This research explores the stabilization of clay soil through the application of geopolymer binder derived from silicomanganese slag (SiMnS) and activated by sodium hydroxide (NaOH). This research aims to evaluate the effects of key parameters, including the percentage of slag, the activator-to-stabilizer ratio, and curing conditions (time and temperature), on the mechanical properties of the stabilized soil. Unconfined compressive strength (UCS) tests were conducted to assess improvements in soil strength, while scanning electron microscopy (SEM) was employed to analyze the microstructural changes and stabilization mechanisms. The results demonstrated that clay soil stabilized with SiMnS-based geopolymers exhibited significant strength enhancement. Specifically, the sample stabilized with 20% SiMnS and an activator-to-slag ratio of 1.6, cured at room temperature for 90 days, achieved a UCS of 27.03 kg & frasl;cm2. The uniaxial strength was found to be positively correlated with the SiMnS content, activator ratio, curing time, and temperature. Additionally, the strain at failure remained below 1.5% for all samples, indicating a marked improvement in soil stiffness. SEM analysis revealed that geopolymerization led to the formation of a dense matrix, enhancing soil particle bonding and overall durability. These results emphasize the potential of SiMnS-based geopolymers as a sustainable and effective soil stabilizer for geotechnical applications.

The paper investigates the effect of curing conditions on the properties of laterite soil-based geopolymer cement. In the experimental testing, calcined laterite soil was used as a solid precursor in the preparation of geopolymer cement. Standard size prismatic geopolymer specimens were prepared and subjected to four curing methods, including open air curing and courses of combined open-air curing and oven curing. The prisms were tested at 3, 7, and 28 days to determine the effect of curing methods on the flexural and compressive strengths. The crushed prisms were further pulverised and analysed to investigate the microstructure, elemental composition, mineralogical phases, chemical bonding, and thermal behaviour. The findings showed that the highest strength at 28 days was obtained with the air curing method. However, the curing methods involving an oven curing course resulted in the highest early strength at 3(early strength) and 7 days.

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.

In this study, ground granulated blast-furnace slag (GGBS) and fly ash (FA) were used as binders, while NaOH (NH) and Na2SiO3 (NS) served as alkali activators. Seawater (SW) was used instead of freshwater (FW) to develop a SW-GGBS-FA geopolymer for solidifying sandy soils. Geopolymer mortar specimens were tested for unconfined compressive strength (UCS) after being curing at room temperature. The results showed that the early strength of the seawater group specimens increased slowly less than that of the freshwater group specimens, while the late strength was 1.16 times higher than that of the freshwater group specimens. Factors including seawater salinity (SS), the GGBS/FA ratio, curing agent (CA) content, and the NH/ NS ratio were examined in this experiment. The results showed that the strength of the specimens was higher for SS of 1.2 %, G90:F10, CA content of 15 %, activator content was 15 %, and NH: NS of 50:50. The pore structure of the mortar specimens was analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and computerized tomography (CT), revealing the mechanisms by which various factors influenced the microstructure. XRD indicated that SW-GGBS-FA geopolymer mortar newly produced Friedel salt and calcium silicate sulfate hydrate (C-S-S-H). The microstructures observed by CT and SEM showed that the pore radius of the seawater specimens was mainly less than 10 mu m, and the maximum crack length was 92.55 mu m. The pore radius of freshwater specimens was larger than that of seawater specimens, and the largest crack was 148.44 mu m, which confirmed that Friedel salt and C-S-S-H fill the pores and increase the UCS of the specimens.

This study developed all-solid-waste-based curing agents using industrial solid wastes-ground granulated blastfurnace slag (GGBS), carbide slag (CS), and sulfate solid wastes (electrolytic manganese residue (EMR), desulfurized-gypsum (DG), and phosphogypsum (PG))-to stabilize engineering sediment waste (ESW). Based on the simplex centroid design, three ternary curing agents (GGBS-EMR-CS (GEC), GGBS-DG-CS (GDC), and GGBSPG-CS (GPC)) were prepared. The optimal ratios for GEC, GDC, and GPC are 60:12:28, 70:27:3, and 70:21:9, respectively. Compared to ordinary Portland cement (OPC), the unconfined compressive strength (UCS) of ESW stabilized with these curing agents increased by 78 %, 178 %, and 98 %, respectively. Sulfate components synergistically activates GGBS and CS, promoting needle-like ettringite (AFt) formation, which fills pores and enhances strength. Meanwhile, COQ emissions and costs were reduced up to 99 % and 73 %, respectively. This study developed all-solid-waste-based curing agents with excellent mechanical performance, low costs, and near net-zero emissions, which provided a sustainable solution for ESW stabilization.

In this study, laboratory aging experiments are conducted to examine the aging effect on the interface shear behavior between soil and geomembrane. In the first stage, the geotechnical index and shear strength parameters of the soils are determined through laboratory experiments. The second stage focuses on examining the shear strength behavior of soil-geomembrane interfaces. The study examines commonly used geomembranes in the world, such as high-density polyethylene and thermoplastic polyolefin. Different synthetic waste leachates prepared in laboratory conditions are used to simulate real field conditions. The aging effects of geomembranes are examined by subjecting them to different pore liquids in the curing pool for 16 months. The surface deformations and roughness of the geomembranes used in the experiments are analyzed using scanning electron microscopy and optical profilometer. The study evaluates the effects of soil properties, pore liquids, and aging on the geomembrane surfaces. Soils with more coarser grains exhibited higher interface friction angles. It has been determined that the interface friction angles were significantly adversely affected by all curing liquids. Acidic mine drainage was found to have the most detrimental effect on the interface friction angles of geomembranes, while coal combustion product leachate caused minimal damage. The results from optical profilometer and scanning electron microscopy analysis aligned with the interface direct shear test results, further supporting the findings from the experiments. The study has shown that the design interface friction resistances are not sufficient for geomembranes exposed to chemicals in the long term. This aspect should be taken into consideration when creating design parameters.

Collapse pits are highly susceptible to secondary hazards such as underground debris flows and slope instability under mining disturbances. These hazards significantly damage the ecological environment of the mining area. To reduce the geological hazards of collapse pits, grouting is used for management. The diffusion pattern and curing mode of slurry under different grouting pressures were investigated through indoor grouting simulation tests, and industrial tests were carried out to assess grouting effects. The results indicate that the slurry is dominated by penetration diffusion and supplemented by splitting diffusion in the moraine. The penetration distance and diffusion radius of the slurry increase linearly with grouting pressure, while the splitting uplift distance and cured volume increase exponentially with grouting pressure. Splitting diffusion consists of three stages: bulging compaction, splitting flow, and passive uplift. Horizontal splitting has a vertical uplift effect on the formation. The slurry primarily consolidates individual moraine particles into a cohesive mass by filling fractures, binding soil particles, and reinforcing interfaces with the rock mass. For different moraine layer structures, full-hole, segmented, and point-based grouting methods were applied. A composite grouting technique, layered grouting with ring solidification, was also introduced, achieving excellent grouting results. This study provides technical support for managing geological hazards in collapse pits caused by block caving mining disturbances and for green mining practices.

This research investigates the use of waste stone dust, a crushing industries byproduct, in combination with cement to enhance the engineering properties of high-plasticity silt. The investigation focuses on evaluating improvements in soil consistency, compaction characteristics, microstructure, and long-term strength behavior. Results indicate that the addition of waste stone dust significantly improves plasticity and compaction characteristics, while the combination of cement and stone dust enhances shear strength more effectively than either material alone. The unconfined compressive strength of untreated soil, initially 57.3 kPa after one day of curing, increased up to 19.4 times after 90 days with 10 % cement addition, with further improvements observed when stone dust was incorporated. Moreover, non-linear regression analysis reveals that strength improvement follows a sigmoidal relationship with cement content and a logarithmic trend with curing time. Furthermore, insights from Consolidated Undrained Triaxial tests and Scanning Electron Microscopy provide further strengthen the stabilization mechanisms of the treated soil. The triaxial results show that adding 6 % cement in natural soil slightly increases the friction angle from 20 degrees to 22 degrees and increases the cohesion from 28 kPa to 60 kPa. However, further addition of 30 % stone dust and 6 % cement slightly improved friction angle and reduced the cohesion from 60 kPa to 26 kPa, which infers that cement primarily increased cohesion, whereas stone dust increases inter-granular friction. More importantly, this study offers a cost-effective solution to enhance behavior, addresses environmental concerns, and improve infrastructure resilience for high-plastic-silt-related problems.

Shallow slope failures occur frequently in the Loess Plateau region and the ecological materials are usually used for slope protection. The mechanical characteristics and strength models of the interface between environmental protection materials and native materials are crucial for evaluating the effectiveness of slope protection. In this study, the polypropylene fiber and guar gum are used for slope protection, and indoor experiments are conducted to elucidate the mechanical performance changes at the interface between untreated loess (UL) and guar gum-treated fiber-reinforcement loess (GFL) under different moisture content and curing time. A damage strength model of the interface between untreated loess and guar gum-treated fiber-reinforcement loess (UL-GFL) is constructed based on statistical damage theory. The results show that guar gum can aggregate and cement loess particles, while polypropylene fiber enhances the friction between loess particle aggregates. The synergistic effect of these two materials significantly improves the strength and hydraulic characteristics of loess. The cohesion and internal friction angle of the interface between untreated loess and guar gum-treated fiber-reinforcement loess decrease with an increase in moisture content and increase with an extended curing time, stabilizing when the curing time exceeds 7 days. The strength model for the interface of untreated loess and guar gum-treated fiber-reinforcement loess is established. The proposed model is verified through experimental data based on the stress-displacement relationship. The findings of this research can provide an important reference for the application of ecological protection materials on loess slopes.

The objective of this study was to enhance the mechanical properties of gravelly soil and to consider the binding and filling effects of xanthan gum and calcium lignosulfonate. To this end, gravelly soil samples were prepared with various dosages of xanthan gum and calcium lignosulfonate, and their curing effects were investigated. The mechanical properties and strength parameters of the cured gravelly soil were investigated using unconfined compressive strength (UCS) tests and conventional triaxial compression tests. Furthermore, scanning electron microscopy (SEM) was employed to examine the microstructure and curing mechanisms of the gravelly soil treated with these additives. The findings demonstrate that as the dosage increases, both xanthan gum and calcium lignosulfonate markedly enhance the compressive strength and shear strength of the gravelly soil. The curing effect of xanthan gum was found to be more pronounced with higher dosages, while the optimal curing effect for calcium lignosulfonate was achieved at a dosage of 4%. The gravelly soil treated with xanthan gum exhibited superior performance compared to that treated with calcium lignosulfonate when the same dosage was used. Moreover, at elevated confining pressures, the binding effect of xanthan gum and calcium lignosulfonate on the gravelly soil was less pronounced than the strength effect imparted by the confining pressure. This suggests that the impact of dosage on the shear strength of the gravelly soil is diminished at higher confining pressures. The stabilization of crushed stone soil by xanthan gum is a complex process that involves two main mechanisms: bonding and cementation, and filling and film-forming. The curing mechanism of calcium lignosulfonate-cured gravelly soil can be summarized as follows: ion exchange, adsorption and encapsulation, and pore filling and binding effects. The findings of this research offer significant insights that are pertinent to the construction of high earth-rock dams and related engineering applications.