Curing agent for flow-state solidified soil and flow-state solidified soil prepared from curing agent

Abstract

The invention discloses a curing agent for flow-state solidified soil and flow-state solidified soil prepared from the curing agent, 100 parts by mass of the curing agent comprises 10-30 parts of cement, 30-50 parts of calcium-based desulfurized fly ash, 2-5 parts of a crystal nucleus type early strength agent, 1-5 parts of an air entraining and water reducing agent and the balance of water; the crystal nucleus type early strength agent comprises nano silicon dioxide and nano hydrated calcium silicate. According to the invention, the interaction between the industrial solid waste calcium-based desulfurized ash and the crystal nucleus type early strength agent is utilized, so that the strength and the fluidity of the fluid-state solidified soil are improved, and the resource utilization of the calcium-based desulfurized ash is realized.

Description

Technical Field

[0001] The invention relates to the technical field of construction mud treatment, in particular to a curing agent for fluidized solidified soil and the fluidized solidified soil made from the curing agent. Background Art

[0002] At present, in the backfill construction process of various building foundation trenches, two types of backfill materials are usually used for backfilling, one is traditional backfill soil, and the other is fluidized solidified soil:

[0003] Traditional backfill soil is mainly solid materials such as sand, gravel, and ash soil. Since there are gaps between the particles of sand, gravel, and ash soil, large-scale mechanical devices are needed to roll and compact the traditional backfill soil after backfilling. For some building foundation pits with narrow space, due to site restrictions, large-scale mechanical devices are inconvenient to operate, resulting in certain limitations in the application of traditional backfill soil.

[0004] Fluidized solidified soil is a new type of backfill material. It is made by mixing waste mud, solidifying agent (including cement) and water in a certain ratio and has certain fluidity and strength. During the construction process, fluidized solidified soil exists in the form of fluid, so it can fill any part of the building space without rolling and compacting after backfilling. After the fluidized solidified soil is backfilled, it will condense into a stable solid by its own physical and chemical action, forming a solid material to fill the building foundation trench.

[0005] Although fluidized solidified soil has the above advantages compared with traditional backfill soil, the existing fluidized solidified soil still has technical problems of low soil strength and poor fluidity. Summary of the invention

[0006] The purpose of the invention is to solve the problems of low soil strength and poor fluidity of existing fluidized solidified soil, and to provide a fluidized solidified soil curing agent and a preparation method thereof.

[0007] In order to achieve the above-mentioned object, the present invention provides a fluidized solidified soil curing agent, which comprises, based on 100 parts by mass, 10 to 30 parts of cement, 30 to 50 parts of calcium-based desulfurized ash, 2 to 5 parts of crystal nucleus type early strength agent, 1 to 5 parts of air-entraining water-reducing agent, and the balance is water; the crystal nucleus type early strength agent comprises nano silicon dioxide and nano calcium silicate hydrate.

[0008] Optionally, the particle sizes of the nano silicon dioxide and the nano calcium silicate hydrate are 10 nm to 40 nm, and the mass ratio is 1:1.

[0009] Optionally, the curing agent further includes: a dispersant, and the mass portion of the dispersant is 0.2 to 0.5 parts.

[0010] Optionally, the air-entraining water-reducing agent includes a polycarboxylic acid-based water-reducing agent.

[0011] Optionally, the cement is silicate cement and / or sulphoaluminate cement.

[0012] Optionally, the strength grade of the silicate cement and the sulphoaluminate cement is above grade 32.5.

[0013] The present invention also provides a fluidized solidified soil, which comprises: engineering mud and the above-mentioned solidifying agent. The mass ratio of the engineering mud to the solidifying agent is 1:(1-2). The solid content of the engineering mud is 16%-18%.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) The present invention utilizes the interaction between industrial solid waste calcium-based desulfurization ash and crystal nucleus-type early strength agent to improve the strength and fluidity of fluidized solidified soil while realizing resource utilization of calcium-based desulfurization ash.

[0016] (2) The preparation process of the present invention is simple and reliable, easy to operate, and the prepared fluidized solidified soil has a wide range of applications and has important application prospects.

[0017] (3) The fluidized solidified soil curing agent provided by the present invention does not require high temperature and high pressure conditions during the preparation process, and only requires simple mixing and stirring at room temperature, which greatly reduces production energy consumption and reduces pressure on the environment, and is in line with the current development trend of green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the preparation process of the fluidized solidified soil of the present invention. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described below in conjunction with embodiments.

[0020] The invention provides a curing agent for fluidized solidified soil. The curing agent comprises, based on 100 parts by mass, 10 to 30 parts of cement, 30 to 50 parts of calcium-based desulfurized ash, 2 to 5 parts of crystal nucleus type early strength agent, 1 to 5 parts of air entraining water reducing agent, and the balance is water; the crystal nucleus type early strength agent comprises nano silicon dioxide and nano calcium silicate hydrate.

[0021] During the experiment, the applicant found that the industrial waste in the steel plant, calcium-based desulfurization ash, can improve the strength and fluidity of fluidized solidified soil. The reason is:

[0022] Calcium-based desulfurization ash contains a certain amount of SiO 2 and Al 2 O 3 , SiO 2 and Al2 O 3 It has an effect of improving the mechanical strength of fluidized solidified soil. In addition, calcium-based desulfurized ash also has a finer particle size and good fluidity. Therefore, using it to prepare fluidized solidified soil can improve the strength and fluidity of fluidized solidified soil, and can further promote the resource utilization of industrial solid waste.

[0023] During the test, it was found that if calcium-based desulfurization ash is used alone, the SiO 2 and Al 2 O 3 The amount of dissolution in water is very low, resulting in very limited improvement in the strength of fluidized solidified soil using calcium-based desulfurized ash alone. Therefore, the present invention further adds a crystal nucleus early strength agent (nano silicon dioxide and nano calcium silicate hydrate) to the fluidized solidified soil, and improves the strength of the fluidized solidified soil through the action of the crystal nucleus early strength agent alone and the interaction between the crystal nucleus early strength agent and the calcium-based desulfurized ash.

[0024] The principle of using crystal nucleus type early strength agent alone to improve the strength of fluidized solidified soil:

[0025] Nano Calcium Silicate Hydrate (Nano CSH)

[0026] During the cement hydration reaction, calcium silicate hydrate (CSH), Ca(OH) 2 Among them, CSH is the main substance to improve the strength of fluidized solidified soil. Therefore, adding crystal nucleus early strength agent nano CSH to fluidized solidified soil will enhance the strength of fluidized solidified soil.

[0027] Nano Silica

[0028] Among the above hydration reaction products, Ca(OH) 2 It will have an adverse effect on the strength of fluidized solidified soil, but the SiO dissolved in water 2 Can be used with Ca(OH) 2 The reaction generates CSH gel, which will remove Ca(OH) 2 Transformed into CSH gel which is beneficial to strength (reaction equation: Ca(OH) 2 +SiO 2 +H 2 O→CSH), so adding crystal nucleus type early strength agent nano-silica into fluidized solidified soil will enhance the strength of fluidized solidified soil.

[0029] The principle of the interaction between the crystal nucleus type early strength agent and the calcium-based desulfurized ash to improve the strength of fluidized solidified soil:

[0030] Crystal core type early strength agent nano CSH and nano SiO 2 Can promote the SiO2 in calcium-based desulfurization ash 2and Al 2 O 3 Dissolution in water to increase the strength of fluidized solidified soil:

[0031] Nano-CSH and Nano-SiO 2 It is a nanoparticle (particle size is 10nm ~ 40nm), the particles are small, dispersed in water can be used as SiO 2 and Al 2 O 3 The crystal growth point induces SiO 2 and Al 2 O 3 Dissolved from calcium-based desulfurization ash and dispersed in water. SiO 2 The dissolution of SiO 2 and Ca(OH) 2 The reaction increases the amount of CSH gel produced and improves the strength of fluidized solidified soil. 2 O 3 It has high hardness and high strength, and can promote the compactness and strength of fluidized solidified soil.

[0032] Furthermore, the crystal nucleus type early strength agent used in the present invention can not only improve the overall strength of the fluidized solidified soil, but also improve the early strength of the fluidized solidified soil, so that the fluidized solidified soil can meet the construction requirements as early as possible to shorten the construction period. The principle is as follows:

[0033] When conventional cement (cement without the crystal nucleus type early strength agent of the present invention) is hydrated at an early stage, the generated hydration product CSH gel is first formed on the surface of cement particles, covering the surface of unhydrated cement particles, making it difficult for unhydrated cement particles to contact with water, thereby preventing cement hydration.

[0034] When the crystal nucleus type early strength agent nano CSH is added to cement, the nano CSH acts as an additional crystal nucleus growth point, so that the CSH gel can not only nucleate and grow on the surface of cement particles, but also nucleate and grow on the nano CSH, effectively weakening the coverage of CSH gel on the surface of cement particles, promoting cement particles to form more CSH gel in the early stage of hydration, accelerating the development of early strength of fluidized solidified soil, and improving the early strength of fluidized solidified soil.

[0035] Furthermore, the calcium-based desulfurization ash used in the present invention is taken from the Meishan Iron and Steel Base of Baowu Group. It is a desulfurization agent slaked lime slurry that is atomized and reacted with SO in the flue gas at high temperature. 2 The desulfurization byproduct obtained by the reaction mainly includes CaO, which reacts with water to generate Ca(OH) 2 , and subsequently SiO 2 Converted into CSH gel to improve the strength of fluidized solidified soil (principle as above).

[0036] The cement used in this application is silicate cement and / or sulphoaluminate cement, with a strength grade of 32.5 or above. These two types of cement are stable in nature, and the hydration product CSH formed by reacting with water can improve the strength of fluidized solidified soil.

[0037] The air-entraining water-reducing agent used in the present application may be a polycarboxylic acid-based water-reducing agent, which has a retarding effect and can adjust the fluidity of fluidized solidified soil.

[0038] In some embodiments, the curing agent further includes, by weight: 0.2 to 0.5 parts of a dispersant (purchased from DCH Chemical International Ltd., DRUM), wherein the main component of the dispersant is an acrylic block copolymer, which can reduce the surface tension of water and improve the fluidity of the fluidized solidified soil.

[0039] The present invention also provides a fluidized solidified soil, comprising: the above-mentioned solidifying agent, and engineering mud. The engineering mud is waste mud generated during the construction of bored pile foundation, underground continuous wall, mud shield and other projects, with a solid content of 16% to 18%.

[0040] In some embodiments, the mass ratio of the engineering mud to the curing agent in the fluidized solidified soil is 1:(1-2).

[0041] like Figure 1 As shown, the present invention also provides a method for preparing the above-mentioned fluidized solidified soil:

[0042] Weigh the curing agent and engineering mud according to the mass ratio, and then use a cement mortar mixer to stir for 10 to 20 minutes to make the ready-to-use fluidized solidified soil. When in use, the fluidized solidified soil can be transported to the construction site by a tank truck for construction and standard curing (temperature 20±2℃, relative humidity ≥95%) to further enhance its strength.

[0043] Example 1

[0044] The present embodiment provides a fluidized solidified soil curing agent, including 10 parts of uniformly mixed ordinary Portland cement, 10 parts of sulphoaluminate cement, 50 parts of calcium-based desulfurized ash, 2 parts of crystal nucleus type early strength agent, 3 parts of air entraining water reducing agent (purchased from Anhui Zhongtie Material Technology Co., Ltd., ZT-1), 0.05 parts of dispersant, and the balance is water.

[0045] The crystal nucleus type early strength agent includes: nano CSH (purchased from Suzhou Sanhe Nano Technology Co., Ltd., SH-nm40) and nano SiO 2 (Purchased from Suzhou Youzi Nanomaterials Co., Ltd., UG-SP15F), the mass ratio of the two is 1:1.

[0046] Example 2

[0047] The present embodiment provides a fluidized solidified soil curing agent, including 15 parts of uniformly mixed ordinary Portland cement, 15 parts of sulphoaluminate cement, 40 parts of calcium-based desulfurized ash, 2 parts of crystal nucleus type early strength agent, 3 parts of air entraining water reducing agent (purchased from Anhui Zhongtie Material Technology Co., Ltd., ZT-1), 0.05 parts of dispersant, and the balance is water.

[0048] The crystal nucleus type early strength agent includes: nano CSH (purchased from Suzhou Sanhe Nano Technology Co., Ltd., SH-nm40) and nano SiO 2 (Purchased from Suzhou Youzi Nanomaterials Co., Ltd., UG-SP15F), the mass ratio of the two is 1:1.

[0049] Application Example 1

[0050] This application example provides a fluidized solidified soil, which is prepared by uniformly mixing the solidifying agent in Example 1 with engineering mud in a mass ratio of 4:6.

[0051] Application Example 2

[0052] This application example provides a fluidized solidified soil, which is prepared by uniformly mixing the solidifying agent in Example 1 with the engineering mud in a mass ratio of 5:5.

[0053] Application Example 3

[0054] This application example provides a fluidized solidified soil, which is prepared by uniformly mixing the solidifying agent in Example 2 with engineering mud in a mass ratio of 4:6.

[0055] Application Example 4

[0056] This application example provides a fluidized solidified soil, which is prepared by uniformly mixing the solidifying agent in Example 2 with the engineering mud in a mass ratio of 5:5.

[0057] Comparative application example 1

[0058] This comparative application example provides a fluidized solidified soil, which differs from application example 1 in that the solidifying agent does not contain a crystal nucleus-type early strength agent.

[0059] Comparative Application Example 2

[0060] This comparative application example provides a fluidized solidified soil, which differs from application example 2 in that the solidifying agent does not contain a crystal nucleus-type early strength agent.

[0061] The test results of the above application examples and comparative application examples are shown in Table 1, which are carried out according to the test method of unconfined compressive strength of inorganic binder stabilized materials T0805-2024 in the test specification for inorganic binder stabilized materials for highway engineering (JTG3441-2024). The water stability coefficient is expressed by the ratio of the unconfined compressive strength of the unconfined compressive strength of the unconfined compressive strength of the unconfined compressive strength specimen after the specimen is cured to the age and soaked in water for 24 hours to the unconfined compressive strength of the specimen after curing to the corresponding age.

[0062] Table 1 Unconfined compressive strength and water stability coefficient of fluidized solidified soil in application examples and comparative examples

[0063]

[0064] It can be seen from the above test data that after adding the curing agent of the present invention, the compressive strength and water stability of the abandoned engineering mud (the 28d unconfined compressive strength of the abandoned engineering mud is 0.02MPa) are significantly improved. The reason why the test parameters of Application Example 3 are higher than those of Application Example 1 can be analyzed as follows: the amount of cement in Application Example 3 is higher than that in Application Example 1; the reason why the test parameters of Application Example 2 are higher than those of Application Example 1 can be analyzed as follows: the amount of abandoned engineering mud in Application Example 2 is small, the amount of curing agent is large, and the hydration activity of cement is high (the ability of cement to react chemically with water in water), thereby improving the strength of the solidified soil. It can be seen from comparative application examples 1, 2 and 1 to 4 that after adding the curing agent of the present invention, the 7d strength of the fluidized solidified soil is significantly improved. The reason can be analyzed as follows: the crystal nucleus type early strength agent of this patent can effectively improve the early strength of the fluidized solidified soil without causing significant reduction in the later strength. At the same time, no harmful ions are introduced and it has good compatibility with cement. The strength of the fluidized solidified soil is effectively improved through the combined action of the crystal nucleus type early strength agent, cement and calcium-based desulfurization ash.

[0065] In summary, the present invention provides a curing agent for fluidized solidified soil, which comprises, by weight, 100 parts by weight: 10 to 30 parts of cement, 30 to 50 parts of calcium-based desulfurized ash, 2 to 5 parts of crystal nucleus-type early strength agent, 1 to 5 parts of air-entraining water-reducing agent, and the balance is water; the crystal nucleus-type early strength agent comprises nano silicon dioxide and nano calcium silicate hydrate. The present invention utilizes the interaction between industrial solid waste calcium-based desulfurized ash and crystal nucleus-type early strength agent, and realizes the resource utilization of calcium-based desulfurized ash while improving the strength and fluidity of fluidized solidified soil.

[0066] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A fluidized solidified soil curing agent, characterized in that: Based on 100 parts by mass, the curing agent includes: 10 to 30 parts of cement, 30 to 50 parts of calcium-based desulfurized ash, 2 to 5 parts of crystal nucleus type early strength agent, 1 to 5 parts of air entraining water reducing agent, and the balance is water; The crystal nucleus type early strength agent comprises nano silicon dioxide and nano calcium silicate hydrate.

2. The fluidized solidified soil curing agent according to claim 1, characterized in that: The particle sizes of the nano silicon dioxide and nano calcium silicate hydrate are 10nm to 40nm.

3. The fluidized solidified soil curing agent according to claim 1, characterized in that: The mass ratio of the nano silicon dioxide to the nano calcium silicate hydrate is 1:

1.

4. The fluidized solidified soil curing agent according to claim 1, characterized in that: The curing agent further includes: a dispersant, and the mass portion of the dispersant is 0.2 to 0.5 parts.

5. The fluidized solidified soil curing agent according to claim 1, characterized in that: The air-entraining water-reducing agent includes a polycarboxylic acid-based water-reducing agent.

6. The fluidized solidified soil curing agent according to claim 1, characterized in that: The cement is silicate cement and / or sulphoaluminate cement.

7. The fluidized solidification soil curing agent according to claim 6, characterized in that: The strength grade of the silicate cement and the sulphoaluminate cement is above grade 32.

5.

8. A fluidized solidified soil, characterized in that: The fluidized solidified soil comprises: engineering mud, and the solidifying agent according to any one of claims 1 to 7.

9. The fluidized solidified soil according to claim 8, characterized in that: The mass ratio of the engineering mud to the curing agent is 1:(1-2).

10. The fluidized solidified soil according to claim 8, characterized in that: The solid content of the engineering mud is 16% to 18%.

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