Curing agent for fluid stabilized soil as well as preparation method and application of curing agent

Abstract

The invention belongs to the technical field of building materials, and particularly relates to a curing agent for fluid stabilized soil and a preparation method and application thereof. The curing agent comprises the following components in parts by weight: 20-40 parts of cement, 20-40 parts of slag, 15-35 parts of steel slag, 10-30 parts of fly ash, 5-15 parts of carbide slag, 1-10 parts of desulfurized gypsum, 0.01-1 part of a hyperdispersant, 0.01-2 parts of an expanding agent and 0.01-0.5 part of an internal curing agent. The curing agent disclosed by the invention has an excellent curing effect, can overcome the problem that high fluidity, high strength and low shrinkage cannot be considered in the existing fluid-state solidified soil technology, can improve the durability of the fluid-state solidified soil, and is suitable for various projects such as foundation backfilling and site leveling.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a curing agent for fluidized solidified soil and a preparation method and application thereof. Background Art

[0002] Fluidized solidified soil is a filling medium with excellent fluidity formed by adding water and fully mixing with soil and solidifying agent as the main components. Compared with the traditional manual rammed earth backfill operation, this technology has many advantages: high fluidity, excellent self-hardening properties, eliminating the step of rolling and forming, significantly improved construction efficiency, and the density and strength can be adjusted according to needs. However, given that its main composition is soil, this type of material is naturally high in viscosity and strong in water absorption. In order to achieve ideal fluidity, the amount of mixing water required far exceeds the basic requirements of the curing agent hydration process, resulting in long setting time, low early strength, slow strength growth, large shrinkage deformation and other problems in the fluidized solidified soil, which in turn poses a challenge to the quality of the project. Therefore, how to ensure the high fluidity of the fluidized solidified soil while improving its compressive strength and reducing its shrinkage cracking has become an urgent problem to be solved. Summary of the invention

[0003] The purpose of the present invention is to overcome the problem that the existing fluidized solidification soil technology cannot take into account high fluidity, high strength and low shrinkage at the same time, and to provide a fluidized solidification soil curing agent and a preparation method and application thereof.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A fluidized solidified soil curing agent, comprising the following components by weight: 20-40 parts of cement, 20-40 parts of slag, 15-35 parts of steel slag, 10-30 parts of fly ash, 5-15 parts of carbide slag, 1-10 parts of desulfurized gypsum, 0.01-1 parts of super dispersant, 0.01-2 parts of expansion agent, and 0.01-0.5 parts of internal curing agent;

[0006] The preparation method of the hyperdispersant comprises the following steps:

[0007] 1) dissolving 90-110 g of lignin in 180-220 ml of dimethyl sulfoxide, heating to 60-70° C., stirring evenly, slowly dropping 45-55 g of dimethyl sulfate, maintaining the reaction temperature in the range of 60-70° C., and carrying out sulfonation reaction for 2-3 hours. After the sulfonation reaction is completed, slowly adding 25-35 g of acrylic acid and 1.5-2.5 g of p-toluenesulfonic acid, and continuing the reaction for 3-4 hours, during which the temperature is kept constant at 70-80° C. After the reaction is completed, adjusting the pH to neutral, washing and drying to obtain a lignin derivative containing sulfonic acid groups and carboxylic acid groups, which is recorded as modified lignin;

[0008] 2) 35-45 g of ethylene glycol and 25-35 g of maleic anhydride are heated to 120-140° C. in 130-170 ml of toluene, 0.8-1.2 g of a titanate catalyst is added, and an esterification reaction is carried out for 4-6 hours, and the reaction temperature is maintained in the range of 120-140° C. After the esterification reaction is completed, 50-70 g of polyethylene glycol is added to continue the reaction for 2-4 hours, during which the temperature is maintained constant at 120-140° C. After the reaction is completed, the solvent and unreacted raw materials are removed by distillation to obtain a polyetherester macromonomer containing an ester group, a hydroxyl group and an ether group, which is recorded as macromonomer A;

[0009] 3) 70-80 g of modified lignin and 15-25 g of macromonomer A are dissolved in 90-110 mL of deionized water, heated to 80-90° C., 1-5 g of sodium methyl propylene sulfonate, 1-5 g of allyl alcohol polyoxyethylene ether and 0.8-1.2 g of benzoyl peroxide are added in sequence, stirred evenly, and copolymerized at 80-90° C. for 3-6 hours under nitrogen protection. After the reaction, the pH is adjusted to neutral, filtered, and dried to obtain the hyperdispersant.

[0010] In the above scheme, the cement is ordinary Portland cement, and its strength grade is not less than 42.5.

[0011] In the above scheme, the slag is blast furnace slag, and its specific surface area is not less than 300m 2 / kg.

[0012] In the above scheme, the steel slag is converter steel slag, and its free calcium oxide content does not exceed 3%.

[0013] In the above scheme, the fly ash is Class I or Class II fly ash, and its ignition loss does not exceed 8%.

[0014] In the above scheme, the free calcium hydroxide content in the carbide slag is not less than 70%.

[0015] In the above scheme, the desulfurized gypsum is a byproduct of flue gas desulfurization in a coal-fired power plant, and its calcium sulfate content is greater than or equal to 80%.

[0016] In the above scheme, the expansion agent is a magnesium oxide expansion agent.

[0017] In the above scheme, the internal curing agent is a high molecular weight water-absorbing resin, and its water absorption rate is not less than 200g / g.

[0018] The present invention also provides a method for preparing the fluidized solidified soil curing agent, comprising: weighing each component in proportion, and fully stirring the components in a stirring device to obtain the fluidized solidified soil curing agent.

[0019] The present invention also claims to protect the use of the curing agent for fluidized solidified soil in the preparation of fluidized solidified soil, and the addition amount of the curing agent in the preparation of fluidized solidified soil is 10%-30% of the mass of clay or silt.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The fluidized soil curing agent provided by the present invention overcomes the problem that the existing fluidized soil curing technology cannot achieve high fluidity, high strength and low shrinkage at the same time. The present invention can significantly improve the strength of fluidized solidified soil and reduce its shrinkage cracking. Firstly, the reduction of water consumption and the "water reservoir" effect of the internal curing agent reduce the number of pores caused by water evaporation during curing, thereby reducing the shrinkage phenomenon caused by water loss. Secondly, the alkaline components in the cement hydration product and carbide slag synergistically act with the sulfate in the desulfurized gypsum to activate the silicon-aluminum substances in the steel slag, slag and fly ash, and promote their hydration reaction. The expansion agent reacts with the hydration product of the cementitious material to generate an expansive substance. The internal curing agent provides a continuous water supply for the hydration reaction of cementitious materials such as cement and the expansion agent, so that the hydration reaction is more sufficient. Various materials are compositely and synergistically generated to generate a large amount of key products such as CSH gel and AFt (ettringite). The CSH gel product increases the density of the cement stone structure, thereby significantly improving the strength of the solidified soil. The ettringite can not only improve the early strength of the solidified soil, but also expands in volume during the formation process, filling the pores in the structural network, thereby improving the ability of the solidified soil to resist shrinkage deformation.

[0022] (2) The present invention innovatively combines multiple steps such as lignin sulfonation, polyethylene glycol esterification and copolymerization to obtain a hyperdispersant with a complex structure containing multiple polar functional groups such as sulfonic acid, carboxylic acid, ester, hydroxyl and ether. This structure gives the hyperdispersant excellent dispersibility and stability. It is adsorbed on the surface of soil particles, and significantly improves the dispersibility between soil particles through electrostatic repulsion, steric hindrance and hydration film lubrication, releasing free water wrapped by soil particles, which helps to improve the fluidity and solidification effect of solidified soil. In addition, the fine particles in fly ash act as "ball bearings" in the solidified soil, which can reduce the friction between particles and further improve the fluidity of the solidified soil. Therefore, the water demand of the fluidized solidified soil can be greatly reduced while ensuring the same fluidity.

[0023] (3) The preparation method of the fluidized solidification soil curing agent provided by the present invention not only takes into account the use of traditional curing materials such as cement and slag through a reasonable component ratio, but also introduces industrial wastes such as steel slag, fly ash, carbide slag, desulfurized gypsum, etc. as resource utilization materials, which not only reduces costs but also is beneficial to environmental protection. In addition, the raw materials are widely available and the preparation process is simple. It only needs to weigh the raw materials in proportion and fully stir them in a mixing equipment. The requirements for operators are relatively low and it is suitable for large-scale production. DETAILED DESCRIPTION

[0024] The technical scheme of the present invention will be described in detail below in conjunction with specific embodiments, but the described embodiments are only partial embodiments of the present invention, and all other embodiments obtained by ordinary technicians in the field without creative work based on the embodiments in the present invention belong to the scope of protection of the present invention. In the following embodiments, unless otherwise specified, the reagents used are all commercially available chemical reagents.

[0025] In a specific embodiment, the cement used is PO 42.5 from Huaxin Cement Co., Ltd.; the slag used is from Wuhan Wuxin New Building Materials Co., Ltd., and its specific surface area is not less than 300m 2 / kg; the steel slag used comes from Wuhan Iron and Steel Co., Ltd., and the steel slag is converter slag, and its free calcium oxide content does not exceed 3%; the fly ash used comes from the Class II ash of Yangluo Power Plant, and its loss on ignition does not exceed 8%; the carbide slag used comes from Hubei Gucheng Donghua Trading Co., Ltd., and the free calcium hydroxide content in the carbide slag is not less than 70%; the desulfurization gypsum used comes from Yangluo Power Plant, which is a by-product of flue gas desulfurization in coal-fired power plants, and its calcium sulfate content is not less than 80%; the expansion agent used is FQY magnesium oxide expansion agent, which comes from Wuhan Sanyuan Special Building Materials Co., Ltd.; the internal curing agent used is a polymer absorbent resin, and its water absorption rate is not less than 200g / g, which comes from Nantong Keli Absorbent Materials Co., Ltd.

[0026] The preparation method of the hyperdispersant used in the present invention specifically comprises the following steps: 1) dissolving 100g of lignin in 200ml of dimethyl sulfoxide, heating to 65°C, stirring evenly, slowly dropping 50g of dimethyl sulfate, keeping the reaction temperature at 65°C, and carrying out sulfonation reaction for 2.5 hours. After the sulfonation reaction is completed, slowly adding 30g of acrylic acid and 2g of p-toluenesulfonic acid, and continuing the reaction for 3.5 hours, keeping the temperature constant at 75°C during the reaction. After the reaction is completed, adjusting the pH to neutral, washing and drying, etc., to obtain a lignin derivative containing sulfonic acid groups and carboxylic acid groups, which is recorded as "modified lignin"; 2) heating 40g of ethylene glycol and 30g of maleic anhydride in 150ml of toluene to 130°C, adding 1g of tetrabutyl titanate, The esterification reaction was carried out for 5 hours, and the reaction temperature was maintained at 130°C; after the esterification reaction was completed, 60g of polyethylene glycol was added and the reaction was continued for 3 hours, during which the temperature was kept constant at 130°C. After the reaction was completed, the solvent and unreacted raw materials were removed by distillation to obtain a polyether ester macromonomer containing ester groups, hydroxyl groups and ether groups, which was recorded as "macromonomer A"; 3) 75g of modified lignin and 20g of macromonomer A were dissolved in 100mL of deionized water, heated to 85°C, 3g of sodium methyl propylene sulfonate, 2g of allyl alcohol polyoxyethylene ether and 1g of benzoyl peroxide were added in sequence, stirred evenly, and copolymerized at 85°C for 4.5 hours under nitrogen protection. After the reaction was completed, a super dispersant was obtained by adjusting the pH to neutral, filtering, drying and other steps.

[0027] The invention provides a fluidized solidified soil curing agent, which comprises the following components in parts by weight: 20-40 parts of cement, 20-40 parts of slag, 15-35 parts of steel slag, 10-30 parts of fly ash, 5-15 parts of carbide slag, 1-10 parts of desulfurized gypsum, 0.01-1 parts of super dispersant, 0.01-2 parts of expansion agent and 0.01-0.5 parts of internal curing agent.

[0028] The present invention also provides a method for preparing the fluidized solidified soil curing agent, comprising: weighing each component in proportion, and fully stirring each component in a stirring device to obtain the fluidized solidified soil curing agent.

[0029] Example 1

[0030] The fluidized solidified soil curing agent comprises the following components in parts by weight: 30 parts of cement, 30 parts of slag, 25 parts of steel slag, 20 parts of fly ash, 10 parts of carbide slag, 5 parts of desulfurized gypsum, 0.5 parts of super dispersant, 1 part of expansion agent, and 0.3 parts of internal curing agent; the components are fully stirred in a stirring device to obtain the fluidized solidified soil curing agent.

[0031] Example 2

[0032] The fluidized solidified soil curing agent comprises the following components in parts by weight: 25 parts of cement, 20 parts of slag, 30 parts of steel slag, 15 parts of fly ash, 15 parts of carbide slag, 3 parts of desulfurized gypsum, 0.05 parts of super dispersant, 1 part of expansion agent, and 0.3 parts of internal curing agent; the components are fully stirred in a stirring device to obtain the fluidized solidified soil curing agent.

[0033] Example 3

[0034] The fluidized solidified soil curing agent comprises the following components in parts by weight: 40 parts of cement, 40 parts of slag, 15 parts of steel slag, 30 parts of fly ash, 5 parts of carbide slag, 1 part of desulfurized gypsum, 0.01 parts of super dispersant, 2 parts of expansion agent and 0.01 parts of internal curing agent; the components are fully stirred in a stirring device to obtain the fluidized solidified soil curing agent.

[0035] Example 4

[0036] The fluidized solidified soil curing agent comprises the following components in parts by weight: 20 parts of cement, 35 parts of slag, 20 parts of steel slag, 25 parts of fly ash, 8 parts of carbide slag, 8 parts of desulfurized gypsum, 0.8 parts of super dispersant, 1.5 parts of expansion agent and 0.4 parts of internal curing agent; the components are fully stirred in a stirring device to obtain the fluidized solidified soil curing agent.

[0037] Example 5

[0038] The fluidized solidified soil curing agent comprises the following components in parts by weight: 35 parts of cement, 25 parts of slag, 35 parts of steel slag, 10 parts of fly ash, 12 parts of carbide slag, 10 parts of desulfurized gypsum, 1 part of super dispersant, 0.2 parts of expansion agent and 0.2 parts of internal curing agent; the components are fully stirred in a stirring device to obtain the fluidized solidified soil curing agent.

[0039] Comparative Example 1

[0040] The fluidized solidified soil curing agent comprises the following components in parts by weight: 30 parts of cement, 30 parts of slag, 25 parts of steel slag, 20 parts of fly ash, 10 parts of carbide slag, 5 parts of desulfurized gypsum, 1 part of expansion agent, and 0.3 parts of internal curing agent; the components are fully stirred in a stirring device to obtain the fluidized solidified soil curing agent.

[0041] Note: The difference between this comparative example and Example 1 is that no hyperdispersant is added in this comparative example.

[0042] Comparative Example 2

[0043] The fluidized solidified soil curing agent comprises the following components in parts by weight: 30 parts of cement, 30 parts of slag, 25 parts of steel slag, 20 parts of fly ash, 10 parts of carbide slag, 5 parts of desulfurized gypsum, and 0.5 parts of super dispersant; the components are fully stirred in a stirring device to obtain the fluidized solidified soil curing agent.

[0044] Note: The difference between this comparative example and Example 1 is that no expansion agent and internal curing agent are added in this comparative example.

[0045] The fluidized solidified soil prepared in the above-mentioned embodiments and comparative examples is made into fluidized solidified soil with a curing agent, the ratio of glue to soil is 2:8, and the ratio of water to material is 0.4. According to the "DBJ51 / T188-2022 Technical Standard for Engineering Application of Premixed Fluidized Solidified Soil", the fluidity and compressive strength of the solidified soil are tested; the size of the volume shrinkage test specimen is 40mm×40mm×160mm, and the specimen is demolded after curing for 1 day after molding. The initial length (length, width, height) is measured with a vernier caliper, and the initial volume is calculated. The curing continues until the end of the age, and the volume of the specimen cured to the age is measured and calculated. The shrinkage deformation of the specimen is expressed as the volume shrinkage rate [(initial volume-age volume) / initial volume×100%]. The performance test results of the fluidized solidified soil obtained in each embodiment and comparative example are shown in Table 1:

[0046] Table 1 Performance test results of fluidized solidified soil obtained in the examples and comparative examples

[0047]

[0048] As shown in Table 1, the fluidity of the fluidized solidified soil prepared in the embodiment is relatively high, reaching 220-280 mm; the 28d strength is relatively high, reaching 6-6.8 MPa; the 28d volume shrinkage is relatively low, with the lowest being only 2.9%. Compared with Example 1, the fluidity of Comparative Example 1 decreases significantly, indicating that the superdispersant of the present invention helps to improve the fluidity of the solidified soil; compared with Example 1, the 28d strength of Comparative Example 2 decreases and the 28d volume shrinkage increases, indicating that the expansion agent and internal curing agent of the present invention help to improve the strength and volume stability of the solidified soil.

[0049] In summary, the fluidized soil curing agent provided by the present invention can overcome the problem that the existing fluidized soil curing technology cannot achieve high fluidity, high strength and low shrinkage at the same time.

[0050] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and its improved conception within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A fluidized solidified soil curing agent, characterized in that: The composition includes the following components by weight: 20-40 parts of cement, 20-40 parts of slag, 15-35 parts of steel slag, 10-30 parts of fly ash, 5-15 parts of carbide slag, 1-10 parts of desulfurized gypsum, 0.01-1 parts of super dispersant, 0.01-2 parts of expansion agent, and 0.01-0.5 parts of internal curing agent; The preparation method of the hyperdispersant comprises the following steps: 1) dissolving 90-110 g of lignin in 180-220 ml of dimethyl sulfoxide, heating to 60-70° C., slowly dropping 45-55 g of dimethyl sulfate, maintaining the temperature at 60-70° C. for sulfonation reaction for 2-3 hours, slowly adding 25-35 g of acrylic acid and 1.5-2.5 g of p-toluenesulfonic acid, and continuing the reaction at 70-80° C. for 3-4 hours, and after the reaction, adjusting the pH to neutral, washing and drying to obtain modified lignin; 2) 35-45 g of ethylene glycol and 25-35 g of maleic anhydride are heated to 120-140° C. in 130-170 ml of toluene, 0.8-1.2 g of a titanate catalyst is added, and an esterification reaction is carried out at 120-140° C. for 4-6 hours. After the esterification reaction is completed, 50-70 g of polyethylene glycol is added and the reaction is continued at 120-140° C. for 2-4 hours. After the reaction is completed, macromonomer A is obtained by distillation; 3) 70-80 g of modified lignin and 15-25 g of macromonomer A are dissolved in 90-110 mL of deionized water, heated to 80-90° C., 1-5 g of sodium methyl propylene sulfonate, 1-5 g of allyl alcohol polyoxyethylene ether and 0.8-1.2 g of benzoyl peroxide are added in sequence, and copolymerization is carried out at 80-90° C. for 3-6 hours under nitrogen protection. After the reaction is completed, the pH is adjusted to neutral, filtered and dried to obtain the super dispersant.

2. The fluidized solidified soil curing agent according to claim 1, characterized in that: The cement is ordinary Portland cement, and its strength grade is not less than 42.

5.

3. The fluidized solidified soil curing agent according to claim 1, characterized in that: The slag is blast furnace slag, and its specific surface area is not less than 300m 2 / kg.

4. The fluidized solidified soil curing agent according to claim 1, characterized in that: The steel slag is converter steel slag, and the free calcium oxide content of the steel slag is not more than 3%; the free calcium hydroxide content of the carbide slag is not less than 70%.

5. The fluidized solidified soil curing agent according to claim 1, characterized in that: The fly ash is Class I or Class II fly ash, and its ignition loss does not exceed 8%.

6. The fluidized solidified soil curing agent according to claim 1, characterized in that: The desulfurized gypsum is a byproduct of flue gas desulfurization in coal-fired power plants, and its calcium sulfate content is not less than 80%.

7. The fluidized solidified soil curing agent according to claim 1, characterized in that: The expansion agent is a magnesium oxide expansion agent.

8. The fluidized solidified soil curing agent according to claim 1, characterized in that: The internal curing agent is a high molecular weight water-absorbing resin, and its water absorption rate is not less than 200g / g.

9. The method for preparing the fluidized solidification soil curing agent according to any one of claims 1 to 8, characterized in that: include: The components are weighed in proportion and stirred evenly to obtain the fluidized solidified soil curing agent.

10. Use of the curing agent for fluidized solidified soil according to any one of claims 1 to 8 in preparing fluidized solidified soil, characterized in that: The amount of the curing agent added in the preparation of fluidized solidified soil is 10%-30% of the mass of clay or silt.

Images