Composite excitation solid waste cementing material for soft soil solidification as well as preparation and application methods of composite excitation solid waste cementing material

Abstract

The invention discloses a composite excitation solid waste cementing material for soft soil solidification and preparation and application methods thereof, and belongs to the technical field of geopolymer materials. Comprising 6.8-7.2 parts of cement kiln ash, 81.8-82.2 parts of mineral powder and 10.6-11.4 parts of a composite activator, and the composite activator is composed of quick lime, gypsum and a high-molecular flocculation agent according to the mass ratio of 10: 1: 0.04. The quick lime, the gypsum and the high-molecular flocculation agent are uniformly stirred to prepare the compound alkali activator, the compound alkali activator is uniformly stirred with the cement kiln ash and the mineral powder to prepare a target material, and the material is uniformly stirred with the soft soil to realize the solidification of the soft soil. According to the method, cement is completely replaced by the kiln dust-based composite excitation cementing material, secondary utilization of industrial wastes such as cement kiln dust and mineral powder is realized, the industrial wastes are uniformly stirred with soft soil, the soft soil foundation is rapidly solidified, and the construction is simple and rapid.

Description

Technical Field

[0001] This invention relates to the field of geopolymer materials technology, and in particular to a composite activated solid waste cementitious material for soft soil solidification and its preparation and application methods. Background Technology

[0002] Soft soil foundation treatment is a crucial step in engineering construction. Currently, the mainstream treatment methods are divided into three categories: physical methods, biological methods, and chemical methods. Physical methods include dynamic compaction, vacuum pumping, preloading, a combination of vacuum and preloading, drainage, and wellpoint dewatering. Their core principle is to rapidly drain pore water from the soft soil through external impact loads or seepage, reducing the effective stress in the soft soil particle structure and thus improving the bearing capacity and deformation resistance of the soft soil foundation. However, these methods have significant drawbacks such as long construction time, long stabilization time, complex procedures, and high treatment costs. Biological methods involve injecting aerobic bacteria, anaerobic bacteria, and nutrient solutions into the soft soil. Through biological processes, they produce CaCO3-like materials that connect solid particles and fill particle pores. However, this method is costly, technically demanding, expensive, and has a long construction period, making it unsuitable for large-area foundation treatment. Chemical methods mainly use cement-based cementitious materials, which are injected into soft soil through powder spraying or grouting. The cementitious materials form a gel that connects soil particles, fills pores, and drains pore water, so that the soft soil foundation meets engineering requirements. However, this method has prominent problems such as large cement consumption, high carbon emissions, and high engineering costs. Moreover, when applied in areas with high groundwater levels, the foundation bearing capacity develops slowly.

[0003] Therefore, from the perspectives of reducing carbon emissions and engineering costs, disposing of solid waste, and reducing environmental pollution, this invention proposes a weak alkali-salt-polymer composite activated solid waste cementing material for soft soil solidification and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a composite activated solid waste cementitious material for soft soil solidification, as well as its preparation and application methods, to solve the problems in the background technology and achieve the dual goals of industrial solid waste resource utilization and efficient solidification of soft soil foundations.

[0005] To achieve the above objectives, the present invention provides a composite activated solid waste cementitious material for soft soil solidification, which is composed of cement kiln ash, blast furnace slag powder and composite alkali activator. The mass fractions of each component are as follows: cement kiln ash 6.8-7.2 parts, blast furnace slag powder 81.8-82.2 parts, and composite alkali activator 10.6-11.4 parts; wherein, the composite alkali activator is composed of quicklime, gypsum and polymeric coagulant.

[0006] Preferably, the mass fractions of each component are: 7.2 parts cement kiln ash, 81.8 parts blast furnace slag powder, and 11 parts composite alkali activator.

[0007] Preferably, the mass ratio of quicklime, gypsum, and polymeric coagulant is 10:1:0.04.

[0008] Preferably, the polymeric coagulant is polyacrylamide.

[0009] Preferably, the blast furnace slag powder is S95 grade ore powder.

[0010] The present invention also provides a method for applying the above-mentioned composite activated solid waste cementitious material for soft soil solidification, wherein the composite activated solid waste cementitious material replaces silicate cement for soft soil foundation treatment.

[0011] Preferably, the composite activated solid waste cementitious material replaces silicate cement and is mixed with soft soil at a cement-sand ratio of 1:8-1:12 to achieve soft soil solidification.

[0012] This invention also provides a method for preparing the above-mentioned composite activated solid waste cementitious material for soft soil solidification, comprising the following steps:

[0013] (1) Weigh quicklime, gypsum and polymeric coagulant, place them in a mixer and stir until uniform to make a composite alkali activator;

[0014] (2) Weigh cement kiln ash, blast furnace slag powder and the composite alkali activator prepared in step (1), put them into a mixer and stir until uniform to obtain cementitious material powder.

[0015] This invention utilizes a composite of gypsum and high-molecular-weight polyacrylamide to activate the activity of cement kiln ash, creating a highly alkaline working environment that in turn activates blast furnace slag powder, thereby achieving alkali activation and preparing a zero-carbon emission cementitious material.

[0016] Therefore, the composite activated solid waste cementitious material for soft soil solidification provided by the present invention, as well as its preparation and application method, has the following beneficial effects:

[0017] (1) Replace cement, reduce environmental pressure and cost: This invention uses industrial solid waste such as cement kiln ash and blast furnace slag S95 grade mineral powder as the main raw materials. The composite activated solid waste cementitious material prepared by industrial solid waste can completely replace silicate cement for soft soil foundation treatment. This not only realizes the resource utilization of industrial solid waste and reduces the environmental pollution caused by solid waste storage, but also significantly reduces the high carbon emission problem caused by cement use, and at the same time reduces the engineering cost.

[0018] (2) Excellent strength of soft soil foundation: The composite activated solid waste cementitious material provided by this invention is mainly composed of cement kiln ash from the cement production process and slag powder from the blast furnace smelting process. The raw material particles of the cementitious material are finer, and the gel generated after the composite activation reaction can quickly coat soft soil particles, fill pores, and form a stable particle structure. The test shows that after treating soft soil with the cementitious material with the optimal ratio, the compressive strength can reach 0.76-0.95 MPa after 3 days and 1.29-1.54 MPa after 7 days.

[0019] (3) Simple preparation and construction process: On the one hand, compared with the current soft soil foundation reinforcement materials that use strong alkaline activators and silicate cement, the composite activated solid waste cementitious material provided by the present invention does not require on-site preparation of alkaline solutions and control of activator modulus during the soft soil foundation reinforcement process. It only needs to mix and stir the raw materials in proportion to make cementitious material, and the soft soil can be solidified after being mixed evenly with the soft soil. On the other hand, since the raw material particles are relatively fine, the composite activated solid waste cementitious material does not need to go through complex processes such as drying, grinding, and high temperature during preparation. It has strong engineering adaptability and high construction efficiency.

[0020] (3) Wide range of applications: It can solidify soft soil with different moisture contents (49%-57%). By adjusting the mortar ratio, it can meet the strength requirements of different engineering scenarios and is suitable for large-area soft soil foundation treatment projects.

[0021] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0022] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the invention should be considered equivalent substitutions and are included within the scope of protection of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the scope of protection of the invention.

[0023] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0024] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0025] Unless otherwise specified, the reagents, instruments, and equipment used in this invention are all commonly used by those skilled in the art, and the testing standards all use national or international standards commonly used in the field, without further explanation.

[0026] Materials used in the following examples:

[0027] Cement kiln ash: Industrial grade, particle size ≤0.075mm.

[0028] Blast furnace slag S95 grade mineral powder: meets the requirements of GB / T 18046-2017 standard.

[0029] The composite alkali activator consists of: quicklime (CaO content ≥90%), gypsum (CaSO4·2H2O content ≥95%), and high molecular weight coagulant (polyacrylamide).

[0030] The soft soil used in the experiment was silty soil with moisture contents of 49.3% (M1 group), 50.4% (M2 group), and 57.1% (M3 group).

[0031] Example 1

[0032] This embodiment provides a method for preparing a composite activated solid waste cementitious material for soft soil solidification, including the following steps:

[0033] (1) Weigh lime, gypsum and polyacrylamide in a mass ratio of 10:1:0.04 and place them in a mixer. Stir for 5 minutes until the mixture is homogeneous to prepare a composite activator.

[0034] (2) Weigh cement kiln ash, blast furnace slag powder and composite activator in a mass ratio of 6.8:81.8:11.4 and place them in a mixer. Stir for 5 minutes and stir evenly to prepare a weak alkali-salt-polymer composite activated solid waste cementitious material powder.

[0035] Example 2

[0036] This embodiment provides a method for preparing a composite activated solid waste cementitious material for soft soil solidification. The only difference from Embodiment 1 is that cement kiln ash, blast furnace slag powder and composite activator are weighed in a mass ratio of 6.8:82:11.2. All other aspects are the same as in Embodiment 1 and will not be repeated here.

[0037] Example 3

[0038] This embodiment provides a method for preparing a composite activated solid waste cementitious material for soft soil solidification. The only difference from Embodiment 1 is that cement kiln ash, blast furnace slag powder and composite activator are weighed in a mass ratio of 6.8:82.2:11. All other aspects are the same as in Embodiment 1 and will not be repeated here.

[0039] Example 4

[0040] This embodiment provides a method for preparing a composite activated solid waste cementitious material for soft soil solidification. The only difference from Embodiment 1 is that cement kiln ash, blast furnace slag powder and composite activator are weighed in a mass ratio of 7.2:81.8:11. All other aspects are the same as in Embodiment 1 and will not be repeated here.

[0041] Example 5

[0042] This embodiment provides a method for preparing a composite activated solid waste cementitious material for soft soil solidification. The only difference from Embodiment 1 is that cement kiln ash, blast furnace slag powder and composite activator are weighed in a mass ratio of 7.2:82:10.8. All other aspects are the same as in Embodiment 1 and will not be repeated here.

[0043] Example 6

[0044] This embodiment provides a method for preparing a composite activated solid waste cementitious material for soft soil solidification. The only difference from Embodiment 1 is that cement kiln ash, blast furnace slag powder and composite activator are weighed in a mass ratio of 7.2:82.2:10.6. All other aspects are the same as in Embodiment 1 and will not be repeated here.

[0045] The weak alkali-salt-polymer composite activated solid waste cementitious materials prepared in Examples 1-6 above were subjected to uniaxial compression tests, and the compressive strength at 7 days, 14 days and 28 days was tested respectively. The material strength is shown in Table 1.

[0046] Table 1: Compressive Strength (MPa) of Composite Activated Cementitious Materials

[0047] 7 days 14 days 28 days Example 1 13.4 17.39 22.18 Example 2 20.27 23.38 28.6 Example 3 21.26 24.37 29.79 Example 4 22.37 25.28 30.3 Example 5 19.89 23.2 28.72 Example 6 19.45 22.92 28.56

[0048] As shown in Table 1, the cementitious material obtained in Example 4 has the best compressive strength, with a 28-day strength of 30.3 MPa, making it the optimal formulation.

[0049] The weak alkali-salt-polymer composite activated solid waste cementitious material prepared in Example 4 of this invention was used to treat soft soil with three groups of silty soil with different moisture contents (M1:49.3%, M2:50.4%, and M3:57.1%) at different mortar-cement ratios (1:8, 1:10, and 1:12) to prepare standard specimens. Uniaxial compression tests were carried out on the M1, M2, and M3 test groups to test the compressive strength after 3 days and 7 days. The results are shown in Table 2.

[0050] Table 2: Compressive strength of specimens after treatment on soft soil foundation

[0051]

[0052] As shown in Table 2, the composite activated solid waste cementitious material prepared by the present invention has a good solidification effect on soft soil with different moisture contents, and the strength of the solidified specimens meets the design requirements of soft soil foundation engineering.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A composite activated solid waste cementitious material for soft soil solidification, characterized in that: It is composed of cement kiln ash, blast furnace slag powder and composite alkali activator. The mass fractions of each component are: cement kiln ash 6.8-7.2 parts, blast furnace slag powder 81.8-82.2 parts and composite alkali activator 10.6-11.4 parts. Among them, the composite alkali activator is composed of quicklime, gypsum and polymer flocculant.

2. The composite activated solid waste cementitious material for soft soil solidification according to claim 1, characterized in that, The mass fractions of each component are as follows: 7.2 parts cement kiln ash, 81.8 parts blast furnace slag powder, and 11 parts composite alkali activator.

3. The composite activated solid waste cementitious material for soft soil solidification according to claim 1, characterized in that, The mass ratio of quicklime, gypsum, and polymeric coagulant is 10:1:0.

04.

4. The composite activated solid waste cementitious material for soft soil solidification according to claim 1, characterized in that: The polymeric coagulant is polyacrylamide.

5. A composite activated solid waste cementitious material for soft soil solidification according to claim 1, characterized in that: The blast furnace slag powder is S95 grade ore powder.

6. The application method of a composite activated solid waste cementitious material for soft soil solidification as described in any one of claims 1-5, characterized in that: The composite activated solid waste cementitious material is used to replace silicate cement for soft soil foundation treatment.

7. The application method of the composite activated solid waste cementitious material for soft soil solidification according to claim 6, characterized in that: The composite activated solid waste cementitious material replaces silicate cement and is mixed with soft soil at a cement-sand ratio of 1:8-1:12 to achieve soft soil solidification.

8. A method for preparing a composite activated solid waste cementitious material for soft soil solidification as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Weigh quicklime, gypsum and polymeric coagulant, place them in a mixer and stir until uniform to make a composite alkali activator; (2) Weigh cement kiln ash, blast furnace slag powder and the composite alkali activator prepared in step (1), put them into a mixer and stir until uniform to obtain cementitious material powder.

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