Due to the serious environmental pollution generated by plastic packaging, chitosan (CS)-based biodegradable films are gradually gaining popularity. However, the limited antioxidant and bacteriostatic capabilities of CS, the poor mechanical properties and water resistance of pure CS films limit their widespread adoption in food packaging. In this study, new multifunctional bioactive packaging films containing monosaccharide-modified CS and polyvinyl alcohol (PVA) were prepared to address the shortcomings of pure CS films. Initially, Maillard reaction (MR) products were prepared by conjugating chitosan with galactose/mannose (CG/CM). The successful preparation of CG/CM was confirmed using UV spectroscopy, fluorescence spectroscopy, fourier transform infrared spectroscopy (FTIR) and high-performance gel permeation chromatography (HPGPC). At an 8 mg/mL concentration, the DPPH radical scavenging activities of CM and CG were 5 and 15 times higher than that of CS, respectively. At the maximum concentration of 200 mu g/mL, both CM and CG exhibited greater inhibitory effects on the growth of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, compared to CS. Additionally, CM and CG demonstrated significantly stronger protection against oxidative damage in Vero cells than CS. These results indicate that CG and CM possess superior antioxidant and antibacterial capabilities in comparison to CS. Then, the effects of the MR on the structures and functional properties of chitosan-based films were extensively examined. Compared with pure CS films, the MR in the CG/CM films significantly changed the film microstructure, enhanced the UV-barrier property and water resistance, and only slightly reduced thermal stability. The MR reduced the tensile strength but increased the elongation at break. Meanwhile, the composite films hold good soil degradation ability. Moreover, the CG/CM films possessed excellent antioxidant and antibacterial properties and demonstrated superior fresh-keeping capacity in the preservation of strawberries and cherry tomatoes (effectively prolonged for at least 2 days or 3-6 days). Our study indicates that CG/CM films can be used as a promising biodegradable antioxidant and antibacterial biomaterial for food packaging.

Silica fume and carbide slag can be used to modify waste mud soil (WMS), which can not only improve the mechanical properties of WMS, but also broaden resource utilization ways of silica fume and carbide slag. For that, in this paper, WMS was modified by adopting 8 % carbide slag and silica fume with different dosages (0, 3 %, 5 %, 7 %, 9 %, and 11 %). Then the small-strain dynamic properties of modified WMS were investigated by using resonance column test, and the microscopic mechanism of modified WMS was analyzed based on Scanning electron microscopy (SEM), Energy dispersive X-ray spectrometer (EDS), Transmission electron microscopy (TEM), X-ray diffraction test (XRD) and Mercury intrusion porosimetry (MIP). It can be found from the resonance column test that the dynamic shear modulus and the damping ratio show an increasing and decreasing trend with the increase of the confining pressure respectively, and both increase with increasing silica fume dosage in the range of 0 to 11 %. A kinetic model applicable to modified WMS was established by introducing the effects of confining pressure and silica fume into the Hardin-Drnevich model. Microscopic testing experiments indicate that there is a reaction between reactive SiO2 in silica fume and Ca(OH)2 in carbide slag, and calcium hydrated silicate (CSH) was generated, which improved the specimen density.

Biological soil crusts (BSCs; biocrusts) are well developed in drylands, which are crucial to the stability and resilience of dryland ecosystems. In the southeastern Gurbantunggut Desert, a typical sandy desert in the middle part of central Asia, engineering development has an increasing negative impact on ecosystems. Fortunately, ecological restoration measures are being implemented, but the exact effect on soil quality is still unclear. In artificial sand-fixing sites on reshaped dunes along the west-east desert road, a total of 80 quadrats (1 m x 1 m) of reed checkerboards after the implementation of sand-fixing measures for 10 years were investigated to determine the BSC development status and soil properties. The algal and lichen crusts accounted for 48.75 % and 26.25 % of the total quadrat number, respectively, indicating an obvious recovery effect of BSC (only 25 % for bare sand). The developmental level of BSC gradually increased from the top to the bottom of the dunes (Li 0 -> Li 6),which was consistent with the distribution pattern of BSCs on natural dunes. Compared with bare sand, the soil organic carbon (13.85 % and 23.07 % increases), total nitrogen (12.55 % and 23.95 % increases), total potassium (9.30 % and 8.24 % increases), and available nitrogen (23.97 % and 61.41 % increases) contents of algal and lichen crusts were significantly increased, and lichen crusts had markedly higher increase effect than algal crusts. The BSC development markedly reduced soil pH (0.49 % and 0.50 % decreased) and increased electrical conductivity(11.99 % and 10.68 % increases), resulting in improved soil microenvironment. Soil properties showed significant linear relationships with BSC development level, and an optimal fitting (R2 = 0.770 or 0.780) was detected for the soil fertility index. Based on the soil property matrix, the bare sands, algal, and lichen crusts were markedly separated along the first axis in the PCA biplot, which once again confirmed the significant positive effect of BSC recovery on soil fertility improvement. Consequently, in the early stage of sand-fixation (e.g., < = 10 years) by reed checkerboards on the damaged desert surface, BSC recovery can well promote and predict soil fertility in this area. The results provide a reliable theoretical basis for the restoration technology and scientific management of degraded sandy desert ecosystems.

In the reinforcement of micro-cracks and soil, cement grouting often suffers from poor injectability due to particle size limitations. While ultra-fine cement produced through physical grinding can address this issue, it significantly increases cost and energy consumption. Moreover, ultra-fine cement is prone to aging when exposed to moisture and CO2 in the air. To address these issues, this study proposes a new approach for in-situ particle size reduction of cement slurry through the mild corrosion of acetic acid. The refining effect of acetic acid on cement particles was investigated, along with its impact on mechanical properties and hydration products. The results show that acetic acid accelerates cement dissolution, promoting early-stage strength development and microstructure formation. The addition of 1.2 wt% acetic acid reduced the D90 particle size of the slurry by 36.4 %. Acetic acid also enhances the release of Ca2+ from clinker, increasing the precipitation of Ca(OH)2, CaCO3, and calcium silicate hydrate (C-S-H) at early stages, which serves as the primary source of early strength. Additionally, it raises the Ca/Si ratio of the early-formed C-S-H gel. However, excessive acetic acid can inhibit the further development of strength at later stages. The research demonstrates that premixed acetic acid activation is an effective approach for enhancing the performance of cementitious grouting materials, with promising potential to reduce energy consumption associated with physical cement grinding.

Water-induced disintegration is a critical issue in soil stabilization. In this study, soda residue (SR) and fly ash (FA) were mixed to improve the properties of high liquid limit clay (HLC), forming soda residue-fly ash stabilized clay (SRFSC), with cement and/or lime for further stabilization. The mix proportions of the SRFSC were optimized by the orthogonal method, using the compaction, unconfined compressive strength, shear, and disintegration tests. Meanwhile, microscopic tests were performed to reveal the possible mechanical mechanisms. The results showed that the SR and FA content are the primary determinants influencing the mechanical properties of SRFSC. When the base proportion is 70 % SR + 20 % FA + 10 % HLC, the strength is highest (2.45 MPa). At this proportion, the specimen with no cementitious material exhibits the best water disintegration resistance (WDR), reaching 107 min. Adding cement and lime can significantly enhance the WDR of the SRFSC, from complete disintegration at 0.28 min to remaining intact after soaking for 28 days. During field application, the cementitious materials content can be adjusted according to the actual conditions. The superior mechanical properties and WDR of SRFSC are mainly due to the good gradation and dense microstructure. The soda residue can provide abundant Ca2+ to enhance both the mechanical properties and WDR of SRFSC.

The main problem in expansive soil treatment with steel slag (SS) is the relatively slow hydration reaction that occurs during the initial period. To circumvent this, SS-treated expansive soil activated by metakaolin (MK) under an alkaline environment was investigated in this study. Based on a series of tests on the engineering properties of the treated soil, it can be reported that SS could enhance the strength and compressibility of expansive soil, with strength increasing by approximately 108 % for SS contents exceeding 10 % compared to 3 % lime-treated soil, and the compression index reducing by 20 %. Further addition of MK plays a dual role, enhancing strength for higher SS content while excessive MK leads to strength reduction due to insufficient pozzolanic reactions and hydration product transformation. Expansive and shrinkage behaviors are notably improved, with a 5 % increase in SS content reducing the free swelling ratio by 0.66 %-5.9 %, and the combination of 15 % SS and 6 % MK achieving a nearly 300 % reduction in the linear shrinkage ratio. Microstructural analysis confirms the formation of hydration gels, densification of the soil structure, and reduced macropores, validating the enhanced mechanical and shrinkage resistance properties of the SS-MK-treated expansive soil. Additionally, to develop predictive models for mechanical and the content of hardening agents (SS and MK), the experimental data are processed utilizing a backpropagation neural network (BPNN). The results of BPNN modeling predict the mechanical properties perfectly, and the correlation coefficient (R) approaches up to 0.98.

Solidified soil (SS) is widely applied for resource utilization of excavated soil (ES), however the waste solidified soil (WSS) may pose environmental hazards in future because of its high pH (>10). WSS is unsuitable for landfill but can be raw materials for preparing recycled solidified soil (RSS) with better mechanical properties than SS. This investigation used OPC and alkali-activated slag (AAS) as binders to solidify ES and WSS and prepare RSS. The mechanical properties of RSS were experimentally verified to be better than SS, increased by over 76 %. The mechanism is that the clay particles in WSS have been solidified to form sand-like particles or adhere to natural sand, resulting in increasing content of sand-sized particles, and the residual clay particles undergo cation exchange under the high pH and Ca2 + content, resulting in a decrease in zeta potential, reducing diffusion layer thickness. As a result, the flowability of RSS increases under the same liquid to solid ratio. The residual unreacted binder particles and high pH in WSS are beneficial for the early and final compressive strength increase of RSS, which allows preparing RSS with lower cost and carbon emission. Finally, the utilization of WSS has significant environmental benefits.

The generation of excess pore water pressure (EPWP) and liquefaction characteristic of soils under seismic loading have long been topics of interest and ongoing discussion. Based on the structural state exhibited in the liquefaction process, the mechanical property of saturated coral sand is divided into solid, pseudo-fluid, and liquid phases. New indices, zeta q (generalized deviator strain evolution) and zeta(y)q (generalized deviator strain evolution rate), are proposed to evaluate the evolution and evolution rate of complex deformation. In the solid phase, the saturated coral sand primarily exhibits the properties of a continuous solid medium, the peak EPWP ratio (rup) shows a power correlation with generalized deviator strain evolution amplitude (zeta qa). While in the pseudo-fluid phase, the saturated coral sand primarily exhibits mechanical behavior characteristic similar to that of a fluid, and the rup shows a significant arctangent function relationship with generalized deviator strain evolution rate amplitude (zeta(y)qa). The correlation of rup with zeta qa and zeta' qaduring liquefaction is significantly affected by loading conditions (cyclic stress ratio, CSR, loading direction angle, alpha sigma, and loading frequency, f). To quantify the impact of these loading conditions on the generation of rup in different phases, unified indicators delta S (for the solid phase) and delta L (for the pseudo-fluid phase) are defined. Eventually, An EPWP model based on mechanical property exhibited in different phases is developed, which has normalized the effects of loading conditions. It provides a comprehensive framework to predict the rup of saturated coral sand under complex geological activities, and this model facilitates the understanding and simulation of the mechanical properties and behavior of saturated coral sand during the liquefaction process.

Foundation soil treatment is a common method used to enhance soil strength in civil engineering, particularly in cold regions where ambient temperatures significantly affect soil mechanical properties. This study investigates the utilization of cement and municipal solid waste incinerator bottom ash (MSWIBA) for stabilizing silty clay under low-temperature curing conditions. Some experiments were performed to investigate the mechanical properties of cement-stabilized silty clay, varying the dosage of bottom ash (BA) and different curing temperatures. The influences of BA dosage, curing temperature and age on the shear and compressive strengths of soils were tested and analyzed. Results demonstrated that the shear strength was influenced by the comprehensive interactions among BA particles, soil particles, and ice crystals. Regardless of curing temperature and age, the shear strength of soil specimen firstly increased and then declined with BA dosage raised, with an optimal BA content range from 20 % to 30 %. Specifically, the 28-d shear strength enhancements of 2.46 %, 15.52 %, 20.20 %, and 11.33 % were observed with each successive 10 % BA addition for soil samples at 10 degrees C curing condition. Curing temperature significantly influenced shear strength, with higher temperatures promoting greater strength due to increased hydration reaction rates. Besides, the cohesion and internal friction angle of samples increased with BA dosage. Furthermore, the axial stress-strain curves illustrated a three-stage process, i.e., initial pore compression, plastic deformation, and decay stages. The compressive strength raised with both the BA dosage and curing age, with positive curing temperatures yielding higher strengths compared to sub-zero temperatures. This study elucidates the complicated mechanical behavior of BA-cement stabilizing silty clay, providing valuable insights into their performance under different curing conditions, and offering an innovative approach for foundation engineering applications in cold regions.

Foamed lightweight soil with red mud (FLS-RM), a new type of subgrade material commonly used in projects such as bridge backfill. In engineering applications, FLS-RM tends to crack after pouring to weaken its properties, which limits its further application, and this situation can be improved by adding fiber into FLS-RM. Thus, this study developed a new type of FLS-RM reinforced by polypropylene fibers, polyester fibers, and kenaf fibers to investigate the changes in the mechanical properties of FLS-RM and its deterioration mechanism. The experimental results showed that the mechanical properties of FLS-RM could be enhanced by the fibers, and the compressive and flexural strengths of FLS-RM specimens reinforced by polypropylene fiber reached 0.87 MPa and 0.85 MPa, respectively, when the fiber length was 12 mm and the content was 0.75 wt% and 1.00 wt%. Design Expert was used to analyze the experimental data to obtain the pattern of the effect of different fiber conditions on the strength of FLS-RM and optimal fiber conditions, and to establish the strength equation. The EDS results revealed that the red mud can be excited to generate an aluminosilicate gel filling in the skeleton under alkaline conditions. The results of the microscopic analysis indicated that the close bonding between the fibers and the matrix increased the friction and mechanical bite between the independent blocks and enhanced the strength of the specimens.