Cement-based early-strength polymer grouting material for replacement construction of elastic short sleeper of subway

Abstract

The invention discloses a cement-based early strength polymer grouting material for replacement construction of an elastic short sleeper of a subway. The cement-based early strength polymer grouting material comprises the following components in percentage by weight: 35-55% of cement, 5-15% of a mineral admixture, 35-55% of graded sand, 2-5% of an expanding agent, 0.1-0.8% of a water reducing agent, 0.05-0.15% of a defoaming agent, 0-0.1% of an early strength agent, 0-0.1% of a retarder, 0.05-0.1% of a thickening agent, 1-4% of a thixotropic agent and 5-10% of modified ceramsite. The fluidity, thixotropy and early strength of the grouting material prepared by taking the modified ceramsite as the raw material are perfectly combined, after the grouting material is poured, as time goes on, cement paste is transformed into thixotropic fluid, at the moment, grout supplementing and surface finishing construction is carried out, grout runout and multiple times of grout supplementing can be greatly avoided, the construction efficiency is improved, and the construction cost is reduced. Even if the foundation pit to be poured has an inclination angle, normal construction can be performed, and the method is extremely suitable for railway system skylight point repair engineering.

Description

Technical Field

[0001] The present invention relates to the technical field of cement-based materials, and particularly to a cement-based early-strength polymer grouting material. Background Art

[0002] Subways have a history of a hundred years since their emergence. With the continuous improvement of the environmental impact assessment requirements for rail transit, corresponding vibration and noise reduction measures are set according to the environmental protection requirements along the line during subway construction. As a medium vibration reduction measure for the track, elastic short sleepers were once widely used. However, after a long time of operation, elastic short sleepers often suffer from diseases such as peeling between the sleeper boot and the ballast bed, enlarged gaps, sleeper hanging in the air, large gauge changes, reduced vibration reduction, and short sleeper cracking, seriously affecting the normal operation of the line. Once the above problems occur, conventional treatment measures can only delay the diseases and cannot eradicate them. Therefore, elastic short sleepers have been successively transformed in various places. Without damaging the existing integral ballast bed, a cement-based grouting material is poured to consolidate the newly designed concrete short sleeper with the existing integral ballast bed sleeper pit, and a low-height upper self-locking double-layer non-linear vibration reduction fastener is adopted to achieve the vibration and noise reduction performance of the original elastic short sleeper.

[0003] The replacement of short sleepers is often carried out during the "skylight point" of the subway. The "skylight point" time period of the subway is generally from 0:00 am to 5:00 am. Construction preparations such as material and tool handling require 0.5 - 1 hour, and 2 hours need to be reserved for the strength growth of the grouting material after pouring and the track restoration. The actual pouring time is only 2 - 3 hours. In addition, the gap between the track slab foundation pit to be poured and the new sleeper is small. Therefore, the cement-based grouting material must have the characteristics of ultra-early strength and high fluidity. Moreover, the subway track operation surface is narrow and it is difficult to carry out mechanical construction, and manual mixing and pouring are required. In addition, due to the influence of track design and subsequent foundation settlement, some track slab foundation pits will show a certain slope, with uneven heights on both sides. When using conventional high-fluidity early-strength grouting materials, "grout leakage" will occur, and "multiple grout replenishments" are required, further reducing the construction efficiency. Therefore, in addition to the characteristics of high early strength and high fluidity, it is also necessary to have extremely excellent thixotropy.

[0004] Patent CN103739255A discloses a high thixotropic cement-based grouting material, which mainly uses biogums, welan gum and guar gum to improve the thixotropy of the grouting material, making it have good stability and high anti-disturbance ability, and is especially suitable for grouting and filling under pressure. This invention achieves high thixotropy by using biogums beyond the conventional dosage range, sacrificing fluidity, without ultra-early strength performance, and it is difficult to meet the requirements of subway track slab foundation pit grouting. Patent CN110590287B discloses a thixotropic grouting material and its preparation method, which is mainly based on the thixotropic properties of SM-1 type vegetable gum, combined with cement-based gelling materials, and uses safer and more environmentally friendly soda ash to replace caustic soda to prepare a high thixotropic grouting material. However, this invention also does not have the characteristics of high early strength, and at the same time sacrifices a certain amount of fluidity, making it difficult to meet the grouting construction requirements during the replacement of elastic short sleepers. Summary of the Invention

[0005] Aiming at the deficiencies of the above prior art, the present invention provides a cement-based early-strength polymer grouting material for the replacement construction of subway elastic short sleepers with high early strength, high fluidity and super thixotropy. The prepared grouting material has excellent combination effects of fluidity, thixotropy and early strength, good properties such as compressive strength and truncated cone fluidity, and can greatly avoid grout leakage and multiple supplementary grouting, improve construction efficiency, and is suitable for foundation pit pouring of emergency repair projects.

[0006] To achieve the above object, the specific technical solutions of the present invention are as follows:

[0007] The present invention provides a cement-based early-strength polymer grouting material for the replacement construction of subway elastic short sleepers, and the raw materials by weight percentage include: 35 - 55% of cement, 35 - 55% of graded sand, 2 - 5% of expansion agent, 1 - 3% of microbeads, 0.1 - 0.5% of water reducer, 0.05 - 0.15% of defoamer, 0.01 - 0.05% of early-strength agent, 0.01 - 0.05% of retarder, 0.05 - 0.1% of thickener, 1 - 4% of thixotropic agent, and 5 - 10% of modified ceramsite.

[0008] Among them, the preparation of the modified ceramsite includes the following steps:

[0009] (1) Pretreatment of porous ceramsite: The porous ceramsite is repeatedly rinsed with tap water and placed in an acidic solution for soaking, filtered, washed, then placed in an alkaline solution for soaking, and after filtering out the porous ceramsite, it is repeatedly rinsed to neutral, and then placed in a silane coupling agent solution for soaking, filtered and dried;

[0010] (2) Preparation of porous ceramsite - biogum composite material: The biogum and absolute ethanol are dispersed in an ultrasonic disperser, then the porous ceramsite is added and dispersed continuously, left standing and sieved, and the residue on the sieve is placed in an oven at 50°C for drying for 2 h to obtain the porous ceramsite - biogum composite material;

[0011] (3) Sealing the porous ceramsite surface: Grind the thixotropic agent in a ball mill, fully mix the porous ceramsite-bio-glue composite material and the ground thixotropic agent in a mixer, and sieve to obtain the modified ceramsite.

[0012] Further preferably, the cement-based early-strength polymer grouting material for replacement construction of the subway elastic short sleeper comprises, by weight percentage, 40-45% cement, 40-45% graded sand, 4% expansion agent, 1% microspheres, 0.3% water reducer, 0.08% defoamer, 0.02% early strength agent, 0.02% retarder, 0.06% thickener, 3-4% thixotropic agent, and 5-10% modified ceramsite.

[0013] Further preferably, the preparation of the modified ceramsite comprises the following steps:

[0014] (1) Pretreatment of porous ceramsite: Rinse the porous ceramsite repeatedly with tap water and soak it in a 1mol / L HCl solution for 12 hours. Filter it out with a sieve, rinse it 2-3 times, soak it in a 1mol / L NaOH solution for 12 hours, filter out the porous ceramsite and rinse it repeatedly until it is neutral, soak it in a 1% concentration silane coupling agent solution for 24 hours, filter it, dry it, and set it aside;

[0015] (2) Preparation of porous ceramsite-bio-glue composite material: The bio-glue and anhydrous ethanol are dispersed in an ultrasonic disperser for 10-20 minutes, and then the porous ceramsite is added and dispersed for another 10-20 minutes. After standing for 4 hours, the mixture is passed through a 200-mesh square sieve, and the residue is placed in a 50°C oven and dried for 2 hours to obtain a porous ceramsite-bio-glue composite material; wherein the mass ratio of bio-glue, anhydrous ethanol, and porous ceramsite is (1-5):1000:(100-200);

[0016] (3) Sealing the porous ceramsite surface: Grind the thixotropic agent in a ball mill to 1-5 μm, mix the porous ceramsite-biogel composite material with the ground thixotropic agent in a mixer for 5-10 minutes, repeat twice, and then sieve to obtain the modified ceramsite.

[0017] Preferably, the porous ceramsite has a spherical or ellipsoidal shape, a particle size of 1-5 mm, a bulk density of 280-350 kg / m3, a porosity of 65-80%, and internal pores are evenly distributed long straight openings with a pore size of 10-50 um and a specific surface area of ≥5 m 2 / g, cylinder pressure strength ≥25MPa, water absorption ≤5%;

[0018] Preferably, the silane coupling agent is one or more of KH550, KH560, and KH570.

[0019] Further preferably, the silane coupling agent is KH570 silane coupling agent.

[0020] Preferably, the bio - adhesive is one or more of welan gum, xanthan gum, and guar gum.

[0021] More preferably, the bio - adhesive is welan gum.

[0022] Preferably, the thixotropic agent is magnesium aluminum silicate, where SiO2≥63%, Al2O3≥19%, MgO≥3%, viscosity (5% aqueous dispersion standing for 24 h)≥2000 mPa·s, thixotropy value (5% aqueous dispersion standing for 24 h)≥7, density 2.4 - 2.6 g / cm 3 , bulk density 300 - 600 kg / m 3 .

[0023] Preferably, the mass ratio of the bio - adhesive, absolute ethanol, and porous ceramsite is (1 - 5):1000:(100 - 200).

[0024] More preferably, the mass ratio of the bio - adhesive, absolute ethanol, and porous ceramsite is 5:1000:100.

[0025] Preferably, the mass ratio of the porous ceramsite - bio - adhesive composite material to the thixotropic agent is 1:(3 - 10).

[0026] More preferably, the mass ratio of the porous ceramsite - bio - adhesive composite material to the thixotropic agent is 1:5.

[0027] Most bio - adhesives are composed of high - molecular - weight polysaccharide substances, having excellent suspension stability and good thixotropy. When at rest or at low flow rates, the molecular chains of the bio - adhesive are hooked and entangled with each other, and the viscosity of its solution increases significantly with the increase of the glue concentration. After breaking through a certain critical point, the viscosity increases almost linearly, which will greatly reduce the fluidity of the grouting material and seriously affect the working performance of grouting. Encapsulating the bio - adhesive in the porous ceramsite can avoid the bio - adhesive coming into contact with water and swelling immediately, reducing its negative impact on the fluidity. After the grouting material is poured, the bio - adhesive gradually disperses in the cement paste, which can effectively prevent the paste from segregation and layering. At the same time, as time goes by, the molecular chains of the bio - adhesive are hooked and entangled with each other, and the thixotropy of the paste increases sharply. When the paste is approximately a non - Newtonian fluid, replenishing the grout can avoid grout leakage and multiple grout replenishments, greatly improving the construction efficiency.

[0028] Magnesium aluminum silicate is an excellent thixotropic agent. Each structural unit contains a sandwich-like arrangement of two layers of silicon-oxygen tetrahedrons sandwiching a silicon-oxygen octahedron. It has a relatively fast dispersion rate in water and can quickly expand into a colloidal dispersion many times larger than its original volume, forming a three-dimensional spatial network structure. When an external force acts, the network structure is destroyed and it is easy to flow. When the external force is removed, the network structure is restored. Magnesium aluminum silicate is dispersed in the cement paste and has almost no effect on the viscosity and fluidity of the grouting material within a certain concentration range. However, when it exceeds a certain critical point, the viscosity of the system will increase sharply and the fluidity will decrease significantly. In the present invention, a part of the magnesium aluminum silicate is premixed in the grouting material powder, and a part exists in the pores of the porous ceramsite as a hole-sealing material, which can effectively reduce its influence on the fluidity of the paste, facilitating pouring construction. As the stirring and pouring proceed, under the driving force of the concentration difference, the magnesium aluminum silicate in the pores of the porous ceramsite gradually diffuses into the cement paste, and the paste gradually transforms into a thixotropic fluid, which can avoid slurry leakage and multiple slurry replenishments, improving construction efficiency.

[0029] Preferably, the cement is a compound of sulphoaluminate cement and ordinary Portland cement, and the compounding ratio is sulphoaluminate cement:ordinary Portland cement = (65 - 95) : (5 - 35).

[0030] More preferably, the compounding ratio of the sulphoaluminate cement and the ordinary Portland cement is (84 - 95) : (5 - 16).

[0031] Preferably, the graded sand is composed of quartz sand or manufactured sand with a mesh size of 20 - 40 meshes and 40 - 70 meshes compounded in a ratio of (40 - 60) : (40 - 60).

[0032] More preferably, the graded sand is composed of quartz sand or manufactured sand with a mesh size of 20 - 40 meshes and 40 - 70 meshes compounded in a ratio of (40 - 50) : (50 - 60).

[0033] According to the embodiments of the present invention, preferably, in the microspheres, SiO2 ≥ 52%, Al2O3 ≥ 22%, the particle size ≤ 45um, and the bulk density is 650 - 750 kg / m 3 , and the sphere density is 2450 - 2550 kg / m 3 .

[0034] Preferably, the expansive agent is a type II calcium sulfoaluminate-calcium oxide composite expansive agent meeting the national standard GB23439, with a restricted expansion rate in water of ≥ 0.05% after 7 days and a restricted expansion rate in air of ≥ -0.01% after 21 days.

[0035] Preferably, the water reducer is a high-performance polycarboxylate water reducer with a water reduction rate of ≥ 25%.

[0036] Preferably, the defoamer is an organosilicon defoamer with an active ingredient of ≥ 65% and a density of 330 - 340 kg / m3 ; preferably, it is P803 silicone defoamer.

[0037] Preferably, the early strength agent is lithium sulfate or lithium carbonate, with a content ≥ 99% and a particle size ≤ 200 mesh, preferably lithium sulfate.

[0038] Preferably, the setting retarder is one or more of tartaric acid, sodium gluconate, and boric acid, preferably tartaric acid.

[0039] Preferably, the thickening agent is hydroxypropyl methyl cellulose ether, preferably hydroxypropyl methyl cellulose ether with a viscosity of 400.

[0040] According to the embodiments of the present invention, the present invention also relates to a method for using a cement-based early strength polymer grouting material for the replacement construction of subway elastic short sleepers. The specific steps are as follows: Mix the raw materials evenly according to the ratio, use a handheld mixer to stir the mixture and water for 60 - 90 s at a water-to-material ratio of 0.14, and then pour. When pouring, it must be grouted from one side of the foundation pit, and it is strictly prohibited to pour from both sides at the same time; After pouring for 2 - 3 min, perform secondary grouting and finishing.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] (1) The bioadhesive is adsorbed in the pores of the porous ceramsite, and the pores are sealed with ultrafine magnesium aluminum silicate, reducing the influence of the bioadhesive on fluidity. At the same time, part of the magnesium aluminum silicate is mixed in the powder, and part of the magnesium aluminum silicate exists in the pores. When stirring, the magnesium aluminum silicate in the powder swells sufficiently, but because the concentration does not reach the critical value, the influence on the fluidity of the slurry is small. At the same time, it takes a certain amount of time for the magnesium aluminum silicate in the pores of the porous ceramsite to "escape" from the pores to swell, avoiding a sharp increase in the viscosity of the system due to excessive concentrations of magnesium aluminum silicate and bioadhesive, which affects pouring.

[0043] (2) After the grouting material is poured, the magnesium aluminum silicate and the bioadhesive swell sufficiently in the system. As time goes by, the cement slurry transforms into a thixotropic fluid. At this time, grouting and finishing construction are carried out, which can greatly avoid bleeding and multiple grouting, and improve construction efficiency.

[0044] (3) The present invention has the characteristics of high early strength, and at the same time perfectly solves the contradictory opposition between high fluidity and high thixotropy of the slurry, and is especially suitable for foundation pit pouring operations in skylight points or emergency repair projects. Specific Embodiments

[0045] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0046] The present invention provides a cement-based early-strength polymer grouting material for the replacement construction of elastic short sleepers in subways. The raw materials, by weight percentage, include: 35-55% of cement, 35-55% of graded sand, 2-5% of an expansive agent, 1-3% of microbeads, 0.1-0.5% of a water reducer, 0.05-0.15% of an antifoaming agent, 0.01-0.05% of an early-strength agent, 0.01-0.05% of a retarder, 0.05-0.1% of a thickener, 1-4% of a thixotropic agent, and 5-10% of modified ceramsite.

[0047] In some examples, the expansive agent is a type II calcium sulfoaluminate-calcium oxide composite expansive agent meeting the national standard GB23439, with a restricted expansion rate in water of ≥0.05% after 7 days and a restricted expansion rate in air of ≥ -0.01% after 21 days.

[0048] In some examples, the water reducer is a high-performance polycarboxylate water reducer with a water reduction rate of ≥25%.

[0049] In some examples, the antifoaming agent is a silicone-based antifoaming agent with an active ingredient of ≥65% and a density of 330-340 kg / m 3 。

[0050] In some examples, the early-strength agent is lithium sulfate or lithium carbonate, with a content of ≥99% and a particle size of ≤200 mesh.

[0051] In some examples, the retarder is one or more of tartaric acid, sodium gluconate, and boric acid.

[0052] In some examples, the thickener is hydroxypropyl methyl cellulose ether, preferably hydroxypropyl methyl cellulose ether with a viscosity of 400.

[0053] Unless otherwise specified, the modified ceramsite in Examples 1-5 is prepared according to the following steps:

[0054] (1) Pretreatment of porous ceramsite: The porous ceramsite is repeatedly rinsed clean with tap water, then soaked in a 1 mol / L HCl solution for 12 h. After filtering with a sieve, it is rinsed 3 times, then soaked in a 1 mol / L NaOH solution for 12 h. After filtering out the porous ceramsite, it is repeatedly rinsed until neutral, and then soaked in a 1% concentration KH570 silane coupling agent solution for 24 h, filtered, and dried for use;

[0055] (2) Preparation of porous ceramsite-bioadhesive composite: 5 g of bioadhesive and 1000 g of absolute ethanol are dispersed in an ultrasonic disperser for 10-20 min, then 100 g of porous ceramsite is added and dispersed for another 20 min. After standing for 24 h, it is passed through a 200-mesh square-hole sieve, and the residue is dried in an oven at 50 °C for 2 h to prepare a porous ceramsite-bioadhesive composite for use;

[0056] (3)Surface Sealing of Porous Ceramsite: Grind magnesium aluminum silicate in a ball mill to 1 - 5 μm. Mix 1 kg of the porous ceramsite - bio - glue composite with 5 kg of the ground magnesium aluminum silicate in a mixer for 5 - 10 minutes. Repeat this process twice, and then sieve to obtain the modified ceramsite.

[0057] Example 1

[0058] A cement - based early - strength polymer grouting material for the replacement construction of subway elastic short sleepers. The raw materials are calculated by weight percentage and include: 38% of sulfoaluminate cement, 3.52% of ordinary Portland cement, 20% of 20 - 40 - mesh quartz sand, 25% of 40 - 70 - mesh quartz sand, 5% of modified ceramsite, 3% of magnesium aluminum silicate, 4% of a sulfoaluminate - calcium oxide composite expansive agent, 1% of micro - beads, 0.3% of polycarboxylate water - reducing agent, 0.08% of P803 silicone defoamer, 0.02% of lithium sulfate, 0.02% of tartaric acid, and 0.06% of hydroxypropyl methyl cellulose ether.

[0059] Example 2

[0060] A cement - based early - strength polymer grouting material for the replacement construction of subway elastic short sleepers. The raw materials are calculated by weight percentage and include: 38% of sulfoaluminate cement, 3.52% of ordinary Portland cement, 20% of 20 - 40 - mesh quartz sand, 20% of 40 - 70 - mesh quartz sand, 10% of modified ceramsite, 3% of magnesium aluminum silicate, 4% of a sulfoaluminate - calcium oxide composite expansive agent, 1% of micro - beads, 0.3% of polycarboxylate water - reducing agent, 0.08% of P803 silicone defoamer, 0.02% of lithium sulfate, 0.02% of tartaric acid, and 0.06% of hydroxypropyl methyl cellulose ether.

[0061] Example 3

[0062] A cement - based early - strength polymer grouting material for the replacement construction of subway elastic short sleepers. The raw materials are calculated by weight percentage and include: 38% of sulfoaluminate cement, 2.52% of ordinary Portland cement, 20% of 20 - 40 - mesh quartz sand, 25% of 40 - 70 - mesh quartz sand, 5% of modified ceramsite, 4% of magnesium aluminum silicate, 4% of a sulfoaluminate - calcium oxide composite expansive agent, 1% of micro - beads, 0.3% of polycarboxylate water - reducing agent, 0.08% of P803 silicone defoamer, 0.02% of lithium sulfate, 0.02% of tartaric acid, and 0.06% of hydroxypropyl methyl cellulose ether.

[0063] Example 4

[0064] For a cement - based early - strength polymer grouting material for the replacement construction of subway elastic short sleepers, in step (2) of the porous ceramsite modification, the mass ratio of bio - glue: absolute ethanol: porous ceramsite is 10:1000:100, and the rest is the same as in Example 1.

[0065] Example 5

[0066] A cement-based early-strength polymer grouting material for the replacement construction of elastic short sleepers in subways. In step (3) of the porous ceramsite modification, the mass ratio of bioadhesive: absolute ethanol: porous ceramsite is 1:1000:200, and the rest is the same as in Example 1.

[0067] Comparative Example 1

[0068] A grouting material, the raw materials are calculated by weight percentage and include: 38% of sulphoaluminate cement, 6.52% of ordinary Portland cement, 25% of quartz sand with a particle size of 20-40 mesh, 25% of quartz sand with a particle size of 40-70 mesh, 4% of sulphoaluminate calcium-calcium oxide composite expansive agent, 1% of microbeads, 0.3% of polycarboxylate water reducer, 0.08% of P803 silicone defoamer, 0.02% of lithium sulphate, 0.02% of tartaric acid, and 0.06% of hydroxypropyl methyl cellulose ether.

[0069] Comparative Example 2

[0070] A grouting material, the raw materials are calculated by weight percentage and include: 38% of sulphoaluminate cement, 3.52% of ordinary Portland cement, 20% of quartz sand with a particle size of 20-40 mesh, 25% of quartz sand with a particle size of 40-70 mesh, 5% of porous ceramsite, 3% of magnesium aluminium silicate, 4% of sulphoaluminate calcium-calcium oxide composite expansive agent, 1% of microbeads, 0.3% of polycarboxylate water reducer, 0.08% of P803 silicone defoamer, 0.02% of lithium sulphate, 0.02% of tartaric acid, and 0.06% of hydroxypropyl methyl cellulose ether.

[0071] Comparative Example 3

[0072] A grouting material, the raw materials are calculated by weight percentage and include: 38% of sulphoaluminate cement, 3.52% of ordinary Portland cement, 20% of quartz sand with a particle size of 20-40 mesh, 25% of quartz sand with a particle size of 40-70 mesh, 5% of porous ceramsite-bioadhesive composite material (not encapsulated, that is, not undergoing step 3 during the preparation process), 3% of magnesium aluminium silicate, 4% of sulphoaluminate calcium-calcium oxide composite expansive agent, 1% of microbeads, 0.3% of polycarboxylate water reducer, 0.08% of P803 silicone defoamer, 0.02% of lithium sulphate, 0.02% of tartaric acid, and 0.06% of hydroxypropyl methyl cellulose ether.

[0073] Comparative Example 4

[0074] A grouting material, the raw materials are calculated by weight percentage and include: 38% of sulphoaluminate cement, 6.52% of ordinary Portland cement, 20% of quartz sand with a particle size of 20-40 mesh, 25% of quartz sand with a particle size of 40-70 mesh, 5% of porous ceramsite-bioadhesive composite material, 4% of sulphoaluminate calcium-calcium oxide composite expansive agent, 1% of microbeads, 0.3% of polycarboxylate water reducer, 0.08% of P803 silicone defoamer, 0.02% of lithium sulphate, 0.02% of tartaric acid, and 0.06% of hydroxypropyl methyl cellulose ether.

[0075] Comparative Example 5

[0076] A grouting material, the raw materials are calculated by weight percentage, including: 38% of sulfoaluminate cement, 3.52% of ordinary Portland cement, 25% of quartz sand with a particle size of 20-40 mesh, 25% of quartz sand with a particle size of 40-70 mesh, 3% of magnesium aluminum silicate, 4% of sulfoaluminate calcium-calcium oxide composite expansive agent, 1% of microbeads, 0.3% of polycarboxylate water reducing agent, 0.08% of P803 silicone defoamer, 0.02% of lithium sulfate, 0.02% of tartaric acid, and 0.06% of hydroxypropyl methyl cellulose ether.

[0077] The grouting materials prepared in Examples 1-5 and Comparative Examples 1-5 were subjected to performance tests. According to the actual working conditions, a high-power handheld mixer was used for stirring in a 25L thickened plastic bucket. The diameter of the lower bottom surface of the plastic bucket was 28.4 cm, the diameter of the upper bottom surface was 32.5 cm, and the height was 38.5 cm. The water-cement ratio was 0.14, and the mixing time was 1 min. The truncated cone fluidity and compressive strength were inspected according to GB / T 50448-2015 "Technical Specification for Application of Cement-based Grouting Materials". The age of compressive strength was selected as 2 h, 24 h, and 28 d, and the initial and final setting times were judged by pressing with fingers.

[0078] To more intuitively reflect the actual effect of the present invention, an experiment was carried out according to the following method by simulating the on-site situation: A cuboid plastic box of a certain size (such as 40 cm * 20 cm * 10 cm) was taken, and one side of the box was lifted by a wooden square at an angle of 5-10° with the ground, and the plastic box was fixed. The uniformly mixed grouting material was poured into the plastic box along the higher side. When the slurry was flush with the shorter side of the plastic box, the pouring was stopped. After 3 min, secondary slurry replenishment was carried out. If there was slurry leakage, the slurry replenishment operation was postponed for another 2 min, and so on until the slurry replenishment was completed. The slurry replenishment time was recorded, and the leaked slurry after curing was collected and weighed. The experimental results are shown in Table 1.

[0079] Table 1 Test Results of Polymer Early Strength Mortar

[0080]

[0081] As can be seen from Table 1, the early strength polymer grouting material prepared according to the technical scheme disclosed in the present invention has high fluidity, high early strength, and good thixotropy, realizing the perfect integration of slurry fluidity and thixotropy, greatly avoiding slurry leakage and multiple slurry replenishment, improving the construction efficiency, and being very suitable for the foundation pit pouring of emergency repair projects, especially suitable for the replacement construction of elastic short sleepers of subways.

Claims

1. A cement-based early-strength polymer grouting material for the replacement construction of elastic short sleepers in the subway, characterized in that, The raw materials are by weight percentage, including 35 - 55% of cement, 35 - 55% of graded sand, 2 - 5% of expansion agent, 1 - 3% of microbeads, 0.1 - 0.5% of water reducing agent, 0.05 - 0.15% of defoaming agent, 0.01 - 0.05% of early strength agent, 0.01 - 0.05% of setting retarder, 0.05 - 0.1% of thickening agent, 1 - 4% of thixotropic agent, and 5 - 10% of modified ceramsite; wherein, the preparation of the modified ceramsite includes the following steps: (1) Pretreatment of porous ceramsite: Rinse the porous ceramsite clean, soak it in an acidic solution, filter, wash, then soak it in an alkaline solution, filter out the porous ceramsite and rinse it to neutral, and then soak it in a silane coupling agent solution, filter and dry. (2) Preparation of porous ceramsite - bio - glue composite: Mix the bio - glue and absolute ethanol evenly, then add the porous ceramsite and continue to mix evenly, let it stand and screen, and dry the residue to obtain the porous ceramsite - bio - glue composite. (3) Surface sealing of porous ceramsite: Grind the thixotropic agent in a ball mill, and fully mix the porous ceramsite - bio - glue composite with the ground thixotropic agent in a mixer, and sieve to obtain the modified ceramsite.

2. The cement-based early-strength polymer grouting material for the replacement construction of subway elastic short sleepers according to claim 1, characterized in that, The raw materials are by weight percentage, including: 40 - 45% of cement, 40 - 45% of graded sand, 4% of expansion agent, 1% of microbeads, 0.3% of water reducing agent, 0.08% of defoaming agent, 0.02% of early strength agent, 0.02% of setting retarder, 0.06% of thickening agent, 3 - 4% of thixotropic agent, and 5 - 10% of modified ceramsite.

3. The cement-based early-strength polymer grouting material for the replacement construction of subway elastic short sleepers according to claim 1, characterized in that, The mass ratio of the bio - glue, absolute ethanol, and porous ceramsite is (1 - 5):1000:(100 - 200); the mass ratio of the porous ceramsite - bio - glue composite to the thixotropic agent is 1:(3 - 10).

4. The cement-based early-strength polymer grouting material for the replacement construction of subway elastic short sleepers according to claim 1, characterized in that, The preparation of the modified ceramsite includes the following steps: (1) Pretreatment of porous ceramsite: Rinse the porous ceramsite repeatedly with tap water until clean, then soak it in 1mol / L HCl solution for 12h, filter it out with a sieve, rinse, then soak it in 1mol / L NaOH solution for 12h, filter out the porous ceramsite and rinse it repeatedly to neutral, and then soak it in 1% concentration silane coupling agent solution for 12h, filter and dry for use. (2) Preparation of porous ceramsite - bio - glue composite: Disperse the bio - glue and absolute ethanol in an ultrasonic disperser for 10 - 20min, then add the porous ceramsite and continue to disperse for 10 - 20min, let it stand for 4h and then sieve through a 200 - mesh square - hole sieve, and dry the residue in an oven at 50℃ for 2h; wherein, the mass ratio of the bio - glue, absolute ethanol, and porous ceramsite is (0.1 - 1):1000:(100 - 200); (3) Surface sealing of porous ceramsite: Grind the thixotropic agent in a ball mill to 1 - 5um, and mix the porous ceramsite - bio - glue composite with the ground thixotropic agent in a mixer for 5 - 10min, and then screen.

5. The cement-based early-strength polymer grouting material for the replacement construction of subway elastic short sleepers according to claim 1, characterized in that, The silane coupling agent is one or more of KH550, KH560, KH570.

6. The cement-based early-strength polymer grouting material for the replacement construction of subway elastic short sleepers according to claim 1, characterized in that, The bio - glue is one or more of welan gum, xanthan gum, guar gum.

7. The cement-based early-strength polymer grouting material for the replacement construction of elastic short tie plates of subways according to claim 1, wherein, The thixotropic agent is magnesium aluminum silicate, with SiO2 ≥ 63%, Al2O3 ≥ 19%, MgO ≥ 3%, viscosity (5% aqueous dispersion standing for 24 h) ≥ 2000 mPa·s, thixotropy value (5% aqueous dispersion standing for 24 h) ≥ 7, density 2.4 - 2.6 g / cm 3 , bulk density 300 - 600 kg / m 3 .

8. The cement-based early-strength polymer grouting material for the replacement construction of subway elastic short sleepers according to claim 1, characterized in that, In the microbeads, SiO2 ≥ 52%, Al2O3 ≥ 22%, particle size ≤ 45um, bulk density 650 - 750 kg / m 3 , sphere density 2450 - 2550 kg / m 3 .

9. The cement-based early-strength polymer grouting material for the replacement construction of subway elastic short sleepers according to claim 1, characterized in that, The graded sand is composed of quartz sand or manufactured sand with a mesh size of 20-40 and 40-70, compounded in a ratio of (40-60) : (40-60).

10. The using method of the cement-based early-strength polymer grouting material for the replacement construction of the elastic short tie of the subway, according to any one of claims 1-9, is characterized in that, Mix the raw materials evenly according to the ratio, use a hand-held mixer to stir the mixture and water for 60-90 s at a water-to-material ratio of 0.14, and then pour. During pouring, grout must be injected from one side of the foundation pit, and it is strictly prohibited to pour from both sides at the same time; after pouring for 2-3 min, perform secondary grout replenishment and surface finishing.

Images