Premixed flow-state solidified soil and preparation method thereof

Abstract

The invention discloses premixed flow-state solidified soil and a preparation method thereof, and the premixed flow-state solidified soil comprises the following components in parts by weight: 100 parts of silty clay; 8 to 15 parts of a curing agent; 48 to 90 parts of water; wherein the curing agent comprises the following components: 10 to 15 parts of sulphoaluminate cement; 40 parts to 55 parts of superfine steel slag powder; 30 to 40 parts of fly ash; 0.5 to 1.5 parts of sodium silicate; 0.1 to 0.3 part of a foaming agent; 0.1 part to 0.2 part of sodium thiocyanate; 0.1 part to 0.2 part of hydroxymethyl cellulose; 0.05 part to 0.2 part of triisopropanolamine; 0.1 part to 0.5 part of calcium nitrate; and 0.5 to 1 part of a polycarboxylic acid water reducing agent. The preparation method of the premixed flow-state solidified soil is suitable for using silty clay as a raw material, and greatly improves the strength, compactness, fluidity and other properties of the premixed flow-state solidified soil.

Description

Technical Field

[0001] The present invention relates to the technical field of building construction, and in particular to a premixed fluidized solidified soil and a preparation method thereof. Background Art

[0002] In recent years, fluidized soil technology has received widespread attention and application in the field of engineering construction due to its advantages of high efficiency, energy saving, and environmental friendliness. Existing research mainly focuses on material optimization, performance improvement, and low-carbon applications, and improves the early strength and impermeability of fluidized soil by developing composite curing agents and other means. In actual engineering applications, fluidized soil significantly simplifies the construction process and greatly improves construction efficiency due to its excellent fluidity and self-compacting properties. At the same time, through the scientific formulation of the curing agent system, its strength can be accurately controlled within a certain range to meet the needs of various backfill projects. It has been successfully applied to many fields such as foundation treatment, foundation pit backfill, and environmental remediation, demonstrating the comprehensive advantages of efficient construction, economic savings, and ecological protection.

[0003] However, current research and development of ready-mixed fluidized soil is mostly focused on materials such as loess, saline soil, and diatomaceous earth. There is relatively little research on ready-mixed fluidized soil using silty clay as the main raw material. The unique engineering properties of silty clay make it face many challenges in engineering applications: it is prone to collapse, softening, frost heave, and even liquefaction when exposed to water, which can easily cause foundation settlement or slope instability; it has low shear strength, high compressibility, and insufficient bearing capacity, which can easily lead to engineering safety hazards in natural or saturated conditions; its strong permeability and erodibility can also affect drainage and the construction environment. When used as a raw material for ready-mixed fluidized soil, when higher fluidity is required, silty clay will exhibit severe water seepage, making it difficult to meet construction requirements.

[0004] Furthermore, existing methods for preparing premixed fluidized soil have limited applicability, making widespread adoption difficult. Due to the significant differences in soil properties, existing technologies are not fully compatible with silty clay, and traditional silty clay processing procedures are complex and costly.

[0005] Therefore, there is an urgent need to develop a premixed fluidized solidification soil and its preparation method for silty clay, which can be easy to operate and low in cost while ensuring that the strength of the solidified soil meets the engineering requirements, thereby ensuring that silty clay can be used on a large scale as a raw material for premixed fluidized solidification soil. This is of great significance for enriching the types of raw materials for premixed fluidized solidification soil and improving its adaptability to actual engineering. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defects in the prior art of using silty clay as a raw material for premixed fluidized solidified soil, such as the problem of water seepage, complex preparation process and difficulty in large-scale promotion and use.

[0007] In order to achieve the above object, the present invention provides a premixed fluidized solidified soil, which comprises, by weight: 100 parts of silty clay; 8 to 15 parts of a curing agent; and 48 to 90 parts of water.

[0008] Wherein, the curing agent comprises the following components:

[0009] Sulphoaluminate cement: 10 to 15 parts;

[0010] Ultrafine steel slag powder: 40 to 55 parts;

[0011] Fly ash: 30 to 40 parts;

[0012] Sodium silicate: 0.5 to 1.5 parts;

[0013] Foaming agent: 0.1 to 0.3 parts;

[0014] Sodium thiocyanate: 0.1 to 0.2 parts;

[0015] Hydroxymethyl cellulose: 0.1 to 0.2 parts;

[0016] Triisopropanolamine: 0.05 to 0.2 parts;

[0017] Calcium nitrate: 0.1 to 0.5 parts;

[0018] Polycarboxylate water reducer: 0.5 to 1 part.

[0019] Optionally, the strength grade of the sulphoaluminate cement is not less than grade 42.5.

[0020] Optionally, the foaming agent is any one of hydrogen peroxide, azodicarbonamide or sodium lauryl sulfate, or a combination of any two or more thereof.

[0021] Optionally, the specific surface area of ​​the ultrafine steel slag powder is not less than 400m 2 / kg.

[0022] Optionally, the polycarboxylate water reducer is an early-strength polycarboxylate water reducer.

[0023] Optionally, the polycarboxylate water reducer is selected from Sika brand early strength polycarboxylate water reducer.

[0024] The present invention also provides a method for preparing the premixed fluidized solidified soil as described above, comprising:

[0025] S1, mixing sulphoaluminate cement, ultrafine steel slag powder, fly ash, sodium silicate, foaming agent, sodium thiocyanate, hydroxymethyl cellulose, triisopropanolamine, calcium nitrate, and polycarboxylate water reducer to obtain a curing agent;

[0026] S2. Take 100 parts of silty clay, 8 parts of curing agent, and 48 to 90 parts of water by weight, add the silty clay, curing agent, and water into a forced mixer and stir them evenly to obtain the premixed fluidized solidified soil.

[0027] Compared with the prior art, the beneficial effects of the present invention include at least:

[0028] The hydroxymethyl cellulose in the premixed fluidized solidified soil of the present invention improves the physicochemical reaction of silty clay. The hydroxymethyl and carboxyl groups in the hydroxymethyl cellulose molecules combine with free radicals through hydrogen bonds to form a "bound water layer". This water layer can reduce the rapid evaporation of surface water and avoid the generation of plastic shrinkage cracks. At the same time, it provides cement particles with components required for hydration, thereby improving early strength development. The use of ultrafine steel slag powder in the premixed fluidized solidified soil reduces the friction between particles through the "ball effect" of the ultrafine particles and increases the slump height under the same conditions. At the same time, the high specific surface area of ​​the ultrafine steel slag powder can adsorb free water and reduce the risk of segregation. At the same time, triisocyanate, sodium thiocyanate and calcium nitrate are added to the curing agent to improve the activity of the main components of the curing agent (cement, steel slag powder and fly ash), accelerate the hydration reaction of the cement, shorten the setting time and improve the early strength. The synergy of ultrafine steel slag powder and fly ash, especially the use of ultrafine steel slag powder, promotes the activity of the steel slag powder and releases calcium hydroxide during hydration, which can stimulate the activity of the fly ash. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below with reference to the embodiments.

[0030] Example 1:

[0031] The curing agent ingredients are calculated by mass as follows: 14 parts of sulphoaluminate cement (strength grade not less than 42.5), 43 parts of ultrafine steel slag powder, 40 parts of fly ash, 1.3 parts of sodium silicate, 0.3 parts of foaming agent, 0.2 parts of sodium thiocyanate, 0.1 parts of hydroxymethyl cellulose, 0.2 parts of triisopropanolamine, 0.4 parts of calcium nitrate, and 0.5 parts of polycarboxylic acid water reducer. The above raw materials are fully mixed and used as the curing agent.

[0032] During the specific construction: take silty clay, according to its dry basis mass, for every 100 parts of silty clay, add 8 parts of curing agent and 48 parts of water (this water includes the mass of water contained in the silty clay and the mass of supplementary water); add the above materials into a forced mixer and mix them thoroughly until uniform, then test their slump and expansion with reference to the national standard "Standard for Test Methods of Ordinary Concrete Mixtures", then cast into molds, leave them to naturally solidify at room temperature for 24 hours, then demould, and test the unconfined compressive strength after 28 days of curing after demoulding.

[0033] Example 2:

[0034] The curing agent ingredients are calculated by mass as follows: 15 parts of sulphoaluminate cement (strength grade not less than 42.5), 48 parts of ultrafine steel slag powder, 34 parts of fly ash, 1.2 parts of sodium silicate, 0.2 parts of foaming agent, 0.1 parts of sodium thiocyanate, 0.2 parts of hydroxymethyl cellulose, 0.1 parts of triisopropanolamine, 0.2 parts of calcium nitrate, and 1 part of polycarboxylic acid water reducer. The above raw materials are fully mixed and used as the curing agent.

[0035] During the specific construction: take silty clay, according to its dry basis mass, for every 100 parts of silty clay, add 8 parts of curing agent and 48 parts of water (this water includes the mass of water contained in the silty clay and the mass of supplementary water); add the above materials into a forced mixer and mix them thoroughly until uniform, then test their slump and expansion with reference to the national standard "Standard for Test Methods of Ordinary Concrete Mixtures", then cast into molds, leave them to naturally solidify at room temperature for 24 hours, then demould, and test the unconfined compressive strength after 28 days of curing after demoulding.

[0036] Example 3:

[0037] The curing agent ingredients are calculated by mass as follows: 12 parts of sulphoaluminate cement (strength grade not less than 42.5), 53 parts of ultrafine steel slag powder, 32 parts of fly ash, 1.45 parts of sodium silicate, 0.2 parts of foaming agent, 0.2 parts of sodium thiocyanate, 0.1 parts of hydroxymethyl cellulose, 0.15 parts of triisopropanolamine, 0.3 parts of calcium nitrate, and 0.6 parts of polycarboxylic acid water reducer. The above raw materials are fully mixed and used as the curing agent.

[0038] During the specific construction: take silty clay, according to its dry basis mass, for every 100 parts of silty clay, add 9 parts of curing agent and 54 parts of water (this water includes the mass of water contained in the silty clay and the mass of supplementary water); add the above materials into a forced mixer and mix them thoroughly until uniform, then test their slump and expansion with reference to the national standard "Standard for Test Methods of Ordinary Concrete Mixtures", then cast into a mold, leave it to naturally solidify at room temperature for 24 hours, then demould, and test the unconfined compressive strength after 28 days of curing after demoulding.

[0039] Example 4:

[0040] The curing agent ingredients are calculated by mass as follows: 10 parts of sulphoaluminate cement (strength grade not less than 42.5), 54 parts of ultrafine steel slag powder, 34 parts of fly ash, 0.75 parts of sodium silicate, 0.3 parts of foaming agent, 0.1 parts of sodium thiocyanate, 0.2 parts of hydroxymethyl cellulose, 0.05 parts of triisopropanolamine, 0.1 parts of calcium nitrate, and 0.5 parts of polycarboxylic acid water reducer. The above raw materials are fully mixed and used as the curing agent.

[0041] During the specific construction: take silty clay, according to its dry basis mass, for every 100 parts of silty clay, add 11 parts of curing agent and 66 parts of water (this water includes the mass of water contained in the silty clay and the mass of supplementary water); add the above materials into a forced mixer and mix them thoroughly until uniform, then test their slump and expansion with reference to the national standard "Standard for Test Methods of Ordinary Concrete Mixtures", then cast into a mold, leave it to naturally solidify at room temperature for 24 hours, then demould, and test the unconfined compressive strength after 28 days of curing after demoulding.

[0042] Example 5:

[0043] The curing agent ingredients are calculated by mass as follows: 14 parts of sulphoaluminate cement (strength grade not less than 42.5), 47 parts of ultrafine steel slag powder, 37 parts of fly ash, 0.65 parts of sodium silicate, 0.2 parts of foaming agent, 0.2 parts of sodium thiocyanate, 0.1 parts of hydroxymethyl cellulose, 0.15 parts of triisopropanolamine, 0.2 parts of calcium nitrate, and 0.5 parts of polycarboxylic acid water reducer. The above raw materials are fully mixed and used as the curing agent.

[0044] During the specific construction: take silty clay, according to its dry basis mass, for every 100 parts of silty clay, add 13 parts of curing agent and 78 parts of water (this water includes the mass of water contained in the silty clay and the mass of the supplementary water); add the above materials into a forced mixer and stir them thoroughly until they are uniform, and then test their slump and expansion with reference to the national standard "Standard for Test Methods of Ordinary Concrete Mixtures", then cast into a mold, leave it to naturally solidify at room temperature for 24 hours, and then demold it. After demolding, cure it for 28 days and then test the unconfined compressive strength.

[0045] Example 6:

[0046] The curing agent ingredients are calculated by mass as follows: 13 parts of sulphoaluminate cement (strength grade not less than 42.5), 50 parts of ultrafine steel slag powder, 34 parts of fly ash, 1.5 parts of sodium silicate, 0.1 part of foaming agent, 0.1 part of sodium thiocyanate, 0.2 part of hydroxymethyl cellulose, 0.1 part of triisopropanolamine, 0.4 part of calcium nitrate, and 0.6 part of polycarboxylic acid water reducer. The above raw materials are fully mixed and used as the curing agent.

[0047] During the specific construction: take silty clay, according to its dry basis mass, for every 100 parts of silty clay, add 14 parts of curing agent and 84 parts of water (this water includes the mass of water contained in the silty clay and the mass of supplementary water); add the above materials into a forced mixer and stir them thoroughly until uniform, then test their slump and expansion with reference to the national standard "Standard for Test Methods of Ordinary Concrete Mixtures", then cast into molds, leave them to naturally solidify at room temperature for 24 hours, then demould, and test the unconfined compressive strength after 28 days of curing after demoulding.

[0048] Example 7:

[0049] The curing agent ingredients are calculated by mass as follows: 13 parts of sulphoaluminate cement (strength grade not less than 42.5), 48 parts of ultrafine steel slag powder, 36 parts of fly ash, 1.1 parts of sodium silicate, 0.3 parts of foaming agent, 0.2 parts of sodium thiocyanate, 0.1 parts of hydroxymethyl cellulose, 0.2 parts of triisopropanolamine, 0.3 parts of calcium nitrate, and 0.8 parts of polycarboxylic acid water reducer. The above raw materials are fully mixed and used as the curing agent.

[0050] During the specific construction: take silty clay, according to its dry basis mass, for every 100 parts of silty clay, add 15 parts of curing agent and 90 parts of water (this water includes the mass of water contained in the silty clay and the mass of the supplementary water); add the above materials into a forced mixer and stir them thoroughly until they are uniform, and then test their slump and expansion with reference to the national standard "Standard for Test Methods of Ordinary Concrete Mixtures", then cast into a mold, leave it to naturally solidify at room temperature for 24 hours, and then demold it. After demolding, cure it for 28 days and then test the unconfined compressive strength.

[0051] According to the "DB 1310 / T 298-2023 Technical Specification for Premixed Fluidized Solidified Soil Filling", premixed fluidized solidified soils with different slumps have different uses, as shown in Table 1 below. The test results of Examples 1 to 7 are shown in Table 2.

[0052] Table 1 Design performance indicators of PFSS

[0053]

[0054] Table 2 Test results of premixed fluidized solidified soil of Examples 1 to 7

[0055]

[0056] As shown in Table 2, the premixed fluidized solidified soil made from the curing agent ratios of Example 1 and Example 4 can be used for roadbed backfill, and the premixed fluidized solidified soil made from the curing agent ratios of Example 2, Example 3, Example 5, Example 6, and Example 7 can be used for fertilizer tank backfill.

[0057] The embodiments of the present invention can all meet the requirements of construction. The goal of adjusting strength and fluidity can be achieved by adjusting the composition of the curing agent. In addition, the strength can be adjusted according to the amount of curing agent added. However, when high strength is required, it is necessary to appropriately increase the amount of curing agent and the amount of cement in the curing agent. The performance of premixed fluidized solidified soil is determined by the synergistic effect of each component: sulphoaluminate cement significantly improves the strength by rapidly generating calcium aluminoferrite. For example, the 28d strength of Example 4 reaches 0.972MPa, but excessive amount (such as Example 7) will cause the later strength to drop to 0.585MPa due to the concentration of hydration heat; ultrafine steel slag powder optimizes density through micro-aggregate filling. The 28d strength of Example 3 is 0.689MPa, while the strength of Example 2 fluctuates to 0.732MPa due to the risk of free CaO. However, when the fluidity requirement is high, it is only necessary to appropriately increase the water-solid ratio to achieve the purpose of improving fluidity. In Example 1, although the cement content in the curing agent is small and the water-solid ratio is low, the strength is high. It can be seen that the strength can be adjusted by the water-solid ratio, but the adverse effect brought is that the fluidity is poor, which is not conducive to construction. In Example 7, the water-solid ratio is high and the fluidity is good, but the strength is low. Therefore, the fluidity can be improved by adjusting the water-solid ratio according to the project needs. In Example 2, due to the use of higher sulphoaluminate cement, not only the shrinkage after solidification can be reduced, but also the strength is improved. The fluidity also maintains a higher fluidity because of the presence of plasticizer. In Example 3, because the cement content is increased, its strength is higher. It can be seen that increasing the cement content can improve the strength to a certain extent. In Example 4, when using ultrafine steel slag powder to replace part of the cement, because the activity of ultrafine steel slag powder is higher, it can replace part of the cement, and the performance is not significantly weakened. Moreover, it can also release calcium ions when it is hydrated, which is beneficial to the solidification of silty clay.

[0058] In summary, the premixed fluidized solidified soil of the present invention uses silty clay as raw material, wherein the curing agent comprises sulphoaluminate cement, ultrafine steel slag powder, fly ash, sodium silicate, foaming agent, sodium thiocyanate, hydroxymethyl cellulose, triisopropanolamine, calcium nitrate, and polycarboxylic acid water reducer. Hydroxymethyl cellulose improves the physicochemical reaction of silty clay and improves the early strength of cement. Ultrafine steel slag powder increases the slump height and reduces the risk of segregation. Triisopropanolamine, sodium thiocyanate, and calcium nitrate accelerate the hydration reaction of cement, shorten the setting time, and greatly improve the overall performance of the premixed fluidized solidified soil.

[0059] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A premixed fluidized solidified soil, characterized in that: Calculated by weight, it comprises: 100 parts of silty clay; 8 to 15 parts of curing agent; 48 to 90 parts of water; Wherein, the curing agent comprises the following components: Sulphoaluminate cement: 10 to 15 parts; Ultrafine steel slag powder: 40 to 55 parts; Fly ash: 30 to 40 parts; Sodium silicate: 0.5 to 1.5 parts; Foaming agent: 0.1 to 0.3 parts; Sodium thiocyanate: 0.1 to 0.2 parts; Hydroxymethyl cellulose: 0.1 to 0.2 parts; Triisopropanolamine: 0.05 to 0.2 parts; Calcium nitrate: 0.1 to 0.5 parts; Polycarboxylate water reducer: 0.5 to 1 part.

2. The ready-mixed fluidized solidified soil according to claim 1, characterized in that: The strength grade of the sulphoaluminate cement is not less than grade 42.

5.

3. The ready-mixed fluidized solidified soil according to claim 1, characterized in that: The foaming agent is any one of hydrogen peroxide, azodicarbonamide or sodium lauryl sulfate, or a combination of any two or more thereof.

4. The ready-mixed fluidized solidified soil according to claim 1, characterized in that: The specific surface area of ​​the ultrafine steel slag powder is not less than 400m 2 / kg.

5. The ready-mixed fluidized solidified soil according to claim 1, characterized in that: The polycarboxylate water reducer is an early strength polycarboxylate water reducer.

6. The ready-mixed fluidized solidified soil according to claim 5, characterized in that: The polycarboxylate water reducer is a Sika brand early strength polycarboxylate water reducer.

7. A method for preparing the premixed fluidized solidified soil according to any one of claims 1 to 6, characterized in that: Include: S1, mixing sulphoaluminate cement, ultrafine steel slag powder, fly ash, sodium silicate, foaming agent, sodium thiocyanate, hydroxymethyl cellulose, triisopropanolamine, calcium nitrate, and polycarboxylate water reducer to obtain a curing agent; S2. Take 100 parts of silty clay, 8 parts to 15 parts of curing agent, and 48 parts to 90 parts of water by weight, add the silty clay, curing agent, and water into a forced mixer and stir them evenly to obtain the premixed fluidized solidified soil.

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