A silicon-aluminum-based rapid curing material of high water content soft soil and a preparation method thereof

Abstract

The application relates to a silicon-aluminum-based rapid curing material of high-water-content soft soil and a preparation method thereof. The silicon-aluminum-based rapid curing material comprises, in parts by weight, 16-18 parts of sand washing filter cake, 2-4 parts of walnut shell, 3-6 parts of metakaolin, 1-2 parts of calcium oxide, 0.5-1 part of silica ash, 0.4-0.8 part of sodium silicate, and 0.1-0.2 part of sodium hydroxide. The application can directly cure high-water-content soft soil, even the soft soil with a water content greater than the liquid limit, and the cured soft soil meets the road use requirements.

Description

Technical Field

[0001] This invention relates to the field of building materials, and in particular to a silica-alumina-based rapid curing material for soft soil with high water content and its preparation method. Background Technology

[0002] With the rapid development of construction projects, soft soil inevitably appears in road engineering. Soft soil is a saturated, weak, cohesive soil. Its soil particles have a negatively charged surface and a large surface area, making it easy for water molecules and cations in the surrounding medium to be absorbed. Therefore, soft soil has engineering characteristics such as high water content, large void ratio, low strength, high compressibility, low permeability coefficient, high sensitivity, structural properties, high salinity, and high organic matter. It is often in a fluid or soft plastic state, which cannot meet the needs of engineering construction and seriously restricts the development of infrastructure.

[0003] Among them, soft soil with high water content has a water content greater than the liquid limit and a void ratio greater than or equal to 1.0. Traditional methods such as dumping, dehydration, heat treatment, and land reclamation are all limited in their application to treating soft soil with high water content. Adding solidifying materials to soft soil causes a hydration reaction with the free water in the soft soil, converting some of the free water into chemically bound water. At the same time, the hydration products can directly bind to the surface of soil particles in the soft soil, coagulating the soil particles into a whole, solid, stable, and durable plate structure. This method not only has good soil properties but also low cost and wide applicability, making it the best choice for solidifying soft soil with high water content in engineering construction both domestically and internationally.

[0004] Currently, the most commonly used soft soil stabilization materials in China are calcium-based stabilization materials such as cement, lime, and slag. However, for soft soil with high water content, these stabilization materials require a very high dosage to cement the soil. Although they can meet certain engineering requirements, the production of cement and quicklime has the disadvantages of high energy consumption and high pollution, which is not conducive to sustainable development and energy conservation and emission reduction.

[0005] Numerous methods have been researched to address the challenge of solidifying soft soils with high moisture content. However, most methods still require pre-drying the soil to bring its moisture content close to the optimum level, especially when dealing with soft soils whose moisture content is significantly higher than the optimum, particularly those near the liquid limit. Therefore, there is still an urgent need for a high-efficiency, low-cost, high-performance solidification material that is well-suited for soft soils with high moisture content. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a silicon-aluminum based rapid curing material for soft soil with high water content and its preparation method, which can directly cure soft soil with high water content, or even soft soil with water content greater than the liquid limit, and meet the requirements for road use after curing.

[0007] The objective of this invention is achieved by at least one of the following technical solutions.

[0008] A silica-alumina-based rapid curing material for high-water-content soft soil, wherein the silica-alumina-based rapid curing material comprises, by weight: 16-18 parts of washed sand filter cake, 2-4 parts of walnut shell, 3-6 parts of metakaolin, 1-2 parts of calcium oxide, 0.5-1 parts of silica fume, 0.4-0.8 parts of sodium silicate, and 0.1-0.2 parts of sodium hydroxide.

[0009] Preferably, the washed sand filter cake is the residual waste residue precipitated by flocculant during the crushing process of manufactured sand or coarse aggregate.

[0010] Preferably, the flocculant is cationic polyacrylamide.

[0011] Preferably, the lignin content in the walnut shell is ≥30%.

[0012] Preferably, the metakaolin has a 7-day activity index ≥ 95%.

[0013] Preferably, the sodium silicate and sodium hydroxide are granular with a particle size ≤1mm.

[0014] Preferably, the water content of the high-moisture soft soil is 10%-100%.

[0015] Preferably, the amount of the silicon-aluminum based rapid curing material is 25-55% of the mass of the cured soil.

[0016] The preparation method of the silica-alumina-based rapid curing material for high water content soft soil includes the following steps:

[0017] The walnut shells are ground to an average particle size of 0.1-1 mm, then dissolved in water. The pH of the solution is adjusted to 9-11. The temperature is raised to 50-70℃, and 1-2 parts of sodium chloroacetate are added dropwise to the reaction solution. The reaction time is controlled to be 1-3 hours to obtain modified walnut shell powder.

[0018] Modified walnut shell powder was added to the washed sand filter cake and mixed evenly to obtain component A;

[0019] After mixing metakaolin, calcium oxide, and silica fume evenly, sodium silicate and sodium hydroxide are added and the mixture is stirred to obtain component B.

[0020] The combination of component A and component B yields a silicon-aluminum based rapid curing material.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1) This invention utilizes cationic flocculants in sand washing filter cake, which can interact with colloidal particles in soft soil, effectively neutralizing the negative charge on the particle surface and promoting soil settling. At the same time, modified lignin can neutralize the surface charge on clay particles in advance, making the particles closer to the distance that is conducive to the adsorption of cationic flocculant molecules. The cationic polymeric flocculant can achieve rapid adsorption during the swelling process, which solves the shortcomings of traditional cationic polymeric flocculants such as high viscosity, long dissolution time, and low charge utilization.

[0023] 2) This invention prepares washed sand filter cake into a high-water-content soft soil solidification material, which solves the problems of easy segregation and bleeding of washed sand filter cake in ordinary concrete and serious loss of workability. The use of washed sand filter cake in the preparation of soft soil solidification material not only reduces the amount of cement used in traditional solidification materials and reduces carbon emissions, but also realizes the high-value utilization of washed sand filter cake.

[0024] 3) This invention uses washed sand filter cake in soft soil with high water content, which not only improves the solid phase composition, but also changes the pore size distribution in the solidified soil based on ions and effectively reduces the voids between filling soil particles. Then, through the alkali activation system, irreversible coagulation and hardening occurs on the surface of soil particles, so that it meets the application requirements of road materials. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below.

[0026] Examples 1-4

[0027] Table 1 shows the specific composition and content of the silica-alumina-based rapid curing materials for high water content soft soil provided in Examples 1-4.

[0028] The sand filter cake used in the example is the residual mud residue formed after the natural rock is crushed, the manufactured sand and stone are separated by washing and screening, the mud is settled by flocculant and then compressed by plate and frame filter press.

[0029] Table 1 Raw material ratios for Examples 1-4

[0030] Washed sand filter cake 16 17 17 18 walnut shell 4 3 3 2 metakaolin 3 4 5 6 Calcium oxide 1 1.5 1.5 2 silica ash 0.5 0.8 0.8 1 Sodium silicate 0.4 0.5 0.7 0.8 Sodium hydroxide 0.1 0.2 0.2 0.2

[0031] Example 5

[0032] This embodiment provides a method for preparing a silica-alumina-based rapid-curing material for soft soil with high water content. Taking Example 3 as an example, other embodiments are prepared using the following method, including the following steps:

[0033] S101, grind 3 parts of walnut shells to an average particle size of 1 mm, then dissolve them in an alkaline solution with pH=10, such as sodium hydroxide solution, at a weight ratio of 1:5. After raising the temperature to 60℃, add 1 part of sodium chloroacetate to the reaction solution and control the reaction time to 2 hours to obtain modified walnut shell powder.

[0034] S102, Modified walnut shell powder is added to 17 parts of washed sand filter cake and mixed evenly to obtain component A;

[0035] S103: Mix 5 parts metakaolin, 1.5 parts calcium oxide, and 0.8 parts silica fume evenly, then add 0.7 parts sodium silicate and 0.2 parts sodium hydroxide and continue mixing to obtain component B;

[0036] S104, a silicon-aluminum based rapid curing material, is obtained by combining components A and B.

[0037] Comparative Example 1

[0038] The formulation of this comparative example is roughly the same as that of Example 3, except that no washed sand filter cake and walnut shells are added, and the preparation method is the same as that of Example 5.

[0039] Comparative Example 2

[0040] The formulation of this comparative example is roughly the same as that of Example 3, except that no walnut shells are added, and the preparation method is the same as that of Example 5.

[0041] The solidified materials prepared in Examples 1-4 and Comparative Examples 1-2 were mixed with silt with a water content of 65% at a mass ratio of 25:100. The compressive strength of the samples was determined according to GB / T 50123-2019 "Standard for Geotechnical Testing Methods". The test results are shown in Table 2.

[0042] Table 2 Basic Properties of Solidified Soil

[0043]

[0044] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A silica-alumina-based rapid-curing material for high-water-content soft soil, characterized in that, The silicon-aluminum based rapid curing material comprises, by weight: 16-18 parts washed sand filter cake, 2-4 parts walnut shells, 3-6 parts metakaolin, 1-2 parts calcium oxide, 0.5-1 parts silica fume, 0.4-0.8 parts sodium silicate, and 0.1-0.2 parts sodium hydroxide. The washed sand filter cake is the residual waste residue precipitated by flocculant during the crushing process of manufactured sand or coarse aggregate. The walnut shells are modified as follows: the walnut shells are ground to an average particle size of 0.1-1 mm, then dissolved in water, the pH of the solution is adjusted to 9-11, the temperature is raised to 50-70℃, and 1-2 parts sodium chloroacetate are added dropwise to the reaction solution. The reaction time is controlled to be 1-3 h.

2. The silica-alumina-based rapid-curing material for high-water-content soft soil as described in claim 1, characterized in that, The flocculant is cationic polyacrylamide.

3. The silica-alumina-based rapid-curing material for high-water-content soft soil as described in claim 1, characterized in that, The lignin content in the walnut shell is ≥30%.

4. The silica-alumina-based rapid-curing material for high-water-content soft soil as described in claim 1, characterized in that, The metakaolin has a 7-day activity index ≥95%.

5. The silica-alumina-based rapid-curing material for high-water-content soft soil as described in claim 1, characterized in that, The sodium silicate and sodium hydroxide are in granular form with a particle size ≤1mm.

6. The silica-alumina-based rapid-curing material for high-water-content soft soil as described in claim 1, characterized in that, The water content of the high-water-content soft soil is 10%-100%.

7. The silica-alumina-based rapid-curing material for high-water-content soft soil as described in claim 1, characterized in that, The amount of the silicon-aluminum based rapid curing material used is 25-55% of the mass of the cured soil.

8. The method for preparing the silica-alumina-based rapid-curing material for high-water-content soft soil as described in any one of claims 1 to 7, characterized in that, The steps include the following: Walnut shells are ground to an average particle size of 0.1-1 mm, then dissolved in water. The pH of the solution is adjusted to 9-11. The temperature is raised to 50-70℃, and 1-2 parts of sodium chloroacetate are added dropwise to the reaction solution. The reaction time is controlled to be 1-3 h to obtain modified walnut shell powder. Modified walnut shell powder was added to the washed sand filter cake and mixed evenly to obtain component A; After mixing metakaolin, calcium oxide, and silica fume evenly, sodium silicate and sodium hydroxide are added and the mixture is stirred to obtain component B. The combination of component A and component B yields a silicon-aluminum based rapid curing material.

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