A soil stabilizer, its preparation method and application

Abstract

The present invention discloses a soil stabilizer, its preparation method and application, which relates to the technical field of engineering materials. In the present invention, through the compounding of various substances, under the interaction of a consolidant, a gelling agent, an early strength agent, an activator, a filler, a water reducing agent and a protective agent, a soil curing agent with high strength, large penetration depth, large compressive strength and good water resistance is obtained. It can reduce the moisture content of the material to facilitate the pressing of subgrade products, and at the same time promote the further hydration reaction of the products, ensuring the strength and stability of the subgrade products, promoting the treatment and disposal of a large amount of silt solid waste, obtaining a resource-based product with high strength and high cost performance, reducing the cost of subgrade products, optimizing the industrial production of the road utilization of silt solid waste, and providing an effective and feasible solution for the preparation of subgrade products from silt solid waste.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering materials, C04B28 / 08, and particularly relates to a soil stabilizer and its preparation method and application. Background Art

[0002] With the development of the national economy and the implementation of various engineering projects, the demand for materials such as stone, cementitious materials, and sand and gravel aggregates is increasing day by day. Among them, in road applications, using solidified soil instead of stone as the roadbed can not only relieve the pressure of the gradual scarcity of materials such as stone and sand and gravel aggregates, but also further reduce the waste generated by road projects and play a role in protecting the environment. However, it is found in the research that the early strength of lime-reinforced roadbed products is high, but the subsequent strength development is slow, and cement reinforcement will result in relatively large shrinkage, leading to pavement cracking.

[0003] A soil solidifying agent is proposed in Chinese Patent Application CN103896541A, which mainly uses industrial waste as raw material. After grinding it and adding a certain activator, the strength of the product can be improved to a certain extent and its water resistance can be enhanced. A soil solidifying agent and its preparation method are proposed in Chinese Patent Application CN106278101A, which mainly utilizes the particle size difference of each component to fill the pores so as to improve the strength of the product. Although the above processes can solidify the soil and improve the strength to a certain extent, they cannot utilize high-moisture-content solid waste, and cannot further reduce the moisture content of the solid waste, resulting in limited application scenarios. In view of the poor solidification performance of the existing soil solidifying agents and their inability to handle high-moisture-content solid waste, there are disadvantages such as low strength, poor crack resistance, poor frost resistance, and high cost of the products. Therefore, there is an urgent need for a soil stabilizer with better performance and capable of handling high-moisture-content solid waste to ensure the strength and stability of subgrade fillers, cushions, and bases. Summary of the Invention

[0004] To solve the above problems, in the first aspect of the present invention, a soil stabilizer is provided, which comprises the following components in parts by weight: 4-15 parts of a consolidant, 4-15 parts of a cementitious agent, 4-8 parts of an early strength agent, 1-10 parts of an activator, 30-60 parts of a filler, 1-5 parts of a water reducer, and 3-7 parts of a protective agent.

[0005] Further, the consolidant is selected from one or more of high alumina cement, portland cement, sulphoaluminate cement, slag portland cement, slag, steel slag cement, and calcium aluminate cement; preferably portland cement and slag.

[0006] Further, the consolidant is portland cement and slag with a weight ratio of 1:(0.5-1.2); preferably 1:1.

[0007] Furthermore, the portland cement is selected from one or more of ordinary portland cement, pure clinker portland cement, slag portland cement, pozzolanic portland cement, fly ash portland cement, and composite portland cement; preferably ordinary portland cement; further preferably, the strength grade of the ordinary portland cement is 42.5R.

[0008] Furthermore, the particle size of the slag is 80 - 400 mesh; preferably 100 - 325 mesh.

[0009] Furthermore, the gelling agent is selected from one or more of quicklime, limestone, magnesite, calcite, carbide slag, shellfish, bleaching powder residue, and quartz; preferably quicklime and carbide slag.

[0010] Furthermore, the gelling agent is quicklime and carbide slag with a weight ratio of 1:(1 - 2); preferably 1:1.5.

[0011] Furthermore, the particle size of the quicklime is 80 - 400 mesh; preferably 200 - 325 mesh.

[0012] Furthermore, the calcium hydroxide content in the carbide slag is 75 - 85 wt%, the particle size is 80 - 325 mesh, and the moisture content is 0.1 - 0.4 wt%; preferably, the calcium hydroxide content is 80 wt%, the particle size is 100 - 200 mesh, and the moisture content is 0.3 wt%.

[0013] Lime easily undergoes hydration, decomposition, and crystallization in the soil, enabling the soil mixture material to generate strength and form a solid mass, thereby increasing the strength of the material and reducing the moisture content of the solid waste to a certain extent. However, quicklime has obvious temperature shrinkage characteristics. When the temperature changes, obvious shrinkage occurs, and foaming also appears, seriously affecting the roadbed compaction degree and appearance quality. The applicant has found that adding carbide slag to the system can improve the temperature shrinkage performance and foaming situation of the material. It is speculated that this may be because the composition of carbide slag is similar to that of quicklime, enabling good mixing, and with the synergistic effect of other additives, promoting the reaction activity of carbide slag, reducing the dosage of quicklime in the system, thereby inhibiting the volume expansion of lime, and further being able to avoid problems such as dry shrinkage cracks and peeling after water evaporation. In addition, after the carbide slag dissolves in water, it will conduct ion exchange with the metal ions on the surface of the raw materials, thinning the water film, promoting the cohesion of the material particles, and at the same time, it will also react to form certain crystals and a protective film, thereby increasing the strength of the material and reducing the cost.

[0014] Furthermore, the early strength agent is selected from one or more of desulfurized gypsum, industrial gypsum, natural gypsum, ferric sulfate, aluminum sulfate, sodium chloride, triethanolamine, triisopropanolamine, and calcium thiosulfate; preferably desulfurized gypsum and aluminum sulfate.

[0015] Further, the early strength agent is desulfurized gypsum and aluminum sulfate with a weight ratio of 1:(1~2); preferably 1:1.2.

[0016] Further, the fineness of the desulfurized gypsum is 100~400 mesh, and the flexural strength is 7~10 MPa; preferably, the fineness is 150 - 250 mesh, and the flexural strength is 8.2 MPa.

[0017] Further, the content of aluminum oxide in the aluminum sulfate is ≥15 wt%, and the particle size is 50 - 200 mesh; preferably, the content of aluminum oxide is ≥17 wt%, and the particle size is 100 mesh.

[0018] Further, the water reducing agent is one or more of polycarboxylic acid, naphthalene series, melamine type, and amino sulfonate; preferably polycarboxylic acid.

[0019] Further, the protective agent is one or more of polyvinyl alcohol, polyvinyl alcohol propylene glycol, sodium polyacrylate, polyacrylamide, lignosulfonate, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, polyvinylpyrrolidone, and poly maleic anhydride; preferably sodium polyacrylate and lignosulfonate.

[0020] Further, the protective agent is sodium polyacrylate and lignosulfonate with a weight ratio of 1:(1.2~3); preferably 1:1.7.

[0021] Further, the activator is one or more of sodium silicate, sodium aluminate, calcium chloride, sodium hydroxide, calcium hydroxide, calcium chloride, and magnesium chloride; preferably sodium silicate, calcium hydroxide, and magnesium chloride.

[0022] Further, the activator is sodium silicate and magnesium chloride with a weight ratio of 1:(0.8~1.7); preferably 1:1.4.

[0023] Further, the filler is one or more of fly ash, slag, coal gangue, recycled aggregate, talcum powder, concrete powder, pulp residue, volcanic ash soil, rice husk ash, and carbon black; preferably a mixture of fly ash, recycled aggregate, and carbon black.

[0024] Further, the filler is fly ash, recycled aggregate, and carbon black with a weight ratio of 1:(1.5~2.5):(3~5); preferably 1:2:4.

[0025] The content of aluminum trioxide in the fly ash is 35~45 wt%, the content of silicon dioxide is 40~55 w%, and the particle size is 200~500 mesh; preferably, the content of aluminum trioxide is 40.2 wt%, the content of silicon dioxide is 50 w%, and the particle size is 325 mesh.

[0026] The recycled aggregate is selected from one or more of Type A, Type B, LC5.0 type, and LC7.5 type; preferably Type A; further preferably, the dry surface density of the Type A recycled aggregate is ≤ 650 kg / m 3 , and the compressive strength is ≥ 0.5 MPa; preferably, the dry surface density is ≤ 600 kg / m 3 , and the compressive strength is ≥ 1.5 MPa.

[0027] The particle size of the carbon black is 100 - 500 mesh; preferably 200 - 400 mesh.

[0028] Adding carbide slag to the above system can significantly reduce the moisture content of the material and has a good effect on improving the strength. However, due to the high water content of carbide slag itself, its addition amount is limited. And the applicant unexpectedly found that mixing fly ash, recycled aggregate and carbon black into the above system can not only synergistically act with quicklime to further reduce the cracking caused by cement dry shrinkage, but also the added carbon black can promote the absorption of sunlight inside the product for improving soil stability, thereby reducing the temperature difference inside and outside the soil stabilizer and accelerating the absorption and evaporation of water. Especially when the weight ratio of fly ash, recycled aggregate and carbon black is 1: (1.5 - 2.5): (3 - 5), it can better improve the strength, crack resistance and frost resistance of the soil stabilizer.

[0029] Further, the average particle size of the mixture after grinding in S2 is less than 0.15 mm; preferably less than 0.075 mm.

[0030] A method for preparing a soil stabilizer according to the second aspect of the present invention includes the following steps:

[0031] S1. Mix and stir a consolidant, a gelling agent, an early strength agent, an activator, a filler, a water reducing agent and a protective agent to obtain a mixture;

[0032] S2. Grind the mixture obtained in S1 to obtain the soil stabilizer.

[0033] Further, the particle size of the soil stabilizer obtained by grinding is below 0.15 mm, preferably below 0.075 mm.

[0034] A third aspect of the present invention is the application of a soil stabilizer in the production of subgrade fillers, cushions and bases.

[0035] Further, the weight percentage of the soil stabilizer in the subgrade product is 0.5 - 5%.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The present invention obtains a soil stabilizer by compounding a consolidant, a gelling agent, an early strength agent, an activator, a filler, a water reducing agent, and a protective agent. It can reduce the moisture content of the materials to facilitate the pressing of subgrade products, and at the same time promote the further hydration reaction of the products, ensuring the strength and stability of the subgrade products, solving the problem of the treatment and disposal of sludge solid waste, obtaining a resource-based product with high strength and high cost performance, reducing the cost of subgrade products, optimizing the industrial production of the road utilization of sludge solid waste, and providing an effective and feasible solution for the preparation of subgrade products from sludge solid waste.

[0038] (2) The soil stabilizer obtained by compounding various substances in the present invention enables the system to undergo a hydration reaction quickly and efficiently. At the same time, the concentration of calcium hydroxide generated by the alkaline substance in the solution quickly reaches saturation and precipitates in the form of hexagonal crystals. The hydration product C—A—H (calcium aluminate hydrate) of the consolidant in the system combines with sulfate ions to form the crystalline substance calcium sulfoaluminate hydrate, adsorbing a large amount of water and reducing the overall moisture content of the product. When the early strength agent in the system is basically consumed, it is transformed into monosulfate calcium sulfoaluminate, improving the product strength to a certain extent; at the same time, the calcium silicate hydrate products generated by the hydration of tricalcium silicate and dicalcium silicate in the consolidant gradually aggregate, seep out of the system in the form of colloidal particles, and gradually coagulate to form a gel (C-S-H gel), enabling the subgrade product to form good strength.

[0039] (3) Through the compounding of the gelling agent, water reducing agent, and protective agent, the present invention greatly improves the hydrophilic property of the materials, weakens the interaction between soil particles and water, and uses the synergistic effect of chemical adsorption and physical separation to remove the water in the soil, greatly enhancing the stability of the raw materials; at the same time, the filler used has little or no hydraulic cementing performance itself, but when present in powder form with water, it can chemically react with calcium hydroxide or other alkaline earth metal hydroxides at normal temperature, especially under hydration treatment conditions, to generate compounds with hydraulic cementing performance, becoming a material to increase strength and durability. Combined with the above-mentioned consolidant and early strength agent, the active substances in the subgrade material can quickly undergo a hydration reaction. The early strength agent hardens while absorbing a certain amount of water, improving the initial strength of the subgrade product and further reducing the influence of the system moisture, while the consolidant further undergoes a hydration reaction with the filler and the active substances of the subgrade material to quickly improve the strength of the product and enhance the stability of the product. The activator interacts with the cementitious material to further enhance the alkalinity of the system, further stimulating the hydration reaction of the consolidant, filler, and active substances of the subgrade material, quickly improving the strength of the product and enhancing the overall strength of the product.

[0040] (4) The soil stabilizer used in the present invention fully disperses the solid waste particles, releases the free water in the solid particles, reduces the moisture content of the material, which is beneficial to the hydration reaction of the silt solid waste and further improves the strength of the product. In addition, it can also enhance the pores in the system, reduce the nucleation energy of the hydration products, further lower the conditions for the hydration reaction, reduce the factory operation cost, and is conducive to the engineering promotion of preparing roadbed products from silt. Detailed implementation manners

[0041] Example 1

[0042] Raw material preparation:

[0043] The solidifying agent is Portland cement and slag with a weight ratio of 1:0.5. Among them, the Portland cement is ordinary Portland cement with a strength grade of 42.5R, and the particle size of the slag is 325 mesh (Shijiazhuang Mayue Building Materials Co., Ltd.);

[0044] The gelling agent is quicklime and carbide slag with a weight ratio of 1:2. Among them, the particle size of the quicklime is 200 mesh (Lingshou Maozhuo Building Materials Co., Ltd.), the calcium hydroxide content in the carbide slag is 80wt%, the particle size is 200 mesh, and the moisture content is 0.3wt% (Hunan Yaobo Chemical Trade Co., Ltd.);

[0045] The early strength agent is desulfurized gypsum and aluminum sulfate with a weight ratio of 1:1. Among them, the fineness of the desulfurized gypsum is 250 mesh, and the flexural strength is 8.2 MPa (Zhejiang Sanlion Group Special Cement Co., Ltd.). The alumina content in the aluminum sulfate is ≥17wt%, and the particle size is 100 mesh (Shandong Landen New Energy Technology Co., Ltd.);

[0046] The activator is water glass and magnesium chloride with a weight ratio of 1:0.8;

[0047] The filler is fly ash, recycled aggregate and carbon black with a weight ratio of 1:1.5:3. Among them, the alumina content in the fly ash is 40.2wt%, the silica content is 50w%, and the particle size is 325 mesh (Shijiazhuang Deze Mineral Products Co., Ltd.). The recycled aggregate is of type A, and the dry surface density of type A recycled aggregate ≤600 kg / m 3 , and the compressive strength ≥1.5 MPa (Langfang Youding Energy Saving Technology Co., Ltd.). The particle size of the carbon black is 200 mesh (Lingshou Jiayuan Mineral Products Processing Factory);

[0048] The water reducing agent is polycarboxylic acid (VR-01);

[0049] The protective agent is sodium polyacrylate (CAS: 9003-04-7) and lignosulfonate with a weight ratio of 1:3.

[0050] Preparation of the soil stabilizer:

[0051] S1. Mix 4 parts of solidifying agent, 4 parts of gelling agent, 4 parts of early strength agent, 1 part of activator, 30 parts of filler, 1 part of water reducing agent and 3 parts of protective agent, and stir to obtain a mixture;

[0052] S2. Grind the mixture obtained in S1 until the average particle size of the mixture reaches below 0.075 mm to obtain the product.

[0053] Example 2

[0054] Raw material preparation:

[0055] The solidifying agent is Portland cement and slag with a weight ratio of 1:1.2. Among them, the Portland cement is ordinary Portland cement with a strength grade of 42.5R, and the particle size of the slag is 325 mesh (Shijiazhuang Mayue Building Materials Co., Ltd.);

[0056] The gelling agent is quicklime and carbide slag with a weight ratio of 1:1. Among them, the particle size of the quicklime is 200 mesh (Lingshou Maozhuo Building Materials Co., Ltd.), the calcium hydroxide content in the carbide slag is 80 wt%, the particle size is 200 mesh, and the water content is 0.3 wt% (Hunan Yaobo Chemical Trade Co., Ltd.);

[0057] The early strength agent is desulfurized gypsum and aluminum sulfate with a weight ratio of 1:2. Among them, the fineness of the desulfurized gypsum is 250 mesh, and the flexural strength is 8.2 MPa (Zhejiang Sanlion Group Special Cement Co., Ltd.). The alumina content in the aluminum sulfate is ≥17 wt%, and the particle size is 100 mesh (Shandong Landian New Energy Technology Co., Ltd.);

[0058] The activator is water glass and magnesium chloride with a weight ratio of 1:1.7;

[0059] The filler is fly ash, recycled aggregate and carbon black with a weight ratio of 1:2.5:5. Among them, the alumina content in the fly ash is 40.2 wt%, the silica content is 50 w%, and the particle size is 325 mesh (Shijiazhuang Deze Mineral Products Co., Ltd.). The recycled aggregate is of type A, and the dry surface density of type A recycled aggregate is ≤600 kg / m3, and the compressive strength is ≥1.5 MPa (Langfang Youding Energy Saving Technology Co., Ltd.). The particle size of the carbon black is 200 mesh (Lingshou Jiayuan Mineral Products Processing Factory);

[0060] The water reducing agent is polycarboxylic acid (VR-01);

[0061] The protective agent is sodium polyacrylate (CAS: 9003-04-7) and lignosulfonate with a weight ratio of 1:1.2.

[0062] Preparation of soil stabilizer:

[0063] S1. 15 parts of a consolidating agent, 15 parts of a gelling agent, 8 parts of an early strength agent, 10 parts of an activator, 60 parts of a filler, 5 parts of a water reducing agent and 7 parts of a protective agent were mixed and stirred to obtain a mixture;

[0064] S2. Grind the mixture obtained in S1 until the average particle size of the mixture reaches less than 0.075 mm.

[0065] Example 3

[0066] Raw materials preparation:

[0067] The consolidating agent is silicate cement and slag in a weight ratio of 1:1, wherein the silicate cement is ordinary silicate cement with a strength grade of 42.5R, and the particle size of the slag is 325 mesh (Shijiazhuang Mayue Building Materials Co., Ltd.);

[0068] The gelling agent is quicklime and carbide slag in a weight ratio of 1:1.5, wherein the quicklime has a particle size of 200 mesh (Lingshou County Maozhuo Building Materials Co., Ltd.), the calcium hydroxide content in the carbide slag is 80wt%, the particle size is 200 mesh, and the moisture content is 0.3wt% (Hunan Yaobo Chemical Trading Co., Ltd.);

[0069] The early strength agent is desulfurized gypsum and aluminum sulfate in a weight ratio of 1:1.2, wherein the fineness of the desulfurized gypsum is 250 mesh and the flexural strength is 8.2MPa (Zhejiang Sanshi Group Special Cement Co., Ltd.), and the content of alumina in the aluminum sulfate is ≥17wt% and the particle size is 100 mesh (Shandong Landing New Energy Technology Co., Ltd.);

[0070] The activator is water glass and magnesium chloride in a weight ratio of 1:1.4;

[0071] The filler is fly ash, recycled aggregate and carbon black in a weight ratio of 1:2:4, wherein the content of aluminum oxide in the fly ash is 40.2wt%, the content of silicon dioxide is 50w%, and the particle size is 325 mesh (Shijiazhuang Deze Mineral Products Co., Ltd.), the recycled aggregate is type A, the dry surface density of type A recycled aggregate is ≤600kg / m3, and the compressive strength is ≥1.5MPa (Langfang Youding Energy Saving Technology Co., Ltd.), and the particle size of carbon black is 200 mesh (Lingshou County Jiayuan Mineral Products Processing Plant);

[0072] The water reducer is polycarboxylic acid (VR-01);

[0073] The protective agent is sodium polyacrylate (CAS: 9003-04-7) and lignin sulfonate in a weight ratio of 1:1.7.

[0074] Preparation of soil stabilizer:

[0075] S1. Mix 9 parts of solidifying agent, 8 parts of gelling agent, 6 parts of early strength agent, 5 parts of activator, 45 parts of filler, 3 parts of water reducing agent and 5 parts of protective agent, and stir to obtain a mixture;

[0076] S2. Grind the mixture obtained in S1 until the average particle size of the mixture reaches below 0.075 mm to obtain the product.

[0077] Example 4

[0078] This example is basically the same as Example 3, except that the gelling agent used in this example is quicklime and carbide slag with a weight ratio of 1:0.5.

[0079] Example 5

[0080] This example is basically the same as Example 3, except that the gelling agent used in this example is quicklime and carbide slag with a weight ratio of 1:3.

[0081] Example 6

[0082] This example is basically the same as Example 3, except that the filler used in this example is fly ash, recycled aggregate and carbon black with a weight ratio of 1:2:2.

[0083] Example 7

[0084] This example is basically the same as Example 3, except that the filler used in this example is fly ash, recycled aggregate and carbon black with a weight ratio of 1:2:6.

[0085] Comparative Example 1

[0086] This comparative example is basically the same as Example 3, except that the gelling agent used in this comparative example is all quicklime.

[0087] Comparative Example 2

[0088] This comparative example is basically the same as Example 3, except that the gelling agent used in this comparative example is all carbide slag.

[0089] Comparative Example 3

[0090] This comparative example is basically the same as Example 3, except that the filler used in this comparative example is fly ash, recycled aggregate and carbon black with a weight ratio of 1:2:0, that is, carbon black is not added.

[0091] Comparative Example 4

[0092] This comparative example is basically the same as Example 3, except that the filler used in this comparative example is fly ash, recycled aggregate and carbon black with a weight ratio of 1:0:4, that is, recycled aggregate is not added.

[0093] Comparative Example 5

[0094] This comparative example is basically the same as Example 3, except that the filler used in this comparative example is fly ash, recycled aggregate and carbon black with a weight ratio of 0:2:4, that is, no fly ash is added.

[0095] Performance Test

[0096] The seven-day compressive strength test was carried out in accordance with JTGE51-2009 "Test Procedures for Inorganic Binding Material Stabilized Materials in Highway Engineering". The test steps are as follows:

[0097] 1. Mix the soil from a certain place in Anhui with the soil stabilizer prepared in each example or comparative example evenly at a weight percentage of 10:1, add appropriate water to the optimum moisture content of 14%, take 200 g of the mixture and pour it into a 50*150 cylindrical mold. Place the entire specimen mold on the press. After the pressure head is pressed into the mold, place it in a constant temperature and humidity box for curing for 6 days. The curing temperature is 20°C and the curing humidity is 95%. After curing, place it in water for curing for 1 day, and the water surface needs to be 2.5 cm higher than the top of the specimen.

[0098] 2. Take out the specimens that have been immersed in water for one day and night from the water, and absorb the water on the surface of the specimens with a soft cloth.

[0099] 3. Measure the diameter D of the specimen with a vernier caliper, accurate to 0.1 mm.

[0100] 4. Place the specimen on the pavement material strength tester, and first place a flat ball seat on the lifting platform for compressive testing. During the test, the loading rate should be kept at 1 mm / min. Record the maximum pressure P (N) when the specimen fails.

[0101] The unconfined compressive strength of the specimen is calculated by the following formula.

[0102]

[0103] In the formula: R c— Unconfined compressive strength of the specimen (MPa);

[0104] P - Maximum pressure when the specimen fails (N);

[0105] A - Cross-sectional area of the specimen (mm 2 )

[0106] πD 2

[0107] D - Diameter of the specimen (mm).

[0108] The material freeze-thaw experiment test was carried out in accordance with JTGE51-2009 "Test Procedures for Inorganic Binding Material Stabilized Materials in Highway Engineering":

[0109] Test procedure:

[0110] 1. Mix the muck from a certain place in Anhui with the soil stabilizers prepared in each example and comparative example evenly at a weight percentage of 10:1. Add appropriate water to the optimal moisture content of 14%. Take 200 g of the mixture and pour it into a cylindrical mold of 50*150. Place the entire specimen mold on a press. After the pressure head is pressed into the mold, place it in a constant temperature and humidity chamber for 27 days. The curing temperature is 20°C and the curing humidity is 95%. After curing, place it in water for 1 day, and the water surface needs to be 2.5 cm higher than the top of the specimen.

[0111] 2. After soaking in water, take out the specimen, wipe off the water on the surface with a wet cloth, and weigh it; measure the height of the specimen with a vernier caliper, accurate to 0.1 mm.

[0112] 3. Take one group of specimens and determine the unconfined compressive strength under non-freezing and thawing conditions in accordance with JTGE51-2009 "Test Procedures for Inorganic Binder Stabilized Materials in Highway Engineering".

[0113] 4. Take one group of specimens for freezing and thawing test. Place the specimens in the low-temperature box according to the numbers to start the freezing and thawing test. The temperature of the low-temperature box is -18°C, and the freezing time is 16 h. Ensure that there is at least 20 mm of space around the specimens to facilitate the flow of cold air. After the freezing test is completed, take out the specimens, measure the height and weigh them, and then immediately place them in a water bath at 20°C for thawing. The thawing time is 8 h. The water surface in the bath should be at least 20 mm higher than the surface of the specimens. After thawing, take out the specimens, dry them, measure the height and weigh them, and this freezing and thawing cycle is completed. Then place them in the low-temperature box for the second freezing and thawing cycle.

[0114] 5. If the average loss rate of the specimens exceeds 5%, the freezing and thawing cycle test can be stopped.

[0115] 6. After the specimens reach the specified number of freezing and thawing cycles, conduct a compressive strength test in accordance with JTGE51-2009 "Test Procedures for Inorganic Binder Stabilized Materials in Highway Engineering".

[0116] 7. Calculate

[0117] In the formula: BDR - the compressive strength loss of the specimen after n freezing and thawing cycles (%);

[0118]

[0119] R dc —— the compressive strength of the specimen after n freezing and thawing cycles (MPa);

[0120] R c —— the compressive strength of the comparison specimen (MPa).

[0121] The specific test results are shown in Table 1.

[0122] Table 1 Performance test results of examples and comparative examples

[0123] Unconfined compressive strength for 7 days / MPa BDR / % Example 1 4.2 81.3 Example 2 4.1 80.1 Example 3 4.8 85.3 Example 4 3.9 78.1 Example 5 3.7 76.2 Example 6 2.8 72.1 Example 7 2.4 70.9 Comparative Example 1 2.3 70.1 Comparative Example 2 2.4 64.6 Comparative Example 3 1.9 70.3 Comparative Example 4 2.5 71.5 Comparative Example 5 1.7 72.3

[0124] In Examples 1 - 3, with the change of the proportion of the agent, the compressive strength of the product and the loss of compressive strength (BDR) of the specimen after freeze - thaw cycles are different, but the unconfined compressive strength for seven days and BDR are both relatively high, which can well meet the requirements of road applications.

[0125] Compared with Example 3, in Example 4, the gelling agent used is quicklime and carbide slag with a weight ratio of 1:0.5, and in Example 5, the gelling agent used is quicklime and carbide slag with a weight ratio of 1:3. The compressive strength of the products in Example 4 and Example 5 both decreases, and BDR also decreases. The reason for the decrease of both in Example 4 may be that the proportion of carbide slag is relatively low. Too low a proportion of carbide slag cannot make quicklime and carbide slag exhibit good gelling properties, cannot form a good synergistic effect with quicklime, and inhibits the hydration reaction activity. On the one hand, the poor gelling property cannot make the test blocks fit tightly, resulting in higher water content in the pores of the test blocks, and the strength loss after freeze - thaw is significantly reduced; the decrease of BDR is due to the problem of the gelling property of the system. Although the system has good hydration activity, due to the overly loose structure, the strength of the hydrated product also decreases significantly. The reason for the decrease of both in Example 5 may be that the proportion of carbide slag is too high, and quicklime cannot play the role of water absorption, resulting in more water between particles, and more pores are formed inside the product by water, so that the strength of the product drops rapidly after the freeze - thaw experiment.

[0126] Compared with Example 3, the unconfined compressive strength for seven days and BDR in Examples 6 and 7 both decrease significantly. The reason for the strength decrease in Example 6 is that the proportion of carbon black is relatively low. Too low a proportion of carbon black cannot play the role of dispersing the system water, cannot homogenize the system water, and the system hydration reaction is restricted to a certain extent, resulting in a decrease in strength; the decrease of the BDR loss rate is due to the excessive accumulation of water in some positions, which is more likely to expand after freeze - thaw, resulting in a lower compressive strength of the product after freeze - thaw. The reason for the strength decrease in Example 7 is that the proportion of carbon black is too high. Too high a proportion of carbon black leads to too fast water loss, and the lack of water inside the system reduces the degree of hydration reaction that itself needs water to participate in, resulting in fewer hydration products and a low compressive strength of the product; the decrease of the BDR loss rate is due to the exposure of the pores inside the system caused by the water loss, and the poor compactness of the product makes the test block have poor freeze - thaw resistance, resulting in a significant decrease in the strength of the test block after the freeze - thaw experiment.

[0127] In Comparative Example 1, both the unconfined compressive strength of the product for seven days and the loss rate of BDR compressive strength decreased significantly. This is because quicklime was used as the gelling agent in its entirety. Although quicklime absorbs water quite significantly, an excessive dosage led to obvious swelling of the product, resulting in foaming and thus a decrease in strength. The decrease in the BDR loss rate was due to the rapid increase in porosity caused by the expansion within the system, weakening the freeze-thaw resistance of the product and leading to a rapid decrease in strength after freeze-thaw cycles.

[0128] In Comparative Example 2, both the unconfined compressive strength of the product for seven days and the loss rate of BDR compressive strength also decreased significantly. This is because carbide slag was used as the gelling agent in its entirety. The main component of carbide slag is calcium hydroxide, which does not have the effect of reducing the moisture content of the system and has a poor water absorption effect, resulting in excessive moisture in the system. On the one hand, the excessive moisture inhibits the hydration activity, and on the other hand, the compactness of the workpiece is relatively low; ultimately leading to a decrease in the compressive strength of the product and a rapid decrease in strength after the product is freeze-thawed.

[0129] In Comparative Example 3, both the unconfined compressive strength of the product for seven days and the loss rate of BDR compressive strength also decreased significantly. This is because carbon black was not used as the filler. The main function of carbon black is to disperse the system moisture to achieve the effect of moisture homogenization. Without adding carbon black, the moisture distribution in the system is uneven, and the hydration reaction itself requires the participation of moisture. The uneven moisture leads to uneven distribution of the formed products, which cannot be closely adhered to each other, thus resulting in a rapid decrease in the compressive strength of the product; at the same time, due to the uneven moisture distribution, the stress distribution of the test block during freeze-thaw is uneven, leading to a rapid decrease in strength after the product is freeze-thawed.

[0130] In Comparative Example 4, the unconfined compressive strength of the product decreased, and the loss rate of BDR compressive strength decreased. This is because recycled aggregate was not used as the filler. The main function of recycled aggregate is to build a good skeleton structure. Without adding aggregate, the initial strength of the product is relatively low. Although a good hydration reaction occurs in the system, the formed products cannot adhere to the skeleton structure and cannot further improve the strength of the product, resulting in a relatively low strength of the product; and the aggregate itself has poor water absorption, adding a certain amount of aggregate can reduce the water absorption of the product and thus ensure the stability of the product. Without adding aggregate, the strength of the product decreases rapidly after freeze-thaw.

[0131] In Comparative Example 5, the unconfined compressive strength of the product decreased significantly, and the loss rate of BDR compressive strength decreased. This is because fly ash was not used as the filler. As a high-quality hydration active substance, fly ash can undergo hydration reactions to further improve the strength of the product to a certain extent. At the same time, fly ash has good water absorption and has a certain gelling material effect, which can make the system adhere; without adding fly ash, the degree of hydration of the product decreases, resulting in a relatively low strength of the product; and due to the decrease in the gelling property within the system, pores are released, leading to a rapid decrease in strength after the product is freeze-thawed.

Claims

1. A soil stabilizer, characterized in that, It comprises the following components in parts by weight: 4-15 parts of a consolidant, 4-15 parts of a gelling agent, 4-8 parts of an early strength agent, 1-10 parts of an activator, 30-60 parts of a filler, 1-5 parts of a water reducing agent, and 3-7 parts of a protective agent; The consolidant is portland cement and slag with a weight ratio of 1:(0.5-1.2); The gelling agent is quicklime and carbide slag with a weight ratio of 1:(1-2); The early strength agent is desulfurized gypsum and aluminum sulfate with a weight ratio of 1:(1-2); The activator is water glass and magnesium chloride with a weight ratio of 1:(0.8-1.7); The filler is fly ash, recycled aggregate and carbon black with a weight ratio of 1:(1.5-2.5):(3-5); The water reducing agent is one or more of polycarboxylic acid, naphthalene series, melamine type, and amino sulfonate; The protective agent is sodium polyacrylate and lignosulfonate with a weight ratio of 1:(1.2-3).

2. The preparation method of the soil stabilizer according to claim 1, characterized in that, It comprises the following steps: S1. Mix and stir the consolidant, gelling agent, early strength agent, activator, filler, water reducing agent and protective agent to obtain a mixture; S2. Grind the mixture obtained in S1 to obtain the product.

3. An application of the soil stabilizer according to claim 1 in the production of subgrade fillers, cushions and bases.

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