A composite soil stabilizer for water-rich, low-temperature conditions

Abstract

This invention discloses a composite soil stabilizer for water-rich, low-temperature conditions, belonging to the technical field of soil stabilizer technology. The composite soil stabilizer provided by this invention comprises the following raw materials in parts by weight: 70-110 parts of main cementitious material, 10-20 parts of auxiliary cementitious material, 3-6 parts of low-temperature early-strength agent, 0.1-0.5 parts of high-efficiency early-strength agent, 5-10 parts of water-absorbing modifier, 3-8 parts of filler, and 1-2 parts of activator. Through the synergistic effect of its components, the composite soil stabilizer provided by this invention effectively solves the problem of solidifying water-rich, low-temperature soils without relying on preheating of raw materials or significant exothermic reactions of the system itself. It achieves rapid early strength, high final strength, and excellent water stability in low-temperature environments (around 0°C).

Description

Technical Field

[0001] This invention belongs to the field of soil stabilizer technology, and particularly relates to a composite soil stabilizer for water-rich and low-temperature conditions. Background Technology

[0002] In the field of geotechnical engineering and foundation treatment, the solidification of water-rich soils (such as silt, soft clay, and gravelly sand) has always been a challenge. These soils have a high natural water content, and are even in a fluid plastic state. When mixed with conventional cement-based solidifiers, the excessive free water will severely dilute the effective concentration of the solidifier, delay and weaken the hydration reaction process of the cement, resulting in extremely slow early strength development of the mixture, making it difficult to form an effective skeleton structure, and thus failing to meet the construction schedule requirements.

[0003] Furthermore, the influence of ambient temperature, especially low temperatures, complicates and exacerbates this problem. When the ambient temperature approaches 0°C, the hydration reaction rate of conventional cement-based hardeners drops sharply. Although the water does not freeze at this temperature, its molecular activity decreases, significantly inhibiting the chemical reaction process between cement minerals and water, leading to near-stagnation in strength development. Simultaneously, near this critical temperature, the already formed weakly solidified structure not only has extremely low strength but is also highly susceptible to water penetration, erosion, and softening when exposed to a water-rich environment for extended periods, causing damage to the microstructure and posing potential engineering safety hazards.

[0004] Existing technologies often have limitations in solving the above problems. For example, Chinese patent CN103013526A discloses a soil stabilizer and a soil stabilization method. This soil stabilizer contains 15-30% fly ash, 4-15% lime, 10-20% water glass, 8-20% caustic soda, 5-16% gypsum, 10-32% ordinary silicate cement, 0.5-3.5% fluorite, and 0-1.5% sodium sulfate. This soil stabilizer is not specifically designed for low temperatures. Ordinary silicate cement hydrates slowly near 0°C and has generally poor water stability, especially after wet-dry cycles, resulting in significant strength loss, making it difficult to meet the requirements for rapid construction. Chinese patent CN119662273A discloses a composite soil stabilizer for resisting wet-dry cycles and its preparation method. The stabilizer comprises the following raw materials: 5-10 parts by weight of polyacrylamide, 20-30 parts by weight of cyclodextrin star derivative, 5-10 parts by weight of polyvinyl alcohol, 5-8 parts by weight of inorganic salt, 5-8 parts by weight of sodium silicate, 10-15 parts by weight of waterborne epoxy resin emulsion, 1-3 parts by weight of polyoxypropylene triamine, and water. The amount of water used makes the solid content of the composite soil stabilizer for resisting wet-dry cycles 25-60 wt%. The cyclodextrin star derivative is prepared by esterification reaction of carboxymethyl-β-cyclodextrin and polyethylene glycol monomethyl ether at a carboxyl to hydroxyl molar ratio of 1:1.1-1.2 under the action of an alkaline catalyst. The polyethylene glycol monomethyl ether has a weight-average molecular weight of 1000-1500 g / mol. The multiple grafted chains of the cyclodextrin star derivative disperse the expansion and contraction stress of the soil during wet-dry cycles in different directions, avoiding stress concentration that damages the molecular structure. However, this curing agent generally has poor water stability, especially showing significant strength loss after wet-dry cycles. Chinese patent CN102676176A discloses a composite ionic soil curing agent and its manufacturing method. Four components—a strong oxidant, an activator, a dispersant, and a curing catalyst—are reacted and aged in a reactor at a mass percentage of 3% each for activator components ① and ②, with the temperature controlled between 30 and 32°C. Then, a dispersant is added and stirred until homogeneous. After reacting for 60 minutes, concentrated H₂SO₄ is finally added, and the reaction temperature is controlled below 60°C, thus forming the composite ionic soil curing agent. In application, its dosage is 0.01-0.1% of the volume of the cured structure after compaction. After dilution with water, it is evenly sprayed onto soil mixed with other inorganic binders and mixed thoroughly. It is then compacted and cured for a certain period to achieve a stable and long-lasting soil curing effect. However, this requires a specific preparation process or strictly controlled conditions. Chinese patent CN117049818A discloses a soil stabilizer for roadbeds in cold regions, comprising 2-2.5% lignin, 14-16% lime powder, 20-23% gravel, 1-2% sulfonate, 5-10% silica fume, 30-35% polyurethane adhesive, 10-15% epoxy resin, and 6-8% diethylenetriamine. However, this patent uses a large amount of organic polymers (such as polyurethane and epoxy resin), resulting in high costs, and the excessive addition of organic matter may affect mixing and compaction.Chinese patent CN109485368A discloses a high-moisture-content soft soil solidifier and its application. The solidifier comprises an expansive component and a cementitious component. The expansive component includes sulfoaluminate cement clinker, gypsum, and lime, while the cementitious component is ordinary silicate cement. The mass ratio of the expansive component to the cementitious component is 0~100:100~0, and the mass ratio of sulfoaluminate cement clinker, gypsum, and lime in the expansive component is 40~60:32~48:8~12. This solidifier can be used to solidify high-moisture-content silty soil, sandy soil, or silty soil with a moisture content of 50~150%. The construction process for soft soil solidification employs deep mixing piles and high-pressure jet grouting piles using a dual-liquid grouting system. However, this solidifier is not specifically designed for low temperatures, and ordinary silicate cement hydrates slowly near 0℃. In summary, some existing antifreeze admixtures are primarily designed for frigid environments below 0°C, preventing physical damage to the structure caused by internal moisture freezing by lowering the freezing point. However, they do not accelerate the hydration reaction of cement at 0°C. Other early-strength admixtures may be effective under normal temperature or water-rich conditions, but struggle to achieve rapid and efficient solidification under the combined adverse effects of low temperature and abundant water. Therefore, there is an urgent need to develop a soil stabilizer that can effectively overcome the water dilution effect and achieve efficient solidification even under water-rich and low-temperature conditions. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a composite soil stabilizer for water-rich, low-temperature conditions. Through the synergistic effect of its components, the composite soil stabilizer effectively solves the problem of solidifying water-rich, low-temperature soils without relying on preheating of raw materials or significant exothermic reactions within the system itself. In low-temperature environments (around 0°C), it achieves rapid early strength, high final strength, and excellent water stability.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a composite soil stabilizer for water-rich, low-temperature conditions, comprising the following raw materials in parts by weight: 70-110 parts of main cementitious material, 10-20 parts of auxiliary cementitious material, 3-6 parts of low-temperature early-strength agent, 0.1-0.5 parts of high-efficiency early-strength agent, 5-10 parts of water-absorbing modifier, 3-8 parts of filler, and 1-2 parts of activator.

[0008] Furthermore, the main cementitious material is composed of sulfoaluminate cement and silicate cement; by weight, the ratio of sulfoaluminate cement to silicate cement is (50~70):(20~40).

[0009] Furthermore, the auxiliary cementing material is selected from blast furnace slag powder.

[0010] Furthermore, the low-temperature early strength agent is selected from calcium nitrate.

[0011] Furthermore, the high-efficiency early-strength agent is selected from lithium carbonate.

[0012] Furthermore, the water-absorbing modifier is selected from quicklime.

[0013] Furthermore, the filler is selected from silica fume.

[0014] Furthermore, the activator is selected from sodium sulfate.

[0015] Furthermore, the composite soil stabilizer for water-rich and low-temperature conditions comprises the following raw materials in parts by weight: 50-70 parts of sulfoaluminate cement, 20-40 parts of silicate cement, 3-6 parts of calcium nitrate, 0.1-0.5 parts of lithium carbonate, 5-10 parts of quicklime, 3-8 parts of silica fume, 10-20 parts of blast furnace slag powder, and 1-2 parts of sodium sulfate.

[0016] Technical principle of the invention:

[0017] 1. Synergistic Effect of "Early Strength-High Strength-Stability": The formulation of this invention is not a simple superposition of materials, but rather a synergistic effect of all components. Sulfoaluminate cement provides early hydration and micro-expansion; calcium nitrate and lithium carbonate accelerate the reaction rate and extent of all cementitious materials at low temperatures; silica fume fills pores, forming a dense structure and blocking moisture migration channels; quicklime assists in water absorption, modification, and provides alkalinity, and utilizes the rapid water absorption and chemical bonding of the components themselves to reduce the effective water-cement ratio. These components promote each other, jointly achieving a performance leap from early strength to high strength, and then to long-term stability.

[0018] 2. Optimization of hydration product composition: Under the action of low-temperature early strength agent, the system can still generate sufficient ettringite (AFt) and low-alkalinity hydrated calcium silicate (CSH) gel. These hydration products have good crystallization, high stability, and good water resistance. They can resist wet-dry cycles and freeze-thaw cycles, and in particular, they can effectively resist soft water erosion, thus achieving the effect of high softening coefficient and good water stability.

[0019] The present invention also provides an application of the composite soil stabilizer for water-rich and low-temperature conditions described above in the solidification of water-rich and low-temperature soils.

[0020] Furthermore, the amount of the composite soil stabilizer is 5% to 12% of the weight of the water-rich, low-temperature soil to be stabilized.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] (1) Significant early strength effect: Under the low temperature curing environment of (5±2)℃, the unconfined compressive strength of the solidified soil can reach more than 0.8MPa after 3 days and more than 1.5MPa after 7 days, which can meet the early construction load requirements.

[0023] (2) High final strength and good water stability: The unconfined compressive strength after 28 days exceeds 3.0 MPa, the softening coefficient is higher than 0.85, and the immersion strength is higher than 2.75 MPa, indicating that the solidified soil has a dense structure and strong resistance to water erosion.

[0024] (3) Potential improvement in freeze-thaw resistance: When the composite soil stabilizer provided by this invention is applied to water-rich and low-temperature soil, it can form a soil structure with high density and low porosity, which provides a good foundation for resisting freeze-thaw cycles. If the ambient temperature occasionally drops below zero, its damage will be significantly lower than that of traditional stabilizers.

[0025] (4) Economic and environmental protection: It makes full use of industrial by-products such as slag powder, which reduces costs and conforms to the concept of green construction. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to specific embodiments.

[0028] This invention provides a composite soil stabilizer for water-rich, low-temperature conditions, comprising the following raw materials in parts by weight: 70-110 parts of main cementitious material, 10-20 parts of auxiliary cementitious material, 3-6 parts of low-temperature early-strength agent, 0.1-0.5 parts of high-efficiency early-strength agent, 5-10 parts of water-absorbing modifier, 3-8 parts of filler, and 1-2 parts of activator.

[0029] In a preferred embodiment, the main cementitious material is composed of sulfoaluminate cement (SAC) and silicate cement; the ratio of sulfoaluminate cement to silicate cement by weight is (50~70):(20~40); the silicate cement is 52.5R grade silicate cement. The sulfoaluminate cement in this invention provides rapid hydration and early strength; the silicate cement is used to ensure later strength, achieving synergistic effects when compounded with SAC.

[0030] In a preferred embodiment, the auxiliary cementitious material is selected from blast furnace slag powder (BFS). The blast furnace slag powder in this invention has potential pozzolanic activity, which contributes significantly to later-stage strength and can effectively improve the durability of hydration products.

[0031] In a preferred embodiment, the low-temperature early-strength agent is selected from calcium nitrate (Ca(NO3)2). Calcium nitrate, as a core additive in this invention, can significantly promote the hydration reaction of the composite soil stabilizer at low temperatures. Furthermore, the combination of calcium nitrate and lithium carbonate can strongly stimulate the hydration activity of cement at low temperatures, overcoming the problem of slow reaction caused by low temperatures.

[0032] In a preferred embodiment, the potent early-strength agent is selected from lithium carbonate (Li2CO3). This invention uses lithium carbonate as a potent early-strength agent, which can significantly accelerate solidification and early strength development with extremely low dosage, and stimulate hydration reactions at low temperatures.

[0033] In a preferred embodiment, the water-absorbing modifier is selected from quicklime (CaO). The quicklime in this invention can rapidly absorb some free water, providing alkalinity and thus activating the cementitious material. Simultaneously, the addition of quicklime improves the cohesiveness of water-rich soils, making them easier to mix and compact.

[0034] In a preferred embodiment, the filler is selected from silica fume. The silica fume in this invention is used to fill pores, thereby improving early strength and density.

[0035] In a preferred embodiment, the activator is selected from sodium sulfate (Na2SO4). The sodium sulfate in this invention is used to activate the active components in blast furnace slag powder and soil, promoting solidification.

[0036] In a preferred embodiment, the composite soil stabilizer for water-rich, low-temperature conditions comprises the following raw materials in parts by weight: 50-70 parts of sulfoaluminate cement, 20-40 parts of silicate cement, 3-6 parts of calcium nitrate, 0.1-0.5 parts of lithium carbonate, 5-10 parts of quicklime, 3-8 parts of silica fume, 10-20 parts of blast furnace slag powder, and 1-2 parts of sodium sulfate.

[0037] The present invention does not have any particular limitation on the preparation method of the composite soil stabilizer for water-rich and low-temperature conditions; it is sufficient to mix the components evenly.

[0038] The present invention also provides an application of the composite soil stabilizer for water-rich and low-temperature conditions described above in the solidification of water-rich and low-temperature soils.

[0039] In a preferred embodiment, the dosage of the composite soil stabilizer is 5% to 12% of the weight of the water-rich, low-temperature soil to be stabilized, more preferably 6% to 10%. The composite soil stabilizer provided by the present invention is in the form of dry powder, and can be thoroughly mixed with the soil to be stabilized using a dedicated mixing machine (such as a mixing pile machine) during use.

[0040] In a preferred embodiment, the water-rich, low-temperature soil includes, but is not limited to, silt; the water content of the water-rich, low-temperature soil is 50-60%, and the temperature is 1-6℃.

[0041] Unless otherwise specified, all parts in this invention represent "parts by weight".

[0042] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels.

[0043] Example 1

[0044] A composite soil stabilizer for water-rich and low-temperature conditions is composed of the following raw materials in parts by weight: 56 parts of sulfoaluminate cement, 27 parts of 52.5R grade silicate cement, 5 parts of calcium nitrate, 0.3 parts of lithium carbonate, 8 parts of quicklime, 6 parts of silica fume, 15 parts of blast furnace slag powder, and 1 part of sodium sulfate.

[0045] The preparation method of the above-mentioned composite soil stabilizer for water-rich and low-temperature conditions is as follows: weigh each raw material according to the weight parts, then mix them evenly to obtain a dry powder composite soil stabilizer for water-rich and low-temperature conditions.

[0046] The composite soil stabilizer prepared in Example 1 was added to a certain area of ​​silt (50% water content, 1℃) at 6% of the weight of the water-rich, low-temperature soil to be stabilized. The soil was cured at (5±2)℃. The unconfined compressive strength, immersion strength and softening coefficient of the stabilized soil were tested. The results are shown in Table 1.

[0047] Table 1

[0048]

[0049] As can be seen from Table 1, when water-rich, low-temperature soil is solidified using the composite soil solidifier provided in Example 1 of this invention, the solidified soil body can achieve an unconfined compressive strength of over 0.8 MPa after 3 days and over 1.5 MPa after 7 days, which can meet the early construction load requirements; the unconfined compressive strength after 28 days exceeds 3.0 MPa, the softening coefficient is higher than 0.85, and the immersion strength is higher than 2.75 MPa, indicating that the solidified soil body has a dense structure and strong resistance to water erosion.

[0050] Compared with existing technologies, the curing agent prepared in this embodiment of the invention, combined with sulfoaluminate cement, calcium nitrate, and lithium carbonate, strongly stimulates the low-temperature hydration reaction, achieving effective and rapid early strength development in low-temperature environments near 0°C, overcoming the bottleneck of conventional formulas that hardly harden at low temperatures. The 3-day strength is ≥0.8MPa, and the 7-day strength is ≥1.5MPa (cured at 5°C), significantly shortening the curing cycle and meeting the tight schedule requirements in low-temperature environments, thus accelerating subsequent processes. The softening coefficient is >0.85, and the structure is optimized through silica fume filling and sulfoaluminate hydration products; it not only has high strength but also emphasizes structural density and durability, better resisting moisture erosion and the effects of wet-dry cycles, making it suitable for water-rich environments. Extensive use of blast furnace slag powder (industrial waste) ensures performance while also considering environmental protection and cost control, making it more suitable for large-scale engineering applications. The addition of quicklime improves the cohesion and water exudation of water-rich soils, facilitating mixing and compaction; the raw materials are easy to mix (dry powder) and improve the workability of water-rich soils, facilitating construction. The composite soil stabilizer prepared by this invention effectively solves the problem of solidification of water-rich soil in low-temperature environment. It has the advantages of early strength, high strength, good water stability and convenient construction, and is particularly suitable for the treatment of soft foundation in cold regions.

[0051] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite soil stabilizer for use in water-rich, low-temperature conditions, characterized in that, The raw materials include the following parts by weight: 70-110 parts of main cementitious material, 10-20 parts of auxiliary cementitious material, 3-6 parts of low-temperature early strength agent, 0.1-0.5 parts of high-efficiency early strength agent, 5-10 parts of water-absorbing modifier, 3-8 parts of filler and 1-2 parts of activator; The main cementitious material is composed of sulfoaluminate cement and silicate cement; by weight, the ratio of sulfoaluminate cement to silicate cement is (50~70):(20~40); the auxiliary cementitious material is blast furnace slag powder; the low-temperature early strength agent is calcium nitrate; the high-efficiency early strength agent is lithium carbonate; and the water-absorbing modifier is quicklime.

2. The composite soil stabilizer for water-rich, low-temperature conditions according to claim 1, characterized in that, The filler is selected from silica fume; and / or the activator is selected from sodium sulfate.

3. The composite soil stabilizer for water-rich, low-temperature conditions according to claim 1, characterized in that, The raw materials include the following parts by weight: 50-70 parts of sulfoaluminate cement, 20-40 parts of silicate cement, 3-6 parts of calcium nitrate, 0.1-0.5 parts of lithium carbonate, 5-10 parts of quicklime, 3-8 parts of silica fume, 10-20 parts of blast furnace slag powder, and 1-2 parts of sodium sulfate.

4. The application of a composite soil stabilizer for water-rich, low-temperature conditions as described in any one of claims 1 to 3 in the solidification of water-rich, low-temperature soils.

5. The application according to claim 4, characterized in that, The amount of the composite soil stabilizer is 5% to 12% of the weight of the water-rich, low-temperature soil to be stabilized.

Images