The reasonable value of good gradation characteristic parameters is key in designing and optimising soil-rock mixed high fill embankment materials. Firstly, the DJSZ-150 dynamic-static large-scale triaxial testing instrument was used for triaxial compression shear tests on compacted skeleton structure soil-rock mixture standard specimens. The changes in strength and deformation indicators under different gradation parameters and confining pressure were analysed. Then, based on the Janbu empirical formula, relationships between parameters K, n, and (sigma 1-sigma 3)ult and the coefficient of uniformity Cu and coefficient of curvature Cc were explored. Empirical fitting formulas for Duncan-Chang model constants a and b were proposed, establishing an improved Duncan-Chang model for soil-rock mixtures considering gradation characteristics and stress states. Finally, based on significant differences in particle spatial distribution caused by gradation changes, three generalised models of matrix-block stone motion from different particle aggregation forms were proposed. Results indicate the standard specimen's strength and deformation indicators exhibit significant gradation effects and stress-state correlations. The improved Duncan-Chang model effectively simulates the stress-strain relationship curve under different gradations and confining pressure, with its characteristics explainable based on the matrix block stone motion generalised model.

Taurine (TAU) has recently been found to have an impactful role in regulating plant responses under abiotic stresses. This study presented the comparative effects of TAU seed priming and foliar spray application on chickpea plants exposed to hexavalent chromium. Taurine priming and foliar applications (1.6 and 2.4 mM) notably modulated morpho-physiological and biochemical responses of plants under Cr(VI) stress. Plants subjected to 25 mg kg-1 soil Cr in the form of potassium dichromate (K2Cr2O7) displayed a significant reduction in growth, chlorophyll, and uptake of essential nutrients (N, K, P, and Ca). Cr(VI) toxicity also resulted in a notable increase in osmolyte accumulation, lipid peroxidation, relative membrane permeability, ROS generation, antioxidant enzyme activities, antioxidant compounds, endogenous Cr levels, and aerial Cr translocation. Taurine abridged lipoxygenase activity to diminish lipid peroxidation owing to the overproduction of ROS initiated by a higher Cr content. The acquisition and assimilation of essential nutrients were augmented by the TAU-related decrease in leaf and root Cr levels. Consequently, TAU enhanced growth by mitigating oxidative damage, reducing Cr content in the aerial parts, and reinforcing the activities of antioxidant enzymes. Compared to foliar spray, TAU seed priming has demonstrated superior efficacy in mitigating Cr phytotoxicity in plants.

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.

In geotechnical engineering, the development of efficient and accurate constitutive models for granular soils is crucial. The micromechanical models have gained much attention for their capacity to account for particle-scale interactions and fabric anisotropy, while requiring far less computational resources compared to discrete element method. Various micromechanical models have been proposed in the literature, but none of them have been conclusively shown to agree with the critical state theory given theoretical proof, despite the authors described that their models approximately reach the critical state. This paper modifies the previous CHY micromechanical model that is compatible with the critical state theory based on the assumption that the microscopic force-dilatancy relationship should align with the macroscopic stress-dilatancy relationship. Moreover, under the framework of the CHY model, the fabric anisotropy can be easily considered and the anisotropic critical state can be achieved with the introduction of the fabric evolution law. The model is calibrated using drained and undrained triaxial experiments and the results show that the model reliably replicates the mechanical behaviors of granular materials under both drained and undrained conditions. The compatibility of the model with the critical state theory is verified at both macroscopic and microscopic scales.

Corn rootworms (CRW) are among the most destructive pests in corn production across the Corn Belt, causing considerable damage through larval feeding on roots. While crop rotation and Bt technologies are widely adopted management strategies, their effectiveness is increasingly compromised by the pest's evolution of resistance and behavioral adaptability. Chemical insecticides applied at planting to target larvae directly serve as an additional tool for corn rootworm control. In this study, we evaluated the performance of various insecticides, applied in-furrow, for managing corn rootworms by assessing Node Injury Scale (NIS), lodging rates, and grain yields from 2020 to 2024. We found that Mode of Action (MOA) 3A insecticides (sodium channel modulators), such as Force Evo (tefluthrin) and Capture LFR (bifenthrin), did not provide substantial efficacy in reducing NIS and lodging rates. In contrast, MOA 1B+3A insecticides (acetylcholinesterase (AChE) inhibitors + sodium channel modulators), such as INDEX (chlorethoxyfos + bifenthrin) and AZTEC HC (tebupirimphos + cyfluthrin), significantly reduced CRW larval damage, particularly under high pest pressure in 2020, 2021 and 2023. Differences in insecticide concentrations did not significantly impact larval control efficacy. Additionally, seasonal rainfall during larval hatching and variation in cumulative corn growing degree days (GDD) strongly influenced the root injury and lodging outcomes. Lower GDD likely limits root regeneration, increasing lodging risk under CRW pressure. These findings demonstrate the values of in-furrow insecticides in managing corn rootworms, particularly under high pest pressure and provide valuable insights for developing integrated pest management strategies to sustain effective CRW larval control and improve crop productivity.

This study presents a hierarchical multiscale approach that combines the finite-element method (FEM) and the discrete-element method (DEM) to investigate tunneling-induced ground responses in coarse-grained soils. The approach considers both particle-scale physical characteristics and engineering-scale boundary value problems (BVPs) simultaneously, accurately reproducing typical tunneling-induced mechanical responses in coarsegrained soils, including soil arching and ground movement characteristics observed in laboratory tests and engineering practice. The study also unveils particle-scale mechanisms responsible for the evolution of soil arching through the underlying DEM-based RVEs. The results show that the rearrangement of microstructures and the deflection of strong contact force chains drive the rotation of macroscopic principal stress and the formation of soil arch. The microscopic fabric anisotropy direction can serve as a quantitative indicator for characterizing soil arching zones. Moreover, the effects of particle size distributions (PSD) and soil densities on ground deformation patterns are interpreted based on the stress-strain responses and contact network characteristics of DEM RVEs. These multiscale insights enrich the knowledge of tunneling-induced ground responses and the same approach can be applied to other geotechnical engineering analyses in coarse-grained soils.

A novel iron-based phosphate cement (IPC), derived from iron-rich smelting slag (ISS), was developed as a sustainable and efficient binder for the stabilization/solidification of trivalent chromium (Cr3+). The mechanical properties, hydration behavior, microstructure, leaching toxicity, chromium chemical forms, and environmental safety of chromium-stabilized iron phosphate cement (CIPC) were thoroughly evaluated. The results showed that, with a mass ratio of ISS to ammonium dihydrogen phosphate (ADP) of 2.0, and even with the addition of 20 % chromium nitrate nonahydrate (CN), the compressive strength of CIPC reached 4.2 MPa after curing for 28 d. Furthermore, chromium leaching was well below 1 mg/L, significantly lower than the GB 5085.3-2007 standard limit of 15 mg/L, demonstrating the effective encapsulation of Cr3+ due to IPC's high early strength. In the IPC system, Cr3+ was primarily stabilized by forming CrPO4 and CrxFe1-x(OH)3 co-precipitates, which were further solidified through the physical encapsulation of IPC hydration products, such as (NH4)2Fe(PO3OH)2 center dot 4H2O, (NH4) (Mg,Ca)PO4 center dot H2O, and FePO4. This process resulted in a solidification efficiency of up to 99 %. BCR analysis confirmed that more than 98 % of the chromium in the CIPC remained in a stable residual form. Finally, the ecological risk index (PERT) was found to be 23.52, far below the safety threshold of 150, indicating the solidified material's long-term environmental safety. This study provides an innovative approach for the reutilization of ISS while effectively stabilizing/solidifying chromium.

A series of large-scale (1:13) model tests of multi-stage loading and unidirectional multi-cycle loading were conducted on semi-rigid piles before and after cement-soil reinforcement in clay. The difference of ultimate bearing capacity between unreinforced and reinforced piles under different criterions is discussed, and their bending moment and displacement distribution rules are revealed. Meanwhile, the cyclic bearing behaviour of the unreinforced and reinforced piles are compared and analyzed, including cyclic load-displacement response, unloading stiffness, cumulative peak & residual displacement, peak & locked in moment. The test results show that the ultimate bearing capacity of the large diameter pile is increased by 34.4 % and the initial stiffness is increased by 56.8 % (reinforced width is 3D and depth is 1D) in the multistage loading test. Comparing the monotonic and cyclic load-displacement curves of unreinforced and reinforced piles obtained by multi-stage loading test and unidirectional multi-cycle loading test respectively, it is found that when the applied load is small, the curve obtained from multistage loading test is almost coincident with the first cycle envelope of all load levels in 1-way multi-cycle loading test, indicating that the cyclic effect is not significant. As the load increases, the difference between the curves becomes larger, indicating that the cyclic loading of higher amplitude causes greater soil disturbance. In addition, after applying cement-soil to the shallow soil around monopile, cement-soil reinforced pile exhibits a more rigid response, specifically manifested as an initial unloading stiffness of 1.76 times that of unreinforced pile, and a slower stiffness degradation rate. Meanwhile, the cyclic peak displacement & residual displacement accumulation of reinforced piles are smaller than that of the unreinforced pile, thereby reducing the development of the locked in moment.

A two-lift gradient design for airport pavements has been proposed to mitigate the functional degradation, especially the salt-frost (S-F) damage induced by deicing slat fluids. Herein, this study focuses on elucidating the mechanism and improvement of incorporating mineral admixtures in the development of a novel S-F resistant surface concrete material, which is of great significance for delaying the functional deterioration of pavement surface in northern China. The results indicated that the filling effect and secondary hydration reaction between the fly ash (FA) and silica fume (SF) and cement hydration products results in a dense spatial network structure, effectively reducing porosity and optimizing pore structure. It was found that SF can effectively improve the frost resistance and salt corrosion resistance of cement mortar, while the influence of FA depends on its content and environmental conditions. The incorporation of FA and SF significantly enhanced the structural density of cement concrete and reduced chloride ion permeability. The improvement in impermeability is most pronounced when both FA and SF are used in combination. In addition, a fitting equation between the admixture content and chloride ion permeability has been established, demonstrating good fitting results. In non-frozen saline soil areas, a large amount of FA or SF could be incorporated; in seasonally frozen areas, the priority should be given to SF to ensure salt corrosion resistance and frost resistance. The findings of this study provide a scientific basis for sustainable airport pavement construction in northern China.

With the increasing utilization of underground space, engineering muck has become a potential urban risk. This study employed a waste-to-waste strategy to promote its low-carbon recycling by using rice husk ash (RHA) as a stabilizer, with a focus on elucidating the stabilization mechanisms through multi-scale analysis. The results showed that RHA synergized with cement, enhancing unconfined compressive strength and water stability, while reducing the specific surface area and swelling potential of the engineering muck. The optimal RHA dosage was found to be between 4 % and 6 %, with cement content ranging from 3 % to 9 %. The multi-scale analysis demonstrated that the stabilization mechanisms of RHA-cement stabilized soil were governed by two main factors: structural enhancement and surface modification, both of which were driven by the promotion of novel hydration products through the incorporation of RHA. Specifically, the needle-like and columnar minerals effectively filled soil pores, forming a dense, robust skeletal structure that enhanced the mechanical properties of the stabilized soil. Meanwhile, the honeycomb-like C-S-H gel adhered to soil particle surfaces, repairing cracks and reinforcing interparticle bonding, thus improving the overall structural integrity. AFM analysis further revealed that the honeycomb-like C-S-H gel consisted of rod-like nanoparticles that were regularly arranged on the soil surface. This feature increased surface roughness, reduced fractal dimensions, and created a multi-scale structure of micro-papillae and nano-hairs with a lotus leaf effect, significantly enhancing the hydrophobic properties of the soil.