Grouting material matched with high-water-content sludge rapid solidification process and use method thereof

Abstract

The application relates to the technical field of soft soil solidification, in particular to a grouting material for a high-water-content silt rapid solidification process and a use method, which comprises 42.5-grade cement, blast furnace slag powder, gypsum, a quick-setting agent, polyvinyl alcohol, aluminum sulfate, polyacrylamide and a water reducing agent; according to the mass fraction, the 42.5-grade cement is 60-70%, the blast furnace slag powder is 20-30%, the gypsum is 2-5%, the quick-setting agent is 3-5%, the polyvinyl alcohol is 0.3-0.7%, the aluminum sulfate is 1-2%, the polyacrylamide is 0.5-1‰, and the water reducing agent is 1-2‰. The grouting material utilizes the early-strength rapid solidification principle of geopolymer materials, and combines various materials such as the quick-setting agent to regulate the hydration rate, so that the silt stratum can be rapidly disposed.

Description

Technical Field

[0001] This invention relates to the field of soft soil stabilization technology, and in particular to a grouting material and its application method for use in conjunction with a rapid stabilization process for high-water-content silt. Background Technology

[0002] In coastal areas such as the Yangtze River Delta and Pearl River Delta in my country, the soil strata are mainly soft, mostly consisting of silt. This silty soil has a high water content and is in a fluid state. Under these geological conditions, it is virtually impossible to form a stable construction platform for the roadbed, and normal construction is impossible without conducting rapid solidification and dehydration experiments.

[0003] Currently, common treatment methods for soft soil foundations include in-situ consolidation and replacement. Replacement generates a large amount of waste soil that cannot be disposed of and may even damage the environment. In-situ consolidation methods often use cement grout or cement-lime grout for mixing, but the material solidification process is slow and the consolidation efficiency is low, often requiring 7 days before the next construction step can be carried out.

[0004] When treating silt formations, pure cement grouting materials cannot achieve rapid solidification, especially when encountering silt formations with high water content. The water-binding capacity is low, the strength at all ages is significantly reduced, the hydration rate is slow, and the consolidation effect is poor. The bearing capacity of the silt formation after cement treatment is significantly insufficient, which cannot improve construction efficiency.

[0005] When lime is used as a soil consolidation material, its main component, calcium oxide (CaO), has strong hygroscopicity and alkalinity. When quicklime comes into contact with moisture in the silt, it rapidly absorbs the moisture and undergoes a hydration reaction to produce calcium hydroxide (Ca(OH)2). This hydration reaction releases a large amount of heat, causing the moisture in the silt to evaporate quickly, thus achieving the purpose of silt disposal. However, lime contributes poorly to the strength of the cementing material and is almost unable to form an effective consolidation body under high-moisture silt conditions. Furthermore, the drying process of lime produces severe odor pollution, affecting residents' lives. In addition, the treated silt is ultimately highly alkaline, making the treatment of dry-base silt extremely difficult.

[0006] Therefore, during the construction of municipal roadbeds, a rapid silt consolidation material is needed, mainly to cope with the rapid transfer and excavation of silt or the rapid solidification of the upper layer of silt, in order to resist the backflow of the lower layer of silt. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a grouting material and its application method for a rapid solidification process for high water content silt. It utilizes the principle of early strength and rapid solidification of geopolymer materials, and combines multiple materials such as accelerators to control the hydration rate, so as to achieve rapid treatment of silt strata.

[0008] To address the aforementioned technical problems, this application provides the following technical solution:

[0009] A grouting material for use in a rapid solidification process for high-moisture sludge comprises 42.5 grade cement, blast furnace slag powder, gypsum, accelerator, polyvinyl alcohol, aluminum sulfate, polyacrylamide, and water-reducing agent; by mass fraction, the composition is: 42.5 grade cement 60%–70%, blast furnace slag powder 20%–30%, gypsum 2%–5%, accelerator 3%–5%, polyvinyl alcohol 0.3%–0.7%, aluminum sulfate 1%–2%, polyacrylamide 0.5‰–1‰, and water-reducing agent 1‰–2‰.

[0010] As a preferred option, the selected 42.5 grade cement includes early-strength 42.5R type and ordinary 42.5 type.

[0011] Preferably, the selected blast furnace slag powder is water-quenched slag powder with a specific surface area > 400 m². 2 / kg, 28d activity index >95%.

[0012] Preferably, the gypsum can be dihydrate gypsum or anhydrous gypsum, or desulfurized gypsum dried at low temperature in a power plant can be used, ground to a specific surface area >350 m². 2 / kg.

[0013] Preferably, the quick-setting agent is a powder made of 30% sodium aluminate, 50% sodium carbonate, and 20% quicklime, and the residue on an 80μm sieve is less than 10%.

[0014] Preferably, the selected polyvinyl alcohol has the chemical formula [C2H4O]. n It is a powdery solid with a medium degree of polymerization.

[0015] Preferably, the polyacrylamide is cationic and cold-water soluble, with a molecular weight of 8 million to 12 million.

[0016] As a preferred option, aluminum sulfate has the chemical formula Al2(SO4)3, is a white powder, and has an effective content greater than 99%.

[0017] As a preferred choice, the water-reducing agent is a naphthalene-based high-efficiency water-reducing agent, namely a purified product of naphthalene sulfonate, which has a water reduction rate of over 25%.

[0018] After the grout is mixed with the soil, the final setting time is 300-400 minutes; the 28-day compressive strength is >1.0 MPa, and the 28-day solidified soil has a higher penetration resistance (P0.0). s The average value is >2.0 MPa.

[0019] The method of using the grouting material described in this invention for the rapid solidification process of high-water-content sludge is as follows:

[0020] When the sludge moisture content is >65%, the material content should be 6%-8%, and the water-cement ratio should be controlled at 0.8. When the sludge moisture content is <65%, the material content should be 3%-5%, and the water-cement ratio should be controlled at 1.0.

[0021] When using it, you should first determine the approximate weight of each cubic meter of silt to be reinforced, determine the specific dosage of the material based on the total volume of silt to be reinforced, and prepare the grouting material according to the recommended water-cement ratio.

[0022] The mineral powder and some gypsum added to the grouting material of this invention form a hydration reaction of the polymer, and the ions dissolved from various minerals couple with each other, mainly including Ca dissolved from the cement material. 2+ OH - SO4 dissolved from gypsum 2- Meanwhile, the glassy structure inside the mineral powder is affected by the OH groups produced during cement hydration. - Excitation produces Al(OH)4 - When the ion concentration in the pores reaches a certain value, the following reaction occurs. During the reaction, a large number of water molecules are combined, and needle-shaped hydration products are produced that intertwine to form a three-dimensional network structure, which binds the sludge particles to achieve the effect of rapid solidification of high water content sludge.

[0023] 3CaSO4·2H2O+2Al(OH)4 - +3Ca 2+ +4OH - +

[0024] 20H₂O→3CaO·Al₂O₃·3CaSO₄·32H₂O (Calcium aluminate)

[0025] The grouting material of this invention contains macromolecular chain organic additives such as polyacrylamide, polyvinyl alcohol, and water-reducing agents, which can ensure that the grout has a certain viscosity and consistency. During the grouting process, the grout is evenly combined with the silt and soil, and is not easily dispersed by groundwater. Compared with traditional cement grout, it has better water dispersibility and is more suitable for in-situ curing processes.

[0026] The accelerator added to the grouting material of this invention can effectively regulate the hydration reaction rate of the material. By utilizing the synergistic effect of sodium aluminate, sodium carbonate and quicklime, the hindrance of organic matter in silt to the hydration process can be effectively reduced. The setting time of the material can be adjusted according to different soft soil conditions and engineering needs.

[0027] Compared with the prior art, the grouting material and its application method for the rapid solidification process of high water content sludge of the present invention have at least the following beneficial effects:

[0028] The grouting material of this invention, combined with the rapid solidification process for high water-content silt, exhibits a significant ability to rapidly bind water in silt formations, with fast setting time and high later-stage strength. Simultaneously, the specific penetration resistance (Ps) is all greater than 2.0 MPa, indicating that the treated silt has a high bearing capacity. Furthermore, the strength data also reflects the material's strong consolidation ability and more complete reaction with silt particles.

[0029] The sludge rapid solidification grouting material of this invention, combined with the application of the double-spraying and double-stirring process, has the characteristics of strong water-binding capacity, short setting time, high early strength, large specific penetration resistance and strong bearing capacity when encountering water-bearing sludge formations, especially high water-bearing sludge formations. At the same time, the use of a large amount of mineral admixtures and organic additives in the formula, and the "synergistic effect" between multiple mineral materials to produce a reinforcing effect, has the advantages of high efficiency, greenness and excellent workability, and has a very broad application prospect.

[0030] The following description, in conjunction with the accompanying drawings, further illustrates the grouting material and its application method for the rapid solidification process of high-water-content sludge according to the present invention. Attached Figure Description

[0031] Figure 1 Microscopic photograph of the hydration products of the grouting material prepared in Example 1. Detailed Implementation

[0032] Example 1

[0033] A grouting material for use in rapid solidification processes of high-moisture sludge comprises the following raw materials by weight percentage: 65% grade 42.5 cement, 26.7% blast furnace slag powder, 2% gypsum, 3.5% accelerator, 0.5% polyvinyl alcohol, 2% aluminum sulfate, 1‰ polyacrylamide, and 2‰ water-reducing agent. The accelerator is formulated from 30% sodium aluminate, 50% sodium carbonate, and 20% quicklime.

[0034] The grouting material in Example 1 has a dosage of 3% and a water-cement ratio of 1.0. This material is labeled as YNGH-1.

[0035] Figure 1 The image shows a microscopic view of the hydration products of the material in Example 1. It can be clearly seen that the needle-like hydration products adhere to the surface of the soil particles and play a role in providing strength support.

[0036] Example 2

[0037] A grouting material for use in rapid solidification processes of high-moisture-content sludge comprises the following raw materials by weight percentage: 61.5% grade 42.5 cement, 30% blast furnace slag powder, 2% gypsum, 4% accelerator, 0.5% polyvinyl alcohol, 1.8% aluminum sulfate, 0.5‰ polyacrylamide, and 1.5‰ water-reducing agent. The accelerator is formulated from 30% sodium aluminate, 50% sodium carbonate, and 20% quicklime.

[0038] The material dosage in Example 2 is 3%, the water-cement ratio is 1.0, and the material is labeled YNGH-2.

[0039] Example 3

[0040] A grouting material for use in rapid solidification processes of high-moisture sludge comprises the following raw materials by weight percentage: 68.5% grade 42.5 cement, 22% blast furnace slag powder, 2.7% gypsum, 4% accelerator, 0.5% polyvinyl alcohol, 2% aluminum sulfate, 1‰ polyacrylamide, and 2‰ water-reducing agent. The accelerator is formulated from 30% sodium aluminate, 50% sodium carbonate, and 20% quicklime.

[0041] The material dosage in Example 3 is 3%, the water-cement ratio is 1.0, and the material is labeled YNGH-3.

[0042] Example 4

[0043] A grouting material for use in rapid solidification processes of high-moisture sludge comprises the following raw materials by weight percentage: 63.5% grade 42.5 cement, 28.7% blast furnace slag powder, 2% gypsum, 3% accelerator, 0.5% polyvinyl alcohol, 2% aluminum sulfate, 1‰ polyacrylamide, and 2‰ water-reducing agent. The accelerator is prepared from 30% sodium aluminate, 50% sodium carbonate, and 20% quicklime.

[0044] The material dosage in Example 4 is 4%, the water-cement ratio is 1.0, and the material is labeled YNGH-4.

[0045] Example 5

[0046] A grouting material for use in rapid solidification processes of high-moisture sludge comprises the following raw materials by weight percentage: 60.5% grade 42.5 cement, 30% blast furnace slag powder, 4% gypsum, 3.7% accelerator, 0.5% polyvinyl alcohol, 1% aluminum sulfate, 1‰ polyacrylamide, and 2‰ water-reducing agent. The accelerator is prepared from 30% sodium aluminate, 50% sodium carbonate, and 20% quicklime.

[0047] The material dosage in Example 5 is 6%, the water-cement ratio is 0.8, and the material is labeled YNGH-5.

[0048] Example 6

[0049] A grouting material for use in rapid solidification processes of high-moisture sludge comprises the following raw materials by weight percentage: 70% grade 42.5 cement, 20.7% blast furnace slag powder, 3% gypsum, 3.5% accelerator, 0.5% polyvinyl alcohol, 2% aluminum sulfate, 1‰ polyacrylamide, and 2‰ water-reducing agent. The accelerator is prepared from 30% sodium aluminate, 50% sodium carbonate, and 20% quicklime.

[0050] The material dosage in Example 6 is 8%, the water-cement ratio is 0.8, and the material is labeled YNGH-6.

[0051] Example 7

[0052] A grouting material for use in rapid solidification processes of high-moisture sludge comprises the following raw materials by weight percentage: 69% grade 42.5 cement, 23.8% blast furnace slag powder, 2.5% gypsum, 3% accelerator, 0.5% polyvinyl alcohol, 1% aluminum sulfate, 1‰ polyacrylamide, and 1‰ water-reducing agent. The accelerator is prepared from 30% sodium aluminate, 50% sodium carbonate, and 20% quicklime.

[0053] The material dosage in Example 7 is 7%, the water-cement ratio is 0.8, and the material is labeled YNGH-7.

[0054] To clarify the product performance and effects in this invention, a commonly used PO42.5 cement group was set as a comparison, with a material admixture of 10% and a water-cement ratio of 0.8. This material was labeled as SNGH-1.

[0055] To clarify the product performance and effects in this invention, a commonly used PO42.5 cement and lime slurry was set as a comparison. The cement to lime ratio was 7:3, the total material content was 10%, and the water-cement ratio was 1.0. This material was labeled as SNGH-2.

[0056] According to the above seven examples of products YNGH-1, YNGH-2, YNGH-3, YNGH-4, YNGH-5, YNGH-6, YNGH-7 and the comparative experimental groups SNGH-1 and SNGH-2, the nine products were mixed with silt soil of different moisture contents in a certain area according to their specific dosage and corresponding water-cement ratio to form cement-soil test blocks of 70.7mm*70.7mm*70.7mm for 7d and 28d strength comparison.

[0057] The crushed solidified silt samples were dried at a low temperature of 30°C until constant weight was achieved. The free water content (w / %) of each sample was tested at 6h and 24h and compared with the initial silt moisture content (w / %).

[0058] The initial and final setting times of consolidated soil in each group were measured using a digital setting time meter. Based on the force values ​​displayed by the digital setting time meter and the projected area of ​​the probe plane, the specific penetration resistance (P0) at 28 days was calculated. s The specific results are shown in Table 1:

[0059] Table 1

[0060]

[0061] As can be seen from the comparison of data in Table 1:

[0062] Pure cement or cement-lime grouting materials cannot achieve rapid solidification when treating silty formations, especially in high-water-content silty formations. They exhibit low water-binding capacity, significantly reduced strength at all ages, slow hydration rate, and poor consolidation, resulting in low specific penetration resistance (P0). s The bearing capacity of the silt strata treated with cement and lime is significantly lower than that of the new grouting materials, indicating that the bearing capacity of the silt strata is obviously insufficient and cannot improve construction efficiency.

[0063] The sludge rapid solidification grouting material of the present invention exhibits significant rapid water-binding ability in sludge formations, fast setting time, high later-stage strength, and lower specific penetration resistance (P). s The strength values ​​are all greater than 2.0 MPa, indicating that the treated sludge has a high bearing capacity. At the same time, the strength data also reflect that the material has a strong consolidation ability and reacts more fully with the sludge particles.

[0064] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A grouting material for use in a process for rapid solidification of high water content sludge, characterized in that: The cement of 42.5 grade, blast furnace slag powder, gypsum, accelerator, polyvinyl alcohol, aluminum sulfate, polyacrylamide and water reducing agent; according to the mass fraction, the cement of 42.5 grade is 60-70%, the mineral powder is 20-30%, the gypsum is 2-5%, the accelerator is 3-5%, the polyvinyl alcohol is 0.3-0.7%, the aluminum sulfate is 1-2%, the polyacrylamide is 0.5‰-1‰ and the water reducing agent is 1‰-2‰; The accelerator is a powder prepared from sodium metaaluminate 30%, sodium carbonate 50%, and quicklime 20%, and the sieve residue is less than 10% after being sieved through a 80 μm sieve; the 42.5 grade cement includes early strength type 42.5R and ordinary 42.5 type; the blast furnace slag powder is prepared by water quenching and cooling, and after being ground, the specific surface area is required to be > 400 m 2 / kg, and the 28d activity index is > 95%; the polyvinyl alcohol has the chemical formula [C2H4O] n , and is a powder solid with medium polymerization degree.

2. A grout material for use in the process of rapid consolidation of high water content clayey silt in combination, according to claim 1, characterized in that: The gypsum is dihydrate gypsum, anhydrite or desulfurization gypsum after low-temperature drying in power plants, ground to a specific surface area > 350 m 2 / kg.

3. A grout material for use in the process of rapid consolidation of high water content clayey silt in combination, according to claim 1, characterized by: The polyacrylamide is a cationic cold water instant soluble type, and the molecular weight is 8-12 million.

4. The grout material for use in the matching high-water-content quick-hardening sludge solidification process according to claim 1, characterized in that: The aluminum sulfate is Al2(SO4)3, which is a white powder, and the effective content is greater than 99%.

5. The grout material for use in the matching high-water-content quick-hardening sludge solidification process according to claim 1, characterized in that: The water reducing agent is a naphthalene series high efficiency water reducing agent, that is, a purified product of naphthalene sulfonate, and the water reducing rate is greater than 25%.

6. A grouting material for use in the rapid curing of high water content clayey sludge according to the process of any one of claims 1-5, characterized in that: After mixing the slurry with soil, the final setting time is 300-400 min; the 28d compressive strength is >1.0 MPa, and the 28d average value of the cured soil's penetration resistance (P s ) is >2.0 MPa.

7. Use of a grouting material for the rapid solidification of high-water-content sludge according to the mixing process of any one of claims 1-6, characterized in that: When the water content of the silt is greater than 65%, the material mixing amount should be 6-8%, and the water-cement ratio is controlled to be 0.8; when the water content of the silt is less than 65%, the material mixing amount should be 3-5%, and the water-cement ratio is controlled to be 1.0; In use, the approximate weight of the reinforced silt per square meter should be determined, the specific mixing amount of the material is determined according to the total square amount, and the grout is prepared according to the recommended water-cement ratio.

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