Coastal soft soil chlorine salt erosion resistance-deliquescence resistance composite curing material based on industrial solid waste as well as preparation method and application of coastal soft soil chlorine salt erosion resistance-deliquescence resistance composite curing material

Abstract

The invention discloses a coastal soft soil chlorine salt erosion resistance-deliquescence resistance composite curing material based on industrial solid waste as well as a preparation method and application of the coastal soft soil chlorine salt erosion resistance-deliquescence resistance composite curing material, and belongs to the technical field of soft soil curing materials. The material comprises the following components in percentage by mass: 45%-55% of modified industrial solid waste-based gel, 12%-18% of a chlorine salt erosion resistant component, 8%-12% of a deliquescence resistant functional component, 4%-7% of a composite activator, 0.8%-1.5% of a nano modifier and the balance of an inert filler. The concrete has excellent chlorine salt erosion resistance and deliquescence resistance, and has the characteristics of low cost, environment friendliness, resource utilization of industrial solid wastes and the like, so that the engineering requirements of long-term stable reinforcement of high-salt-content and high-water-content soft soil foundations in coastal areas are met.

Description

Technical Field

[0001] This invention belongs to the field of soft soil solidification materials technology, specifically relating to a composite solidification material for coastal soft soil based on industrial solid waste that is resistant to chloride salt erosion and deliquescence, its preparation method, and its application. Background Technology

[0002] In soft soil foundation treatment projects in coastal areas, solidification is a commonly used technique to improve soil strength and engineering performance. Currently, traditional inorganic cementing materials such as cement and lime remain the mainstream choice in the field of soft soil solidification. Their mechanism of action mainly relies on the hydration reaction to generate cementing products such as CSH, thereby achieving the bonding of soil particles and filling of pores.

[0003] However, coastal soft soil is characterized by high chloride content, high water content, large porosity, and low strength, which limits the practical application of traditional solidification materials. For example, chloride ions readily react with cement hydration products, leading to structural deterioration and long-term strength reduction in the solidified body. Furthermore, solidified soil is prone to deliquescence and salt reversion in high-humidity and high-salt environments, affecting the long-term stability of engineering structures. While existing solidification systems based on industrial solid waste have made some progress in resource utilization, they lack a systematic and coordinated design for chloride erosion and deliquescence resistance, making it difficult to balance both aspects and meet the long-term service requirements of coastal soft soil under special working conditions.

[0004] In summary, to address the urgent needs in the field of coastal soft soil solidification, developing composite solidification materials that combine excellent resistance to chloride salt erosion, deliquescence resistance, low cost, and environmental friendliness is a crucial issue that urgently needs to be resolved. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a composite solidification material for coastal soft soil based on industrial solid waste that resists chloride salt erosion and deliquescence, as well as its preparation method and application. This provides a composite solidification material suitable for coastal soft soil, which combines excellent resistance to chloride salt erosion and deliquescence, while also being low-cost, environmentally friendly, and utilizing industrial solid waste resources. This will meet the engineering needs for long-term stable reinforcement of soft soil foundations with high salinity and high moisture content in coastal areas.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a composite curing material for coastal soft soil based on industrial solid waste, which is resistant to chloride salt erosion and deliquescence. By mass percentage, it comprises 45%~55% modified industrial solid waste-based gel, 12%~18% chloride salt erosion resistant component, 8%~12% deliquescence resistant functional component, 4%~7% composite activator, 0.8%~1.5% nano-modifier, and the remaining mass percentage is inert filler.

[0007] In one embodiment, the nano-modifier is selected from nano-silicon nitride with a particle size range of 5~10nm and a purity of ≥99.5%; the inert filler is selected from quartz sand powder with a particle size controlled at 100~200μm, wherein the SiO2 content is ≥98% and the moisture content is ≤0.5%.

[0008] In one embodiment, the modified industrial solid waste-based gel is composed of pretreated blast furnace slag, fly ash, and recycled construction waste concrete powder, with a mass ratio of 3:2:1; the chloride-resistant component is composed of hydroxyapatite, hydrated calcium silicate whiskers, and modified zirconium oxide, with a mass ratio of 5:3:2; the deliquescence-resistant functional component is composed of calcium stearate, nano-silica, and activated metakaolin, with a mass ratio of 4:3:3; and the composite activator is composed of water glass, sodium hydroxide, and potassium carbonate, with a mass ratio of 6:3:1.

[0009] In one embodiment, the preparation process of the modified industrial solid waste-based gel is as follows: Blast furnace slag raw material was calcined and activated at 850℃ for 2.5h to obtain pretreated blast furnace slag; carbon particles in fly ash were removed by air separation, and then screened and dried to obtain fly ash with a carbon content ≤3%; construction waste concrete was crushed, and then 0.3% of triethanolamine (by mass of recycled construction waste concrete powder) was added as a grinding aid for grinding, followed by screening and drying to obtain recycled construction waste concrete powder; the pretreated blast furnace slag, fly ash and recycled construction waste concrete powder were mixed evenly, and steam at 95℃ and 98% humidity was introduced for curing for 8 hours with intermittent stirring during curing to obtain modified industrial solid waste-based gel.

[0010] In one embodiment, the preparation process of the chloride-resistant component is as follows: Zirconia is surface-modified using silane coupling agent KH-560 as a modifier, wherein the amount of modifier is 3.5% of the mass of zirconia, and modified zirconia is obtained after drying; hydroxyapatite with a particle size in the range of 15~25μm and calcium silicate hydrate whiskers with an aspect ratio of 20~30 are mixed with the modified zirconia to obtain the chloride-resistant component.

[0011] In one embodiment, the preparation process of the anti-hygroscopic functional component is as follows: Metakaolin is calcined at 700°C for 3 hours for activation treatment, and then cooled to obtain activated metakaolin; calcium stearate with a purity ≥98% and a particle size of 20~40nm and a specific surface area ≥200m² are selected. 2A mixture of / g nano-silica and activated metakaolin was used to prepare an anti-deliquescence functional component.

[0012] In one embodiment, the preparation process of the composite activator is as follows: water glass, sodium hydroxide and potassium carbonate are mixed, and then deionized water accounting for 20% of the total mass of the composite activator is added to dissolve them, thereby obtaining the composite activator.

[0013] This invention also provides a method for preparing the aforementioned composite solidification material for coastal soft soil based on industrial solid waste, which is resistant to chloride salt erosion and deliquescence, comprising the following steps: Modified industrial solid waste-based gel, chloride-resistant premix, deliquescence-resistant premix, and inert filler are initially mixed until homogeneous. Then, a composite activator is continuously added, and the mixing speed is increased to carry out the hydration reaction. Nano-modifiers are then added in batches at intervals to obtain a preliminary composite curing material. Finally, the material is dried and sieved to obtain a chloride-resistant and deliquescence-resistant composite curing material for coastal soft soil based on industrial solid waste.

[0014] In one embodiment, the process of adding the nano-modifier in batches at intervals is as follows: the nano-modifier is added in three equal parts, with an interval of 5 minutes between each addition, and the stirring speed is maintained at 500 rpm during the addition process; after all the nano-modifier is added, stirring is continued for 15 minutes.

[0015] This invention also provides an application of a composite solidification material for coastal soft soil based on industrial solid waste, which is resistant to chloride salt erosion and deliquescence, in the foundation treatment of coastal areas.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a composite solidification material for coastal soft soil based on industrial solid waste, designed to resist chloride erosion and deliquescence. By constructing a multi-level synergistic system of "modified industrial solid waste-based gel – chloride erosion-resistant components – deliquescence-resistant functional components – composite activator – nano-modifier," it achieves, for the first time, a systematic inhibition of the dual degradation mechanism of chloride erosion and deliquescence-induced salt return in coastal soft soil. The solidification effect of the composite solidification material on the coastal soft soil is mainly achieved through physicochemical reactions: 1) Gelation: Under the action of the composite activator, the modified industrial solid waste-based gel undergoes a hydration reaction to generate a large amount of CSH gel and CAH gel, filling the pores of the soft soil, cementing soil particles, and forming a dense solidified structure. 2) Chloride erosion resistance: Hydroxyapatite reacts chemically with chloride to generate stable chloroapatite. Hydrated calcium silicate whiskers and zirconium oxide form a physical barrier, blocking chloride ion diffusion and inhibiting chloride erosion of the solidified body. 3) Anti-deliquescence effect: Calcium stearate forms a hydrophobic film on the surface of the solidified body. Nano-silica and metakaolin optimize the microstructure of the solidified body, reduce porosity, reduce water intrusion, and prevent the solidified body from deliquescence and salt return. 4) Nano-modification effect: Nano-silicon nitride fills the micropores of the solidified body, improves the density and mechanical properties of the solidified body, and enhances its impermeability and durability.

[0017] This technical solution not only breaks through the performance bottleneck of traditional solidification materials in high-salt coastal environments, but also uses all industrial solid waste and conventional chemical raw materials, which greatly reduces raw material costs and carbon emissions, in line with the development trend of green and low-carbon construction. Its preparation process is adapted to industrial continuous production, with strong parameter controllability and stable product quality. The construction method is compatible with conventional roadbed treatment processes, requires no special equipment, and is easy to promote and apply on a large scale.

[0018] The data from the examples show that the prepared solidified body has an unconfined compressive strength of ≥4.5 MPa after 28 days, a chloride salt erosion resistance coefficient of ≥0.85, and a deliquescence resistance of ≤3.5%, fully meeting the strength, durability, and stability requirements for long-term service of foundations in coastal areas. Detailed Implementation

[0019] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0020] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0021] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0022] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0023] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0024] This invention provides a chloride-salt erosion- and deliquescence-resistant composite solidification material for coastal soft soil based on industrial solid waste, its preparation method, and its application. It belongs to the field of soft soil solidification material technology, specifically involving a chloride-salt erosion- and deliquescence-resistant composite solidification material suitable for coastal soft soil, its preparation and application method, and is particularly suitable for the reinforcement treatment of soft soil foundations with high salinity and high moisture content in coastal areas. It can be widely used in the foundation treatment field of coastal roads, port terminals, land reclamation and other projects.

[0025] The curing principle of the above-mentioned composite curing material for coastal soft soil based on industrial solid waste, which is resistant to chloride salt erosion and deliquescence, is as follows: On the one hand, a composite solidification material for coastal soft soil based on industrial solid waste, resistant to chloride salt erosion and deliquescence, is provided, with the following specific composition: The chloride-resistant and deliquescence-resistant composite curing material of the present invention is composed of modified industrial solid waste-based gel, chloride-resistant component, deliquescence-resistant functional component, composite activator, nano-modifier and inert filler by mass percentage, with each component accounting for 45%~55%, 12%~18%, 8%~12%, 4%~7%, and 0.8%~1.5% by mass, respectively, and the remaining mass percentage is inert filler.

[0026] The modified industrial solid waste-based gel uses S95 grade blast furnace slag from steel plants, Class I fly ash from power plants, and recycled powder from crushed and ground construction waste concrete as raw materials. The mass ratio of the three raw materials is strictly controlled at 3:2:1.

[0027] Among them, blast furnace slag needs to undergo calcination activation treatment at a specific temperature and time. The calcination temperature is set at 850℃ and the holding time is 2.5 hours to improve its cementitious activity. Fly ash needs to be separated by airflow separation to remove carbon particles. After separation, the carbon content needs to be controlled within 3% to ensure the sufficiency of subsequent hydration reaction. Recycled construction waste concrete powder needs to be crushed to a particle size of less than 20mm by a jaw crusher and then sent to a ball mill for grinding. During the grinding process, 0.3% of triethanolamine by weight of recycled powder needs to be added as a grinding aid. After grinding, it is sieved through an 80μm square hole sieve. The residue needs to be ≤5%. Then, the sieved recycled powder is placed in a 105℃ drying equipment for 3 hours to reduce the moisture content to below 0.8%. Finally, the three pretreated raw materials are mixed evenly and steam at 95℃ and 98% humidity is introduced for curing for 8 hours. During the curing process, it needs to be stirred for 5 minutes every hour at a stirring speed of 100rpm to ensure that the raw materials react fully to form a stable cementitious structure.

[0028] The chloride-resistant component consists of hydroxyapatite, hydrated calcium silicate whiskers, and modified zirconium oxide in a mass ratio of 5:3:2.

[0029] Hydroxyapatite powder with a particle size of 15-25 μm and a purity of ≥98% is selected to ensure its reactivity with chloride salts. The aspect ratio of hydrated calcium silicate whiskers is controlled at 20-30. Within this range, the aspect ratio can better form a framework structure in the solidified body, improving crack resistance. Zirconia needs to undergo surface modification treatment. The modifier is silane coupling agent KH-560, and the amount of modifier is 3.5% of the mass of zirconia. The modification process is carried out in a stirred modifier at 60℃ with a stirring speed of 300 rpm for 2 hours. After modification, the zirconia is placed in an 80℃ drying equipment for 1.5 hours to remove excess moisture and enhance its compatibility with other components.

[0030] The anti-deliquescence functional components include calcium stearate, nano-silica, and activated metakaolin in a mass ratio of 4:3:3.

[0031] Calcium stearate must have a purity of ≥98%, and its hydrophobic properties allow it to form a protective film on the surface of the cured body, reducing moisture intrusion; the particle size of nano-silica should be controlled between 20 and 40 nm, with a specific surface area ≥200 m². 2 / g, the fine particle size can fill the micropores of the solidified body and improve the density; metakaolin needs to be activated by calcination at 700℃ for 3 hours, with a calcination heating rate of 12℃ / min, and then rapidly cooled to room temperature after calcination to activate its potential activity and enhance its synergistic effect with other components.

[0032] The composite activator is composed of water glass, sodium hydroxide and potassium carbonate in a mass ratio of 6:3:1.

[0033] The water glass used is an industrial-grade product with a modulus of 2.8 to ensure sufficient alkaline activation ability; the purity of sodium hydroxide is ≥96% and the purity of potassium carbonate is ≥98%, both of which must be in powder form without clumping to ensure uniform dissolution in water.

[0034] The nano-modifier uses nano-silicon nitride with a particle size range of 5~10nm and a purity of ≥99.5%. This particle size range can effectively fill the micropores of the cured body and improve the mechanical properties and impermeability of the cured body.

[0035] The inert filler is made of quartz sand powder with a particle size controlled between 100 and 200 μm, containing ≥98% SiO2 and ≤0.5% moisture. Using this filler can reduce the cost of curing materials and adjust the volume stability of the cured body to avoid shrinkage and cracking.

[0036] On the other hand, a method for preparing a composite solidification material for coastal soft soil based on industrial solid waste that is resistant to chloride salt erosion and deliquescence is provided.

[0037] The composite curing material is produced using a continuous industrial production process. The entire production process is divided into four parts: raw material pretreatment unit, mixing and stirring unit, composite molding unit, and post-treatment unit. The operation details of each unit are as follows: (a) Raw material pretreatment unit First, the lumpy blast furnace slag is fed into a jaw crusher for preliminary crushing. The slag particle size after crushing should be ≤50mm. Then, the slag after preliminary crushing is fed into an impact crusher for secondary crushing. The slag particle size after secondary crushing should be ≤10mm. After crushing, the slag is fed into a rotary kiln for calcination and activation. The rotary kiln heating rate is set to 15℃ / minute. When the temperature reaches 850℃, it is maintained at this temperature for 2.5 hours. During the calcination process, the temperature inside the kiln needs to be monitored in real time to ensure that the temperature fluctuation does not exceed ±5℃. After calcination, the slag is naturally cooled to room temperature. During the cooling process, it should be protected from rain or moisture. After cooling, it is sent to a sealed silo for later use.

[0038] Fly ash is fed into an air classifier, and the airflow speed is adjusted to 12 m / s. At this airflow speed, carbon particles and large particulate impurities in the fly ash will be separated due to density differences. After sorting, qualified fly ash is collected and its carbon content is tested to ensure that the carbon content is ≤3%. At the same time, the particle size is tested by sieving to ensure that the particle size is ≤80μm. Qualified fly ash is sent to a drying equipment and dried at 80℃ for 2 hours to make the moisture content ≤0.5%. After drying, it is sent to a special silo for later use.

[0039] Construction waste concrete blocks are fed into a jaw crusher and crushed to a particle size ≤20mm. During the crushing process, steel bars are removed using magnetic separation equipment, and impurities such as wood and plastic are manually removed. The impurity-removed concrete blocks are then fed into a ball mill, with 0.3% of triethanolamine by weight of the concrete blocks added as a grinding aid. The ball mill is set to a grinding speed of 400 rpm for 4 hours. After grinding, the material is fed into an 80μm vibrating screen for sieving. The material that passes through the screen is returned to the ball mill for regrinding, while the material that passes through the screen is sent to a dryer and dried at 105℃ for 3 hours. During the drying process, the material is turned over every 30 minutes to ensure uniform drying. The moisture content of the dried material must be ≤0.8%, and then it is sent to a silo for later use.

[0040] Zirconia powder was placed in a stirred modifier, and a measured amount of silane coupling agent KH-560 (3.5% of the zirconia mass) was added. The feed inlet of the modifier was closed, the equipment was started, the temperature was adjusted to 60℃, the stirring speed was 300 rpm, and the modification process lasted for 2 hours. During this period, samples were taken every 30 minutes to observe the dispersion of the zirconia powder to avoid agglomeration. After the modification was completed, the zirconia powder was sent to an 80℃ dryer to dry for 1.5 hours. After drying, it was placed in a sealed bag for later use.

[0041] Natural kaolin is fed into a rotary kiln, and the heating rate is set to 12℃ / minute. When the temperature inside the kiln reaches 700℃, it is maintained at this temperature for calcination for 3 hours. During the calcination process, the ventilation inside the kiln needs to be controlled to ensure that the kaolin is fully activated. After calcination, the meta-kaolin is quickly removed and placed in a cooling tank to cool to room temperature. During the cooling process, the meta-kaolin should be prevented from absorbing moisture from the air. After cooling, it is sent to a sealed silo for later use.

[0042] (ii) Mixing and stirring unit Weigh out the pretreated blast furnace slag, fly ash, and recycled construction waste concrete powder in a mass ratio of 3:2:1. Feed the three raw materials into the twin-shaft paddle mixer simultaneously, close the mixer feed door, start the equipment, set the mixing speed to 250 rpm, and the mixing time to 30 minutes. During the mixing process, open the observation window every 10 minutes to check the mixing of materials and ensure that there is no obvious stratification. After the mixing is completed, send the mixed base material into the intermediate silo. The intermediate silo must be kept sealed to prevent the material from getting damp.

[0043] The mixed substrate in the intermediate silo is sent into the steam curing kettle. The kettle door is closed, saturated steam is introduced, and the temperature and humidity inside the kettle are adjusted to 95°C and 98%, respectively. The curing time is set to 8 hours. During the curing process, the stirring device is started every hour at a speed of 100 rpm for 5 minutes to ensure that the material is heated evenly and reacts fully. After the curing is completed, the exhaust valve of the kettle is opened to slowly release the steam. After the pressure inside the kettle drops to atmospheric pressure, the kettle door is opened, and the modified industrial solid waste-based gel is taken out and allowed to cool naturally to room temperature before being sent to the next process.

[0044] Weigh hydroxyapatite, hydrated calcium silicate whiskers, and modified zirconium oxide in a mass ratio of 5:3:2. Feed the three raw materials into a high-speed mixer, set the stirring speed to 800 rpm, and the stirring time to 20 minutes. During the stirring process, the material temperature needs to be monitored to ensure that the temperature does not exceed 60℃ (if the temperature is too high, it needs to be cooled by the jacket). After the stirring is completed, take a sample to test the mixing uniformity to ensure that there are no local lumps. After passing the test, the chloride salt corrosion resistant premix is ​​obtained and sent to a special silo for later use.

[0045] Weigh calcium stearate, nano silica, and activated metakaolin in a mass ratio of 4:3:3. Feed the three raw materials into a high-speed mixer, set the stirring speed to 900 rpm, and the stirring time to 15 minutes. During the stirring process, observe the dispersion state of the materials to avoid agglomeration of nano silica. After the stirring is completed, the anti-hygroscopic premix is ​​obtained and sent to the silo for later use.

[0046] Weigh water glass, sodium hydroxide, and potassium carbonate in a mass ratio of 6:3:1. Add the three raw materials to a stirred dissolving machine, add deionized water (20% of the total mass of the composite activator), start the dissolving machine, set the temperature to 50℃ and the stirring speed to 400 rpm, and stir for 30 minutes. During the dissolving process, continuous stirring is required to ensure that the sodium hydroxide and potassium carbonate are completely dissolved and that no solid particles remain. After dissolution, the composite activator solution is obtained and sent to an insulated storage tank (maintained at 50℃) for later use to prevent crystallization.

[0047] (III) Composite Molding Unit According to the production plan, the modified industrial solid waste-based gel, chloride-resistant premix, deliquescence-resistant premix, and inert filler are weighed by mass percentage and fed into the planetary mixer simultaneously. The feed inlet is closed, the stirring speed is set to 350 rpm, and the stirring time is 40 minutes. During the stirring process, the mixing status of the materials needs to be checked every 10 minutes to ensure that each component is evenly distributed. After the stirring is completed, a sample is taken to test the uniformity of the basic mixture. If it passes the test, it proceeds to the next stage.

[0048] Slowly add the composite activator solution to the planetary mixer over a period of 10 minutes to prevent local concentration of the activator solution. After the activator solution is added, increase the stirring speed to 500 rpm and stir for 25 minutes. During this time, adjust the material temperature through the mixer jacket to keep it between 45 and 55°C (heat through the jacket if the temperature is too low, and cool through the jacket if the temperature is too high) to ensure that the hydration reaction proceeds fully.

[0049] Nano-modifier addition and mixing: Finally, add nano-silicon nitride to the mixer. The nano-silicon nitride needs to be added in three parts, with an interval of 5 minutes between each addition. Each addition is 1 / 3 of the total amount. During the addition process, maintain a stirring speed of 500 rpm. After all the nano-silicon nitride has been added, continue stirring for 15 minutes. After stirring, the initial product of the composite curing material is obtained. Take a sample to test the uniformity and moisture content of the initial product (the moisture content must be ≤1.5%). After passing the test, it is sent to the post-processing unit.

[0050] (iv) Post-processing unit The initial product of the composite curing material is fed into a drum dryer. The drying temperature is set to 85℃ and the drying time is 4 hours. During the drying process, the drum speed needs to be controlled at 10 rpm to ensure that the material is heated evenly and dried thoroughly inside the drum. During the drying process, samples are taken every hour to test the moisture content of the material. When the moisture content drops below 1.0%, the drying is stopped.

[0051] The dried material is fed into a 45μm vibrating screen for sieving. During the sieving process, the feeding speed is controlled at 50kg / min to avoid screen blockage. The material on the screen is collected and returned to the ball mill for re-grinding. After grinding, it is sieved again until all of it passes through the 45μm screen. The material under the screen is a qualified composite curing material semi-finished product.

[0052] The qualified composite curing material semi-finished product is sent to the finished product warehouse and quantitatively packaged by an automatic packaging machine. The packaging specification is 25kg per bag. During the packaging process, it is necessary to ensure that the packaging bag is sealed and intact to prevent the material from getting damp. After packaging, the product name, production date, shelf life, batch number and other information are marked on the packaging bag. Then it is sent to the finished product warehouse for storage. The warehouse must be kept dry and ventilated, with the temperature controlled at 5~30℃ and the relative humidity ≤60%. During the storage process, it is necessary to check regularly whether the material is damp or clumped.

[0053] Another aspect is the application of a composite curing material for coastal soft soil based on industrial solid waste, which is resistant to chloride salt erosion and deliquescence. The specific method of using the composite curing material is as follows.

[0054] The specific steps for using composite solidification materials to solidify coastal soft soil are as follows: Step 1, Pretreatment of coastal soft soil: On-site collection of soft coastal soil, removal of stones, weeds, plastic and other impurities, and feeding into a soil crusher to break down to a particle size ≤20mm.

[0055] The broken soft soil is sent to the drying yard and mechanically dried to reduce its moisture content. The drying frequency is once every 2 hours, and the drying time is adjusted according to the initial moisture content, so that the moisture content of the soft soil is reduced to the optimum moisture content ±2% (the optimum moisture content is determined by compaction test, which is generally 28%~35%).

[0056] For excessively high chloride content (Cl - For soft soil with a content > 0.8%, add 3% to 5% of desulfurized gypsum by weight of the soft soil during the sun-drying process, stir evenly, let stand for 12 hours, and carry out pre-desalination treatment.

[0057] Step 2, Ingredient Preparation and Mixing: Weigh out 18% to 25% of the dry weight of the soft soil composite curing material (adjust the amount according to the initial strength of the soft soil and design requirements), and weigh out 12% to 15% of the weight of the composite curing material deionized water. Mix the water with the composite curing material and stir evenly to make a paste-like curing slurry.

[0058] The pretreated soft soil is fed into a forced mixer. The mixer is started (180 rpm), and the solidification slurry is slowly added while mixing. The mixing time is 15 minutes to ensure that the soft soil and the solidification slurry are mixed evenly to form a solidified soil mixture.

[0059] Step 3, spreading and compaction: The solidified soil mixture is transported to the construction site and spread in layers using a paver. Each layer is 250-300mm thick, and segregation should be avoided during the paving process.

[0060] After paving is completed, a vibratory roller is used for compaction. The compaction sequence is from light to heavy and from slow to fast. The initial rolling speed is 1.5 km / h, which is then increased to 2.5 km / h. The number of rolling passes is 6 to 8, until the compaction degree is ≥96% (tested according to the "Specifications for Testing Geotechnical Engineering of Highways" JTG 3430-2020).

[0061] Step 4, Maintenance: After compaction, cover the solidified soil surface with a moisture-retaining geotextile, and then cover it with a plastic film for curing. Keep the geotextile moist during the curing period.

[0062] The curing temperature should be controlled between 15 and 35℃, and the curing time should be no less than 28 days. During the curing period, vehicles are prohibited from passing through and heavy objects are prohibited from being piled up.

[0063] After curing for 7, 14, and 28 days, unconfined compressive strength, chloride erosion resistance coefficient, and deliquescence resistance were tested to ensure that the design requirements were met.

[0064] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0065] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0066] Example 1 This embodiment provides a composite curing material for coastal soft soil based on industrial solid waste that is resistant to chloride salt erosion and deliquescence. By mass percentage, it includes 45% modified industrial solid waste-based gel, 18% chloride salt erosion resistant component, 12% deliquescence resistant functional component, 7% composite activator, 1.5% nano-modifier, and 16.5% inert filler.

[0067] Experimental results: 28-day unconfined compressive strength 4.8 MPa, chloride erosion resistance coefficient 0.88, deliquescence resistance 3.2%. Example 2 This embodiment provides a composite curing material for coastal soft soil based on industrial solid waste that is resistant to chloride salt erosion and deliquescence. By mass percentage, it includes 50% modified industrial solid waste-based gel, 15% chloride salt erosion resistant component, 10% deliquescence resistant functional component, 5.5% composite activator, 1.2% nano-modifier, and 18.3% inert filler.

[0068] Experimental results: 28-day unconfined compressive strength 5.2 MPa, chloride erosion resistance coefficient 0.91, deliquescence resistance 2.8%. Example 3 This embodiment provides a composite curing material for coastal soft soil based on industrial solid waste that is resistant to chloride salt erosion and deliquescence. By mass percentage, it includes modified industrial solid waste-based gel: 53%, chloride salt erosion resistant component: 13%, deliquescence resistant functional component: 9%, composite activator: 4.5%, nano modifier: 1.0%, and inert filler: 19.0%.

[0069] Experimental results: 28-day unconfined compressive strength 5.0 MPa, chloride erosion resistance coefficient 0.89, deliquescence resistance 3.0%. Example 4 This embodiment provides a composite curing material for coastal soft soil based on industrial solid waste that is resistant to chloride salt erosion and deliquescence. By mass percentage, it includes 55% modified industrial solid waste-based gel, 12% chloride salt erosion resistant component, 8% deliquescence resistant functional component, 4% composite activator, 0.8% nano-modifier, and 20.2% inert filler.

[0070] Experimental results: 28-day unconfined compressive strength 4.6 MPa, chloride erosion resistance coefficient 0.86, deliquescence resistance 3.4%. Experimental results show that the 28-day unconfined compressive strength of the solidified bodies in all embodiments is ≥4.5MPa, the chloride erosion resistance coefficient is ≥0.85, and the deliquescence resistance rate is ≤3.5%, fully meeting the long-term stability requirements for foundation reinforcement in coastal engineering construction. Under different formulation proportions, each performance indicator shows stable and excellent performance. Among them, the formulation combination of Example 2 (50% modified industrial solid waste-based gel, 15% chloride erosion resistant component, 10% deliquescence resistant functional component, 5.5% composite activator, 1.2% nano-modifier, and 18.3% inert filler) has the best overall performance, indicating that the formulation design of this invention has good flexibility and reliability. Through the synergistic effect of multiple components, it can effectively solve the solidification problem caused by high salt and high water content in coastal soft soil, while realizing the resource utilization of industrial solid waste, combining technological advancement and engineering practicality.

[0071] In summary, the composite curing material of this invention addresses the characteristics of coastal soft soil with high salt and high moisture content by simultaneously improving its resistance to chloride erosion and deliquescence through multi-component synergistic design. Utilizing industrial solid waste as the main raw material reduces material costs and achieves resource utilization of solid waste. The preparation process employs continuous industrial production, resulting in high production efficiency and stable product quality. The method of use is simple and easy to implement, construction is convenient, and the curing effect is significant. After curing, the unconfined compressive strength of the soft soil after 28 days is ≥4.5 MPa, the chloride erosion resistance coefficient is ≥0.85, and the deliquescence resistance rate is ≤3.5%, meeting the long-term stability requirements of engineering construction in coastal areas.

[0072] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A composite solidification material for coastal soft soil based on industrial solid waste, characterized in that, By mass percentage, it includes 45%~55% modified industrial solid waste-based gel, 12%~18% chloride salt erosion resistant components, 8%~12% deliquescence resistant functional components, 4%~7% composite activator, 0.8%~1.5% nano-modifier, and the remaining mass percentage is inert filler.

2. The composite solidification material for coastal soft soil based on industrial solid waste, resistant to chloride salt erosion and deliquescence, as described in claim 1, is characterized in that... The nano-modifier is selected from nano-silicon nitride with a particle size range of 5~10nm and a purity of ≥99.5%; the inert filler is selected from quartz sand powder with a particle size controlled at 100~200μm, wherein the SiO2 content is ≥98% and the moisture content is ≤0.5%.

3. The composite solidification material for coastal soft soil based on industrial solid waste, resistant to chloride salt erosion and deliquescence, as described in claim 1, is characterized in that... The modified industrial solid waste-based gel is composed of pretreated blast furnace slag, fly ash, and recycled construction waste concrete powder, with a mass ratio of 3:2:

1. The chloride-resistant component is composed of hydroxyapatite, hydrated calcium silicate whiskers, and modified zirconium oxide, with a mass ratio of 5:3:

2. The deliquescence-resistant functional component is composed of calcium stearate, nano-silica, and activated metakaolin, with a mass ratio of 4:3:

3. The composite activator is composed of water glass, sodium hydroxide, and potassium carbonate, with a mass ratio of 6:3:

1.

4. The composite solidification material for coastal soft soil based on industrial solid waste, resistant to chloride salt erosion and deliquescence, as described in claim 3, is characterized in that... The preparation process of the modified industrial solid waste-based gel is as follows: The blast furnace slag raw material was calcined and activated at 850℃ for 2.5h to obtain pretreated blast furnace slag; carbon particles in fly ash were removed by air separation, and then screened and dried to obtain fly ash with carbon content ≤3%; Construction waste concrete is crushed, and then 0.3% of triethanolamine (by weight of recycled construction waste concrete powder) is added as a grinding aid for grinding. After grinding, it is sieved and dried to obtain recycled construction waste concrete powder. Pretreated blast furnace slag, fly ash and recycled construction waste concrete powder are mixed evenly and steam at 95°C and 98% humidity is introduced for curing for 8 hours. During the curing process, the mixture is stirred intermittently to obtain modified industrial solid waste-based gel.

5. The composite solidification material for coastal soft soil based on industrial solid waste, resistant to chloride salt erosion and deliquescence, as described in claim 3, is characterized in that... The preparation process of the anti-chloride salt corrosion component is as follows: Zirconia is surface modified with silane coupling agent KH-560 as a modifier, wherein the amount of modifier is 3.5% of the mass of zirconia, and modified zirconia is obtained after drying; hydroxyapatite with a particle size in the range of 15~25μm and calcium silicate hydrate whiskers with an aspect ratio of 20~30 are mixed with modified zirconia to obtain the anti-chloride salt corrosion component.

6. The composite solidification material for coastal soft soil based on industrial solid waste, resistant to chloride salt erosion and deliquescence, as described in claim 3, is characterized in that... The preparation process of the anti-hygroscopic functional component is as follows: Activated metakaolin was prepared by calcining at 700℃ for 3 hours and then cooling. Calcium stearate with a purity ≥98% and a particle size of 20~40nm with a specific surface area ≥200m² were selected. 2 A mixture of / g nano-silica and activated metakaolin was used to prepare an anti-deliquescence functional component.

7. The composite solidification material for coastal soft soil based on industrial solid waste, resistant to chloride salt erosion and deliquescence, as described in claim 3, is characterized in that... The preparation process of the composite activator is as follows: Water glass, sodium hydroxide, and potassium carbonate are mixed, and then deionized water, accounting for 20% of the total mass of the composite activator, is added to dissolve them to obtain the composite activator.

8. A method for preparing a chloride-resistant and deliquescence-resistant composite solidification material for coastal soft soil based on industrial solid waste, as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Modified industrial solid waste-based gel, chloride-resistant premix, deliquescence-resistant premix, and inert filler are initially mixed until homogeneous. Then, a composite activator is continuously added, and the mixing speed is increased to carry out the hydration reaction. Nano-modifiers are then added in batches at intervals to obtain a preliminary composite curing material. Finally, the material is dried and sieved to obtain a chloride-resistant and deliquescence-resistant composite curing material for coastal soft soil based on industrial solid waste.

9. The preparation method of the anti-chloride salt erosion-anti-deliquescence composite solidification material for coastal soft soil based on industrial solid waste according to claim 8, characterized in that, The process of adding the nano-modifier in batches at intervals is as follows: the nano-modifier is added in three equal parts, with an interval of 5 minutes between each addition, and the stirring speed is maintained at 500 rpm during the addition process; after all the nano-modifier is added, stirring is continued for 15 minutes.

10. The application of a composite solidification material for coastal soft soil based on industrial solid waste, as described in any one of claims 1 to 7, in foundation treatment in coastal areas.