A hydroxylated lignin composite cement-solidified soil admixture and preparation method thereof

Abstract

The invention discloses a hydroxylated lignin composite cement-cured soil admixture and a preparation method thereof, and specifically relates to the field of cement-cured soil admixtures, wherein a hydroxylated lignin composite cement-cured soil admixture comprises the following components in parts by weight: 10-30 parts of lignin, 10-30 parts of sodium hydroxide, 2-6 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 1500-1700 parts of water. The admixture prepared by the invention has the effects of improving cement hydration, cement-cured soil strength, and curing durability.

Description

Technical Field

[0001] The invention relates to the technical field of cement-solidified soil admixtures, and in particular to a hydroxylated lignin composite cement-solidified soil admixture and a preparation method thereof. Background Art

[0002] With the increasing development of infrastructure, the excavation of underground projects has produced a large amount of slag, and most of the slag has poor engineering performance, which poses a challenge to the resource utilization of slag. A curing agent is a soil hardener that can directly bond soil particles or react with clay minerals to form a cementitious material at room temperature. Due to its excellent performance in improving soil performance, the application field of solidified soil has been expanded in recent years, such as roadbed construction, embankment reinforcement, and unburned bricks. Cement, as the most common soil curing agent, has been widely used all over the world, such as Japan and Thailand. However, cement production has high energy consumption and large carbon emissions. Therefore, industrial waste slag-type cementitious materials such as desulfurized gypsum, steel, slag, fly ash, etc. have been widely studied because of their green, low-carbon and outstanding economic benefits. However, industrial waste slag-type curing agents have certain defects, namely, large dosage, generally 10%-25% of dry soil, which greatly increases the transportation cost of the curing agent. In addition, industrial waste slag is highly regional and the production sites are scattered. The above factors restrict the engineering promotion and application of engineering waste slag. Therefore, studying an organic solidifying admixture that can be added in small amounts to reduce the amount of cement used and at the same time improve the performance of solidified soil is of great significance for improving the resource utilization of slag. Summary of the invention

[0003] In view of the shortcomings of the prior art, the object of the present invention is to provide a hydroxylated lignin composite cement-solidified soil admixture and a preparation method thereof.

[0004] The above object of the present invention is achieved through the following technical solutions:

[0005] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0006] 10-30 parts of lignin;

[0007] 10-30 parts of sodium hydroxide;

[0008] γ-(2,3-epoxypropoxy)propyltrimethoxysilane 2-6 parts;

[0009] 1500-1700 parts of water.

[0010] The present invention realizes the effective bonding of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, lignin and soil particles through the following steps, and improves the strength and water stability of the solidified soil. First, lignin is decomposed under the action of sodium hydroxide, increasing its hydroxyl groups, and the silicon oxides in the soil particles are corroded under alkaline conditions, and the surface hydroxyl groups are also increased. Then, the Si-OH group of γ-(2,3-epoxypropoxy)propyltrimethoxysilane undergoes dehydration condensation with the hydroxyl groups in the soil particles or cement hydration products to form a strong bond. Finally, the epoxy group of silane opens the ring under alkaline conditions and combines with the hydroxyl groups of lignin to achieve the connection between silane and lignin. Through these reactions, γ-(2,3-epoxypropoxy)propyltrimethoxysilane not only connects lignin and soil particles together, but also forms an overall structure through the long chain action of lignin, promotes cement hydration, and significantly improves the strength and water stability of the solidified soil.

[0011] Furthermore, the lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 30-60 mg / g.

[0012] Hydroxylation of lignin can significantly improve its effect in the reaction with γ-(2,3-epoxypropoxy)propyltrimethoxysilane and other matrices. First, hydroxylation increases the number of hydroxyl groups in lignin, improves its reactivity, makes it easier to react with the epoxy groups in silane, and promotes chemical bonding. Second, more hydroxyl polar groups enhance the interfacial bonding between lignin and silane and cement or soil particles, improving the overall structure of the material. In addition, hydroxylation improves the water solubility and dispersibility of lignin, ensuring its uniform distribution in the cement or soil matrix, thereby enhancing the cementing properties. By increasing the number of hydroxyl groups, lignin can react with more γ-(2,3-epoxypropoxy)propyltrimethoxysilane to form a more stable three-dimensional network structure, which helps to improve the strength and water stability of cement-cured soil. Better dispersibility and reactivity can also promote the hydration process of cement and further improve its final strength. At the same time, hydroxylation can also reduce the interference of impurities in lignin on the cement hydration reaction, ensuring that it plays a more efficient role in the reaction, thereby improving the performance and durability of the overall material.

[0013] Furthermore, the invention also comprises 0.5-1.5 parts of silver-carrying zeolite particles.

[0014] Furthermore, the D50 particle size of the silver-loaded zeolite particles is 100-500 μm.

[0015] The introduction of silver-loaded zeolite particles not only effectively inhibits harmful bacteria through its antibacterial properties, especially those that degrade and decompose lignin, but also maintains the stability of the solidified material and extends its service life. The antibacterial properties of silver ions in silver-loaded zeolite help reduce the reproduction of microorganisms in the solidified soil and prevent the degradation of material properties due to microbial activity. At the same time, this particle structure synergizes with the cementing system formed by lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane to further enhance the stability and strength of cement solidification, allowing the solidified soil to maintain high strength and water stability during long-term use. This admixture not only improves the mechanical properties of cement-solidified soil, but also ensures its durability through antibacterial effects, effectively avoiding degradation problems caused by microbial erosion.

[0016] Furthermore, the lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane are preformed into a preform, and the preform comprises the following components in parts by weight:

[0017] 10-30 parts of lignin;

[0018] γ-(2,3-epoxypropoxy)propyltrimethoxysilane 2-6 parts;

[0019] 20-30 parts of alkali agent;

[0020] 20-30 parts of acid agent.

[0021] Furthermore, the alkaline agent is selected from sodium carbonate and / or sodium bicarbonate, and the acid agent is selected from one or more of citric acid, tartaric acid or boric acid.

[0022] Furthermore, the method for preparing the preform comprises the following steps: mixing lignin, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, an alkali agent and an acid agent uniformly and then pressing the mixture into sheets.

[0023] By adopting the above technical solution, the preform is conducive to effectively preventing the reaction of components caused by moisture or environmental changes during storage and transportation, and is more convenient to use at the construction site. The material in the form of tablets is easy to carry, store and put, which reduces the complexity of the operation of traditional liquid or powder admixtures and improves the construction efficiency. On the other hand, prefabricating lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane into a preform helps to ensure the uniformity of the mixing of lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane. The alkali and acid react in water to produce a large number of bubbles. Under the action of the bubbles, the reaction between lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane is faster, and lignin can combine with some epoxy groups in γ-(2,3-epoxypropoxy)propyltrimethoxysilane more quickly to form a prepolymer, so that after the admixture is mixed with cement and soil, the admixture can quickly play a role, more evenly and quickly promote the splash of cement, so that the soil particles are more firmly combined faster. Furthermore, the reaction of the alkali and acid in water to produce a large number of bubbles will also promote the uniformity of the dispersion of the silver-loaded zeolite particles, and a trace amount of γ-(2,3-epoxypropoxy)propyltrimethoxysilane will also be mixed with the silver-loaded zeolite particles under the action of the bubbles. During the solidification process of the admixture and the soil, the silver-loaded zeolite particles that have adsorbed a trace amount of γ-(2,3-epoxypropoxy)propyltrimethoxysilane will be more evenly dispersed in the solidified soil and will be more firmly and stably.

[0024] Furthermore, the lignin is pretreated before being preformed into a preform with γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and the pretreatment comprises the following steps:

[0025] A1: Mix lignin and saturated glucose solution evenly and heat to evaporate water into syrup;

[0026] A2: Add the syrup into a sealed container and inject 30-40 atmospheres of pressure, then cool to room temperature;

[0027] A3: The cooled syrup solids are crushed into particles.

[0028] Furthermore, the D50 particle size of the particles is not greater than 1 mm.

[0029] On the one hand, pre-treatment of lignin before making it into a preform can improve the reaction activity of lignin. On the other hand, the particles formed by lignin and glucose will also produce a large number of bubbles with a certain pressure after encountering water during the disintegration of the preform. These bubbles directly act on the lignin, so that the preform can disintegrate more quickly and accelerate the dispersion of the preform.

[0030] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0031] S1: Mix all components evenly according to the proportion;

[0032] S2: heating by reflux of condenser tube, controlling the temperature at 45-60°C, and the reaction time at 20-40 minutes;

[0033] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention utilizes lignin to decompose under the action of sodium hydroxide to increase hydroxyl groups and improve the binding force with silicon oxides in soil particles. At the same time, the Si-OH group of γ-(2,3-epoxypropoxy)propyltrimethoxysilane dehydrates and condenses with hydroxyl groups in cement or soil, thereby enhancing the bonding strength of the material. Through the ring-opening reaction of silane epoxy groups and lignin under alkaline conditions, a strong connection between lignin and silane is formed, which further promotes the hydration reaction of cement and improves the mechanical properties of the solidified soil. In addition, the hydroxylation treatment of lignin increases the number and reaction activity of its hydroxyl groups, improves the uniform distribution and bonding effect of the material, and thus constructs a stable three-dimensional network structure. The introduction of silver-loaded zeolite particles effectively inhibits the degradation of lignin by microorganisms and prolongs the service life of the solidified material. The further innovation of the present invention is particularly reflected in the optimized design of the preform and pretreatment. First, the prefabricated body effectively avoids the reaction of components caused by moisture or environmental changes during storage and transportation by premixing lignin, silane coupling agent, alkali agent and acid agent and pressing them into sheets, ensuring the rapid reaction of each component at the construction site. In addition, the alkali agent and acid agent react in water to produce bubbles, which can accelerate the reaction of lignin with silane epoxy groups, making the admixture act faster and more evenly in cement and soil, significantly improving construction efficiency and cement hydration reaction.

[0036] The pretreatment step further enhances the reactivity of lignin. By mixing with glucose solution and pressurizing to form syrupy particles, this pretreatment not only increases the binding force between lignin and silane, but also produces bubbles when the preform disintegrates and encounters water, which helps to accelerate the dissolution and dispersion of the preform, further improving the reaction speed and uniformity of the admixture. Therefore, the pretreatment and preform design jointly ensure the high performance of the admixture, significantly improving the strength, durability and water stability of the solidified soil. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with embodiments.

[0038] Example 1

[0039] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0040] 20 parts of lignin;

[0041] 20 parts of sodium hydroxide;

[0042] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0043] 1600 parts of water.

[0044] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0045] S1: Mix all components evenly according to the proportion;

[0046] S2: heating by condenser reflux, controlling the temperature at 40°C, and the reaction time for 40 minutes;

[0047] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0048] Example 2

[0049] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0050] 10 parts of lignin;

[0051] 10 parts of sodium hydroxide;

[0052] γ-(2,3-epoxypropoxy)propyltrimethoxysilane 2 parts;

[0053] 1500 parts of water.

[0054] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0055] S1: Mix all components evenly according to the proportion;

[0056] S2: heating by condenser reflux, controlling the temperature at 45°C, and the reaction time for 20 minutes;

[0057] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0058] Example 3

[0059] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0060] 30 parts of lignin;

[0061] 30 parts of sodium hydroxide;

[0062] γ-(2,3-epoxypropoxy)propyltrimethoxysilane 6 parts;

[0063] 1700 parts of water.

[0064] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0065] S1: Mix all components evenly according to the proportion;

[0066] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 20 minutes;

[0067] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0068] Example 4

[0069] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0070] 15 parts of lignin;

[0071] 15 parts of sodium hydroxide;

[0072] 4 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane;

[0073] 1600 parts of water.

[0074] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0075] S1: Mix all components evenly according to the proportion;

[0076] S2: heating by condenser reflux, controlling the temperature to 50°C, and the reaction time to 30 minutes;

[0077] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0078] Example 5

[0079] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0080] 30 parts of lignin;

[0081] 30 parts of sodium hydroxide;

[0082] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0083] 1500 parts of water.

[0084] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0085] S1: Mix all components evenly according to the proportion;

[0086] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0087] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0088] Example 6

[0089] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0090] 30 parts of lignin;

[0091] 30 parts of sodium hydroxide;

[0092] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0093] 1500 parts of water.

[0094] The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 30 mg / g.

[0095] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0096] S1: Mix all components evenly according to the proportion;

[0097] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0098] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0099] Example 7

[0100] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0101] 30 parts of lignin;

[0102] 30 parts of sodium hydroxide;

[0103] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0104] 1500 parts of water.

[0105] The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 45 mg / g.

[0106] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0107] S1: Mix all components evenly according to the proportion;

[0108] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0109] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0110] Example 8

[0111] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0112] 30 parts of lignin;

[0113] 30 parts of sodium hydroxide;

[0114] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0115] 1500 parts of water.

[0116] The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 60 mg / g.

[0117] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0118] S1: Mix all components evenly according to the proportion;

[0119] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0120] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0121] Example 9

[0122] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0123] 30 parts of lignin;

[0124] 30 parts of sodium hydroxide;

[0125] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0126] 0.5 parts of silver-loaded zeolite particles;

[0127] 1500 parts of water.

[0128] The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 50 mg / g.

[0129] The D50 particle size of the silver-loaded zeolite particles is 100 μm.

[0130] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0131] S1: Mix all components evenly according to the proportion;

[0132] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0133] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0134] Example 10

[0135] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0136] 30 parts of lignin;

[0137] 30 parts of sodium hydroxide;

[0138] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0139] 1.5 parts of silver-loaded zeolite particles;

[0140] 1500 parts of water.

[0141] The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 50 mg / g.

[0142] The D50 particle size of the silver-loaded zeolite particles is 500 μm.

[0143] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0144] S1: Mix all components evenly according to the proportion;

[0145] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0146] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0147] Embodiment 11

[0148] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0149] 30 parts of lignin;

[0150] 30 parts of sodium hydroxide;

[0151] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0152] 1 part of silver-loaded zeolite particles;

[0153] 1500 parts of water.

[0154] The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 50 mg / g.

[0155] The D50 particle size of the silver-loaded zeolite particles is 300 μm.

[0156] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0157] S1: Mix all components evenly according to the proportion;

[0158] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0159] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0160] Example 12

[0161] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0162] 30 parts of lignin;

[0163] 30 parts of sodium hydroxide;

[0164] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0165] 1500 parts of water.

[0166] The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 50 mg / g.

[0167] Lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane are preformed into a preform, and the preform includes the following components in parts by weight:

[0168] 10 parts of lignin;

[0169] γ-(2,3-epoxypropoxy)propyltrimethoxysilane 2 parts;

[0170] 20 parts of alkali agent;

[0171] 20 parts of acid.

[0172] The alkaline agent is sodium bicarbonate, and the acid agent is citric acid.

[0173] The preparation method of the preform comprises the following steps: mixing lignin, gamma-(2,3-epoxypropoxy)propyltrimethoxysilane, an alkali agent and an acid agent uniformly and then pressing the mixture into sheets.

[0174] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0175] S1: Mix all components evenly according to the proportion;

[0176] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0177] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0178] Example 13

[0179] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0180] 30 parts of lignin;

[0181] 30 parts of sodium hydroxide;

[0182] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0183] 1 part of silver-loaded zeolite particles;

[0184] 1500 parts of water.

[0185] The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 50 mg / g.

[0186] The D50 particle size of the silver-loaded zeolite particles is 500 μm.

[0187] Lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane are preformed into a preform, and the preform includes the following components in parts by weight:

[0188] 10 parts of lignin;

[0189] γ-(2,3-epoxypropoxy)propyltrimethoxysilane 2 parts;

[0190] 20 parts of alkali agent;

[0191] 20 parts of acid.

[0192] The alkaline agent is sodium bicarbonate, and the acid agent is citric acid.

[0193] The preparation method of the preform comprises the following steps: mixing lignin, gamma-(2,3-epoxypropoxy)propyltrimethoxysilane, an alkali agent and an acid agent uniformly and then pressing the mixture into sheets.

[0194] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0195] S1: Mix all components evenly according to the proportion;

[0196] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0197] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0198] Embodiment 14

[0199] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0200] 30 parts of lignin;

[0201] 30 parts of sodium hydroxide;

[0202] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0203] 1 part of silver-loaded zeolite particles;

[0204] 1500 parts of water.

[0205] The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 50 mg / g.

[0206] The D50 particle size of the silver-loaded zeolite particles is 500 μm.

[0207] Lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane are preformed into a preform, and the preform includes the following components in parts by weight:

[0208] 30 parts of lignin;

[0209] γ-(2,3-epoxypropoxy)propyltrimethoxysilane 6 parts;

[0210] 30 parts of alkali agent;

[0211] 30 parts of acid.

[0212] The alkaline agent is sodium bicarbonate, and the acid agent is citric acid.

[0213] The preparation method of the preform comprises the following steps: mixing lignin, gamma-(2,3-epoxypropoxy)propyltrimethoxysilane, an alkali agent and an acid agent uniformly and then pressing the mixture into sheets.

[0214] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0215] S1: Mix all components evenly according to the proportion;

[0216] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0217] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0218] Embodiment 15

[0219] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0220] 30 parts of lignin;

[0221] 30 parts of sodium hydroxide;

[0222] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0223] 1 part of silver-loaded zeolite particles;

[0224] 1500 parts of water.

[0225] The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 50 mg / g.

[0226] The D50 particle size of the silver-loaded zeolite particles is 500 μm.

[0227] Lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane are preformed into a preform, and the preform includes the following components in parts by weight:

[0228] 20 parts of lignin;

[0229] 4 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane;

[0230] 25 parts of alkali agent;

[0231] 25 parts of acid.

[0232] The alkaline agent is sodium bicarbonate, and the acid agent is citric acid.

[0233] The preparation method of the preform comprises the following steps: mixing lignin, gamma-(2,3-epoxypropoxy)propyltrimethoxysilane, an alkali agent and an acid agent uniformly and then pressing the mixture into sheets.

[0234] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0235] S1: Mix all components evenly according to the proportion;

[0236] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0237] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0238] Example 16

[0239] A hydroxylated lignin composite cement-stabilized soil admixture comprises the following components in parts by weight:

[0240] 30 parts of lignin;

[0241] 30 parts of sodium hydroxide;

[0242] γ-(2,3-Epoxypropoxy)propyltrimethoxysilane 3 parts;

[0243] 1 part of silver-loaded zeolite particles;

[0244] 1500 parts of water.

[0245] The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 50 mg / g.

[0246] The D50 particle size of the silver-loaded zeolite particles is 500 μm.

[0247] The lignin is first pre-treated, and the pre-treatment comprises the following steps:

[0248] A1: Mix lignin and saturated glucose solution at a mass ratio of 1:50 and heat until the water evaporates to form a syrup;

[0249] A2: Add the syrup into a sealed container and inject it to 40 atmospheres of pressure, then cool it to room temperature;

[0250] A3: The cooled syrup solids are crushed into particles.

[0251] The D50 particle size of the particles is 0.8 mm.

[0252] Lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane are preformed into a preform, and the preform includes the following components in parts by weight:

[0253] 20 parts of lignin;

[0254] 4 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane;

[0255] 25 parts of alkali agent;

[0256] 25 parts of acid.

[0257] The alkaline agent is sodium bicarbonate, and the acid agent is citric acid.

[0258] The preparation method of the preform comprises the following steps: mixing lignin, gamma-(2,3-epoxypropoxy)propyltrimethoxysilane, an alkali agent and an acid agent uniformly and then pressing the mixture into sheets.

[0259] A method for preparing the above-mentioned hydroxylated lignin composite cement-cured soil admixture comprises the following steps:

[0260] S1: Mix all components evenly according to the proportion;

[0261] S2: heating by condenser reflux, controlling the temperature at 60°C, and the reaction time for 40 minutes;

[0262] S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

[0263] Comparative Example

[0264] The additive used in Comparative Example 1 includes the following components in parts by weight which are stirred and mixed uniformly:

[0265] 20 parts of lignin;

[0266] 20 parts of sodium hydroxide;

[0267] 1600 parts of water.

[0268] Detection Methods

[0269] Curing performance test

[0270] First, add cement at 7% of the dry weight of the soil to be solidified and dry mix evenly. The geotechnical properties of the soil are shown in Table 1:

[0271]

[0272] Then, the admixture solution prepared in the examples and comparative examples was added, and the amount of water to be added was calculated according to the optimum moisture content at the maximum dry density of the soil material and added to the mixture. Compacted, cured at a curing temperature of 25°C for 7 days. Finally, the unconfined compressive strength (UCS) of the solidified soil material was tested, and the unconfined compressive strength (UCS) of the solidified soil material was tested after being placed in the sludge for 6 months.

[0273] The test results are shown in Table 2. The control group is soil solidified only with cement.

[0274]

[0275] Conclusion: It can be seen from the above test results that the curing performance of cement-cured soil is significantly improved after adding the admixture prepared by the present invention, and when lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane are preformed into a preform, the antibacterial ability of the silver-loaded zeolite particles is also significantly improved.

[0276] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A hydroxylated lignin composite cement-stabilized soil admixture, characterized in that: The composition comprises the following components in parts by weight: 10-30 parts of lignin; 10-30 parts of sodium hydroxide; γ-(2,3-epoxypropoxy)propyltrimethoxysilane 2-6 parts; 1500-1700 parts of water; The lignin and γ-(2,3-epoxypropoxy)propyltrimethoxysilane are preformed into a preform, and the preform includes the following components in parts by weight: 10-30 parts of lignin; γ-(2,3-epoxypropoxy)propyltrimethoxysilane 2-6 parts; 20-30 parts of alkali agent; 20-30 parts of acid agent.

2. The hydroxylated lignin composite cement-stabilized soil admixture according to claim 1, characterized in that: The lignin is partially hydroxylated and pretreated, and the hydroxyl value of the lignin after the hydroxylation pretreatment is 30-60 mg / g.

3. The hydroxylated lignin composite cement-stabilized soil admixture according to claim 1, characterized in that: Also included are 0.5-1.5 parts of silver-loaded zeolite particles.

4. The hydroxylated lignin composite cement-stabilized soil admixture according to claim 3, characterized in that: The D50 particle size of the silver-loaded zeolite particles is 100-500 μm.

5. The hydroxylated lignin composite cement-stabilized soil admixture according to claim 1, characterized in that: The alkaline agent is selected from sodium carbonate and / or sodium bicarbonate, and the acid agent is selected from one or more of citric acid, tartaric acid or boric acid.

6. The hydroxylated lignin composite cement-stabilized soil admixture according to claim 1, characterized in that: The preparation method of the preform comprises the following steps: lignin, gamma-(2,3-epoxypropoxy)propyltrimethoxysilane, an alkali agent and an acid agent are uniformly mixed and then tabletted.

7. The hydroxylated lignin composite cement-stabilized soil admixture according to claim 1, characterized in that: The lignin is pretreated before being preformed into a preform with γ-(2,3-epoxypropoxy)propyltrimethoxysilane. The following steps are involved: A1: Mix lignin and saturated glucose solution evenly and heat to evaporate water into syrup; A2: Add the syrup into a sealed container and inject 30-40 atmospheres of pressure, then cool to room temperature; A3: The cooled syrup solids are crushed into particles.

8. The hydroxylated lignin composite cement-stabilized soil admixture according to claim 7, characterized in that: The D50 particle size of the particles is no greater than 1 mm.

9. A method for preparing a hydroxylated lignin composite cement-stabilized soil admixture according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: Mix all components in proportion; S2: heating by reflux of condenser tube, controlling the temperature at 45-60°C, and the reaction time at 20-40 minutes; S3: After the reaction is completed, cool to room temperature and keep in liquid form for later use.

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