A low shrinkage epoxy resin grouting material and its preparation and use method

Abstract

The application discloses a kind of low shrinkage epoxy resin grouting material and its preparation and use method, belong to civil engineering material technical field.The raw material includes: epoxy resin 100 parts, active diluent 20~40 parts by mass fraction, the amount of epoxy curing agent is 20%~80% of the total mass of epoxy resin and diluent, and the amount of coated porous shrinkage compensation powder in epoxy resin grouting material is 2vol%~10vol%;Coated porous shrinkage compensation powder is with complete closed coating film on the surface, and the raw material of coating film is coated polymer emulsion, including: acrylic polymer emulsion or styrene-acrylic emulsion.The application designs a kind of porous powder with complete closed coating film on the surface, and combines pressure grouting construction to build "pressure energy storage-rebound compensation" dynamic shrinkage regulation mechanism, solves the problem of large curing shrinkage of epoxy resin grouting material, and has almost no effect on the viscosity and strength of epoxy resin grouting material.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering materials technology, specifically relating to a low-shrinkage epoxy resin grouting material and its preparation and application methods. Background Technology

[0002] Concrete structures are the most widely used structural form in civil engineering. During service, they are inevitably subject to cracking due to various factors such as load, temperature deformation, wet-dry cycles, alkali-aggregate reaction, and uneven foundation settlement. The presence of cracks not only reduces the overall integrity and mechanical load-bearing capacity of the structure but also provides channels for harmful media such as moisture, chloride ions, and carbon dioxide to penetrate, accelerating the corrosion of internal steel reinforcement and the deterioration of the concrete matrix, seriously affecting the safety, durability, and service life of the concrete structure.

[0003] Drilling and grouting is currently the most common and effective technique for repairing concrete cracks. Among these methods, epoxy resin grouting materials are the preferred choice for concrete crack repair projects due to their high bonding strength, excellent mechanical properties, good chemical corrosion resistance, and ease of use. However, commercially available epoxy resin grouting materials experience significant volume shrinkage during the curing process due to the cross-linking polymerization reaction between the epoxy groups and the epoxy curing agent, typically ranging from 2% to 3%. This curing shrinkage generates substantial shrinkage stress, leading to poor adhesion between the grouting material and the concrete crack interface.

[0004] In existing technologies, methods such as adding inorganic fillers, thermoplastic resins, and expandable monomers are commonly used to reduce the shrinkage rate of epoxy resins, but all have drawbacks. For example, Chinese patent CN112480851A: A UV adhesive for reducing curing shrinkage and its preparation method, utilizes the ring-opening polymerization volume expansion characteristics of expandable monomers (such as spirocyclic orthocarbonates) to complement the curing shrinkage of prepolymers. It also adds nanoscale metal or ceramic powders of the same type as the powder bed powder to reduce organic-inorganic interface defects and improve system density. However, expandable monomers are expensive, and the expansion rate is only 5%~10%, limiting the overall expansion. Another example is Chinese patent CN107189351A: Low-viscosity, low-toxicity epoxy resin grouting material and its preparation method, which uses toughening agents to form an "island structure" in the system to alleviate curing internal stress, but the reduction in shrinkage rate is limited. For example, Chinese patent CN119875302A describes a low-shrinkage epoxy resin composition and its application in IPM encapsulation. This patent uses the filling effect of spherical silica fillers to suppress molecular chain shrinkage during curing. However, adding fillers increases the viscosity of the epoxy resin grouting material and reduces its potability. Another example is Chinese patent CN118184957A, which describes a method for reducing shrinkage stress in photocurable coatings using shape memory azophenyl microcapsules. This patent prepares shape memory microcapsules containing azophenyl groups through interfacial polymerization, stretches and deforms them into ellipsoids, and then adds them to photocurable resin. During curing, the photothermal effect of the azophenyl groups and the resin shrinkage stress work together to trigger the microcapsules to quickly recover their spherical shape, compensating for curing shrinkage through volume increase. However, epoxy resin grouting materials cannot achieve this compensation effect in concrete cracks where there is no light source. For example, a Chinese patent (CN116239950A) describes a method and application of using microspheres to reduce shrinkage stress in UV-cured coatings. This patent designs microspheres containing photoacid generators and nano-calcium carbonate particles. During the UV curing process, the photoacid generator decomposes and releases acid radicals, which react with calcium carbonate to generate CO2 microbubbles. The volume of these microbubbles compensates for the shrinkage stress during curing. However, since epoxy resin grouting materials do not have a light source in concrete cracks, they cannot achieve the compensation effect.

[0005] Therefore, developing an epoxy resin grouting material with low curing shrinkage, low cost, low viscosity, high strength, and compatibility with existing construction processes is of great engineering significance and application value for improving the quality of concrete crack repair and ensuring the long-term service of concrete structures. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-shrinkage epoxy resin grouting material and its preparation and application method.

[0007] The objective of this invention is achieved through the following technical solution: The first aspect of this invention is to provide a low-shrinkage epoxy resin grouting material, comprising, by weight, 100 parts epoxy resin, 20-40 parts reactive diluent, coated porous shrinkage compensating powder, and epoxy curing agent. The amount of epoxy curing agent is 20%-80% of the total mass of the epoxy resin and the reactive diluent. The amount of coated porous shrinkage compensating powder in the low-shrinkage epoxy resin grouting material is 2 vol%-10 vol%. The coated porous shrinkage compensating powder is a porous powder with a completely sealed coating film on its surface. The porous powder is selected from one or more of porous alumina, porous silica, and porous silicon carbide. The pore size of the porous powder is 0.1-10 μm, and the pore volume is ≥0.2 mL / g. The raw material for the coating film is a coating polymer emulsion, including acrylic polymer emulsion or styrene-acrylic emulsion. The amount of the coating polymer emulsion is 2%-10% of the mass of the porous powder.

[0008] This invention addresses the problems of high curing shrinkage, easy generation of shrinkage stress, and reduced bonding durability of existing epoxy resin grouting materials by providing a low-shrinkage epoxy resin grouting material for concrete crack repair. It achieves this by adding surface-modified high-strength, high-porosity porous powder to the epoxy resin grouting material, constructing a dynamic shrinkage control mechanism of "pressure energy storage-rebound compensation": utilizing the relatively high pressure (above 1 MPa) commonly applied in conventional concrete chemical grouting, the air within the compressible powder is compressed and stored; when the epoxy resin grouting material gels and shrinks, the stored energy is released to compensate for the shrinkage, thus achieving precise compensation for volume shrinkage during epoxy resin curing, while ensuring the grouting material's injection performance, mechanical properties, and durability.

[0009] Specifically, the shrinkage compensation solution of this application is achieved through a porous powder coated with a closed protective membrane, namely the coated porous shrinkage compensation powder described in this application, which forms a combination of a large-pore structure and a closed coating membrane. This powder has a special structure that can be partially compressed and expanded. When the external pressure increases, the closed membrane contracts along the pores into the interior space of the powder, reducing its space occupation; similarly, when the external pressure decreases, the closed membrane rebounds and recovers, compensating for and occupying the corresponding space. According to Boyle's law, the air compression inside the powder under different grouting pressures is shown in Table 1 below.

[0010] Table 1 Relationship between grouting pressure and gas compressibility in powder ducts

[0011] Specifically, during the grouting process, the air in the internal channels of the coated porous shrinkage-compensating powder is compressed by external pressure, storing elastic potential energy. When the epoxy resin cures and cross-links, causing volume shrinkage, the compressed gas in the channels simultaneously rebounds and expands, releasing elastic potential energy to compensate for the plastic and chemical shrinkage during resin curing, achieving a dynamic balance between shrinkage and compensation. Tests have shown that the curing shrinkage rate of the grouting material of this invention can be reduced to below 0.5%, lower than the 2%~3% shrinkage rate of traditional epoxy resin grouting materials.

[0012] The porous powder selected in this application can be one or more high-porosity, high-strength powders such as porous alumina, porous silica, and porous silicon carbide. This allows the resulting coated porous shrinkage-compensating powder to maintain high compressive strength while providing high-porosity pore space to compensate for shrinkage. The coating film is an acrylic resin film or a styrene-acrylic film. The raw materials are usually acrylic polymer emulsions or styrene-acrylic emulsions. Both polymer emulsions have good compatibility with epoxy resin and can effectively form a sealing film, preventing resin from entering the powder pores during the mixing of epoxy resin grouting materials. Preferably, acrylic polymer emulsions and styrene-acrylic emulsions with low film-forming strength are used, enabling the isostatic compressive strength after coating to be 0.05~0.1 MPa. During crack grouting, the coating film is crushed by the grouting pressure, allowing the grouting material to enter the powder pores, compressing the air within the pores and storing elastic potential energy. After the epoxy resin grouting material enters the gelation stage, the resin molecules undergo a cross-linking reaction, resulting in volume shrinkage and a decrease in the internal grouting pressure. Simultaneously, the compressed porous powder releases its stored elastic potential energy to compensate for the cross-linking shrinkage of the resin system. At a grouting pressure of 1 MPa, the air volume shrinkage rate within the powder is 90.8%. However, due to constraints during the gelation process of the epoxy resin grouting material, its strength at gelation is approximately 0.01 MPa (the air volume shrinkage rate within the powder at a grouting pressure of 0.01 MPa), preventing the complete release of compressed air. The air compensation shrinkage per unit space within the powder is 90.80% - 8.98% = 81.82%.

[0013] The coated porous shrinkage compensation powder has a spherical, near-spherical, or amorphous particle shape, preferably spherical or near-spherical. This avoids the agglomeration and accumulation of the coated porous shrinkage compensation powder due to surface structure effects; at the same time, spherical and near-spherical particles have a lower specific surface area, resulting in a smaller negative impact on the viscosity of the epoxy resin grouting system.

[0014] The density of the coated porous shrinkage-compensating powder is 1.01~1.10 g / cm³. 3 The preferred density is 1.03~1.07 g / cm³. 3The corresponding pore volume is 0.5~0.7mL / g (tested according to GB / T21650.1), and the pore space of each unit volume of powder accounts for 50%~70% of the total powder volume. The pressure of the epoxy resin grouting material injected into the crack changes from 1.0MPa when injected to 0.01MPa when gelled. The shrinkage compensation within the powder pore space is about 80%, that is, the shrinkage compensation per unit volume of powder reaches 40%~56%. The density of this powder is similar to that of the epoxy resin grouting material, which can stably suspend within the epoxy grouting system and achieve uniform dispersion, avoiding the failure of the shrinkage compensation function due to system stratification.

[0015] The dosage of the coated porous shrinkage-compensating powder in the epoxy resin grouting material is 2 vol% to 10 vol%, preferably 3 vol% to 5 vol%, with each unit volume of powder compensating for shrinkage of 40% to 56%, corresponding to a shrinkage compensation of 1.2% to 2.8%. When the powder is added at a low dosage (≤5 vol%), it can maintain a uniformly dispersed suspension in the epoxy resin grouting system, with virtually no impact on the viscosity of the epoxy resin grouting material. As the powder dosage further increases, the particles become difficult to maintain a uniformly dispersed suspension, leading to an increase in the viscosity of the epoxy resin grouting material and a decrease in its injectability.

[0016] The internal porous structure of the coated porous shrinkage compensation powder has a pore size of 0.1~10μm (tested according to GB / T21650.1), preferably 1.0~2.0μm. The pores are interconnected and form a continuous structure. Based on the Yang-Laplace equation D=4γcosθ / P, theoretical calculations show that under a grouting pressure of 1MPa, the contact angle θ between the epoxy resin grouting material and the powder approaches 0°, and the surface tension γ is approximately 30mN / m. Theoretically, the powder pore size should not be less than 0.12μm. During the curing and shrinkage stage of the epoxy resin grouting material, the overall system pressure decreases, and capillary forces still exist as the grout is squeezed out from the internal pores of the powder. Therefore, the internal pore size of the powder needs to be limited to the above-mentioned reasonable range to meet the requirements of grouting and shrinkage compensation. The continuous pores maximize the utilization of the internal space of the powder.

[0017] The particle size of the coated porous shrinkage-compensating powder is 2~50μm, preferably 10~20μm. Smaller particle size results in a larger specific surface area, requiring more epoxy resin grouting material. Incorporating high specific surface area powder into epoxy resin grouting material significantly increases system viscosity and reduces grout injectability. Furthermore, according to GB50728 standards, cracks with a width of 0.05~1.5mm or greater require grouting with Class A structural adhesives such as epoxy resin grouting material. To avoid excessively large powder particles clogging the 0.05mm crack channels and causing incomplete grouting, the powder particle size is controlled within the aforementioned reasonable range.

[0018] The compressive strength of the coated porous shrinkage compensation powder is ≥40MPa (tested according to GB / T43091), preferably ≥70MPa. During the grouting process, the compressed part is the air inside the powder pores. This air is a stress weak point in the epoxy resin grouting material. The porous powder itself has high structural strength and can play a skeleton support effect in the epoxy grouting curing system. Under service stress conditions, it can effectively avoid this stress weak point from becoming a structural weak defect.

[0019] The coated porous shrinkage-compensating powder is coated with a low-film-strength acrylic polymer emulsion or styrene-acrylic emulsion to form a film. The elongation at break of the coated film is ≤1%, the isostatic compressive strength is 0.05~0.1MPa (tested according to JC / T2284), and the film thickness is 0.02~0.2μm. This brittle, low-strength coating ensures that the resin cannot penetrate into the powder pores during the mixing of the epoxy resin grouting material, and also allows the coating to rupture under pressure (≥0.2MPa) during grouting construction, allowing the liquid epoxy resin grouting material to enter the powder pores and compress the air inside.

[0020] The epoxy resin is selected from one or more of bisphenol F type epoxy resin 170, AFG-90 aminophenol trifunctional epoxy resin, and AFG-80 amino tetrafunctional epoxy resin. Preferably, epoxy resin 170 is used in combination with polyepoxy functional resin to balance low viscosity and mechanical properties of the cured product.

[0021] The reactive diluent is selected from one or more of the following: C12-14 benzyl glycidyl ether, resorcinol diglycidyl ether, glycerol triglycidyl ether, propoxyglycerol triglycidyl ether, etc., which have monoepoxy, diepoxy, or polyepoxy functional groups. It is used to reduce the viscosity of epoxy resin grouting materials, improve their injectability, ensure injection performance under low pressure, and participate in the curing reaction without the volatilization of small molecules.

[0022] The epoxy curing agent is selected from one or more of Evonik 2636 curing agent, Evonik I-965 curing agent, and isophorone diamine. Preferably, it is a room-temperature curing isophorone diamine, which enables rapid curing at room temperature, produces a cured product with excellent toughness, and is suitable for on-site construction environments.

[0023] Preferably, the raw materials also include additives, which are selected from one or more of BYK-A530 defoamer, BYK-111 wetting and dispersing agent, and silane coupling agent. The total amount of the additives does not exceed 5% of the mass of the epoxy resin. Specifically, the amount of BYK-A530 defoamer is 0.1% to 1.0% of the mass of the epoxy resin; the amount of BYK-111 wetting and dispersing agent is 0.1% to 1.0% of the mass of the epoxy resin, used to improve the wettability of the epoxy resin grouting material to porous powders; the silane coupling agent is preferably one of KH-550 and KH-560, used in an amount of 0.5% to 3.0% of the mass of the epoxy resin, used to improve the wettability of the epoxy resin grouting material to porous powders and the bonding strength at the interface of concrete cracks.

[0024] A second aspect of the present invention is to provide a method for preparing the above-mentioned low-shrinkage epoxy resin grouting material, comprising the following steps: S1 Powder Pretreatment: The porous powder is placed in an oven at 105~120℃ and dried for 2~4 hours to completely remove moisture and volatile impurities from the pores, and then cooled to room temperature for later use.

[0025] S2 Fluidized Bed Coating Modification: The dried porous powder is fed into a fluidized bed, and the fluidizing air is turned on to make the porous powder in a stable suspension state. The powder is preheated to 40~60℃. The coating polymer emulsion is atomized through the atomizing nozzle at the top of the fluidized bed and sprayed onto the surface of the suspended porous powder. At the same time, hot air is introduced for synchronous drying, forming a complete and continuous closed coating film on the surface of the porous powder. The solid content of the coating polymer emulsion is 10~30wt%, ensuring that a complete coating film can be formed without clogging the powder pores.

[0026] S3 Post-treatment: After spraying, continue fluidized drying for 10-30 minutes to allow the coating film to fully solidify. After cooling to room temperature, sieve to remove agglomerated particles and obtain the coated porous shrinkage compensation powder.

[0027] S4 grout preparation: The epoxy resin, the reactive diluent, and the coated porous shrinkage compensating powder are mixed according to the specified ratio and stirred at high speed at 100~500 r / min for 2~10 min to uniformly disperse the powder, thus obtaining an epoxy resin premix. Before use, the epoxy resin premix and the epoxy curing agent are mixed according to the specified ratio and stirred at 100~500 r / min for 3~5 min, followed by vacuum degassing for 2~5 min to obtain the low-shrinkage epoxy resin grouting material.

[0028] Preferably, in step S2, the fluidizing air velocity is 0.5~2.0 m / s, the hot air temperature is 60~90℃, and the atomization pressure is 0.2~0.5 MPa.

[0029] This invention also provides a method for preparing and using the low-shrinkage epoxy resin grouting material, which is compatible with conventional graded pressure grouting processes in engineering projects. It does not require additional construction equipment and procedures and can be directly promoted and applied.

[0030] A third aspect of the present invention is to provide a method of using the aforementioned low-shrinkage epoxy resin grouting material, comprising the following steps: A1 Pressure Grouting: Using a graded pressurization process of 0.05MPa~1.0MPa, the prepared low-shrinkage epoxy resin grouting material is pressed into the cracks of the concrete until the pressure of the low-shrinkage epoxy resin grouting material at the crack reaches 1.0MPa and remains stable for 10 minutes, then the inlet and outlet of the grouting are sealed.

[0031] A2 Curing and Maintenance: After grouting is completed, cure at room temperature until the grout is completely cured to complete the crack repair.

[0032] Specifically, the graded pressurization process is as follows: the initial grouting pressure is 0.05~0.5MPa, and after stabilizing for 5~10 minutes, the pressure is gradually increased to 0.8~1.0MPa, with each pressure increase not exceeding 0.2MPa. Each pressure is stabilized for 5~7 minutes, and finally, the pressure of the low-shrinkage epoxy resin grouting material at the crack reaches 1.0MPa and remains stable for 10 minutes. Using a graded pressurization process of 0.05~1.0MPa can improve the grouting depth and initial filling properties. Combined with the grouting material of this application, the grouting after epoxy resin curing and shrinkage is dense, the interface is not easily debonded, and the durability is good.

[0033] The beneficial effects of this invention are: (1) This invention designs a porous powder with a completely sealed coating on its surface, constructing a dynamic shrinkage control mechanism of "pressure energy storage-rebound compensation," which reduces the curing shrinkage of epoxy resin grouting materials during the gelation stage. During the pressurized grouting process of concrete cracks, the air inside the sealed channels of the coated porous powder in the epoxy resin grouting material is compressed, storing elastic potential energy; when the epoxy resin cures and cross-links, the volume shrinkage causes a decrease in the pressure of the epoxy resin grouting material, and the compressed gas inside the powder channels rebounds and expands synchronously, releasing elastic potential energy to compensate for the plastic and chemical shrinkage during the resin curing process, achieving a dynamic balance between shrinkage and compensation. Tests show that the curing shrinkage rate of the grouting material of this invention can be reduced to below 0.5%, far lower than the 2%~3% shrinkage rate of traditional epoxy resin grouting materials.

[0034] (2) The present invention preferably uses spherical or near-spherical materials with a density of 1.03~1.07 g / cm³. 3Porous alumina, porous silica, porous silicon carbide, or other high-porosity, high-strength powders with a pore volume of 0.5~0.7mL / g, a proportion of 3vol%~5vol% in epoxy resin grouting materials, a pore size of 1.0~2.0μm, a particle size of 10μm~20μm, and a compressive strength ≥40MPa are used as the porous powder substrate. The internal pore size of the resulting powder is preferably 1.0~2.0μm, and the pores have a continuous, interconnected structure. Based on the Yang-Laplace equation theory, this pore size range can satisfy the smooth impregnation of epoxy resin grouting materials under a grouting pressure of 1MPa, and can also maintain the stability of the grout extrusion from the pores during the curing shrinkage stage using capillary force, thus meeting the requirements of grouting and shrinkage compensation; the interconnected pores can maximize the utilization of the internal space of the powder.

[0035] The optimal powder particle size avoids clogging of cracks larger than 0.05mm, ensuring grout injectability, while also reducing specific surface area to minimize negative impacts on the viscosity of the epoxy resin system and prevent powder agglomeration due to surface structure effects. A high pore volume (0.6~0.7mL / g) provides ample gas storage space, maximizing rebound compensation. A proportion of 3vol%~5vol% in the epoxy resin grouting material avoids excessive addition leading to poor injectability. Simultaneously, the high-strength skeleton structure (compressive strength ≥40MPa) provides support for the gas within the powder channels, preventing powder breakage under pressure during service. It also acts as a reinforcing filler, improving the compressive strength, elastic modulus, and other mechanical properties of the epoxy resin grouting material, thus resolving the contradiction of decreased mechanical properties caused by traditional shrinkage modification techniques. Testing shows that the grouting material of this invention has a curing shrinkage rate ≤0.5%, viscosity ≤100cps, and compressive strength ≥70MPa.

[0036] (3) The present invention forms a complete and continuous resin-sealed coating film on the surface of high-strength porous powder through fluidized bed atomization coating process. On the one hand, it can effectively prevent epoxy resin grouting material from invading the internal pores of the powder during the mixing process, ensuring the sealing and gas storage capacity of the pores and ensuring the stable performance of shrinkage compensation effect. On the other hand, the coating film can improve the interfacial compatibility between porous powder and epoxy resin matrix, improve the dispersion of powder in resin system, and avoid problems such as increased slurry viscosity and decreased grouting performance caused by powder agglomeration.

[0037] (4) The grouting material of the present invention is fully compatible with the 0.05~1.0MPa graded pressure grouting process commonly used in engineering. No adjustments need to be made to the existing construction equipment and procedures. It is convenient to construct and can be widely used in crack pressure grouting repair projects of various concrete structures such as industrial and civil buildings, bridges, tunnels, water conservancy and hydropower, and rail transit. It has broad application prospects and significant engineering value. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] This invention provides a technical solution: A low-shrinkage epoxy resin grouting material, by weight, comprises: 100 parts epoxy resin, 20-40 parts reactive diluent, coated porous shrinkage compensating powder, and epoxy curing agent. The amount of epoxy curing agent is 20%-80% of the total mass of the epoxy resin and the reactive diluent. The amount of coated porous shrinkage compensating powder in the low-shrinkage epoxy resin grouting material is 2 vol%-10 vol%. The coated porous shrinkage compensating powder is a porous powder with a complete closed coating film on its surface. The porous powder is selected from one or more of porous alumina, porous silica, and porous silicon carbide. The pore size of the porous powder is 0.1-10 μm, and the pore volume is ≥0.2 mL / g. The raw material of the coating film is a coating polymer emulsion, including acrylic polymer emulsion or styrene-acrylic emulsion. The amount of the coating polymer emulsion is 2%-10% of the mass of the porous powder.

[0040] Preferably, the coated porous shrinkage-compensating powder has a particle size of 2~50μm, a compressive strength ≥40MPa, and a density of 1.01~1.10g / cm³. 3 The coated porous shrinkage-compensating powder has a film elongation at break of ≤1%, an isostatic compressive strength of 0.05~0.1MPa, and a film thickness of 0.02~0.2μm.

[0041] The epoxy resin is selected from one or more of bisphenol F type epoxy resin 170, AFG-90 aminophenol trifunctional epoxy resin, and AFG-80 amino tetrafunctional epoxy resin. Preferably, epoxy resin 170 is used in combination with polyepoxy functional resin to balance low viscosity and mechanical properties of the cured product.

[0042] The reactive diluent is selected from one or more of the following: C12-14 benzyl glycidyl ether, resorcinol diglycidyl ether, glycerol triglycidyl ether, propoxyglycerol triglycidyl ether, etc., which have monoepoxy, diepoxy, or polyepoxy functional groups. It is used to reduce the viscosity of epoxy resin grouting materials, improve their injectability, ensure injection performance under low pressure, and participate in the curing reaction without the volatilization of small molecules.

[0043] The epoxy curing agent is selected from one or more of Evonik 2636 curing agent, Evonik I-965 curing agent, and isophorone diamine. Preferably, it is a room-temperature curing isophorone diamine, which enables rapid curing at room temperature, produces a cured product with excellent toughness, and is suitable for on-site construction environments.

[0044] Preferably, the raw materials also include additives, which are selected from one or more of BYK-A530 defoamer, BYK-111 wetting and dispersing agent, and silane coupling agent. The total amount of the additives does not exceed 5% of the mass of the epoxy resin. Specifically, the amount of BYK-A530 defoamer is 0.1% to 1.0% of the mass of the epoxy resin; the amount of BYK-111 wetting and dispersing agent is 0.1% to 1.0% of the mass of the epoxy resin, used to improve the wettability of the epoxy resin grouting material to porous powders; the silane coupling agent is preferably one of KH-550 and KH-560, used in an amount of 0.5% to 3.0% of the mass of the epoxy resin, used to improve the wettability of the epoxy resin grouting material to porous powders and the bonding strength at the interface of concrete cracks.

[0045] A method for preparing a low-shrinkage epoxy resin grouting material includes the following steps: S1 Powder Pretreatment: The porous powder is placed in an oven at 105~120℃ and dried for 2~4 hours, then cooled to room temperature for later use.

[0046] S2 Fluidized Bed Coating Modification: The dried porous powder is fed into a fluidized bed, and the fluidizing air is turned on to keep the porous powder in a stable suspension state. The fluidizing air velocity is 0.5~2.0 m / s, and the powder is preheated to 40~60℃. The coating polymer emulsion is atomized through the atomizing nozzle of the fluidized bed and sprayed onto the surface of the suspended porous powder. At the same time, hot air is introduced for simultaneous drying at a temperature of 60~90℃, forming a complete and continuous closed coating film on the surface of the porous powder. The solid content of the coating polymer emulsion is 10wt%~30wt%.

[0047] S3 Post-treatment: After spraying, continue fluidized drying for 10-30 minutes, cool to room temperature, and then sieve to remove agglomerated particles to obtain the coated porous shrinkage compensation powder.

[0048] S4 grout preparation: The epoxy resin, the reactive diluent, the additives, and the coated porous shrinkage compensating powder are mixed according to the specified ratio and stirred at high speed until homogeneous to obtain an epoxy resin premix. Before use, the epoxy resin premix is ​​mixed with the epoxy curing agent according to the specified ratio, stirred until homogeneous, and then vacuum degassed to obtain the low-shrinkage epoxy resin grouting material.

[0049] A method for using a low-shrinkage epoxy resin grouting material includes the following steps: A1 Pressure Grouting: A graded pressurization process of 0.05MPa~1.0MPa is adopted. The prepared low-shrinkage epoxy resin grouting material is pressed into the cracks of the concrete. The initial grouting pressure is 0.05~0.5MPa. After stabilizing the pressure for 5~10 minutes, the pressure is gradually increased to 0.8~1.0MPa. The pressure increase of each stage does not exceed 0.2MPa. Each stage is stabilized for 5~10 minutes. Finally, the pressure of the low-shrinkage epoxy resin grouting material at the crack reaches 1.0MPa and remains stable for 10 minutes. Then the inlet and outlet of the grouting material are sealed.

[0050] A2 Curing and Maintenance: After grouting is completed, cure at room temperature until the grout is completely cured to complete the crack repair. Example 1

[0051] The preparation process and usage method of the low-shrinkage epoxy resin grouting material in Example 1 are basically the same as those in the specific implementation method, and the specific implementation is as follows: The low-shrinkage epoxy resin grouting material formulation of Example 1, by weight, is as follows: 50 parts of 170 epoxy resin, 50 parts of AFG-90 aminophenol trifunctional epoxy resin, 20 parts of glycerol triglycidyl ether, 10 parts of resorcinol diglycidyl ether, 1 part of KH-560 silane coupling agent, 0.3 parts of BYK-111 wetting and dispersing agent, 0.3 parts of BYK-A530 silicone defoamer, and isophorone diamine at 23% of the total epoxy resin weight. Coated porous alumina powder is added at 3 vol% of the epoxy resin grouting material.

[0052] The preparation and application method of low-shrinkage epoxy resin grouting material includes the following steps: S1 Powder Pretreatment: Select porous alumina powder with a particle size of 15μm, a pore size of 2μm, a pore volume of 0.7mL / g, and a compressive strength of 75MPa. Dry it in an oven at 110℃ for 3h to remove moisture and impurities from the pores, and then cool it to room temperature for later use.

[0053] S2 Fluidized Bed Coating Modification: The dried porous alumina powder is fed into a fluidized bed, and the fluidizing air velocity is adjusted to 1.0 m / s to make the powder in a stable suspension state. The powder is preheated to 50°C. An acrylic polymer emulsion with a solid content of 20% is prepared, and the emulsion dosage is 5% of the mass of the porous alumina powder. The emulsion is atomized and sprayed onto the surface of the suspended powder through the atomizing nozzle at the top of the fluidized bed at an atomizing pressure of 0.2 MPa. At the same time, 80°C hot air is introduced for synchronous drying, forming a complete and closed coating film on the powder surface.

[0054] S3 Post-treatment: After spraying, continue fluidized drying at 70℃ for 20 minutes to fully solidify the coating film. After cooling to room temperature, pass through a 3000-mesh sieve to remove agglomerated particles and obtain coated porous alumina powder.

[0055] S4 grout preparation: Add 170 epoxy resin, AFG-90 aminophenol trifunctional epoxy resin, glycerol triglycidyl ether, resorcinol diglycidyl ether, coated porous alumina powder, KH-560 silane coupling agent, and BYK-A530 silicone defoamer to a mixing tank according to the specified ratio. Stir at 200 rpm for 5 minutes to ensure uniform dispersion of the powder, obtaining an epoxy resin premix. Before use, mix the epoxy resin premix with isophorone diamine according to the specified ratio, stir at 300 rpm for 4 minutes, and then degas under vacuum for 3 minutes to obtain a low-shrinkage epoxy resin grouting material.

[0056] A1 Pressure Grouting: A graded pressurization process is adopted. The initial grouting pressure is 0.05MPa. After stabilizing the pressure for 8 minutes, the pressure is increased by 0.2MPa at each stage, and finally pressurized to 1.0MPa. The pressure of the epoxy resin grouting material at the crack reaches 1.0MPa and remains stable for 10 minutes. Then the inlet and outlet of the grouting are sealed.

[0057] A2 Curing and Maintenance: After grouting, cure at room temperature (25℃) for 7 days until the grout is completely cured, thus completing the crack repair. Example 2

[0058] The preparation process and usage method of the low-shrinkage epoxy resin grouting material in this embodiment 2 are basically the same as those in the specific implementation method. The raw material formula is basically the same as that in embodiment 1. The difference from embodiment 1 is that the proportion of coated porous alumina powder in the epoxy resin grouting material is 4 vol. Example 3

[0059] The preparation process and usage method of the low-shrinkage epoxy resin grouting material in this embodiment 3 are basically the same as those in the specific implementation method. The raw material formula is basically the same as that in embodiment 1. The difference from embodiment 1 is that the proportion of coated porous alumina powder in the epoxy resin grouting material is 5 vol. Example 4

[0060] The preparation process and usage method of the low-shrinkage epoxy resin grouting material in Example 4 are basically the same as those in the specific implementation method. The raw material formula is basically the same as that in Example 1. The difference from Example 1 is that the porous powder selected is porous silica powder. The resulting coated porous silica powder has a particle size of 15μm, a pore size of 2μm, a pore volume of 0.5mL / g, and a compressive strength of 76MPa. Comparative Example 1

[0061] Comparative Example 1 is a conventional epoxy resin grouting material. The formula is basically the same as that of Example 1, except that no coated porous alumina powder is added. The other components, proportions, preparation and usage methods are the same as those of Example 1. Comparative Example 2

[0062] Comparative Example 2 is an epoxy resin grouting material modified with uncoated powder. The formula is basically the same as that of Example 1, except that uncoated porous alumina powder (same specifications as in Example 1) is added to replace coated porous alumina powder. The other components, proportions, preparation and usage methods are the same as those of Example 1. Comparative Example 3

[0063] Comparative Example 3 is a low-performance porous powder modified epoxy resin grouting material. The formula is basically the same as that of Example 1, except that the compressive strength of the coated porous alumina powder is 40 MPa. The other components, proportions, preparation and usage methods are the same as those of Example 1. Comparative Example 4

[0064] Comparative Example 4 is an epoxy resin grouting material modified with low dosage of porous powder. The formula is basically the same as that of Example 1, except that the proportion of coated porous alumina powder in the epoxy resin grouting material is 1 vol%. The other components, proportions, preparation and usage methods are the same as those of Example 1. Comparative Example 5

[0065] Comparative Example 5 is an epoxy resin grouting material modified with a high dosage of porous powder. The formula is basically the same as that of Example 1, except that the proportion of coated porous alumina powder in the epoxy resin grouting material is 8 vol%. The other components, proportions, preparation and usage methods are the same as those of Example 1. Performance Test Results and Analysis

[0066] The grouting materials prepared in Examples 1-4 and Comparative Examples 1-5 were subjected to performance tests, and the test results are shown in Table 2: Table 2 Performance test results of the examples and comparative examples

[0067] In the testing items, viscosity and compressive strength are tested according to DL / T1041, and curing shrinkage is tested according to ISO3521.

[0068] The test results in Table 1 show that: 1. As shown in Examples 1-3 and Comparative Example 1, the curing shrinkage rate of epoxy resin grouting material decreases with increasing dosage of coated porous powder. The shrinkage rate of Comparative Example 1 is 2.20%, while the shrinkage rates of Examples 1-3 are all below 0.50%, indicating that 3 vol% to 5 vol% of coated porous powder can effectively reduce curing shrinkage. Within this dosage range, the powder has less than 5% influence on the grout viscosity and slightly improves the compressive strength.

[0069] 2. As can be seen from Comparative Example 2 and Example 1, the uncoated porous powder will be invaded by epoxy resin slurry into the pores during stirring, resulting in a significant reduction in its shrinkage compensation effect.

[0070] 3. As can be seen from Comparative Example 3 and Example 1, the compressive strength of epoxy resin grouting material decreased by 25% after incorporating low-strength porous powder.

[0071] 4. As can be seen from Comparative Example 4 and Example 1, the low-dosage coated porous powder with 1 vol% has insufficient shrinkage compensation effect, and its curing shrinkage rate is only reduced to 1.54%, which is much higher than 0.44% in Example 1.

[0072] 5. As can be seen from Comparative Example 5 and Examples 1-3, the high dosage of 8 vol% coated porous powder will increase the viscosity of the slurry to more than 3 times the original, significantly reducing the groutability and failing to meet the construction requirements.

[0073] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A low-shrinkage epoxy resin grouting material, characterized in that: The raw materials, by weight, include: 100 parts epoxy resin, 20-40 parts reactive diluent, coated porous shrinkage compensating powder, and epoxy curing agent. The amount of epoxy curing agent is 20%-80% of the total mass of the epoxy resin and the reactive diluent. The amount of coated porous shrinkage compensating powder in the low-shrinkage epoxy resin grouting material is 2 vol%-10 vol%. The coated porous shrinkage compensation powder is a porous powder with a complete closed coating film on its surface. The porous powder is selected from one or more of porous alumina, porous silica, and porous silicon carbide. The pore size of the porous powder is 0.1~10μm and the pore volume is ≥0.2mL / g. The raw material for the coating film is a coating polymer emulsion, including: acrylic polymer emulsion or styrene-acrylic emulsion, and the amount of the coating polymer emulsion used is 2% to 10% of the mass of the porous powder.

2. The low-shrinkage epoxy resin grouting material according to claim 1, characterized in that: The coated porous shrinkage-compensating powder has a particle size of 2~50μm, a compressive strength ≥40MPa, and a density of 1.01~1.10g / cm³. 3 .

3. The low-shrinkage epoxy resin grouting material according to claim 1, characterized in that: The coated porous shrinkage-compensating powder has a film elongation at break of ≤1%, an isostatic compressive strength of 0.05~0.1MPa, and a film thickness of 0.02~0.2μm after film formation.

4. The low-shrinkage epoxy resin grouting material according to claim 1, characterized in that: The epoxy resin is selected from one or more of bisphenol F type epoxy resin 170, AFG-90 aminophenol trifunctional epoxy resin, and AFG-80 amino tetrafunctional epoxy resin.

5. The low-shrinkage epoxy resin grouting material according to claim 1, characterized in that: The active diluent is selected from one or more of C12-14 benzyl glycidyl ether, resorcinol diglycidyl ether, glycerol triglycidyl ether, and propoxyglycerol triglycidyl ether.

6. The low-shrinkage epoxy resin grouting material according to claim 1, characterized in that: The epoxy curing agent is selected from one or more of Evonik 2636 curing agent, Evonik I-965 curing agent, and isophorone diamine.

7. The low-shrinkage epoxy resin grouting material according to claim 1, characterized in that: The raw materials also include additives, which are selected from one or more of BYK-A530 defoamer, BYK-111 wetting and dispersing agent, and silane coupling agent, and the total amount of the additives does not exceed 5% of the mass of the epoxy resin.

8. A method for preparing a low-shrinkage epoxy resin grouting material as described in any one of claims 1 to 7, characterized in that: Includes the following steps: S1 Powder pretreatment: The porous powder is placed in an oven at 105~120℃ and dried for 2~4 hours, then cooled to room temperature for later use; S2 Fluidized bed coating modification: The dried porous powder is fed into a fluidized bed, the fluidizing air is turned on to make the porous powder in a stable suspension state, and the temperature is preheated to 40~60℃. The coated polymer emulsion is atomized through the atomizing nozzle of the fluidized bed and sprayed onto the surface of the suspended porous powder, while hot air is simultaneously introduced for drying, forming a complete and continuous closed coating film on the surface of the porous powder. The solid content of the coated polymer emulsion is 10~30wt%. S3 Post-treatment: After spraying, continue fluidized drying for 10-30 minutes, cool to room temperature, and then sieve to remove agglomerated particles to obtain the coated porous shrinkage compensation powder. S4 slurry preparation: Mix the epoxy resin, the reactive diluent, and the coated porous shrinkage compensation powder according to the specified ratio, and stir at high speed until uniform to obtain epoxy resin premix. Before use, the epoxy resin premix and the epoxy curing agent are mixed according to the specified ratio, stirred evenly, and then vacuum degassed to obtain the low-shrinkage epoxy resin grouting material.

9. The method for preparing the low-shrinkage epoxy resin grouting material according to claim 8, characterized in that: In S2, the fluidizing air velocity is 0.5~2.0m / s, the hot air temperature is 60~90℃, and the atomization pressure is 0.2~0.5MPa.

10. A method of using a low-shrinkage epoxy resin grouting material as described in any one of claims 1 to 7, characterized in that: Includes the following steps: A1 Pressure Grouting: Using a graded pressurization process of 0.05MPa~1.0MPa, the prepared low-shrinkage epoxy resin grouting material is pressed into the cracks of the concrete until the pressure of the low-shrinkage epoxy resin grouting material at the crack reaches 1.0MPa and remains stable for 10 minutes, then the inlet and outlet of the grouting are sealed. A2 Curing and Maintenance: After grouting is completed, cure at room temperature until the grout is completely cured to complete the crack repair.

11. The method of using the low-shrinkage epoxy resin grouting material according to claim 10, characterized in that: The graded pressurization process is as follows: the initial grouting pressure is 0.05~0.5MPa, and after stabilizing the pressure for 5~10 minutes, the pressure is gradually increased to 0.8~1.0MPa, with each pressure increase not exceeding 0.2MPa. Each pressure is stabilized for 5~10 minutes, and finally the pressure of the low-shrinkage epoxy resin grouting material at the crack reaches 1.0MPa and remains stable for 10 minutes.

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