Curing agent for deep mixing pile of soft soil foundation as well as preparation method and application of curing agent

Abstract

The invention provides a curing agent for a deep mixing pile of a soft soil foundation as well as a preparation method and application of the curing agent. The curing agent comprises the following raw materials in parts by weight: 24-32 parts of blast furnace slag, 6-13 parts of fly ash, 26-34 parts of sulphoaluminate cement, 26-33 parts of gypsum, 2-5 parts of an alkali activator and 0.1-0.5 part of a water reducing agent. The mixing pile curing agent provided by the invention enables soil particles to form good solidification, the solidified soil body is high in strength and good in stability, the mixing pile curing agent is particularly suitable for a soft soil foundation with high water content, the construction process is simple, the construction efficiency is improved, the cement consumption is reduced, the mixing pile curing agent conforms to the low-carbon and environment-friendly concept, and the engineering cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, relates to a curing agent, and particularly relates to a curing agent for deep mixing piles in soft soil foundations, its preparation method and application. Background Art

[0002] In the urban construction of coastal areas, soft soil foundations are widespread. Due to their low strength and large deformation, they are prone to problems such as uneven settlement of the foundation, cracks, and even foundation instability during the engineering construction process. These problems not only affect the stability and safety of buildings, but also may increase the complexity and cost of construction. Therefore, the reinforcement treatment of soft soil foundations has become one of the key measures to ensure the engineering quality.

[0003] The deep mixing pile technology is a common foundation reinforcement method and has been widely used in the treatment of soft soil foundations. The traditional deep mixing pile technology usually uses cement as a curing agent, which is forcibly mixed with the underground soil by a deep mixing machine to solidify the soil, and the strength and stability of the soil are enhanced by the gelling property of the cement. However, this method faces some problems in practical applications. First, in soft clay layers (such as silt, clay, etc.), the consolidation between soil particles and cement is poor, resulting in difficulty for the cement slurry to fully combine with the soil, and the strength of the pile body is often low, making it difficult to achieve the expected reinforcement effect. Second, as a traditional soil curing agent, cement has a high usage cost, and a large amount of carbon dioxide is emitted during its production process, increasing the environmental burden and economic pressure of the project. Therefore, how to reduce the amount of cement used, improve the curing effect, and reduce the environmental impact has become an urgent problem to be solved in the current soil reinforcement technology.

[0004] In this context, in recent years, geopolymers green gel materials based on industrial solid wastes have gradually attracted attention and shown broad application prospects in the field of soil reinforcement.

[0005] CN117756491A discloses an environment-friendly curing agent for solidifying soft soil, its preparation method and application. The composition of the environment-friendly curing agent includes: 70 - 100% of cement, 3 - 4% of gypsum, 5 - 15% of blast furnace slag, 1 - 3% of a high molecular polymerization reaction catalyst, and 3 - 7% of calcium-based bentonite. The high molecular polymerization reaction catalyst includes calcium lignosulfonate, triethanolamine, and sodium polyacrylate. In the components of this curing agent, cement is still the main component with a large dosage, and a composite reaction catalyst with complex components also needs to be added, which is not conducive to reducing the construction cost and environmental protection burden.

[0006] CN119263764A discloses a fly ash-based early strength curing agent and its preparation method and application. The components of the curing agent include: 55-65% low-calcium fly ash, 8-10% cement, 3-5% slag, 3-5% lime, 3-6% phosphogypsum, 2-4% strong oxidant and 8-10% alkali activator. The curing agent has a high content of low-calcium fly ash, and the early curing strength is improved, but the compressive strength is insufficient in the later stage of curing.

[0007] Therefore, a mixing pile curing agent that can effectively consolidate the characteristics of soft soil foundation, has high curing strength, a wide source of raw materials and a low price is of great significance to actual construction. Summary of the invention

[0008] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a curing agent for deep mixing piles in soft soil foundations, and a preparation method and application thereof, so as to effectively consolidate the soft soil foundation during the construction of deep mixing piles, while ensuring the curing effect, reducing the amount of cement used and reducing the project cost.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a curing agent for deep mixing piles in soft soil foundations, wherein the raw material composition of the curing agent comprises, by weight: 24-32 parts of blast furnace slag, 6-13 parts of fly ash, 26-34 parts of sulphoaluminate cement, 26-33 parts of gypsum, 2-5 parts of alkali activator, and 0.1-0.5 parts of water reducer.

[0011] The mixing pile curing agent provided by the present invention uses blast furnace slag, fly ash, sulphoaluminate cement and gypsum as main raw materials. Under the action of alkali excitation, the blast furnace slag and fly ash are depolymerized and then polycondensed to form a kind of solidifying agent mainly composed of SiO 4 and AlO 4 The tetrahedral structural units are bonded alternately through shared oxygen to form a three-dimensional spatial network structure of geopolymer cementitious materials. Sulfate cement combines with water to hydrate and generate hydrated calcium silicate and calcium aluminate. At the same time, gypsum plays a role in regulating the setting and early strength. Various materials interact with each other and the fluidity of the curing agent slurry is improved by the water reducer, thereby achieving good consolidation with soil particles. The solidified soil has high strength and good stability, especially for soft soil foundations with high water content. The curing effect is good. Among them, the amount of cement used is reduced, the production of carbon dioxide is reduced, and waste materials are recycled to reduce engineering costs.

[0012] The weight proportion of the blast furnace slag is 24-32 parts, for example, it can be 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts or 32 parts, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] The weight parts of the fly ash are 6 - 13 parts. For example, it can be 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts or 13 parts, but not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0014] The weight parts of the sulfoaluminate cement are 26 - 34 parts. For example, it can be 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts or 34 parts, but not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0015] The weight parts of the gypsum are 26 - 33 parts. For example, it can be 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts or 33 parts, but not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0016] The weight parts of the alkali activator are 2 - 5 parts. For example, it can be 2 parts, 3 parts, 4 parts or 5 parts, but not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0017] The weight parts of the water - reducing agent are 0.1 - 0.5 parts. For example, it can be 0.1 part, 0.2 part, 0.3 part, 0.4 part or 0.5 part, but not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0018] In the present invention, the blast furnace slag is S95 - grade granulated blast furnace slag powder that meets the national standard GB / T 18046 - 2007.

[0019] Preferably, the composition of the blast furnace slag includes: CaO 35 - 50wt%, SiO 2 25 - 45wt%, Al 2 O 3 10 - 20wt%, MgO 5 - 10wt%, Fe 2 O 3 0.5 - 2.0wt%.

[0020] In the blast furnace slag, the CaO content is 35 - 50wt%. For example, it can be 35wt%, 40wt%, 45wt% or 50wt%, but not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0021] In the blast furnace slag, SiO 2The content is 25 - 45 wt%, for example, it can be 25 wt%, 30 wt%, 35 wt%, 40 wt% or 45 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable. In the blast furnace slag, Al 2 O 3 The content is 10 - 20 wt%, for example, it can be 10 wt%, 12 wt%, 15 wt%, 18 wt% or 20 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0022] In the blast furnace slag, the content of MgO is 5 - 10 wt%, for example, it can be 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt% or 10 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0023] In the blast furnace slag, the content of Fe 2 O 3 is 0.5 - 2.0 wt%, for example, it can be 0.5 wt%, 1.0 wt%, 1.5 wt% or 2.0 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0024] Preferably, the activity index of the blast furnace slag is ≥95%, for example, it can be 95%, 96%, 97%, 98%, 99% or 100%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0025] Preferably, the specific surface area of the blast furnace slag is ≥450 m 2 / kg, for example, it can be 450 m 2 / kg, 480 m 2 / kg, 500 m 2 / kg, 550 m 2 / kg, 600 m 2 / kg or 800 m 2 / kg, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0026] Preferably, the fineness of the blast furnace slag is that the residue on a 45 - μm sieve is ≤10%, for example, it can be 10%, 8%, 5%, 3% or 1%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0027] In the present invention, the fly ash meets the index requirements of Class II fly ash in the national standard GB / T 1596 - 2005.

[0028] Preferably, the composition of the fly ash includes: SiO 240 - 55 wt%, Al 2 O 3 30 - 45 wt%, CaO 2 - 10 wt%, Fe 2 O 3 2 - 8 wt%.

[0029] In the fly ash, the content of SiO 2 is 40 - 55 wt%, for example, it can be 40 wt%, 45 wt%, 50 wt% or 55 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0030] In the fly ash, the content of Al 2 O 3 is 30 - 45 wt%, for example, it can be 30 wt%, 35 wt%, 40 wt% or 45 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0031] In the fly ash, the content of CaO is 2 - 10 wt%, for example, it can be 2 wt%, 5 wt%, 8 wt% or 10 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0032] In the fly ash, the content of Fe 2 O is 2 - 8 wt%, for example, it can be 2 wt%, 4 wt%, 5 wt%, 6 wt% or 8 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0033] Preferably, the particle size of the fly ash is such that the residue on a 45 μm sieve is ≤ 25%, for example, it can be 25%, 20%, 15%, 10% or 5%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0034] Preferably, the 28 - day activity index of the fly ash is ≥ 75%, for example, it can be 75%, 80%, 85%, 90%, 95% or 100%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0035] Preferably, the specific surface area of the fly ash is ≥ 350 m 2 / kg, for example, it can be 350 m 2 / kg, 400 m 2 / kg, 450 m 2 / kg, 500 m 2 / kg, 600 m 2 / kg or 800 m 2 / kg, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0036] In the present invention, the gypsum meets the index requirements of secondary gypsum in the national standard GB / T 5483-2008.

[0037] Preferably, the fineness of the gypsum is such that the residue on a 150μm sieve is ≤15%, for example, it can be 15%, 12%, 10%, 5% or 1%, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0038] Preferably, the content of calcium sulfate dihydrate in the gypsum is ≥90%, for example, it can be 90%, 92%, 95%, 98% or 100%, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0039] Preferably, the alkali activator includes sodium hydroxide and / or sodium silicate.

[0040] In the present invention, the sodium hydroxide used meets the index requirements of industrial sodium hydroxide in GB / T 209-2018.

[0041] Preferably, the water reducer includes a polycarboxylate water reducer.

[0042] In the present invention, the polycarboxylate water reducer used meets the index requirements in GB8076-2008.

[0043] In a second aspect, the present invention provides a method for preparing the curing agent described in the first aspect, and the preparation method includes the following steps:

[0044] (1) Mix blast furnace slag, fly ash, sulfoaluminate and gypsum to obtain a dry mixture;

[0045] (2) Mix the dry mixture with an alkali activator solution and react to obtain a pre-mixed material;

[0046] (3) Mix the pre-mixed material with a water reducer solution to obtain the curing agent.

[0047] The preparation method provided by the present invention first mixes the main component raw materials, then undergoes alkali activation to generate a hydration reaction, resulting in gelation, and has good fluidity under the action of a water reducer, enabling good consolidation.

[0048] Preferably, the solid content of the alkali activator solution is 2-10%, for example, it can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0049] Preferably, the temperature of the mixing reaction in step (2) is 5-40°C. For example, it can be 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C or 40°C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0050] Preferably, the solid content of the water reducer solution is 15-25%. For example, it can be 15%, 18%, 20%, 22% or 25%, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0051] In a third aspect, the present invention provides an application of the curing agent described in the first aspect, and the curing agent is used for deep mixing piles in soft soil foundations.

[0052] Preferably, the soil moisture content of the soft soil foundation is 40-90%. For example, it can be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] (1) The mixing pile curing agent provided by the present invention forms a gel by alkali activation of waste resources such as slag and fly ash, has good fluidity under the action of a water reducer, enables soil particles to form good consolidation, and the cured soil has high strength and good stability, especially suitable for soft soil foundations with high moisture content.

[0055] (2) The mixing pile curing agent provided by the present invention can quickly shorten the construction period, and the construction can be completed by using the two-spray and one-stir process, improving the construction efficiency.

[0056] (3) The curing agent provided by the present invention reduces the cement consumption, reduces the generation of carbon dioxide, utilizes waste resources, conforms to the concept of low-carbon environmental protection, and the raw materials are cheap, reducing the project cost. Specific Embodiments

[0057] The technical solutions of the present invention will be further described below through specific embodiments.

[0058] To clearly illustrate the technical solutions of the present invention, in the specific embodiments, the composition of the blast furnace slag powder used, by mass percentage, includes: CaO 35.4wt%, SiO 2 30.2wt%, Al 2 O 3 18.9wt%, MgO 6.5wt%, Fe 2 O 3 1.36wt%, TiO 23.62wt%SO 3 2.42wt%Na 2 O 1.13wt%, other impurities 0.47wt%

[0059] The composition of the fly ash used, in terms of mass percentage, includes: SiO 2 49wt%Al 2 O 3 35wt%, CaO9wt%, Fe 2 O 3 3wt%,TiO 2 1.23wt%SO 3 0.42wt%, MgO 0.62wt%, Na 2 O 1.26wt%, other impurities 0.47wt%.

[0060] The grade of sulphoaluminate cement is R.SAC42.5.

[0061] The polycarboxylate water reducer used is a DFTR-PCE polycarboxylate water reducer with a solid content of 20%.

[0062] Example 1

[0063] This embodiment provides a curing agent for deep mixing piles in soft soil foundation, and the raw material composition of the curing agent includes, by weight:

[0064] 24 parts of S95 grade granulated blast furnace slag powder, 6 parts of fly ash, 26 parts of sulphoaluminate cement, 26 parts of gypsum, 3 parts of sodium hydroxide, and 0.2 parts of polycarboxylate water reducer.

[0065] The preparation method of the curing agent comprises the following steps:

[0066] (1) According to the weight percentage, 3 parts of sodium hydroxide and 7 parts of water were mixed and stirred at room temperature for 15 minutes at a stirring rate of 35 r / min to prepare an alkaline activator solution, wherein the solid content was 30%;

[0067] (2) 0.2 parts of polycarboxylate water reducer and 0.8 parts of water were mixed and stirred at a constant speed for 15 minutes at a stirring rate of 55 r / min to prepare a polycarboxylate water reducer solution, wherein the solid content was 20%;

[0068] (3) 24 parts of S95 grade granulated blast furnace slag powder, 6 parts of fly ash, 26 parts of sulphoaluminate cement, and 26 parts of gypsum were mixed and stirred for 30 minutes to obtain a dry mix;

[0069] (4) pouring the alkali activator solution into the dry mix and stirring to uniformly mix to obtain a premix;

[0070] (5) Stir the obtained pre-mixed material and the polycarboxylate superplasticizer solution evenly to obtain the curing agent.

[0071] Example 2

[0072] This example provides a curing agent for deep mixing piles in soft soil foundations. The raw material composition of the curing agent includes, by weight:

[0073] 28 parts of S95 grade granulated blast furnace slag powder, 10 parts of fly ash, 34 parts of sulfoaluminate cement, 33 parts of gypsum, 4 parts of sodium hydroxide, and 0.3 parts of polycarboxylate superplasticizer.

[0074] The preparation method of the curing agent includes the following steps:

[0075] (1) By weight, mix 3 parts of sodium hydroxide and 9 parts of water at room temperature and stir for 15 minutes at a stirring rate of 35 r / min to prepare an alkali activator solution with a solid content of 30%;

[0076] (2) Mix 0.3 parts of polycarboxylate superplasticizer and 1.2 parts of water and stir evenly for 15 minutes at a stirring rate of 55 r / min to prepare a polycarboxylate superplasticizer solution with a solid content of 20%;

[0077] (3) Mix 28 parts of S95 grade granulated blast furnace slag powder, 10 parts of fly ash, 34 parts of sulfoaluminate cement, and 33 parts of gypsum and stir for 30 minutes to obtain a dry mixture;

[0078] (4) Pour the alkali activator solution into the dry mixture and stir evenly to obtain a pre-mixed material;

[0079] (5) Stir the obtained pre-mixed material and the polycarboxylate superplasticizer solution evenly to obtain the curing agent.

[0080] Example 3

[0081] This example provides a curing agent for deep mixing piles in soft soil foundations. The raw material composition of the curing agent includes, by weight:

[0082] 32 parts of S95 grade granulated blast furnace slag powder, 13 parts of fly ash, 34 parts of sulfoaluminate cement, 26 parts of gypsum, 5 parts of sodium hydroxide, and 0.4 parts of polycarboxylate superplasticizer.

[0083] The preparation method of the curing agent includes the following steps:

[0084] (1) By weight, mix 5 parts of sodium hydroxide and 12 parts of water at room temperature and stir for 15 minutes at a stirring rate of 35 r / min to prepare an alkali activator solution with a solid content of 30%;

[0085] (2) Mix 0.4 parts of polycarboxylate superplasticizer and 1.6 parts of water, and stir evenly at a speed of 55 r / min for 15 minutes to prepare a polycarboxylate superplasticizer solution, where the solid content is 20%.

[0086] (3) Mix 32 parts of S95 grade granulated blast furnace slag powder, 13 parts of fly ash, 34 parts of sulfoaluminate cement, and 26 parts of gypsum, and stir for 30 minutes to obtain a dry mixture.

[0087] (4) Pour the alkali activator solution into the dry mixture and stir evenly to obtain a pre-mixed material.

[0088] (5) Stir and evenly mix the obtained pre-mixed material with the polycarboxylate superplasticizer solution to obtain the curing agent.

[0089] Comparative Example 1

[0090] This comparative example provides a curing agent, and the curing agent is cement.

[0091] The grade of the cement is P.O42.5.

[0092] Comparative Example 2

[0093] This comparative example provides a curing agent. The raw material composition of the curing agent, compared with Example 1, does not add polycarboxylate superplasticizer, and the rest are the same as in Example 1.

[0094] The preparation method of the curing agent, compared with Example 1, does not add polycarboxylate superplasticizer solution, and the rest are the same as in Example 1.

[0095] Comparative Example 3

[0096] This comparative example provides a curing agent. The raw material composition of the curing agent, compared with Example 1, replaces gypsum with lime of equal mass, and the rest are the same as in Example 1.

[0097] The preparation method of the curing agent, compared with Example 1, replaces gypsum with lime of equal mass, and the rest are the same as in Example 1.

[0098] Comparative Example 4

[0099] This comparative example provides a curing agent. The raw material composition of the curing agent, compared with Example 1, replaces sulfoaluminate cement with Portland cement of equal mass, and the rest are the same as in Example 1.

[0100] The preparation method of the curing agent, compared with Example 1, replaces sulfoaluminate cement with Portland cement of equal mass, and the rest are the same as in Example 1.

[0101] Comparative Example 5

[0102] This comparative example provides a curing agent. The raw material composition of the curing agent is the same as that of Example 1 except that the S95 grade granulated blast furnace slag powder is 20 parts.

[0103] The preparation method of the curing agent is the same as that of Example 1 except that the S95 grade granulated blast furnace slag powder is controlled to be 20 parts.

[0104] Comparative Example 6

[0105] This comparative example provides a curing agent. The raw material composition of the curing agent is the same as that of Example 1 except that the S95 grade granulated blast furnace slag powder is 35 parts.

[0106] The preparation method of the curing agent is the same as that of Example 1 except that the S95 grade granulated blast furnace slag powder is controlled to be 35 parts.

[0107] Performance test

[0108] The curing agent provided in the examples and comparative examples is uniformly mixed with water at a ratio of 1:1.2 and stirred for 3 minutes to obtain a curing agent slurry.

[0109] In a soft soil layer with a natural water content of 50% and a soil density of 1.78 g / cm 3 , the high-pressure jet grouting pile construction technology is adopted. The curing agent slurry is constructed according to a pile diameter of 850 mm, a height of 10 m, and an admixture ratio of 20%. Cores are taken at 3 days, 7 days, and 28 days respectively, and the unconfined compressive strength is detected. The obtained results are listed in Table 1.

[0110] Table 1

[0111]

[0112]

[0113] As can be seen from Table 1, the curing agent provided by the present invention has a good curing effect, the strength of the cured soil is high, and it is suitable for soft soil foundations with high water content.

[0114] Compared with Example 1, in Comparative Example 1, the consolidation strength of cement used is far inferior to that of the curing agent of the present invention, and cement cannot form a gelled structure and is difficult to meet the consolidation requirements. In Comparative Example 2, there is no water reducer, and the performance of the curing agent slurry cannot be regulated, and the consolidation effect is reduced. In Comparative Example 3, gypsum is replaced with lime, resulting in a decrease in the curing strength. This is because the lime will shrink in volume when hardening, and a large amount of water evaporation will cause capillary water loss and shrinkage, forming more voids and microcracks in the soil. These voids and cracks will weaken the connection between soil particles and reduce the overall strength of the soil. In Comparative Example 4, sulphoaluminate cement is replaced with ordinary Portland cement, and the consolidation strength decreases. The calcium sulfonate generated by the hydration of sulphoaluminate cement has a high needle-shaped or columnar crystal structure. This crystal structure can be interwoven to form a tight network structure, which plays a good anchoring and cementing role on soil particles, thereby improving the overall strength and stability of the solidified soil. The hydration of ordinary Portland cement mainly generates products such as calcium silicate gel. Although it can also play a cementing role, its structure is relatively loose, and its binding force and cementing effect with soil particles are not as good as the hydration product of sulphoaluminate cement. In addition, ordinary Portland cement will also generate calcium hydroxide during the hydration process. Calcium hydroxide may react with some acidic substances in the soil, further affecting the cementing effect, resulting in a decrease in the strength of the solidified soil. In Comparative Examples 5 and 6, the mineral powder has a certain activity and can undergo a secondary hydration reaction when it acts together with cementitious materials such as cement. When the mineral powder content is too low, the substances participating in the secondary hydration reaction are reduced, and the generated hydration products with cementitious properties, such as calcium silicate gel, are also reduced accordingly, resulting in insufficient cementing substances between soil particles, and the soil particles cannot be effectively and tightly bonded together, thereby causing the overall strength of the solidified soil to decrease. When the mineral powder is excessive, the concentration of alkaline substances such as cement may be diluted, destroying the alkaline environment that is conducive to the hydration reaction, resulting in an insufficient alkaline environment that is difficult to stimulate, making the cement hydration reaction incomplete, and the generated hydration products are reduced, thereby failing to provide sufficient cementing effect to enhance the connection between soil particles, resulting in a decrease in the strength of the solidified soil.

[0115] In summary, the mixing pile curing agent provided by the present invention forms gelation by alkali activation of waste resources such as slag and fly ash, has good fluidity under the action of a water reducer, and enables soil particles to be well consolidated. The solidified soil has high strength and good stability, and is particularly suitable for soft soil foundations with high water content.

[0116] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A curing agent for deep mixing piles in soft soil foundation, characterized in that: The raw material composition of the curing agent includes, by weight: 24-32 parts of blast furnace slag, 6-13 parts of fly ash, 26-34 parts of sulphoaluminate cement, 26-33 parts of gypsum, 2-5 parts of alkali activator, and 0.1-0.5 parts of water reducing agent.

2. The curing agent according to claim 1, characterized in that The blast furnace slag comprises: CaO 35-50wt%, SiO2 25-45wt%, Al2O3 10-20wt%, MgO 5-10wt%, Fe2O3 0.5-2.0wt%; Preferably, the activity index of the blast furnace slag is ≥95%; Preferably, the specific surface area of ​​the blast furnace slag is ≥450m 2 / kg; Preferably, the blast furnace slag has a fineness of 45 μm and a sieve residue of ≤10%.

3. The curing agent according to claim 1 or 2, characterized in that The fly ash comprises: SiO2 40-55wt%, Al2O3 30-45wt%, CaO 2-10wt%, Fe2O3 2-8wt%; Preferably, the fly ash has a particle size of 45 μm and a sieve residue of ≤25%; Preferably, the 28-day activity index of the fly ash is ≥75%; Preferably, the specific surface area of ​​the fly ash is ≥350m 2 / kg.

4. The curing agent according to any one of claims 1 to 3, characterized in that The fineness of the gypsum is 150 μm and the residue on the sieve is ≤15%; Preferably, the calcium sulfate dihydrate content of the gypsum is ≥ 90%.

5. The curing agent according to any one of claims 1 to 4, characterized in that The alkaline activator includes sodium hydroxide and / or sodium silicate.

6. The curing agent according to any one of claims 1 to 5, characterized in that The water reducing agent includes a polycarboxylate water reducing agent.

7. A method for preparing a curing agent according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: (1) mixing blast furnace slag, fly ash, sulphoaluminate and gypsum to obtain a dry mix; (2) mixing the dry mix with an alkali activator solution to obtain a premix; (3) Mixing the premix with a water reducing agent solution to obtain the curing agent.

8. The preparation method according to claim 7, characterized in that: The solid content of the alkaline activator solution is 2-20%; Preferably, the temperature of the mixing reaction in step (2) is 5-40°C.

9. The preparation method according to claim 7 or 8, characterized in that: The solid content of the water reducing agent solution is 15-25%.

10. Use of a curing agent as claimed in any one of claims 1 to 6, characterized in that: The curing agent is used for deep mixing piles in soft soil foundation; The soil moisture content of the soft soil foundation is 40-90%.

Images