porosity and amplifying microcrack coalescence. FA-GBFS mitigates the diffusion-leaching of aggressive/original ions and suppresses the formation of corrosion products, thereby inhibiting the initiation and propagation of microcracks. In contrast, FA-SF and FA-MK promote the formation of ettringite/gypsum and crystallization bloedite/glauberite, which facilitates the formation of trunk-limb-twig cracks.

Shale formations have recently gained plenty of attention owing to their large amounts of reserves. Horizontal drilling and hydraulic fracturing are the proposed approaches for the development of shale formations. The extended information of the mechanical properties of shale formation is crucial for designing a successful hydraulic fracturing operation. On the other hand, the mechanical properties of such organic-rich formations are greatly affected by the mechanical characteristics of the present kerogen (organic matter), which dramatically changes during the maturation process. In this study, a Qingshankou shale sample containing kerogen type I is mechanically investigated at different maturity levels using the grid nanoindentation approach. To this end, the original immature sample is artificially matured during hydrous (HP) and anhydrous (AHP) pyrolysis. More than 930 nanoindentation tests were performed on grids of 9 x 8 on the surface of 13 samples with different maturities. The test results showed that the presence of water during pyrolysis can significantly affect the shale sample's mechanical characteristics. In higher temperatures and higher levels of maturity, the role of water becomes more pronounced. During hydrous pyrolysis, kerogen produces larger amounts of oil and bitumen, which become progressively porous. While the original sample showed a Young's modulus value of more than 48 GPa, and it fluctuated between approximately 19 and 32 GPa during the HP scenario and between 17 and 34 GPa during the AHP process. In terms of hardness, the original sample exhibited an initial value of about 1.1 GPa and more mature samples reflected hardness values in the range of approximately 0.3 and 0.97 GPa in both scenarios. According to the trends of mechanical properties during maturation, mechanical properties decreased at the initial stage of maturation and remained relatively constant during the oil window. Then, another decline was detected at the wet-gas window's closure. In the dry-gas window, HP and AHP scenarios exhibited different behaviors mainly due to the chemical structure of the kerogen residue. 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Surface layers of agricultural machinery working bodies are subjected to intensive abrasive wear during operation, which leads to rapid wear of equipment and reduction of its service life. To increase the wear resistance of the working surfaces of tools, the method of induction cladding using 'Sormait-1' materials is widely used. However, after coating, additional heat treatment is required, which improves physical and mechanical properties of the material and increases its durability. When using electrofriction technology (EFT) hardening, the surface of the parts is subjected to melting under the influence of electric arcs, which affects the surface characteristics of the coatings. In this work, two types of surface treatment of L53 steel were investigated: induction cladding using 'Sormait-1' material, as well as a combination of induction cladding and subsequent electrofriction treatment. The coatings were characterized and compared with the substrate in terms of the following parameters: microstructure, phase composition, hardness distribution, and friction-wear characteristics. After induction cladding of the Sormait-1 material, a dendritic structure was formed; however, subsequent electrofriction treatment resulted in a reduction of this dendritic structure, which contributed to an increase in the hardness of the material. The average hardness of the coatings after electrofriction treatment was 786 HV0.1, which is more than three times the hardness of the substrate. Furthermore, the influence of structural characteristics and hardness on abrasive wear resistance was examined in accordance with ASTM G65 international standards. Field tests were conducted on plough shares before and after electrofriction hardening to evaluate their performance. Each ploughshare was scanned with a structured 3D scanner before and after use in the field. From the scan data, the cutting-edge profile was calculated and three key parameters were determined: linear wear, volumetric wear, and mass reduction. According to the results of field tests, it was found that the service life of the blades hardened by electrofriction technology was 12%-14% higher compared to serial blades processed by induction cladding with the use of 'Sormait-1' material. Operational tests of hardened plough shares confirmed the results of laboratory tests and proved the advantages of electrofriction technology for increasing the wear resistance of soil tillage machine working bodies.

The application of fiber-reinforced polymer (FRP) composites as piling materials in harsh environments has gained popularity due to their high corrosion resistance. FRP composites can be fabricated using different types of epoxy resin matrices and fibers. This study aims to investigate the interface behavior between sand and FRP materials with varying levels of hardness, with a particular emphasis on the abrasive surface wear of FRP. Monotonic interface shear tests (under normal stresses of 50, 100, 200, and 400 kPa) and interface shear tests repeated 20 times (under normal stresses of 200 and 400 kPa) are performed. The local surface roughness of the FRP plates is measured for tested samples under both monotonic and repeated loadings using laser scanning to evaluate the accumulated abrasion effect. The results of monotonic tests indicate that under a given shear displacement and normal stress, the samples with softer FRP plates exhibit higher interface friction angles and more pronounced dilative behavior. Following repeated tests, the interface friction angles of softer FRP specimens decrease, while the surface roughness of the FRP plates gradually increases. However, for the softest FRP plate, its surface is severely damaged after repeated tests under high normal stress levels, leading to unstable changes in the test results.

Most of the biomass of cereal straw is chopped and left on the field as organic fertilizer, but its conversion into fertilizer depends on the quality of chopping, which is influenced by the wear of the chopping blades. The aim of the study was to determine the influence of the contamination of the cereal straw on the wear of the combine chopper blades. The study was conducted during the harvest in 2022, when 30 +/- 1% of the grain was lodged and contaminated with abrasive soil particles (poor conditions), and in 2023, when the straw was unlodged and clean (excellent conditions). Six sets of blades with different mechanical and geometric properties were selected. The results showed that the wear ranges were very different: 1.47-2.99 g/100 ha in 2022 and 0.72-2.14 g/100 ha in 2023. For micro-abrasive wear, the hardness of the blades (349-568 HV) and the cutting edge angle (20 degrees-29 degrees) were important factors of their wear resistance. When the clean straw was chopped, the influence of the blade hardness and cutting edge angle on wear was not significant, and the wear was less. The wear of the blades had a sinusoidal character, which was related to the position of the blades on the chopping drum. This character depends on the design of the chopper and not on the straw quality.

In recent years, the issue of increasing the wear resistance of the working bodies of agricultural machinery designed for cutting and breaking the soil has received special attention. The surface layers of working bodies of agricultural machinery during operation are subjected to intensive abrasive wear, which leads to rapid wear of equipment and a reduction in its service life. The induction cladding method using materials such as Sormait-1 is widely used to increase the wear resistance of tool working surfaces. However, after coating, additional heat treatment is required to improve the physical and mechanical properties of the material and increase its durability. In electrofriction technology (EFT) hardening, the surfaces of the parts are subjected to melting under the influence of electric arcs. In this work, three types of surface treatment of L53 steel have been investigated: induction cladding using Sormait-1, electrofriction treatment, and a combination of induction cladding followed by electrofriction treatment. The microstructure was analyzed using optical microscopy and scanning electron microscopy. Erosion and abrasion tests were carried out in accordance with ASTM G65 and ASTM G76-04 international standards to evaluate the wear resistance of the materials under mechanical stress. A dendritic structure was formed after the induction cladding of the Sormait-1 material, but subsequent electrofriction treatment resulted in a reduction of this dendritic structure, which contributed to an increase in the hardness of the material. However, the highest hardness, reaching 965 HV, was recorded after electrofriction treatment of L53 steel. This is explained by needle martensite in the structure, which is formed as a result of quenching. Further, the influence of structural characteristics and hardness on erosion and abrasion wear resistance was examined. The analysis showed that the material microstructure and hardness have a decisive influence on the improvement of wear resistance, especially under conditions of intensive erosion and abrasive friction.

The compaction characteristics of gravelly soil are affected by gravel hardness. To investigate the evolution and influencing mechanism of different gravel hardness on the compaction characteristics of gravelly soil, heavy compaction tests and crushing tests were conducted on gravelly soils with gravels originated from hard, soft and extremely soft rocks. According to orthogonal experiments and variance analysis, it was found that hardness has a significant impact on the maximum dry density of gravelly soil, followed by gravel content, and lastly, moisture content. For gravel compositions with an average saturated uniaxial compressive strength less than 60 MPa, the order of compacted maximum dry density is soft gravels > hard gravels > extremely soft gravels. Each type of gravelly soil has a threshold for gravel content, with 60% for hard and soft gravels and 50% for extremely soft gravels. Beyond these thresholds, the compacted dry density decreases significantly. There is a certain interaction between hardness, gravel content, and moisture content. Higher hardness increases the influence of gravel content, whereas lower hardness increases the influence of moisture content. Gravelly soils with the coarse aggregate (CA) between 0.7 and 0.8 typically achieve higher dry densities after compaction. In addition, the prediction equations for the particle breakage rate and CA ratio in the Bailey method were proposed to estimate the compaction performance of gravelly soil preliminarily. The results further revealed the compaction mechanism of different gravelly soils and can provide reference for subgrade filling construction.

Strong winds, particularly in the absence of disaster-resistant designs, significantly impact the stability of greenhouse foundations and eventually lead to structural damage and potential harm to crops. As a countermeasure, rebar stakes are commonly used to reinforce the foundations of non-disaster-resistant greenhouses. This study evaluates the pull-out resistance (Rpull-out) of rebar stakes considering various factors like soil compaction, embedded length, installation duration and angle, and changes in soil water content against uplift pressure by strong winds. A combination of field (i.e., the cone penetration test and rebar stake pull-out test) and laboratory (i.e., the compaction test, soil compaction meter test, and soil box test) tests are performed for the assessment of Rpull-out. The results indicate that Rpull-out increases with higher soil compaction, greater embedded length, longer installation duration, and an inclined installation angle. The soil compaction exerts the most significant impact; 90% to 100% of the soil compaction rate has approximately 10 folds higher Rpull-out than the 60-70% compaction rate. If the embedded length is increased from 20 cm to 40 cm, there is a two-fold increase in the average of Rpull-out. Inclined installation of rebar stakes increases Rpull-out by 250% to 350% compared to vertical installation, and rebar stakes installed prior to the uplift event have 1.5 to 6.4 fold increases in Rpull-out than those with instant installation. Additionally, we observed variations in the surface soil moisture due to climatic changes introducing variability in Rpull-out. These findings lead to the proposition of efficient rebar stake installation methods, contributing to the enhanced stability of a greenhouse.

Multiple-compaction demonstrates cyclic loading on laterite soils used in highway construction and its effects on engineering properties. The method determines the mechanical stability of derived soils from porphyritic granite, granite gneiss, and charnockite. Fifty-one soil samples were obtained from the horizons of the laterite soil profiles. Four sets of dynamic compactions were carried out on each sample. Index engineering properties such as specific gravity, Atterberg limits, and particle size distribution were investigated before and after multiple-compaction. The changes in engineering properties and moisture-density characteristics were investigated using the granulometric modulus and hardness index. Through multiple-compaction, larger grains in soils derived from granite gneiss and porphyritic granite disintegrated into smaller particles. The fine grains break down more easily than the large grains of quartz bound by clayey materials in charnockite-derived soils. Interestingly, the maximum dry density and optimum moisture content remain consistent in porphyritic and granite gneiss-derived soils after multiple compactions. Based on the densification and behaviour of the derived soils under multiple compaction in highway construction, porphyritic granite and granite gneiss-derived soils are more suitable as engineering materials than charnockite-derived soils.

This study was conducted to determine the effect of traffic stress by soil compaction on zoysiagrass by analyzing the aerial and underground parts and hyperspectral analysis. Zoysiagrass plants were subjected to a compaction strength gradient from 35 to 80 kgf/cm 2 to confirm the compaction resistance and recoverable limit and measure the physiological change during stress. Changes in leaf color, photosynthesis, and hyperspectral reflectance due to continuous weak and strong traffic stress were measured, and vegetation indices were evaluated for the critical traffic stress injury assessment. As a result, the stem of the zoysiagrass was severely damaged up to 70 kgf/cm 2 based on soil hardness. The recoverable limit strength of soil compaction was 55 kgf/cm 2 under weak response pressure conditions. Collectively, our results show that the damage of weak compaction strength on the zoysiagrass was quickly recovered after the stop of traffic stress, especially since the growth of the underground part was increased by weak traffic stress. However, if the compaction strength above 65 kgf/cm 2 lasted for a long time, the growth of the underground part is limited by lowering the energy supply for the recovery occurred, in turn, the recovery occurred slowly after the compaction was stopped. Among the vegetation indices obtained from hyperspectral data, pigment specific simple ratio for chlorophyll a (PSSRa), pigment specific simple ratio for chlorophyll b (PSSRb), and pigment specific simple ratio for carotenoids (PSSRc) were effective in evaluating the damage of traffic stress.