Composite admixture for marine silt stratum grouting slurry and preparation method thereof

Abstract

The application relates to the technical field of admixture composite materials, and particularly discloses a composite admixture for sea silt stratum grouting slurry and a preparation method thereof. The composite admixture for sea silt stratum grouting slurry comprises the following components in parts by weight: water reducing agent 1.5-2 parts; anti-permeation agent 3-5 parts; magnesium oxide 5-8 parts; hydroxypropyl methylcellulose 0.1-0.3 parts; sodium dodecyl benzene sulfonate 0.05-0.15; sodium hexametaphosphate 3-6 parts; and modified polypropylene fiber 0.6-1.2 parts. The modified polypropylene fiber is prepared through the following steps: S1, taking polypropylene fiber raw materials, performing ultrasonic cleaning with acetone, drying, and then sequentially performing immersion in an ethanol solution and a calcium chloride solution, washing with water and drying to obtain pretreated polypropylene fiber; and S2, after coating a silane coupling agent on the surface of the pretreated polypropylene fiber, spraying polyacrylamide and active silicate powder to obtain the modified polypropylene fiber. The composite admixture for sea silt stratum grouting slurry can effectively inhibit the expansion of microcracks under the erosion of a marine environment.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of admixture composite materials, in particular to a composite admixture for a slurry for grouting in a marine silt stratum and a preparation method thereof. BACKGROUND

[0002] China's marine engineering has entered a large-scale construction period, and the construction and operation of drilling platforms, cross-sea bridges, deep-water ports, and submarine tunnels under marine environments are booming. Adverse geology is one of the important threats to engineering construction and operation.

[0003] When construction is carried out in coastal beach areas, marine silt strata are common strata in marine engineering. Due to their poor self-stability, the mechanical properties of the marine silt strata, which are characterized by "three highs and two lows", bring great difficulties to construction. Grouting is a common method for overcoming the defects of marine silt strata. By injecting slurry into the marine silt stratum for reinforcement, the bearing capacity of the marine silt stratum is significantly improved, meeting the construction requirements and improving the overall construction quality.

[0004] However, the marine environment is quite different from the terrestrial environment. The harmful ions in seawater have a strong erosive and destructive effect, and under the action of seepage, the grouting reinforcement body is significantly deteriorated, which further causes the grouting reinforcement body to be damaged, greatly reducing its stability and service life. Therefore, a water-reducing agent is usually used to improve the impermeability of the grouting reinforcement body, and a water-reducing agent is used to improve the density of the grouting reinforcement body. Through the improvement of the density and impermeability, the durability of the grouting reinforcement body in the marine environment is improved.

[0005] According to the related technology in the above, the inventors believe that microcracks will inevitably occur in the grouting reinforcement body during the formation process. Under the erosion of the marine environment, the microcracks are easily expanded to form larger cracks. Although the improvement of the impermeability and density of the grouting reinforcement body can resist the erosion of the marine environment to a certain extent, it cannot effectively prevent the expansion of the microcracks. Therefore, there is an urgent need to propose a solution to solve the above technical problems. SUMMARY

[0006] In order to effectively prevent the expansion of the microcracks in the grouting reinforcement body under the erosion of the marine environment, the application provides a composite admixture for a slurry for grouting in a marine silt stratum and a preparation method thereof.

[0007] In a first aspect, the application provides a composite admixture for a slurry for grouting in a marine silt stratum, which adopts the following technical solution:

[0008] A composite admixture for a slurry for grouting in a marine silt stratum comprises the following components by weight:

[0009] 1.5-2 parts of a water-reducing agent;

[0010] Anti-permeation agent 3-5 parts;

[0011] Magnesium oxide 5-8 parts;

[0012] Hydroxypropyl methyl cellulose 0.1-0.3 parts;

[0013] Sodium dodecyl benzene sulfonate 0.05-0.15;

[0014] Sodium hexametaphosphate 3-6 parts;

[0015] Modified polypropylene fiber 0.6-1.2 parts;

[0016] The modified polypropylene fiber is prepared by the following steps:

[0017] S1, taking polypropylene fiber raw material, washing with acetone under ultrasonic and then drying, then immersing in ethanol solution and calcium chloride solution in sequence, and then washing with water and drying, to obtain pretreated polypropylene fiber;

[0018] S2, after coating silane coupling agent on the surface of the pretreated polypropylene fiber, spraying polyacrylamide and active silicate powder, to obtain modified polypropylene fiber.

[0019] By adopting the above technical solution, magnesium oxide as an expanding agent can reduce the shrinkage and deformation of the grouting slurry; hydroxypropyl methyl cellulose can give the grouting slurry excellent viscosity, and increase the plasticity and smoothness of the grouting slurry in the operation process, which is beneficial to the stable application effect of the grouting slurry; sodium dodecyl benzene sulfonate can improve the interaction between cement particles, forming a more firm combination, thereby improving the strength and impermeability of the grouting reinforced body formed by the grouting slurry; sodium hexametaphosphate can react with cement to generate a stable gel body, which can effectively plug pores and improve the compactness and hardness of the grouting reinforced body.

[0020] Meanwhile, the polypropylene fiber raw material is modified. During the modification process, the polypropylene fiber raw material is cleaned by acetone, so that the surface becomes clean; after the treatment of ethanol and calcium chloride, the surface of the polypropylene fiber becomes rough and active functional groups are released; after the treatment of silane coupling agent, the polyacrylamide and active silicate fully act on the polypropylene fiber, so that the polyacrylamide and active silicate can be stably loaded on the surface of the polypropylene fiber, and then the modified polypropylene fiber is obtained. The modified polypropylene fiber has a prominent inhibitory effect on the occurrence and expansion of microcracks in the grouting reinforced body. When microcracks occur and expand to the modified polypropylene fiber, the active silicate and calcium ions of the grouting reinforced body form a soluble complex, which is combined with the polyacrylamide to effectively repair the microcracks, and relies on the polypropylene fiber, so that the microcracks are not easy to expand to form larger cracks. In this way, a composite admixture for grouting slurry of marine silt stratum with more excellent quality can be obtained.

[0021] Preferably, the weight ratio of the polyacrylamide and the active silicate is 1:(3.5-6.3).

[0022] By adopting the above technical solution, the polyacrylamide and the active silicate in the above weight ratio can be stably loaded on the polypropylene fiber and play a more excellent cooperation effect with each other, not only can bring more outstanding repair effect to the microcrack, but also can form a close combination with the polypropylene fiber and stably and durably exist, thereby making the overall application effect of the modified polypropylene fiber more outstanding.

[0023] Preferably, the weight ratio of the polyacrylamide and the active silicate is 1:4.5.

[0024] By adopting the above technical solution, the polyacrylamide and the active silicate in the above weight ratio can play the most excellent effect in combination with the polypropylene fiber, and the performance of suppressing the expansion of the microcrack in the grouting reinforcement body is better.

[0025] Preferably, the diameter of the polypropylene fiber raw material is 20-50μm, and the length is 2-3mm.

[0026] By adopting the above technical solution, the polypropylene fiber raw material in the above specification can be uniformly dispersed when the modified polypropylene fiber is applied, and is more suitable for connecting and cooperating with the polyacrylamide and the active silicate to suppress the expansion of the microcrack. When the specification is smaller, the modified polypropylene fiber is not easy to disperse, and when the specification is larger, the network structure formed by the modified polypropylene fiber is relatively loose, the anisotropy is poor, and the applicability to the microcrack is poor. Therefore, the application of the polypropylene fiber raw material in the above specification can bring a composite admixture for grouting slurry of marine silt stratum with more excellent and stable quality.

[0027] Preferably, the functional auxiliary agent with a weight fraction of 2.5-4.5 parts is further added in the component, the functional auxiliary agent is composed of bamboo fiber and polyvinyl alcohol, and the weight ratio of the bamboo fiber and the polyvinyl alcohol is (2-4):1.

[0028] The bamboo fiber has strong toughness, can better inhibit the expansion of micro cracks, and has natural antibacterial property, and is durable and stable in application. The polyvinyl alcohol is partially filled in the pore structure of the bamboo fiber by using the porosity and adsorption of the bamboo fiber to protect the bamboo fiber. When the functional additive is applied to the grouting slurry, the polyvinyl alcohol can combine with calcium ions in the grouting slurry to form a strong bonding force, and the toughness of the bamboo fiber can greatly inhibit the expansion of micro cracks. At the same time, the functional additive can also have excellent compounding and synergistic effect with the modified polypropylene fiber, and the complementary network structure can significantly improve the performance of inhibiting the expansion of micro cracks.

[0029] Preferably, the weight ratio of the bamboo fiber and the polyvinyl alcohol is 3:1.

[0030] By adopting the above technical scheme, the functional additive composed of the bamboo fiber and the polyvinyl alcohol in the above weight ratio has outstanding compounding effect with the modified fiber, and the corresponding effect brought by the application is excellent.

[0031] Preferably, the diameter of the bamboo fiber is 20-50μm, and the length is 1.3-2.8mm.

[0032] By adopting the above technical scheme, the bamboo fiber with the above specifications can better cooperate with the modified polypropylene fiber, and the complementary and perfect combined system formed by the network structure of the two can better inhibit the expansion of micro cracks.

[0033] Preferably, the water reducing agent is one or a combination of several of polycarboxylic acid type water reducing agent, naphthalene sulfonate type water reducing agent, lignin type water reducing agent and melamine type water reducing agent.

[0034] By adopting the above technical scheme, the water reducing agent molecules have adsorption, dispersion and lubrication effect on cement particles, can adjust the fluidity of the grouting slurry, make the grouting slurry have high construction effect, and then make the finally formed grouting reinforced body have high strength. The above types of water reducing agents are suitable for the preparation of the composite admixture for marine silt stratum grouting slurry, and bring excellent stability.

[0035] Preferably, the anti-permeation agent is one or a combination of several of silicate anti-permeation agent, organic silicon anti-permeation agent and polymer anti-permeation agent.

[0036] By adopting the above technical scheme, the anti-permeation agent can improve the density of the grouting reinforced body and improve the anti-permeation ability. The above types of anti-permeation agents can all play excellent stability after being applied to prepare the composite admixture for marine silt stratum grouting slurry.

[0037] In a second aspect, the application provides a preparation method of a composite admixture for marine silt stratum grouting slurry, which adopts the following technical scheme:

[0038] A preparation method of a composite admixture for marine silt stratum grouting slurry, comprising the following steps:

[0039] (1) Prepare raw materials containing water reducing agent, anti-permeation agent, magnesium oxide, hydroxypropyl methyl cellulose, sodium dodecyl benzene sulfonate, sodium hexametaphosphate and modified polypropylene fiber according to the proportion;

[0040] (2) Mix the water reducing agent, anti-permeation agent, magnesium oxide, hydroxypropyl methyl cellulose, sodium dodecyl benzene sulfonate and sodium hexametaphosphate in step (1) uniformly, then add the modified polypropylene fiber and mix uniformly, to obtain the composite admixture for marine silt stratum grouting slurry.

[0041] By adopting the above technical scheme, the above preparation steps are simple to operate, and the components of the raw materials are mixed uniformly and then applied to the grouting slurry, which is convenient for production and use, and can ensure that the composite admixture for marine silt stratum grouting slurry has excellent and stable application effect.

[0042] In summary, the application has the following beneficial effects:

[0043] 1. The polypropylene fiber raw material is modified to obtain modified polypropylene fiber loaded with polyacrylamide and active silicate, so that the composite admixture for marine silt stratum grouting slurry containing the modified polypropylene fiber has a strong inhibitory effect on the expansion of microcracks through the cooperation between polyacrylamide and active silicate and relying on polypropylene fiber, thereby making the grouting reinforcement body have excellent stability under the erosion of the marine environment;

[0044] 2. The use of the functional additive composed of bamboo fiber and polyvinyl alcohol can not only significantly improve the inhibition of microcrack expansion, but also have excellent synergistic effect with the modified polypropylene fiber, thereby further improving the application effect of the composite admixture for marine silt stratum grouting slurry. DETAILED DESCRIPTION

[0045] The application will be further described in detail below in combination with examples.

[0046] The raw materials used in each preparation example and embodiment of the application are commercially available, except for special instructions:

[0047] The polyacrylamide is purchased from Foshan Sanzhong Environmental Protection Technology Co., Ltd., and the model is BIBO-PAM.

[0048] Polyvinyl alcohol is purchased from Anhui Longyang Environmental Protection Technology Co., Ltd. Polyvinyl alcohol 2488;

[0049] Active silicate is purchased from Beijing Wantu Ming Technology Co., Ltd. Active flaky silicate 987;

[0050] Polypropylene fiber is provided by Shandong Hongsheng Engineering Material Co., Ltd.;

[0051] Bamboo fiber is provided by Shandong Jiuyuan Textile Co., Ltd.

[0052] Polycarboxylic acid type water reducing agent is purchased from Liaoning Kelong Fine Chemical Co., Ltd. Type R-209;

[0053] Naphthalene sulfonate type water reducing agent is purchased from Fuzhou Poseidon Chemical Co., Ltd. Type PMS-100;

[0054] Silicate anti-permeability agent is purchased from Chiping Zetai Building Material Co., Ltd. Type ZTFS-1;

[0055] Organosilicon anti-permeability agent is purchased from Chiping Zetai Building Material Co., Ltd. Type ZT-3.

[0056] Preparation example of raw materials and / or intermediates

[0057] Preparation example 1

[0058] A modified polypropylene fiber is prepared by the following steps:

[0059] S1, take polypropylene fiber raw materials, ultrasonic cleaning with acetone and then dry, then immerse in 70% ethanol solution and 6% calcium chloride solution in turn for 60 min, then wash with water and dry, to obtain pretreated polypropylene fiber;

[0060] S2, after coating KH-550 silane coupling agent on the surface of the pretreated polypropylene fiber, spray polyacrylamide and active silicate powder, the spraying amount is 12% of the mass of the polypropylene fiber raw materials, to obtain the modified polypropylene fiber.

[0061] Note: In the above steps, the weight ratio of polyacrylamide and active silicate is 1:4.5; the diameter of the polypropylene fiber raw materials is 35 μm, and the length is 2.5 mm.

[0062] Preparation example 2

[0063] A modified polypropylene fiber, which is different from preparation example 1, is that the weight ratio of polyacrylamide and active silicate is 1:3.5.

[0064] Preparation example 3

[0065] A modified polypropylene fiber, which is different from preparation example 1, is that the weight ratio of polyacrylamide and active silicate is 1:6.3.

[0066] Preparation Example 4

[0067] A modified polypropylene fiber, which is different from Preparation Example 1 in that the weight ratio of polyacrylamide and active silicate is 1:4.9.

[0068] Preparation Example 5

[0069] A modified polypropylene fiber, which is different from Preparation Example 1 in that the weight ratio of polyacrylamide and active silicate is 1:3.3.

[0070] Preparation Example 6

[0071] A modified polypropylene fiber, which is different from Preparation Example 1 in that the weight ratio of polyacrylamide and active silicate is 1:6.5.

[0072] Preparation Example 7

[0073] A modified polypropylene fiber, which is different from Preparation Example 1 in that the diameter of the polypropylene fiber raw material is 20 μm and the length is 2 mm.

[0074] Preparation Example 8

[0075] A modified polypropylene fiber, which is different from Preparation Example 1 in that the diameter of the polypropylene fiber raw material is 50 μm and the length is 3 mm.

[0076] Preparation Example 9

[0077] A modified polypropylene fiber, which is different from Preparation Example 1 in that the diameter of the polypropylene fiber raw material is 15 μm and the length is 1.5 mm.

[0078] Preparation Example 10

[0079] A modified polypropylene fiber, which is different from Preparation Example 1 in that the diameter of the polypropylene fiber raw material is 55 μm and the length is 3.5 mm.

[0080] Preparation Example 11

[0081] A modified polypropylene fiber, which is different from Preparation Example 1 in that, in the operation of Step S2, polyacrylamide is not sprayed.

[0082] Preparation Example 12

[0083] A modified polypropylene fiber, which is different from Preparation Example 1 in that, in the operation of Step S2, active silicate is not sprayed.

[0084] Preparation Example 13

[0085] A modified polypropylene fiber, which is different from Preparation Example 1 in that, in the operation of step S2, polyacrylamide and active silicate are not sprayed.

[0086] Example

[0087] Example 1

[0088] A composite admixture for a marine silt stratum grouting slurry, the components and their respective weights are shown in Table 1, and is prepared by the following steps:

[0089] (1) Prepare raw materials containing water reducing agent, anti-permeation agent, magnesium oxide, hydroxypropyl methyl cellulose, sodium dodecylbenzenesulfonate, sodium hexametaphosphate and modified polypropylene fiber according to the ratio;

[0090] (2) Mix the water reducing agent, anti-permeation agent, magnesium oxide, hydroxypropyl methyl cellulose, sodium dodecylbenzenesulfonate and sodium hexametaphosphate in step (1) uniformly, the stirring speed is 200 r / min, the stirring time is 20 min, then add the modified polypropylene fiber, mix uniformly, the stirring speed is 300 r / min, the stirring time is 10 min, to obtain the composite admixture for a marine silt stratum grouting slurry.

[0091] Note: The modified polypropylene fiber in the above steps is obtained in Preparation Example 1; the water reducing agent is a polycarboxylic acid type water reducing agent; the anti-permeation agent is a silicate anti-permeation agent.

[0092] Example 2-3

[0093] A composite admixture for a marine silt stratum grouting slurry, which is different from Example 1 in that the components and their respective weights are shown in Table 1.

[0094] Table 1 Components and their weight fractions (kg / portions) in Examples 1-3

[0095] Component Example 1 Example 2 Example 3 Water reducing agent 1.75 1.5 2 Anti-permeation agent 4 5 3 Magnesium oxide 6.5 8 5 Hydroxypropyl methylcellulose 0.2 0.1 0.3 Sodium dodecylbenzenesulfonate 0.1 0.05 0.15 Sodium hexametaphosphate 4.5 3 6 Modified polypropylene fiber 0.9 1.2 0.6

[0096] Example 4

[0097] A composite admixture for a marine silt stratum grouting slurry, which is different from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 2.

[0098] Example 5

[0099] A composite admixture for a marine silt stratum grouting slurry, which is different from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 3.

[0100] Example 6

[0101] A composite admixture for a grouting slurry for a marine mud ground layer, which differs from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 4.

[0102] Example 7

[0103] A composite admixture for a grouting slurry for a marine mud ground layer, which differs from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 5.

[0104] Example 8

[0105] A composite admixture for a grouting slurry for a marine mud ground layer, which differs from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 6.

[0106] Example 9

[0107] A composite admixture for a grouting slurry for a marine mud ground layer, which differs from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 7.

[0108] Example 10

[0109] A composite admixture for a grouting slurry for a marine mud ground layer, which differs from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 8.

[0110] Example 11

[0111] A composite admixture for a grouting slurry for a marine mud ground layer, which differs from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 9.

[0112] Example 12

[0113] A composite admixture for a grouting slurry for a marine mud ground layer, which differs from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 10.

[0114] Example 13

[0115] A composite admixture for a grouting slurry for a marine mud ground layer, which differs from Example 1 in that the water reducing agent is a naphthalene sulfonate-based water reducing agent.

[0116] Example 14

[0117] A composite admixture for a grouting slurry for a marine mud ground layer, which differs from Example 1 in that the permeability inhibitor is an organic silicon permeability inhibitor.

[0118] Example 15

[0119] A composite admixture for sea silt stratum grouting slurry, different from example 1 is that 3.5 parts of functional additives are added to the components, the functional additives are composed of bamboo fiber and polyvinyl alcohol in a weight ratio of 3:1, the diameter of the bamboo fiber is 35 μm, and the length is 2 mm.

[0120] Example 16

[0121] A composite admixture for sea silt stratum grouting slurry, different from example 15 is that the weight of the functional additives added is 2.5 parts.

[0122] Example 17

[0123] A composite admixture for sea silt stratum grouting slurry, different from example 15 is that the weight of the functional additives added is 4.5 parts.

[0124] Example 18

[0125] A composite admixture for sea silt stratum grouting slurry, different from example 15 is that the functional additives are composed of bamboo fiber and polyvinyl alcohol in a weight ratio of 2:1.

[0126] Example 19

[0127] A composite admixture for sea silt stratum grouting slurry, different from example 15 is that the functional additives are composed of bamboo fiber and polyvinyl alcohol in a weight ratio of 4:1.

[0128] Example 20

[0129] A composite admixture for sea silt stratum grouting slurry, different from example 15 is that the functional additives are composed of bamboo fiber and polyvinyl alcohol in a weight ratio of 4.2:1.

[0130] Example 21

[0131] A composite admixture for sea silt stratum grouting slurry, different from example 15 is that the functional additives are composed of bamboo fiber and polyvinyl alcohol in a weight ratio of 1.8:1.

[0132] Example 22

[0133] A composite admixture for sea silt stratum grouting slurry, different from example 15 is that the diameter of the bamboo fiber is 20 μm, and the length is 1.3 mm.

[0134] Example 23

[0135] A composite admixture for sea silt stratum grouting slurry, different from example 15 is that the diameter of the bamboo fiber is 50 μm, and the length is 2.8 mm.

[0136] Example 24

[0137] A composite admixture for a grouting slurry for a marine mud layer, which is different from Example 15 in that the diameter of the bamboo fiber is 15 μm and the length is 1.2 mm.

[0138] Example 25

[0139] A composite admixture for a grouting slurry for a marine mud layer, which is different from Example 15 in that the diameter of the bamboo fiber is 55 μm and the length is 3 mm.

[0140] Example 26

[0141] A composite admixture for a grouting slurry for a marine mud layer, which is different from Example 15 in that the raw material does not contain the bamboo fiber.

[0142] Example 27

[0143] A composite admixture for a grouting slurry for a marine mud layer, which is different from Example 15 in that the raw material does not contain the polyvinyl alcohol.

[0144] Comparative Example

[0145] Comparative Example 1

[0146] A composite admixture for a grouting slurry for a marine mud layer, which is different from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 11.

[0147] Comparative Example 2

[0148] A composite admixture for a grouting slurry for a marine mud layer, which is different from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 12.

[0149] Comparative Example 3

[0150] A composite admixture for a grouting slurry for a marine mud layer, which is different from Example 1 in that the modified polypropylene fiber is obtained in Preparation Example 13.

[0151] Comparative Example 4

[0152] A composite admixture for a grouting slurry for a marine mud layer, which is different from Example 15 in that the raw material does not contain the modified polypropylene fiber.

[0153] Comparative Example 5

[0154] A composite admixture for a grouting slurry for a marine mud layer, which is different from Example 1 in that the modified polypropylene fiber is replaced with the corresponding weight ratio of polypropylene fiber raw material, polyacrylamide and active silicate.

[0155] Performance test Test sample: The composite admixture for marine silt stratum grouting slurry obtained in Examples 1-27 was used as test sample 1-27, and the composite admixture for marine silt stratum grouting slurry obtained in Comparative Examples 1-5 was used as control sample 1-5.

[0156] Test method: 1.5% of the composite admixture for marine silt stratum grouting slurry, 70% of C35 ordinary portland cement, and 28.5% of water were mixed by stirring to obtain a uniform mixture, which was poured into a steel mold with a size of 150 mm x 150 mm x 100 mm. After 36 h, the mold was removed, and the formed grouting reinforced body was cured in an environment with a temperature of 22°C and a humidity of 95% for 28 days. The breaking strength of the grouting reinforced body after forming was measured using a YAW-300C hydraulic pressure testing machine, and the value was recorded as the initial value. At the same time, the grouting reinforced body after forming was immersed in seawater, and the seawater area was selected to be within a range of 10 nautical miles to 12 nautical miles from Zhoushan offshore. After 20 days of maintenance, the grouting reinforced body was taken out and dried. The breaking strength of the grouting reinforced body was measured in the same way, and the value was recorded as the experimental value. Finally, the breaking strength loss rate of the grouting reinforced body was calculated, and the breaking strength loss rate = (initial value-experimental value) / initial value. According to the above test method, test samples 1-27 and control samples 1-5 were tested in turn, and the corresponding breaking strength loss rates obtained were recorded in Table 2 below. The greater the breaking strength loss rate, the more likely the grouting reinforced body is to expand microcracks after seawater erosion, and thus the more likely the grouting reinforced body is to break.

[0157] Table 2 Test results of test samples 1-27 and control samples 1-5

[0158]

[0159]

[0160]

[0161] In combination with Example 1 and Comparative Examples 1-3 and in combination with Table 2, it can be seen that the polypropylene fiber raw material is modified to obtain modified polypropylene fiber loaded with polyacrylamide and active silicate. Through the synergistic effect of polyacrylamide and active silicate, and relying on polypropylene fiber, the expansion of microcracks can be well inhibited, and thus the breaking strength loss rate measured is lower. If either of polyacrylamide and active silicate is loaded on polypropylene fiber alone to obtain modified polypropylene fiber, the effect of inhibiting the expansion of microcracks is effective, and is far inferior to the excellent effect of Example 1. In combination with Comparative Example 5 and in combination with Table 2, it can be seen that if modification is not used, and only polypropylene fiber, polyacrylamide, and active silicate are simply mixed, the corresponding effect brought by application will be greatly reduced, and the breaking strength loss rate measured will also be relatively high.

[0162] It can be seen from the combination of Example 1 and Examples 4-8 and Table 2 that when the weight ratio of polyacrylamide and active silicate is 1:(3.5-6.3), the corresponding effect of excellent stability can be achieved, and when the weight ratio of polyacrylamide and active silicate is 1:4.5, the corresponding effect is the most excellent, and the composite admixture for marine mud stratum grouting slurry obtained can significantly affect the expansion of microcracks after application. When the mixing ratio of polyacrylamide and active silicate exceeds the above range, the test measured fracture strength loss rate is significantly increased, indicating that the anti-crack expansion effect is relatively poor.

[0163] It can be seen from the combination of Example 1 and Examples 7-10 and Table 2 that when the diameter of the polypropylene fiber raw material is 20-50 μm and the length is 2-3 mm, it can better cooperate with polyacrylamide and active silicate to suppress the expansion of microcracks. When the above specification range is exceeded, the fracture strength loss rate will increase significantly, because the smaller specification is not easy to disperse, and the larger specification has poor applicability to microcracks.

[0164] It can be seen from the combination of Example 1 and Examples 15-19 and Table 2 that the addition of a functional additive composed of bamboo fiber and polyvinyl alcohol in a weight ratio of (2-4):1 can further improve the anti-crack expansion capacity, and the fracture strength loss rate is significantly reduced. It can be seen from the combination of Examples 20-21 and Table 2 that when the ratio of bamboo fiber and polyvinyl alcohol exceeds the above range, the effect will be lost. It can be seen from the combination of Examples 26-27 and Table 2 that the use of bamboo fiber or polyvinyl alcohol alone can improve the ability to suppress the expansion of microcracks, but the improvement effect is limited and far inferior to the excellent effect of the combination of the two.

[0165] It can be seen from the combination of Example 15 and Examples 22-25 and Table 2 that when the diameter of the bamboo fiber is 20-50 μm and the length is 1.3-2.8 mm, it can better complement and cooperate with the modified polypropylene fiber, thereby significantly improving the ability to suppress the expansion of microcracks. When bamboo fiber exceeding the above specification range is selected, the effect of the functional additive application will be lost. It can be seen from the combination of Example 1, Comparative Examples 3-4 and Table 2 that the functional additive and the modified polypropylene fiber can play a synergistic effect, so that the composite admixture for marine mud stratum grouting slurry can more effectively suppress the expansion of microcracks under the erosion of marine environment.

[0166] The specific embodiments are only an explanation of the present application, which is not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A composite admixture for marine silt ground grouting slurry, characterized by, Components comprising the following parts by weight: Water reducing agent 1.5-2 parts; Anti-permeable agent 3-5 parts; Magnesium oxide 5-8 parts; Hydroxypropyl methyl cellulose 0.1-0.3 parts; Sodium dodecyl benzene sulfonate 0.05-0.15 parts; Sodium hexametaphosphate 3-6 parts; Modified polypropylene fiber 0.6-1.2 parts; The modified polypropylene fiber is prepared by the following steps: S1, take the polypropylene fiber raw material, clean it with acetone ultrasonic, then dry, then immerse it in ethanol solution and calcium chloride solution in turn, then wash with water and dry, to obtain pretreated polypropylene fiber; S2, after coating the surface of the pretreated polypropylene fiber with silane coupling agent, spray polyacrylamide and active silicate powder, to obtain modified polypropylene fiber; The active silicate is active flaky silicate 987 purchased from Beijing Wantu Ming Technology Co., Ltd.; The weight ratio of the polyacrylamide and the active silicate is 1:(3.5-6.3); The diameter of the polypropylene fiber raw material is 20-50 μm, and the length is 2-3 mm; The functional additive is added in the components, and the weight fraction of the functional additive is 2.5-4.5 parts, the functional additive is composed of bamboo fiber and polyvinyl alcohol, and the weight ratio of the bamboo fiber and the polyvinyl alcohol is (2-4):1; The diameter of the bamboo fiber is 20-50 μm, and the length is 1.3-2.8 mm.

2. The compound admixture for sea-mud stratum grouting slurry according to claim 1, characterized in that: The weight ratio of the polyacrylamide and the active silicate is 1:4.

5.

3. The compound admixture for sea-mud stratum grouting slurry according to claim 1, characterized in that: The weight ratio of the bamboo fiber and the polyvinyl alcohol is 3:

1.

4. The compound admixture for sea-mud stratum grouting slurry according to claim 1, characterized in that: The water reducing agent is one or a combination of polycarboxylic acid type water reducing agent, naphthalene sulfonate type water reducing agent, lignin type water reducing agent and melamine type water reducing agent.

5. The compound admixture for sea-mud stratum grouting slurry according to claim 1, characterized in that: The anti-permeable agent is one or a combination of silicate anti-permeable agent, organic silicon anti-permeable agent and polymer anti-permeable agent. The anti-permeable agent is one or a combination of silicate anti-permeable agent, organic silicon anti-permeable agent and polymer anti-permeable agent.

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