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.

To improve the utilization rates of soda residue (SR) and fly ash (FA), reduce environmental pollution, and enhance the mechanical properties of marine clay (MC), this study proposes mixing SR, FA, and MC with cement and /or lime to prepare soda residue-fly ash stabilized soil (SRFSS). Using an orthogonal design for the proportions, the study analyzes the compaction performance, unconfined compressive strength (UCS), and shear strength of SRFSS. The influence of various factors on the mechanical properties of SRFSS was investigated through range and variance analyses. The mechanical mechanism was revealed from the perspectives of grading and cementation. The results indicate that SR and FA significantly impact the mechanical properties of SRFSS. The range and variance analysis results are consistent: SR content of 30% and 70% has the most significant impact on compaction performance and UCS, respectively, while 20% FA content has the greatest effect on shear strength. The recommended base proportion is 70% SR + 20% FA + 10% MC. The gradation and cementitious properties jointly influence the mechanical performance and microstructure of SRFSS, G8 has the lowest planar porosity, at only 0.89%. The calcium (Ca) content in SRFSS specimens with different proportions shows significant variation, from 5.0 to 53.6 wt%, while the silicon (Si)/Al ratio (0.76-2.73) shows relatively small fluctuations. The primary hydration products include calcium hydroxide (Ca(OH)2), calcium silicate hydrate (C-S-H), and ettringite (AFt).

Improving the engineering and mechanical properties of marine clay (MC) by modifying it with soda residue (SR) and fly ash (FA), and stabilising with cement and /or lime to create Soda residue-Fly ash stabilised soil (SRFSS). Using the orthogonal design, the mechanical properties of SRFSS were analyzed, recommending a basic proportion of 70% SR + 20% FA + 10% MC. Results showed SR significantly impacted optimum water content (OWC), unconfined compressive strength (UCS), and water absorption quality. FA influenced the maximum dry density (MDD), while cohesion (c) was mainly affected by lime and cement. Cement had a higher unit contribution rate to mechanical indices than lime, except for MDD and OWC. The excellent properties of SRFSS were derived from good gradation and the cementation action of the materials. This research provides a solution for improving MC properties and promoting solid waste reutilisation.

The solid waste soda residue (SR) exhibits a high content of soluble salts, and the liquid phase soluble salts in soda residue soil (SRS) undergo phase transition crystallization during cooling process, leading to subgrade salt expansion and deformation damage. In order to explore the salt mechanisms of SRS, this paper systematically analyzes the impact of SR content on the salinization and salt expansion characteristics of SRS using soluble salt tests and salt expansion experiments. Combined with X-ray diffractometry (XRD) and low-temperature frost shrink tests, the study analyzed the salt expansion process of SRS. The results indicate that under different SR content, SRS is classified as chloride saline soil. The SRS is categorized into weak saline soil, moderate saline soil, strong saline soil, and over-saline soil with different soda residue dosage. During cooling from 20 degrees C to -25 degrees C, all SRS groups exhibit initial salt expansion followed by frost shrink deformation characteristics. As the SR content increases within the 0 % - 40 % range, the temperature range for severe salt expansion gradually decreases from 5 degrees C to -15 degrees C. At 25% SR content, SRS exhibits the most severe salt expansion, while excessively high SR content inhibits the crystallization of sulfate salt phase transitions. The study identifies three stages in the salt expansion process of SRS: promotion stage, severe stage, and inhibition stage. The research findings provide valuable insights for the prevention of salt expansion in SRS and the widespread utilization of SR in road applications.

To broaden the sources of earthwork and the utilization of soda residue (SR) and fly ash (FA), SR, FA, and clay were mixed to form a soda-residue soil (SRS) by adding externally moderate content of lime or/and cement for further stabilization. Through the orthogonal scheme, 9 groups of proportions were designed. Subsequently, the unconfined compressive strength (UCS) at different curing ages was conducted. Afterward, the stress-strain pattern, the UCS and water absorption, the sensitivity of factors and levels to UCS, and the deformation modulus were analyzed. Finally, the enhancement mechanism of SRS from physicochemical reactions was explored by analyzing gradation and microstructure. The results show that the patterns of stress-strain curves on SRS at different curing ages are similar; all have obvious stress peaks, and the specimens of SRS present a brittle failure. With the extension of curing ages, the UCS of all proportions increased; the UCS of the G2 group increased the most, reaching 85.44%, and the G9 group increased the least, only 1.92%. However, the water absorption quality decreased, and G6 decreased the most (37.53%), G7 decreased the least (0.84%), and UCS and water absorption quality showed a negative correlation. The sensitivity of each factor to UCS was different; the SR was the most sensitive at 7 d, but the lime was the most sensitive at 28 d. The sensitivity of each factor level (content) to UCS remains unchanged at different curing ages. There is a linear relationship between the deformation modulus and UCS. The analysis demonstrates that the better strength properties of SRS are mainly determined by the superior gradation and the reaction of materials.

The durability of soft soil stabilized by Portland cement -soda residue (PC -SR) subjected to dry -wet cycles remains relatively unclear now despite previous studies have extensively examined the engineering attributes of soft soil stabilized by PC -SR. Therefore, this study delineates the impacts of dry -wet cycles on the macro and micro features of soft soil stabilized by PC -SR. Based on the orthogonal test design, the unconfined compressive tests, Xray diffraction test, scanning electron microscopy, and mercury intrusion porosimetry tests were conducted to analyze the impact of dry -wet cycles on the strength, mineral components and microstructural characteristics of stabilized soil cured for 28 days. The experimental findings revealed that the strength of soil stabilized by PC -SR initially ascends and subsequently declines after dry -wet cycles. At the microscale, the tests showed that the drywet cycles transform the microstructure of stabilized soil by damaging the cementation among soil particles, expanding the pore diameter, and forming macropores and fissures. Combined with macro and micro results, it is shown that in the initial stage of the dry -wet cycle, the continuous hydration reaction promotes the increase of the microstructure density of solidified soil. However, under the continuous influence of the dry -wet cycle, the dissolution and expansion of mineral components lead to the degradation of the microstructure, which leads to the decline of the macro strength of the stabilized soil, further revealing the mechanism of the macro strength of the stabilized soil rising first and then decreasing. This study showed that Portland cement -soda residue treatment was efficient to prevent the deterioration from the dry -wet cycles.

Shield tunnel muck are usually discarded due to high water content and poor engineering properties, resulting in occupation of land sources and waste of soil sources. Meanwhile, large amounts of industrial waste such as carbide slag (CS) and soda residue (SR) are landfilled with a low reuse rate, which poses a threat to the natural environment. This study aims to improve waste shield tunnel muck using CS and SR and traditional lime, and the improved tunnel muck is expected to be used in subgrade filling to provide a new approach to solve this dilemma. A series of physical, mechanical, subgrade property, and microcosmic tests were conducted on shield tunnel muck improved by CS, SR and lime. The effects of different mixing proportions on the properties of improved tunnel muck were examined. The micro-improvement mechanisms of CS and SR on tunnel muck were explored. Results indicate that the addition of CS or SR can effectively improve the physical and mechanical properties of shield tunnel muck. CS plays a significantly role than SR in improving physical and mechanical properties of tunnel muck. A synergistic enhancement is observed as the combined CS and SR are added, and the optimal mixing proportion of tunnel muck to CS to SR is found to be 100:6:2 with a fixed lime content of 4 %. The alkaline environment created by the synergistic action of CS and SR promotes the dissolution of the active ions in soils, and the generated crystals and gelling products of hydration significant contribute to soil improvement. The tunnel muck improved with appropriate CS or SR content could meet the requirements for light or medium traffic load levels and can be effectively utilized as subgrade filling.