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Learn more: PMC Disclaimer | PMC Copyright Notice Sci Rep . 2026 Feb 25;16:11064. doi: 10.1038/s41598-026-41736-4 Search in PMC Search in PubMed View in NLM Catalog Add to search Experimental study on the disintegration characteristics of rare earth tailings improved by BF-MICP Zhongqun Guo Zhongqun Guo 1 School of Civil Engineering and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000 China 2 National Engineering Research Center for Ionic Rare Earth, Ganzhou, 341000 China Find articles by Zhongqun Guo 1, 2, ✉ , Xi Cao Xi Cao 1 School of Civil Engineering and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000 China Find articles by Xi Cao 1 , Jianqi Wu Jianqi Wu 1 School of Civil Engineering and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000 China Find articles by Jianqi Wu 1 , Yukun Zhong Yukun Zhong 1 School of Civil Engineering and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000 China Find articles by Yukun Zhong 1 , Qiangqiang Liu Qiangqiang Liu 1 School of Civil Engineering and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000 China Find articles by Qiangqiang Liu 1 Author information Article notes Copyright and License information 1 School of Civil Engineering and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000 China 2 National Engineering Research Center for Ionic Rare Earth, Ganzhou, 341000 China ✉ Corresponding author. Received 2025 Nov 19; Accepted 2026 Feb 23; Collection date 2026. © The Author(s) 2026 Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/ . PMC Copyright notice PMCID: PMC13043710 PMID: 41741533 Abstract The disintegration resistance of building foundation filling materials is directly related to the stability, safety, and durability of geotechnical engineering. Improving the disintegration characteristics of tailings is of significant importance for the comprehensive utilization of tailing waste. This study adopts basalt fiber (BF) and microbial induced carbonate precipitation (MICP) technology in combination (BF-MICP) to improve the typical rare earth tailings from South China. A systematic evaluation of the disintegration resistance of the modified tailings under wet-dry cycling conditions is conducted. Using a self-made test device, disintegration tests on the rare earth tailings under different modification conditions were carried out, and the effects of MICP treatment and fiber content on disintegration time and disintegration rate were analyzed. Microstructural analysis techniques such as XRD, FTIR, SEM, and EDS were employed to reveal the microscopic mechanism of the BF-MICP modification of the rare earth tailings. The results show that the addition of BF alone only slightly delays the disintegration process. Compared to unmodified tailings, the disintegration time of BF-modified tailings is extended to 940–1080 s, and the maximum mass loss per unit time is reduced to 6.1%–8.5%. However, it does not fundamentally inhibit the disintegration of the tailings upon contact with water. After BF-MICP treatment, the disintegration resistance of the tailings is significantly improved. The BF-MICP tailings maintain structural integrity after 4800 s of immersion, with the disintegration rate significantly reduced to 32%–45%. Moreover, the treated tailings retain good integrity after multiple wet-dry cycles. Keywords: Rare earth tailings, Basalt fiber, MICP, Disintegration, Mechanism Subject terms: Engineering, Environmental sciences, Materials science, Solid Earth sciences Introduction Rare earth, as a strategic national resource, generates a large volume of tailings during its mining process 1 , 2 . According to statistics, the historical accumulation of rare earth tailings in southern China alone amounts to hundreds of millions of tons 3 . These tailings not only occupy valuable land resources, but their loose structure and susceptibility to erosion pose a serious threat to the ecological environment of the mining areas and surrounding regions, such as soil erosion, heavy metal migration, and diffusion 4 , 5 . Meanwhile, the construction of various building foundations has a significant demand for natural sand and gravel, resulting in increased resource consumption and environmental pressure. Therefore, exploring methods for large-scale, low-cost disposal of rare earth tailings, especially utilizing them in roadbed construction and other foundation engineering, offers significant environmental, economic, and social benefits. Many scholars believe that appropriately modified rare earth tailings have the potential to be used as roadbed fill material 6 , 7 . However, a key bottleneck to the large-scale application of rare earth tailings in roadbed engineering is their poor resistance to disintegration. Southern China is characterized by a subtropical monsoon climate with abundant rainfall and intense sunlight, resulting in a very significant wet-dry cycling effect 8 . Under repeated rainfall infiltration and intense sunlight evaporation, the bonds between rare earth tailing particles are easily broken, causing the structure to rapidly disintegrate and become muddy. This may lead to a sharp decrease in the strength of the roadbed fill material and increased settlement deformation 9 , 10 . Therefore, improving the disintegration resistance of rare earth tailings under wet-dry cycling conditions is a crucial prerequisite for their successful application as a roadbed fill material. Internationally and domestically, common improvement techniques for tailings include physical compaction, chemical stabilization (e.g., cement, lime, or polymer binders), and recently developed biological methods. While these methods can enhance mechanical properties to varying degrees, they often face limitations in long-term durability under cyclic environmental conditions, high cost, secondary environmental impacts, or poor compatibility with fine-grained tailings. In particular, under the subtropical monsoon climate of southern China with pronounced wet-dry cycles, conventional chemical stabilization may suffer from brittleness, leaching, or carbonation degradation. These shortcomings highlight the need for a more robust, eco-friendly, and cost-effective synergistic improvement strategy. Microbially Induced Calcite Precipitation (MICP) technology, as an emerging biocementation method for soil improvement, has shown significant potential in the geotechnical engineering field in recent years 11 , 12 . This technique utilizes the urease activity of specific microorganisms (such as Sporosarcina pasteurii ) to decompose urea, producing carbonate ions that combine with calcium ions in the environment to form calcium carbonate crystals. These crystals precipitate in the pores and on the surfaces of soil particles, effectively cementing the particles, improving soil strength, and reducing permeability 13 , 14 . However, the calcium carbonate cement formed by pure MICP technology is relatively brittle. Under the shrinkage stress and repeated hydraulic actions caused by wet-dry cycles, its long-term durability and stability may be insufficient 15 , 16 . Basalt Fiber (BF), as a high-performance inorganic fiber, possesses high strength, high modulus, excellent weather resistance (acid and alkali resistance, resistance to high and low temperatures), anti-aging properties, and good compatibility with cement-based materials 17 , 18 . When incorporated into soil, BF can provide reinforcement, bridging, and crack-blocking functions, significantly enhancing the soil’s tensile, shear, and toughness properties. Combining BF with MICP technology is expected to produce a synergistic enhancement effect 18 . Currently, a lot of scholars have made significant research achievements in the fields of building foundation, filling materials improvement, and the resource utilization of rare earth tailings. For instance, Li et al. 19 utilized secondary recycled waste from rare earth tailings as a raw material to prepare Portland cement, revealing the mechanisms by which such waste affects cement yield and performance. Zhang et al. 20 prepared alkali-activated geopolymers using ion-adsorption rare earth tailings, which were applied to solidify/stabilize heavy metals and to manufacture green construction materials, offering a new approach for their resource utilization. Morley et al. 21 were the first to use tailings as active anode materials for lithium-ion batteries, confirming their electrochemical activity and further demonstrating the potential of the tailings. However, systematic studies on the feasibility of using modified rare earth tailings as engineering foundation fill materials have not yet been conducted, especially regarding whether their disintegration characteristics meet the requirements of geotechnical engineering. Exploration of this innovative research direction is of great significance for overcoming key technical bottlenecks in the resource utilization of rare earth tailings in southern China and for promoting green, low-carbon, and sustainable practices in geotechnical engineering. In view of this, this study takes typical rare earth tailings from southern China as the research object, focusing on their disintegration deterioration under dry-wet alternating environments. It investigates the improvement effect and mechanism on the disintegration characteristics of BF-MICP treated tailings. Through systematic laboratory tests, the influence of laws of different fiber contents, MICP treatment conditions, and their combinations on the disintegration resistance, integrity, and microstructural evolution of the improved tailings under simulated dry-wet cycles is quantitatively evaluated. The synergistic mechanism of fiber reinforcement and microbial mineralization is clarified, providing a scientific basis and technical support for the practical application of this technology in rare earth tailings. Materials Tailings sample The tailings soil used in this study was collected from a rare earth mining area in Longyan City, Fujian Province, as shown in Fig. 1 (a). The map in Fig. 1 (a) was created using the standard map service from the Standard Map Service System of China, with sampling locations added by the authors. According to the field investigation, significant runoff traces of leaching agents and chemical dissolution phenomena were observed on the ground surface of the mining area, along with large areas of exposed soil. Tailings soil sampling was carried out in the planned mining area of the rare earth mine. To avoid errors and adverse effects caused by differences in soil properties from different sampling points on the improvement effect of rare earth tailings, the collected rare earth mining soil was subjected to indoor leaching tests using a magnesium sulfate solution with a concentration of 6% and a pH of 2 as the leaching agent. After 14 days of leaching and following pH adjustment, rare earth tailings (hereinafter referred to as “rare earth tailings”) were obtained through artificial simulation of the leaching process by saline leaching agents 22 . Fig. 1. Open in a new tab Sampling location, physical properties, microstructural features, and mineral composition of ionic rare earth tailings. ( a ) Location and field photographs of the rare earth tailings sampling site. ( b ) Macroscopic appearance of the rare earth tailings and their particle size distribution curve. ( c ) Microstructural characteristics and mineral composition of the rare earth tailings. The particle size distribution of the rare earth tailings was analyzed using a Bettersize 3000plus laser diffraction particle size and shape analyzer (LDA), as shown in Fig. 1 (b). The distribution of particles is as follows: clay (d p < 0.05 mm), silt (0.05 mm < d p < 0.75 mm), and sand (0.075 mm < d p < 2.00 mm) account for 13.2%, 45.9%, and 40.9%, respectively. Scanning electron microscopy (SEM) analysis of the rare earth tailings samples was performed using a Zeiss Sigma 500 scanning electron microscope from Germany. Additionally, X-ray fluorescence (XRF) analysis was conducted using an Axios-max XRF spectrometer from PANalytical, Netherlands, using the fused-bead method. The chemical composition results indicate that the tailings are primarily composed of SiO₂ (37.5 wt%), Al₂O₃ (28.1 wt%), and Fe₂O₃ (20.7 wt%), along with minor amounts of K₂O, TiO₂, and Na₂O. Of particular environmental concern, the content of the heavy metal Pb, expressed as PbO, is 0.19 wt%, and the content of the heavy metal Zn, expressed as ZnO, is 0.17 wt%, which necessitates careful evaluation in the safety assessment of the modified tailings. The microscopic pore structure and mineral composition of the tailings samples are shown in Fig. 1 (c). Standard compaction tests, soil pH tests, and liquid-plastic limit tests were conducted to measure the maximum dry density, optimum moisture content, and soil pH value of the rare earth tailings. The natural moisture content of the soil samples was determined using the ring knife method. The test results are shown in Table 1 . Table 1. Basic physical properties of rare earth tailings. Water Content ω(%) Density ρ/(g/cm 3 0 Liquid Limit W L (%) Plastic Limit W P (%) Plasticity Index I P pH Value 22.71 1.73 32.1 19.4 12.7 8.56 Open in a new tab Experimental microorganisms The bacterium used in this study is Sporosarcina pasteurii , which was purchased from the China General Microbiological Culture Collection Center (CGMCC), with the strain number CGMCC 1.3687. This bacterium secretes highly active urease during its life cycle, which catalyzes the hydrolysis of urea (CO(NH₂)₂ + 2 H₂O → 2NH₄⁺ + CO₃²⁻), producing ammonium ions (NH₄⁺) and carbonate ions (CO₃²⁻). These ions combine with exogenously added calcium ions (Ca²⁺) in the environment to form calcium carbonate (CaCO₃) precipitates 23 . These precipitates preferentially nucleate at the surface of the bacteria and at the contact points between soil particles, helping to cement loose particles and fill voids, thereby improving the soil’s compressive strength, shear stiffness, and reducing permeability. At the same time, the negatively charged bacteria and carbonate ions have the ability to adsorb and encapsulate heavy metal ions, which can transform the free heavy metal ions in the tailings into insoluble solid-phase minerals (ZnCO₃, Pb₃(CO₃)₂(OH)₂), thus stabilizing the heavy metal pollutants 24 , 25 . A schematic diagram of the microbial-induced calcium carbonate precipitation process and mechanism is shown in Fig. 2 . Fig. 2. Open in a new tab Schematic diagram of the microbial-induced calcium carbonate precipitation process and mechanism. The bacteria were initially cultured and scaled up using liquid and solid media, as shown in Fig. 3 . The composition of the medium consists of 5.0 g/L peptone, 3.0 g/L beef extract, 20.0 g/L urea, and 20.0 g/L agar powder, which is added only to the solid medium. After entirely dissolving and mixing the components, the pH of the medium was adjusted to 7.0 ± 0.1 using a 1 mol/L NaOH solution. The bacteria were inoculated into 250 mL of the liquid medium, which had been sterilized at high temperature. The medium was incubated in a constant-temperature shaking incubator at 30 °C and 150 rpm for 24 h, followed by centrifugation at 4 °C and 8000 rpm for 8 min. The supernatant was discarded, and the bacterial pellet was collected and evenly spread on the surface of a pre-sterilized solid medium. The culture was aerobically incubated at 37.3 °C for 48 h to form dense colonies. Finally, the bacterial biofilm was scraped off using a sterile spatula and inoculated into 1000 mL of sterilized liquid medium. The above cultivation process was repeated to complete the initial and scaled-up culture of the bacteria, resulting in the experimental bacterial suspension 26 . Fig. 3. Open in a new tab Bacterial cultivation and growth. The cementing solution is mainly prepared from equimolar concentrations of urea (CO(NH₂)₂) and calcium chloride (CaCl₂) along with a nutrient medium containing specific components. It is a liquid medium that provides a suitable environment and the necessary nutrients for bacterial growth and reproduction 27 . Its composition is detailed in Table 2 . Table 2. Composition of the cementing solution. CO(NH 2 ) 2 (g) CaCl 2 (g) NH 4 Cl (g) NaHCO 3 (g) Nutrient broth (g) DI water (ml) 60.0 111.0 10.0 2.12 3.0 1000 Open in a new tab Basalt Fiber Basalt fiber (BF) is a high-performance inorganic fiber produced from natural volcanic rock (basalt) by rapid drawing after high-temperature melting. Its chemical composition is mainly composed of silicon dioxide (SiO₂, approximately 45–55%), aluminum oxide (Al₂O₃, approximately 12–18%), iron oxides (FeO + Fe₂O₃, approximately 8–15%), as well as calcium and magnesium oxides 28 . Figure 4 shows the morphological characteristics of basalt fiber (BF) and the microscopic features of its fiber surface. Fig. 4. Open in a new tab Morphological characteristics of BF. Experimental methods Preparation of modified tailings In this study, two modification schemes of tailings were prepared for the investigation of disintegration characteristics: (1) tailings modified solely with basalt fiber (BF group); (2) tailings modified with basalt fiber in combination with microbially induced calcium carbonate precipitation (BF-MICP group). In both modification schemes, the basalt fiber content was set at 0.20%, 0.40%, 0.60%, and 0.80%. For the BF-MICP modification scheme, a bacterial solution with a concentration of 1 mol/L was used. The design of the modification schemes is shown in Table 3 . Table 3. Experimental design of modification schemes for rare earth tailings. Protocol Basalt Fiber MICP 1 0.20% No 2 0.40% No 3 0.60% No 4 0.80% No 5 0.20% Yes 6 0.40% Yes 7 0.60% Yes 8 0.80% Yes Open in a new tab The preparation process for the basalt fiber-modified sample (BF group) is as follows: Basalt fiber (BF) and dried rare earth tailings were weighed according to the preset mass fractions and mixed. A mechanical stirrer was used to thoroughly mix the materials, ensuring the uniform dispersion of the fibers. The mixture was then layered and placed into a cylindrical mold (φ39.1 mm × H40 mm), with each layer compacted to ensure density. After molding, the sample was demolded and cured under standard curing conditions for 7 days 29 . The preparation process for the basalt fiber combined with MICP-modified sample (BF-MICP group) is as follows: Basalt fiber (BF) and bacterial solution were weighed according to the preset mass fractions and mixed with dried rare earth tailings. The mixture was mechanically stirred until homogeneous. The mixture was then layered and compacted into a mold to form the sample. After demolding, the sample was immediately wrapped with geotextile fabric, which has good permeability, to form a flexible package. The wrapped sample was then completely submerged in a cementation solution and treated using a cyclic immersion method for 7 days. After treatment, the geotextile fabric was removed, and the sample was cured under standard conditions for an additional 7 days. Disintegration test under wet-dry cycles To systematically investigate the disintegration characteristics of rare earth tailings under wet-dry cycles, a self-designed disintegration test device was developed in this study based on typical disintegration test principles 30 (as shown in Fig. 5 ). The device enables synchronous monitoring via a force sensor (with an accuracy of 0.1 g) and a high-definition camera system, enabling dynamic recording of mass loss and morphological changes during disintegration. Prior to testing, the force sensor was calibrated using standard weights, and the system’s overall measurement error was controlled within ± 1.0% to ensure data reliability and the reproducibility of the process. The device mainly consists of: a cylindrical glass disintegration tank with a diameter of 30 cm and a height of 40 cm for soaking the samples; a sample rack made of fine metal mesh (aperture 0.1 mm), which supports the sample and allows moisture to penetrate; the aforementioned force sensor for monitoring the mass change of the sample during the disintegration process; a metal frame to connect and fix all the components; as well as a data acquisition system and a camera system. The experimental steps are as follows: Fig. 5. Open in a new tab Sample preparation and test equipment. (1) Device Assembly and Positioning: The sample rack is connected to the force sensor and fixed to the metal frame. The assembled unit is then placed vertically in the glass disintegration tank. Finally, the disintegration sample is placed on the sample rack, and the camera system is set up. (2) Sample Immersion: Deionized water is slowly poured into the glass disintegration tank until the water level is level with the surface of the sample rack. The platform at the bottom of the disintegration tank is adjusted to ensure that the sample is completely submerged instantly. (3) Data Recording Start: Once the water has been added, the data acquisition system of the force sensor and the camera system are simultaneously activated to record the initial mass data (t = 0) and the initial shape of the sample. (4) Real-Time Monitoring: Throughout the experiment, the force sensor continuously monitors the remaining mass of the sample. The high-definition camera synchronously captures the dynamic changes in the disintegration morphology of the sample, while also recording the time information for later calculation of the disintegration rate. (5) Experiment Termination: The experiment is terminated when the reading of the force sensor stabilizes, indicating that the disintegration is essentially complete 31 . For samples that need to undergo wet-dry cycles, after completing one cycle of the disintegration test in water (Steps 1–5), the residual sample is removed and placed in a 105 °C constant temperature drying oven for 24 h until it reaches a constant weight (moisture content ≈ 0%). The dried sample is then reinstalled into the device, and Steps 1–5 are repeated for the next wet cycle disintegration test. The disintegration rate Dt is calculated using formula (1): 1 Where: represents the initial mass of the sample, represents the mass of the sample at time t during the disintegration test, represents the saturated density of the sample, represents the density of water, which is 1.0 g/cm³, represents the reading from the force sensor, in units of (N). Calcium carbonate precipitation measurement test The amount of calcium carbonate generated is a key indicator for evaluating the effectiveness of MICP (Microbially Induced Calcite Precipitation) repair, as it directly reflects the completion degree of the microbial-induced carbonate precipitation reaction and the cementation strength. It plays an important role in enhancing the structural stability of soil, especially in improving resistance to disintegration 32 . In this study, the calcium carbonate production rate of the repaired samples was determined using the hydrochloric acid immersion method: After microbial grouting treatment and demolding, the soil samples were dried in an oven at 105 °C to constant weight, denoted as m1. Then, the samples were soaked in 20% dilute hydrochloric acid until no bubbles were produced. The excess acid was removed by vacuum filtration using a 0.45 μm filter membrane, followed by multiple rinses with deionized water to completely filter out soluble salts. The soil samples were then placed back in the oven and dried at 105 °C to constant weight, denoted as m2. The carbonate production rate was calculated using formula (2). 2 Microstructure Testing This study used an X-ray diffractometer (Bruker-D8-ADVANCE, Germany) to determine the mineral composition of samples before and after BF-MICP modification, and phase analysis of the test results was performed using MDI Jade 9.0 software. A Nicolet iS50 Fourier Transform Infrared Spectrometer was employed to characterize the molecular bonding features of the samples. After obtaining the spectral data, baseline calibration and peak assignment analysis were conducted using OMNIC 9.2 software. The micro-pore structure of the samples and the fiber distribution in the soil were observed and analyzed using a Zeiss Sigma 500 scanning electron microscope (Germany), followed by chemical substance detection on the sample surface using an EDS scanning energy spectrometer. Result and Analysis The effect of BF improvement on the disintegration of rare earth tailings The disintegration characteristics of rare earth tailings improved by BF with different dosages (0.20%, 0.40%, 0.60%, 0.80%) are shown in Fig. 6 . The unmodified sample completely disintegrated after soaking for 680 s (disintegration rate of 100%), with the maximum mass loss being 9.6 g. Based on its disintegration characteristics, it can be divided into three stages: the initial slow disintegration stage (0–60 s), where the surface of the sample gradually absorbs water and slightly expands, with only a small amount of soil particles shedding, while bubbles continuously rise to the surface; the rapid disintegration stage (60–300 s), where the sample undergoes intense structural damage, a large number of soil particles continuously shed, leading to an increase in water turbidity, and the maximum mass loss occurs; and the residual disintegration stage (300–680 s), where a stable low-speed disintegration continues until complete disintegration, with a small amount of mass loss and slight fluctuations. Fig. 6. Open in a new tab Disintegration characteristics of rare earth tailings improved by BF. After BF improvement, the time for complete disintegration of the samples was extended, and the disintegration rate was reduced to some extent. The complete disintegration times for the samples with BF dosages of 0.2%, 0.4%, 0.6%, and 0.8% were extended to 940 s, 1040 s, 1000 s, and 1080 s, respectively, and the corresponding maximum disintegration mass decreased to 8.6 g, 6.8 g, 8.2 g, and 6.3 g. However, BF improvement did not change the disintegration pattern of the samples. The four improved samples still exhibited a similar disintegration pattern to the unmodified sample, with only differences in the duration of each stage and the disintegration intensity. The phenomenon described above is attributed to the following: With the addition of BF, the fibers anchor and interact with soil particles, increasing the friction between soil particles. The increased friction during disintegration helps to hinder the migration of soil particles and reduce the disintegration rate 33 , 34 . However, the hydration stress of swelling clay minerals, such as montmorillonite, in the tailings was not alleviated. The single BF modification can only delay the destruction process through mechanical anchoring of the fibers, but it cannot fundamentally change the nature of the complete disintegration of the rare earth tailings when they come into contact with water. The effect of BF-MICP improvement on the disintegration of rare earth tailings The disintegration characteristics of rare earth tailings improved by BF-MICP with different dosages (0.20%, 0.40%, 0.60%, 0.80%) are shown in Fig. 7 . The BF-MICP technology significantly improved the disintegration characteristics of rare earth tailings. Compared with the unimproved sample (complete disintegration at 680 s) and the single BF-improved samples (complete disintegration at 940–1080 s), all BF-MICP-improved samples maintained their general shape without structural failure after the initial 4800 s of immersion, with the disintegration ratio significantly reduced to 30%-45%. Specifically, the 0.20% BF-MICP group showed a disintegration ratio of 42% and a maximum mass loss of 1.8 g; the 0.40% BF-MICP group showed 38% and 2.2 g; the 0.60% BF-MICP group showed 34% and 1.6 g; and the 0.80% BF-MICP group showed 31% and 1.7 g. The disintegration ratio gradually decreased with increasing BF dosage. Fig. 7. Open in a new tab Disintegration characteristics of rare earth tailings improved by BF-MICP. The disintegration process still exhibited typical three-stage characteristics: an initial slow stage (0–60 s, rate < 1.01 g/20 s) manifested as progressive surface exfoliation; a rapid disintegration stage (60–450 s, peak rate 1.0–3.0 g/20 s); and a residual stable stage (> 450 s, rate < 0.1 g/20 s). The disintegration process shown in the figure also clearly indicates that the turbidity of water in the BF-MICP improved groups was significantly lower than that in the untreated and BF-improved groups. The occurrence of the above phenomena can be attributed to the following reasons: The introduction of MICP utilizes highly active urease continuously produced by Sporosarcina pasteurii during its metabolic processes. This promotes urea hydrolysis and subsequent combination with calcium ions, inducing the formation of calcium carbonate crystals. These crystals function by filling pores and cementing soil particles within the soil matrix, thereby enhancing soil strength. Additionally, they encapsulate or bridge hydrophilic clay particles (such as montmorillonite) within larger aggregate structures, effectively inhibiting hydration expansion, reducing the disintegration rate, and improving sample integrity 35 , 36 . Simultaneously, the cementation effect of MICP and the mechanical anchoring effect of BF are synergistically enhanced, fundamentally altering the inherent characteristic of rare earth tailings to completely disintegrate upon water contact. The effect of BF-MICP improvement on the disintegration of rare earth tailings under wet-dry cycles After BF-MICP modification, the rare earth tailings samples maintained structural integrity in the initial disintegration test, so the undisintegrated samples were selected for the subsequent wet-dry cycle tests. As shown in Fig. 8 , the disintegration characteristic curves of BF-MICP modified samples with different fiber contents during the first to fifth wet-dry cycles are presented. Overall, the disintegration behaviors in the first to fifth cycles were quite similar. All the samples exhibited a rapid disintegration rate at the beginning, which gradually slowed down, eventually reaching a stable stage where disintegration almost ceased. The main differences were reflected in the significant variation in the cumulative disintegration amount across the different fiber contents in each stage. Fig. 8. Open in a new tab Disintegration characteristics of BF-MICP modified rare earth tailings under wet-dry cycle conditions. With the increase in the number of wet-dry cycles, the total disintegration amount of all samples showed a gradual decreasing trend. Taking the 0.2% fiber content group as an example, the maximum disintegration amount in the first cycle was 4.2%, which decreased to 2.1% by the fifth cycle. Other fiber content groups followed the same trend. Furthermore, the BF content significantly influenced the disintegration behavior. In general, as the fiber content increased, the cumulative disintegration amount of the samples gradually decreased, indicating that the reinforcing effect of BF, together with the cementitious substances produced by MICP, helped fill the pores and enhanced the connections between particles. This, in turn, improved the structural stability and anti-disintegration ability of the samples. After multiple cycles, the surface soil of the samples gradually eroded and was lost, leaving a dense structure formed by the mutual cementation of fibers and calcium carbonate. This effectively inhibited further disintegration, reducing the overall failure tendency of the samples 37 . The disintegration process of rare earth tailings improved by BF combined with MICP at different dosages (0.20%, 0.40%, 0.60%, 0.80%) during wet and dry cycles is shown in Fig. 9 . For samples with different BF dosages, the disintegration behavior during the five wet-dry cycles was similar: surface soil particles were gradually dissolved by water, causing the overall sample size to decrease without any large, sudden peeling. The changes in disintegration mass were mainly reflected in the slow loss of fine particles. The primary difference between samples with different BF dosages was the rate of volume reduction: samples with lower fiber content exhibited faster volume shrinkage, while those with higher fiber content showed a noticeable slowdown. Fig. 9. Open in a new tab Disintegration process of rare earth tailings improved by BF-MICP under wet-dry cycles. This phenomenon can be explained by the combined improvement mechanism of BF and MICP: moisture first dissolves surface soil particles, causing them to gradually detach and expose the dense, reticulated skeletal structure formed by the interweaving of calcium carbonate crystals and BF 38 . However, during wet–dry cycles, the loss of surface soil leads to a gradual weakening of the skeletal support, which eventually also detaches slowly 39 , 40 . When the BF content is relatively low, the number of soil particles that can be jointly anchored by BF and MICP is limited, resulting in weak structural integrity and thus a faster disintegration rate. With increasing BF content, the cementation–reinforcement system formed by fibers and calcium carbonate can restrain more soil particles and enhance structural continuity, thereby effectively suppressing disintegration and improving the anti-disintegration performance of the specimens. Calcium carbonate precipitation In this study, calcium carbonate content tests were conducted on specimens treated with different improvement techniques; the sampling locations and test results are shown in Fig. 10 . The results indicate that the calcium carbonate content of untreated specimens was 3.98%, and no significant change occurred after BF treatment. In contrast, specimens treated with MICP–BF exhibited a marked increasing trend in calcium carbonate content, with all specimens reaching approximately 12.0%. This result demonstrates that the introduction of MICP technology successfully induced the precipitation of calcium carbonate, which cemented soil particles and fibers, thereby generating about 8% new calcium carbonate within the specimens. Fig. 10. Open in a new tab Calcium carbonate content. Microscopic mechanism analysis The SEM images of rare earth tailings samples under different improvement techniques are shown in Fig. 11 (a). The images reveal that the untreated tailings samples have a loose structure with well-developed porosity. After BF treatment, fibers intertwine with soil particles, enhancing the friction and compaction between the particles. In contrast, the samples treated with BF-MICP exhibit a denser structure, with precipitated calcium carbonate interwoven with BF, forming stable agglomerates 41 . Fig. 11. Open in a new tab Effects of different improvement techniques on the calcium carbonate content and microstructural characteristics of rare earth tailings: ( a ) SEM images of untreated and BF-MICP treated tailings. ( b ) EDS images of untreated and BF-MICP treated tailings. ( c ) XRD patterns for tailings with different BF contents. ( d ) FTIR patterns for tailings with different BF contents. An EDS surface scan of the Ca element in the samples is shown in Fig. 11 (b). The images reveal that in the untreated samples 42 , the Ca element is present in low abundance and uniformly dispersed. The BF-MICP treated samples, however, exhibit a pronounced localization and enrichment of Ca, confirming the substantial generation of calcium carbonate, consistent with the previous calcium carbonate content test results 43 , 44 . The XRD spectra of rare earth tailings samples under different improvement techniques are shown in Fig. 11 (c). Compared to the untreated control group, the XRD spectrum of the BF-treated samples shows no significant change. In contrast, the XRD spectrum of the BF-MICP treated samples displays noticeable peak variations and the appearance of new characteristic peaks, indicating changes in the mineral composition and the formation of new mineral phases 45 . Specifically, a significantly enhanced characteristic peak is observed at 2 θ = 25 ° to 29.4 °, which, when compared with standard PDF cards, is confirmed to correspond to the diffraction peak of calcite (CaCO₃) 46 . Moreover, the intensity of the diffraction peak corresponding to hydrophilic montmorillonite (e.g., at 2 θ ≈ 26.8 ° or other main montmorillonite peaks) shows a significant decrease 47 . This phenomenon does not imply the removal of montmorillonite, but rather reflects a decrease in its relative content or a weakening of its effective diffraction ability. The main reason is that, on the one hand, the newly formed calcite crystals extensively cover the surface of clay particles (especially the highly hydrophilic montmorillonite), enveloping or bridging them within larger agglomerates. On the other hand, the extracellular polymeric substances (EPS) produced by microbial metabolism can also adsorb and encapsulate clay particles. This encapsulation and cementation significantly alter the surface state of montmorillonite particles and their dispersion in the soil, leading to a relative decrease in the XRD diffraction intensity. The FTIR spectra of rare earth tailings samples under different improvement techniques are shown in Fig. 11 (d). Compared to the untreated control group, the spectra of the BF-treated samples are essentially consistent in shape. However, the spectra of the BF-MICP treated samples show relatively significant characteristic differences in certain specific peaks. Specifically: a deformation peak around 794 cm⁻¹, caused by the in-plane bending vibration of CO; a deformation peak around 896 cm⁻¹, caused by the out-of-plane bending vibration of CO₃²⁻; a deformation peak around 1052 cm⁻¹, caused by the stretching vibration of CO₃²⁻; and a deformation peak around 1756 cm⁻¹, caused by the stretching vibration of CO 48 , 49 . These characteristic peaks are all attributed to calcium carbonate (CaCO₃). The BF-MICP treated samples exhibit much stronger characteristic peaks of CaCO₃ compared to the untreated control group, confirming that the MICP process successfully induced the formation of stable calcium carbonate crystals, consistent with the XRD diffraction peak of CaCO₃ at 29.4 °. Additionally, an absorption peak around 1650 cm⁻¹ is observed, corresponding to the antisymmetric vibration of the -COOH group in organic matter. This peak is significantly enhanced in the BF-MICP treated samples, indicating that microbial metabolism and proliferation increased the biomass of the samples, leading to a rise in organic matter 50 , 51 . The absorption peaks around 3400 cm⁻¹ to 3700 cm⁻¹ in the spectrum are primarily due to the vibrations of clay minerals in the samples, with a sharp peak at 3750 cm⁻¹ and a broad peak at 3520 cm⁻¹, which are characteristic of montmorillonite, representing its structural hydroxyl group and interlayer water -OH stretching vibrations, respectively 52 . In the BF-MICP treated samples, the intensity of the absorption peaks corresponding to these clay components is relatively reduced, indicating a decrease in the clay content, which supports the findings from the XRD analysis. Mechanism analysis of BF/BF-MICP improvement on rare earth tailings This study explores the anti-disintegration mechanism of BF/BF-MICP improved rare earth tailings at the microscopic level, analyzing it in conjunction with insights into the disintegration mechanism of the tailings themselves. As previous studies have shown, the mechanism of BF improved rare earth tailings is primarily reflected in its physical anchorage and the increased friction between soil particles. As shown in Fig. 12 (a), BF, by being thoroughly mixed with the tailings, forms a complex interwoven network structure between the fibers and the tailings particles. These fibers act as bridges in the tailings soil, which, to some extent, reduces the phenomenon of structural loosening and disintegration caused by moisture intrusion, enhancing the integrity and anti-disintegration ability of the tailings. Therefore, BF delays the failure process of the tailings sample. Fig. 12. Open in a new tab Schematic diagram of improvement mechanisms for BF/BF-MICP. To further improve the anti-disintegration property and structural strength, the MICP technology was introduced to form a BF-MICP synergistic improvement system. As shown in Fig. 12 (b), the mechanism includes: urea being hydrolyzed under the action of microorganisms (such as Sporosarcina pasteurii ) to generate CO₃²⁻ and NH₃, providing an alkaline environment and promoting the combination of carbonate ions with Ca²⁺ in the solution to form CaCO₃ precipitates. These CaCO₃ crystals deposit between the tailings particles and progressively intertwine with and encapsulate the BF fibers, forming a “fiber–calcium carbonate–soil particle” three-dimensional cementation network. This structure not only significantly enhances the interparticle cementation force but also works in synergy through fiber bridging and calcite filling to inhibit particle dispersion in aqueous environments. More importantly, this three-dimensional network demonstrates notable adaptability during wet-dry cycles (as illustrated in Fig. 12 c). Upon wetting, the hydrophilicity and elasticity of the fibers help buffer partial expansion stress, while the water retention within the calcite crystal interstices contributes to maintaining cementation integrity. During drying, the bridging effect of the fibers restrains the propagation of desiccation cracks, and the carbonate precipitates provide a continuous binding constraint. Together, they resist the structural deterioration induced by cyclic stresses. Therefore, the BF-MICP improvement not only suppresses disintegration through physical reinforcement but also achieves chemical cementation via biomineralization, synergistically enhancing the engineering properties of rare earth tailings. Conclusions (1) BF improvement can delay but not prevent disintegration. With increasing BF content (0.2%-0.8%), the complete disintegration time of samples extended to 940–1080 s, and the maximum mass loss decreased to 6.1–8.5 g. The primary mechanism involves increased friction through fiber mechanical anchoring; however, it cannot inhibit the hydration expansion of minerals such as montmorillonite, thus failing to alter the inherent nature of ultimate disintegration upon water contact. (2) BF-MICP improvement significantly enhances anti-disintegration performance. The samples maintained structural integrity after 4800 s of water immersion, with disintegration ratios reduced to 32%-45%. The calcium carbonate generated by MICP synergistically cemented with BF fibers, filling pores and inhibiting clay expansion, fundamentally improving the disintegration characteristics of the tailings. (3) BF-MICP improved samples exhibit excellent long-term stability. After five wet-dry cycles, the cumulative disintegration amount decreased with increasing fiber content. As the number of cycles increased, the cumulative disintegration gradually reduced due to the enhanced damage resistance of the fiber-calcium carbonate skeletal structure. (4) Microstructural analysis confirmed that the BF-MICP joint improvement formed dense aggregate structures, with enriched calcite precipitation and weakened montmorillonite diffraction peaks. FTIR analysis showed intensified characteristic peaks of calcium carbonate and increased organic matter, indicating that microbial cementation effectively encapsulated clay particles and improved the structural stability of rare earth tailings. (5) From the perspective of engineering application, the BF-MICP synergistic improvement technique offers a viable pathway for the resource utilization of rare earth tailings in subgrade and other fill engineering projects. Through the combined effect of biomineralization cementation and fiber reinforcement, this technology significantly enhances the water stability of the tailings, thereby providing an effective technical solution to address the disintegration of fill materials in rainy and humid environments. Author contributions Conceptualization, methodology, writing—original draft, and figure work have been verified by Z.Q. Guo, X. Cao, J.Q. Wu. Formal analysis, writing—reviewing and editing have been done by Z.Q. Guo, X. Cao, Q. Q. Liu, Supervision, revision work has been done by J.Q. Wu. Q. Q. Liu. All authors have reviewed the manuscript. Funding This research was funded by the National Natural Science Foundation of China (52364012, 52564018), the Natural Science Foundation of Jiangxi Province, China (20224BAB214035), and the Key Laboratory of Ionic Rare Earth Resources and Environment, Ministry of Natural Resources of the People’s Republic of China (2023IRERE403). Data availability The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request. Declarations Competing interests The authors declare no competing interests. Footnotes Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. References 1. Deng, X. Y. et al. Recovery process of polyurethane-enhanced Anammox for the treatment of ammonia nitrogen leached from rare earth tailings: Removal performance, structure changes and biodiversity evolution. Environ. Technol. Innov. 34 , 103552. 10.1016/j.eti.2024.103552 (2024). [ Google Scholar ] 2. Hajdu-Rahkama, R. & Kinnunen, P. Tailings valorisation: Opportunities to secure rare earth supply and make mining environmentally more sustainable. J. Clean. Prod. 520 , 146147. 10.1016/j.jclepro.2025.146147 (2024). [ Google Scholar ] 3. Wang, X. M. et al. Contamination status and health risk assessment of potentially toxic trace elements in soils surrounding rare earth tailings in China: A retrospective review. Ecotoxicol. Environ. Saf. 298 , 118270. 10.1016/j.ecoenv.2025.118270 (2024). [ DOI ] [ PubMed ] [ Google Scholar ] 4. Janot, N. et al. Localization and speciation of rare earth elements in mine tailings from ion-adsorption clay deposits, Southern China: Insights from microfocused X-ray fluorescence spectroscopy. J. Hazard. Mater. Adv. 17 , 100609. 10.1016/j.hazadv.2025.100609 (2024). [ Google Scholar ] 5. Tian, S. et al. Leaching characteristics and environmental impact of heavy metals in tailings under rainfall conditions: A case study of an ion-adsorption rare earth mining area. Ecotoxicol. Environ. Saf. 281 , 116642. 10.1016/j.ecoenv.2024.116642 (2024). [ DOI ] [ PubMed ] [ Google Scholar ] 6. Zhang, B. F. et al. Recycling of an ion-adsorption type rare earth tailing in a low-carbon construction material: Performance modulation and life cycle assessment. Constr. Build. Mater. 475 , 141167. 10.1016/j.conbuildmat.2025.141167 (2025). [ Google Scholar ] 7. Li, W. X. et al. Pioneer plants enhance soil multifunctionality by reshaping underground multitrophic community during natural succession of an abandoned rare earth mine tailing. J. Hazard. Mater. 472 , 134450. 10.1016/j.jhazmat.2024.134450 (2025). [ DOI ] [ PubMed ] [ Google Scholar ] 8. Gallage, C., Jayakody, S., Abeykoon, T., Biyanvilage, D. & Rajapakse, J. A laboratory-based test procedure for the investigation of slaking-induced changes in geotechnical properties of tailing dam embankment materials. Heliyon 10 (4), e26489. 10.1016/j.heliyon.2024.e26489 (2025). [ DOI ] [ PMC free article ] [ PubMed ] [ Google Scholar ] 9. Saldanha, R. B. et al. A decision-making flowchart for tailings stabilization: Assessing environmental and economic impacts. J. Clean. Prod. 519 , 145893. 10.1016/j.jclepro.2025.145893 (2025). [ Google Scholar ] 10. Wang, X. Y. et al. Study on the Effect of EICP Combined with Nano-SiO₂ and Soil Stabilizer on Improving Loess Surface Strength. Buildings 15 (12), 2025 10.3390/buildings15121998 (1998). [ Google Scholar ] 11. Huang, H. Y. et al. Polyethylene microplastics interfere with MICP-based cadmium remediation: A dual-system evaluation of microbial performance and environmental response. J. Hazard. Mater. 497 , 139541. 10.1016/j.jhazmat.2025.139541 (2025). [ DOI ] [ PubMed ] [ Google Scholar ] 12. Chen, S. G., Kang, B., Zha, F. S. & Chen, X. B. Synergistic solidification of heavy metal tailings by polyethylene glycol (PEG) and microorganisms. Environ Technol Innovation . 36 , 103788. 10.1016/j.eti.2024.103788 (2025). [ Google Scholar ] 13. Duan, Y. T., Yuan, Q., Yu, C. Q. & Zheng, C. L. A large-scale study on solidification of gold tailings based on microbially induced carbonate precipitation (MICP). Biogeotechnics 3 (3), 100164. 10.1016/j.bgtech.2025.100164 (2025). [ Google Scholar ] 14. Zhai, Y. X. et al. Improvement of MICP-treated sandy soils against acid rain erosion. Constr. Build. Mater. 411 , 134467. 10.1016/j.conbuildmat.2024.134467 (2024). [ Google Scholar ] 15. Diao, Y. et al. Coupling effect of fiber reinforcing and biomimetic chemically induced calcium carbonate precipitation cementing on mechanical performance of biomimetic mineralized mortar. J Mater. Res Technol. 35 , 5688–5697. 10.1016/j.jmrt.2025.02.157 (2024). [ Google Scholar ] 16. Zhang, G. Z., Liu, C., Zhang, J., Wang, H. & Liu, J. Enhanced MICP efficacy for cracks repair of marine mortar with coral sand: Coupled effects of seawater and basalt fiber on products morphology. Constr. Build. Mater. 470 , 140647. 10.1016/j.conbuildmat.2025.140647 (2025). [ Google Scholar ] 17. Shu, Y. et al. Fiber-reinforced microbially induced carbonate precipitation (MICP) for enhancing soil stability: Mechanisms, effects, and future prospects. J. Build. Eng. 94 , 109955. 10.1016/j.jobe.2024.109955 (2025). [ Google Scholar ] 18. Zhang, H. & Sun, W. F. Mechanical properties and failure behavior of 3D printed thermoplastic composites using continuous basalt fiber under high-volume fraction. Def. Technol. 27 , 237–250. 10.1016/j.dt.2022.07.010 (2023). [ Google Scholar ] 19. Li, C. et al. Preparation and properties of Portland cement from secondary recycle waste of rare earth tailing. Constr. Build. Mater. 406 , 133337. 10.1016/j.conbuildmat.2023.133337 (2023). [ Google Scholar ] 20. Zhang, B. F. et al. Ion-adsorption type rare earth tailings for preparation of alkali-based geopolymer with capacity for heavy metals immobilization. Cem. Concr Compos. 134 , 104768. 10.1016/j.cemconcomp.2022.104768 (2022). [ Google Scholar ] 21. Morley, J. D. et al. Mine tailings as active electrode materials for Li-ion batteries. Cell. Rep Sustain . 2 (10), 100494. 10.1016/j.crsus.2025.100494 (2023). [ Google Scholar ] 22. Jiang, Y. et al. A Review of the Main rare earth ore smelting processes in the world: From traditional methods to new technologies. J. Rare Earths . 10.1016/j.jre.2025.07.027 (2023). [ Google Scholar ] 23. Zhang, X. S. et al. Improved methods, properties, applications and prospects of microbial induced carbonate precipitation (MICP) treated soil: A review. Biogeotechnics 3 (1), 100123. 10.1016/j.bgtech.2024.100123 (2023). [ Google Scholar ] 24. Wang, Y. et al. State-of-the-art review of soil erosion control by MICP and EICP techniques: Problems, applications, and prospects. Sci. Total Environ. 912 , 169016. 10.1016/j.scitotenv.2023.169016 (2023). [ DOI ] [ PubMed ] [ Google Scholar ] 25. Li, G. et al. Mechanical properties of aeolian sand cemented via microbially induced calcite precipitation (MICP). Sci. Rep. 14 , 21739. 10.1038/s41598-024-73986-5 (2024). [ DOI ] [ PMC free article ] [ PubMed ] [ Google Scholar ] 26. Lapierre, F. M. & Huber, R. Revisiting the urease production of MICP-relevant bacterium Sporosarcina pasteurii during cultivation. Biocatal. Agric. Biotechnol . 55 , 102981. 10.1016/j.bcab.2023.102981 (2023). [ Google Scholar ] 27. Wei, S. P., Xiao, F. R., Dong, H. Z. & Chen, H. J. Carbonate polymorph formation in microbially induced calcium carbonate precipitation (MICP): Influencing factors, mechanisms, and knowledge gaps. Earth-Sci. Rev. 265 , 105129. 10.1016/j.earscirev.2025.105129 (2023). [ Google Scholar ] 28. Guo, R., Li, J. Y., Huo, X. Y. & Wang, Z. K. Durability experimental study and service life evaluation of basalt-PVA fibre-reinforced concrete in chloride-rich environments. Case Stud. Constr. Mater. 23 , e05060. 10.1016/j.cscm.2025.e05060 (2023). [ Google Scholar ] 29. Lapierre, F. M. et al. Revealing nutritional requirements of MICP-relevant Sporosarcina pasteurii DSM33 for growth improvement in chemically defined and complex media. Sci. Rep. 10 , 22448. 10.1038/s41598-020-79904-9 (2020). [ DOI ] [ PMC free article ] [ PubMed ] [ Google Scholar ] 30. Sun, Y. L. et al. Anti-disintegration property of red soil treated with building gypsum powder. Appl. Clay Sci. 273 , 107832. 10.1016/j.clay.2025.107832 (2023). [ Google Scholar ] 31. Liu, L. M. et al. Research on the disintegration performance of fibre-reinforced vegetative cement-soil (VCS). Case Stud. Constr. Mater. 22 , e04437. 10.1016/j.cscm.2025.e04437 (2025). [ Google Scholar ] 32. Thaue, W., Iwanami, M., Nakayama, K. & Chijiwa, N. MICP using calcium-rich waste solution from acetic acid treatment as a calcium source to improve the properties of recycled coarse aggregate. Constr. Build. Mater. 489 , 142333. 10.1016/j.conbuildmat.2025.142333 (2025). [ Google Scholar ] 33. Jiang, R., Wang, J. D., Xiao, T. & Zhang, D. F. Effect of sisal fibers on the disintegration characteristics of sisal fiber-amended loess. Constr. Build. Mater. 453 , 139032. 10.1016/j.conbuildmat.2024.139032 (2023). [ Google Scholar ] 34. Wang, Y., Zhu, P., Li, X. X. & Liu, C. Immobilization of Multiple Heavy Metals in Contaminated Soil Using Multi-Walled Carbon Nanotubes Enhanced MICP. Chem. Eng. J. 522 , 167716. 10.1016/j.cej.2025.167716 (2023). [ Google Scholar ] 35. Yuan, X. Q. et al. An experimental investigation of dispersive soils treated by microbially induced calcium carbonate precipitation (MICP). Constr. Build. Mater. 446 , 137941. 10.1016/j.conbuildmat.2024.137941 (2024). [ Google Scholar ] 36. Nagy, B. & Kustermann, A. Rehabilitation of Porous Building Components and Masonry by MICP Injection Method. Buildings 13 (5), 1273. 10.3390/buildings13051273 (2023). [ Google Scholar ] 37. Zhao, X. Q. et al. Disintegration characteristics and microscopic mechanism of soda residue-fly ash stabilized clay. J. Build. Eng. 107 , 112676. 10.1016/j.jobe.2025.112676 (2025). [ Google Scholar ] 38. Sun, Y., Liu, Q., Xu, H., Wang, Y. & Tang, L. Influences of different modifiers on the disintegration of improved granite residual soil under wet and dry cycles. Int. J. Min. Sci. Technol. 32 (4), 831–845. 10.1016/j.ijmst.2022.05.003 (2022). [ Google Scholar ] 39. Tu, S. et al. Effect of Watermelon Seed Urease Induced Calcium Carbonate Precipitation (WSICP) on Collapsible Loess Improvement Based on Unconfined Compression and Direct Shear Tests. Discov Sustain. 6 , 569. 10.1007/s43621-025-01448-7 (2025). [ Google Scholar ] 40. Xu, K. et al. Mechanical properties and disintegration behavior of EICP-reinforced sea sand subjected to drying-wetting cycles. Biogeotechnics 1 (2), 100019. 10.1016/j.bgtech.2023.100019 (2025). [ Google Scholar ] 41. Zúñiga-Barra, H. et al. Sustainable Biocementation of Mine Tailings: Reduction of Urea Requirements through Bicarbonate-based MICP. Environ. Technol. Innov. 39 , 104255. 10.1016/j.eti.2025.104255 (2025). [ Google Scholar ] 42. Niu, L. et al. Double enzyme enhanced microbial induction of carbonate precipitation (E-MICP) to improve mechanical properties of sandy soil and its biocementation mechanism. J Environ. Chem Eng . 13 , 115349. 10.1016/j.jece.2025.115349 (2025). [ Google Scholar ] 43. Wang, Y., Zhu, P., Li, X. X. & Liu, C. Immobilization of multiple heavy metals in contaminated soil using multi-walled carbon nanotubes enhanced MICP. Chem. Eng. J. 522 , 167716. 10.1016/j.cej.2025.167716 (2025). [ Google Scholar ] 44. Liu, M. et al. How to balance cadmium immobilization and greenhouse gas emissions when using microbial induced-calcite precipitation (MICP): Regulate the N/Ca molar ratio and dosage. J Environ. Chem Eng. 13 , 116351. 10.1016/j.jece.2025.116351 (2025). [ Google Scholar ] 45. Wang, Y. R., Zhang, T. L. & Wang, X. X. Removal mechanism of lead by the composite of clinoptilolite, biochar, and Ca(OH)₂ and its application in acid wastewater. Environ. Technol Innovation . 37 , 104024. 10.1016/j.eti.2025.104024 (2025). [ Google Scholar ] 46. Chen, H. Y. et al. Activated calcium-rich serpentine tailings and their superefficient removal for arsenite, arsenate and cadmium. Environ. Technol. Innov. 35 , 103726. 10.1016/j.eti.2024.103726 (2025). [ Google Scholar ] 47. Zhao, G. W. et al. Modifying behavior of calcined waste phosphorus slag on the dispersivity and mechanical properties of dispersive soil. Soils Found. 64 , 101524. 10.1016/j.sandf.2024.101524 (2024). [ Google Scholar ] 48. He, Z. F. et al. Synergistic mechanism and application of microbially induced carbonate precipitation (MICP) and inorganic additives for passivation of heavy metals in copper-nickel tailings. Chemosphere 311 , 136981. 10.1016/j.chemosphere.2022.136981 (2024). [ DOI ] [ PubMed ] [ Google Scholar ] 49. Gandhi, H. et al. Carbon capture and sequestration through landfill-derived Bacillus strains: Enhanced microbially induced calcite precipitation for sustainable bio-brick production. Constr. Build. Mater. 491 , 142600. 10.1016/j.conbuildmat.2025.142600 (2025). [ Google Scholar ] 50. Wang, X. J. et al. Multiple effects of microbially induced calcium precipitation on bacteria under different molar volumes of organic pollutants. J. Environ. Manage. 370 , 122591. 10.1016/j.jenvman.2024.122591 (2025). [ DOI ] [ PubMed ] [ Google Scholar ] 51. Li, Y. et al. Synergistic enhancement of cadmium immobilization and soil fertility through biochar and artificial humic acid-assisted microbial-induced calcium carbonate precipitation. J. Hazard. Mater. 476 , 135140. 10.1016/j.jhazmat.2024.135140 (2025). [ DOI ] [ PubMed ] [ Google Scholar ] 52. Yang, L. et al. The stabilizing effect and mechanism of nano-silica on bubbles in cemented paste backfill. Powder Technol. 470 , 122005. 10.1016/j.powtec.2025.122005 (2026). [ Google Scholar ] Associated Data This section collects any data citations, data availability statements, or supplementary materials included in this article. Data Availability Statement The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request. 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