An ultra-fine grouting material for repairing concrete cracks in an alpine environment, a preparation method and application thereof

Abstract

The application discloses a kind of high-cold environment concrete narrow gap repair superfine grouting materials and preparation method and application thereof.The high-cold environment concrete narrow gap repair superfine grouting material is composed of the following raw materials by weight: sulphoaluminate cement clinker 4000-8000 parts, dihydrate gypsum 500-1000 parts, ordinary portland cement 500-1000 parts, silica fume 200-1000 parts, limestone powder 200-1000 parts, slag 1000-2000 parts, lithium carbonate 1-5 parts, boric acid 20-30 parts, polycarboxylate superplasticizer 20-30 parts, thickening agent 1-10 parts, calcium formate 10-80 parts, and water 3500-4000 parts.The grouting material does not contain aggregate, can enter the crack with size <0.05mm, prevent the expansion of very narrow crack;in addition, the grouting material is directly mixed with water with temperature <5℃ in cold environment, has long operable time, and can reach predetermined compressive strength and bending strength within 1 day.

Description

Technical Field

[0001] This invention belongs to the field of grouting repair and reinforcement, and specifically relates to an ultrafine grouting material for repairing narrow cracks in concrete in cold environments, its preparation method, and its application. Background Technology

[0002] Numerous engineering projects in cold, high-altitude plateau regions involve deep valleys and prolonged low temperatures. Grouting materials are widely used for emergency ground reinforcement and water / leak plugging, but most existing grouting materials are only suitable for ambient temperature conditions. Due to the low surface temperatures on plateaus, coupled with the abundance of meltwater from mountain peaks and seeping water from glacial lakes at the foot of mountains in the rock joints and fissures, grouting operations are conducted at extremely low temperatures. This low temperature affects the early strength development of conventional grouting materials, making it difficult to achieve the same results as at ambient temperatures. Summary of the Invention

[0003] This invention provides an ultrafine grouting material for repairing narrow cracks in concrete in cold environments, its preparation method, and its application, with the aim of achieving rapid repair of extremely narrow cracks in cold environments.

[0004] Based on this, the present invention provides the following technical solution:

[0005] The first aspect of this invention provides an ultrafine grouting material for repairing narrow cracks in concrete in cold environments. This ultrafine grouting material for repairing narrow cracks in concrete in cold environments is composed of the following raw materials in parts by weight: 4000-8000 parts of sulfoaluminate cement clinker, 500-1000 parts of dihydrate gypsum, 500-1000 parts of ordinary silicate cement, 200-1000 parts of silica fume, 200-1000 parts of limestone powder, 1000-2000 parts of slag, 1-5 parts of lithium carbonate, 20-30 parts of boric acid, 20-30 parts of polycarboxylate superplasticizer, 1-10 parts of thickener, 10-80 parts of calcium formate, and 3500-4000 parts of water.

[0006] In conjunction with the first aspect of the present invention, in some embodiments, the water-cement ratio of the ultrafine grouting material for repairing concrete cracks in cold environments is 0.3 to 0.4; preferably, the water-cement ratio of the ultrafine grouting material for repairing concrete cracks in cold environments is 0.35.

[0007] In conjunction with the first aspect of the present invention, in some embodiments, the temperature of the water is 1 to 5°C.

[0008] In conjunction with the first aspect of the present invention, in some embodiments, the content of calcium formate is 50 parts.

[0009] In conjunction with the first aspect of the invention, some embodiments include:

[0010] The Fe2O3 content in the sulfoaluminate cement clinker is not less than 5 wt%; and / or,

[0011] The CaO content in the slag is not less than 40 wt%; and / or,

[0012] The ordinary Portland cement is graded PO 42.5; and / or,

[0013] The CaSO4·2H2O content in the dihydrate gypsum is not less than 97%; and / or,

[0014] The limestone powder contains no less than 95% CaCO3; and / or,

[0015] The specific surface area of ​​the silica fume is not less than 21000 m². 2 / kg; and / or,

[0016] The thickener is hydroxypropyl methylcellulose; and / or,

[0017] The polycarboxylate superplasticizer is one of Sika, BASF, or Clariant.

[0018] A second aspect of the present invention provides a method for repairing narrow cracks in concrete in cold environments, comprising:

[0019] In natural environments, the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is mixed into a grout.

[0020] The grout is injected into cracks in concrete or rock and left to cure naturally for one day.

[0021] In conjunction with the second aspect of the present invention, in some embodiments, the temperature of the natural environment is -5 to 5°C.

[0022] In conjunction with the second aspect of the invention, in some embodiments, the width of the crack is <1 mm.

[0023] In conjunction with a second aspect of the invention, in some embodiments, the temperature of the water does not exceed 5°C.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] 1. Compared with existing cement-based repair materials, the grouting material provided by this invention does not contain aggregate and can penetrate cracks with a size of <0.05mm, preventing the expansion of extremely narrow cracks.

[0026] 2. The grouting material provided by the present invention can be directly mixed with water at a temperature of <5℃ in a cold environment, which also makes the viscosity of the grout increase slowly and has a longer working time in a cold environment.

[0027] 3. The grouting material provided by this invention has a fast hydration speed. After being injected into the crack under pressure, it can reach the predetermined compressive and flexural strength within one day in a cold environment, and can then be coated with a waterproof coating or other protective coating. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 Diagram illustrating the action mechanism of each component in an ultrafine grouting material for repairing narrow concrete joints in high-altitude and cold environments;

[0030] Figure 2 The solidification and demolding conditions of the grouting materials of Examples 1-4 and Comparative Example 1 under environmental conditions of -3 to 3℃ are shown.

[0031] Figure 3 The solidification and demolding of the grouting material in Comparative Example 10 under environmental conditions of -3 to 3℃.

[0032] Figure 4 The flowability development curves of the grouting materials of Examples 1-4 and Comparative Example 1 within 1 hour under environmental conditions of -3 to 3℃ are shown.

[0033] Figure 5 The expansion rate development curves of the grouting materials of Examples 1-4 and Comparative Example 1 at an environmental temperature of -3 to 3℃ for 28 days are shown. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0035] For simplicity, this invention only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range. Similarly, any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of the range is included within that range. Therefore, each point or individual value can be used as its own lower or upper limit and combined with any other point or individual value, or combined with other lower or upper limits, to form an unspecified range.

[0036] It should be noted that, in the description of this invention, unless otherwise stated, "above" and "below" include the stated number, and "multiple" in "one or more" means two or more. Relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0037] In the description of this invention, the terms "any embodiment / mode," "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment / mode or example, which are included in at least one embodiment / mode or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0038] The above description of the invention is not intended to describe every disclosed embodiment or implementation of the invention. Exemplary embodiments are described in more detail below. These embodiments can be used in various combinations. In each example, the listing is merely representative and should not be construed as exhaustive.

[0039] Ultrafine grouting material for repairing narrow cracks in concrete in high-altitude and cold environments:

[0040] As described in the background section, existing grouting materials exhibit slow hydration and strength gain in frigid environments. To improve the strength gain rate of grouting materials, warm water is added to accelerate cement hydration. However, adding warm water shortens the workable time of the grouting material and may even cause excessive viscosity and reduced fluidity, preventing it from smoothly entering narrow gaps, thus requiring highly skilled operators. Furthermore, while aggregates are commonly added to grouting materials, which enhance compressive and flexural strength, they also hinder entry into narrow gaps. Omitting aggregates, although making entry into narrow gaps possible, reduces the material's strength, increases shrinkage, and results in poor repair effects.

[0041] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided by this invention is composed of the following raw materials in parts by weight: 4000-8000 parts of sulfoaluminate cement clinker, 500-1000 parts of dihydrate gypsum, 500-1000 parts of ordinary silicate cement, 200-1000 parts of silica fume, 200-1000 parts of limestone powder, 1000-2000 parts of slag, 1-5 parts of lithium carbonate, 20-30 parts of boric acid, 20-30 parts of polycarboxylate superplasticizer, 1-10 parts of thickener, 10-80 parts of calcium formate, and 3500-4000 parts of water.

[0042] The grouting material of this invention does not contain aggregate, thus allowing it to penetrate narrow gaps. Furthermore, the grouting material uses cold water, resulting in a longer working time. This grouting material is formulated with six cementing materials: sulfoaluminate cement clinker, dihydrate gypsum, ordinary silicate cement, silica fume, limestone powder, and slag. This combination gives the grouting material good fluidity and rapid hydration in cold environments. Its flexural and compressive strengths meet requirements within one day, after which the grouting device can be removed, and waterproof and UV-resistant coatings can be applied. Additionally, this grouting material exhibits the advantage of slight volume expansion, preventing shrinkage cracks in the repaired gaps.

[0043] In the grouting material of this invention, sulfoaluminate cement and ordinary silicate cement have a mutually promoting hydration effect; gypsum dihydrate provides raw materials for the hydration of sulfoaluminate cement, accelerating the hydration reaction and the setting of the grouting material; silica fume has a small particle size and a large specific surface area, exhibiting extremely strong surface activity. After mixing with cement materials, the pozzolanic effect and micro-aggregate effect result in a denser grout structure; slag has a stable chemical composition and can replace the fly ash widely used in traditional grouting materials, reducing the drying shrinkage of the grout during hydration and effectively improving the stability of the grout; calcium formate can improve the crystal morphology of the main hydration products, increasing the skeleton strength of the grouting material, thereby further improving the overall strength. Furthermore, this invention incorporates a large proportion of silica fume, slag, and other mineral waste into the grouting material, promoting the conversion and utilization of industrial waste.

[0044] This invention controls the water-cement ratio of the ultrafine grouting material for repairing concrete cracks in cold environments to be 0.3–0.4; preferably, the water-cement ratio is 0.35. This water-cement ratio ensures that the grouting material has high fluidity and high strength, and avoids excessive drying shrinkage. This invention also controls the water-cement ratio of the ultrafine grouting material for repairing concrete cracks in cold environments to be 5–8:1.

[0045] In this invention, calcium formate in the grouting material serves as an admixture for early strength in cement. Preferably, the calcium formate content is 50 parts. This invention also experimented with adding aluminum sulfate and triethanolamine, which are also cement early strength agents. The initial fluidity and strength of the grouting material after one day of setting were tested. As shown in Table 1, the early compressive strength of the concrete was insufficient after aluminum sulfate and triethanolamine replaced calcium formate.

[0046] In this embodiment of the invention, the Fe2O3 content in the sulfoaluminate cement clinker is 5 wt%, the CaO content in the slag is 40 wt%, the ordinary Portland cement grade is PO 42.5, the CaSO4·2H2O content in the slag and dihydrate gypsum is 97 wt%, the CaCO3 content in the limestone powder is 95 wt%, and the specific surface area of ​​silica fume is 21000 m². 2 / kg, the thickener is hydroxypropyl methylcellulose, and the polycarboxylate superplasticizer is Sika, or BASF or Clariant can also be used. To ensure that the test results are not lower than those listed in the embodiments of this invention, those skilled in the art should select materials with property values ​​that are not lower than those selected in this invention, that is:

[0047] The Fe2O3 content in sulfoaluminate cement clinker is not less than 5 wt%; and / or,

[0048] The CaO content in the slag is not less than 40 wt%; and / or,

[0049] Ordinary Portland cement grade is PO 42.5; and / or,

[0050] The CaSO4·2H2O content in gypsum dihydrate is not less than 97 wt%; and / or,

[0051] The CaCO3 content in the limestone powder is not less than 95 wt%; and / or,

[0052] The specific surface area of ​​silica fume is not less than 21000 m². 2 / kg; and / or,

[0053] The thickener is hydroxypropyl methylcellulose; and / or,

[0054] The polycarboxylate superplasticizer is one of Sika, BASF, or Clariant.

[0055] Repair methods for narrow concrete cracks in high-altitude and cold environments:

[0056] The present invention provides a method for repairing narrow cracks in concrete in cold environments, comprising:

[0057] In natural environments, the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is mixed into a grout.

[0058] The grout is injected into cracks in concrete or rock and left to cure naturally for one day.

[0059] In conjunction with the second aspect of the present invention, in some embodiments, the temperature of the natural environment is -5 to 5°C.

[0060] In conjunction with the second aspect of the invention, in some embodiments, the width of the crack is <1 mm. Preferably, the width of the crack is <0.5 mm; further, the width of the crack is <0.1 mm.

[0061] In conjunction with the second aspect of the present invention, in some embodiments, the temperature of the water used for the grouting material is 1 to 5°C.

[0062] Example

[0063] The following describes embodiments of the present invention. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0064] Example 1:

[0065] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this embodiment is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 30 parts of calcium formate, and 3500 parts of water at 3°C.

[0066] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments includes the following specific steps:

[0067] First, sulfoaluminate cement clinker, dihydrate gypsum, ordinary silicate cement, silica fume, limestone powder, and slag are mixed to obtain component A. Then, lithium carbonate, boric acid, polycarboxylate superplasticizer, and hydroxypropyl methylcellulose are mixed to obtain component B. Finally, calcium formate is dissolved in water to obtain component C. Component A is placed in a mixer and mixed at low speed for 1-3 minutes until homogeneous. While mixing, component B is evenly added to the mixing pot. After mixing is complete, the mixer is kept at low speed, and component C is slowly poured into the mixing pot at a uniform speed and mixed for 30 seconds before stopping. The slurry deposited at the bottom of the mixing pot is scraped off with a scraper to ensure that there are no lumps deposited or adhered to the surface of the mixing pot. Finally, the mixture is rapidly stirred for 1-2 minutes to ensure that the slurry is fully mixed and homogeneous, resulting in the grouting material.

[0068] Example 2:

[0069] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this embodiment is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 50 parts of calcium formate, and 3500 parts of water at 3°C.

[0070] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments includes the following specific steps:

[0071] First, sulfoaluminate cement clinker, dihydrate gypsum, ordinary silicate cement, silica fume, limestone powder, and slag are mixed to obtain component A. Then, lithium carbonate, boric acid, polycarboxylate superplasticizer, and hydroxypropyl methylcellulose are mixed to obtain component B. Finally, calcium formate is dissolved in water to obtain component C. Component A is placed in a mixer and mixed at low speed for 1-3 minutes until homogeneous. While mixing, component B is evenly added to the mixing pot. After mixing is complete, the mixer is kept at low speed, and component C is slowly poured into the mixing pot at a uniform speed and mixed for 30 seconds before stopping. The slurry deposited at the bottom of the mixing pot is scraped off with a scraper to ensure that there are no lumps deposited or adhered to the surface of the mixing pot. Finally, the mixture is rapidly stirred for 1-2 minutes to ensure that the slurry is fully mixed and homogeneous, resulting in the grouting material.

[0072] Example 3:

[0073] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this embodiment is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 100 parts of calcium formate, and 3500 parts of water at 3°C.

[0074] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is the same as that in Example 1.

[0075] Example 4:

[0076] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this embodiment is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 150 parts of calcium formate, and 3500 parts of water at 3°C.

[0077] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is the same as that in Example 1.

[0078] Example 5:

[0079] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this embodiment is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 200 parts of calcium formate, and 3500 parts of water at 3°C.

[0080] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is the same as that in Example 1.

[0081] Comparative Example 1:

[0082] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this comparative example is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, and 3500 parts of water at 3°C.

[0083] The specific steps for preparing the above-mentioned grouting material are as follows:

[0084] First, sulfoaluminate cement clinker, dihydrate gypsum, ordinary silicate cement, silica fume, limestone powder, and slag are mixed to obtain component A. Then, lithium carbonate, boric acid, polycarboxylate superplasticizer, and hydroxypropyl methylcellulose are mixed to obtain component B. Component A is placed in a mixer and mixed at low speed for 1-3 minutes until homogeneous. While mixing, component B is evenly added to the mixing pot. After mixing is complete, the mixer is kept at low speed, and water is slowly poured into the mixing pot at a uniform rate, and mixing is stopped after 30 seconds. The slurry deposited at the bottom of the mixing pot is scraped off with a scraper to ensure that there are no lumps deposited or adhered on the surface of the mixing pot. Finally, the mixture is rapidly stirred for 1-2 minutes to ensure that the slurry is fully mixed and homogeneous, resulting in the grouting material.

[0085] Comparative Example 2:

[0086] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this comparative example is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 10 parts of triethanolamine, and 3500 parts of water at 3°C.

[0087] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is the same as that in Example 1.

[0088] Comparative Example 3:

[0089] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this comparative example is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 20 parts of triethanolamine, and 3500 parts of water at 3°C.

[0090] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is the same as that in Example 1.

[0091] Comparative Example 4:

[0092] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this comparative example is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 40 parts of triethanolamine, and 3500 parts of water at 3°C.

[0093] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is the same as that in Example 1.

[0094] Comparative Example 5:

[0095] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this comparative example is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 60 parts of triethanolamine, and 3500 parts of water at 3°C.

[0096] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is the same as that in Example 1.

[0097] Comparative Example 6:

[0098] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this comparative example is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 50 parts of aluminum sulfate, and 3500 parts of water at 3°C.

[0099] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is the same as that in Example 1.

[0100] Comparative Example 7:

[0101] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this comparative example is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 100 parts of aluminum sulfate, and 3500 parts of water at 3°C.

[0102] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is the same as that in Example 1.

[0103] Comparative Example 8:

[0104] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this comparative example is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 200 parts of aluminum sulfate, and 3500 parts of water at 3°C.

[0105] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is the same as that in Example 1.

[0106] Comparative Example 9:

[0107] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this comparative example is composed of the following raw materials in parts by weight: 4500 parts of sulfoaluminate cement clinker, 800 parts of dihydrate gypsum, 700 parts of ordinary silicate cement, 1000 parts of silica fume, 1000 parts of limestone powder, 2000 parts of slag, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, 300 parts of aluminum sulfate, and 3500 parts of water at 3°C.

[0108] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments is the same as that in Example 1.

[0109] Comparative Example 10:

[0110] The ultrafine grouting material for repairing narrow cracks in concrete in cold environments provided in this comparative example is composed of the following raw materials in parts by weight: 10,000 parts of ordinary silicate cement, 5 parts of lithium carbonate, 30 parts of boric acid, 20 parts of polycarboxylate superplasticizer, 10 parts of hydroxypropyl methylcellulose, and 3,500 parts of water at 3°C.

[0111] The preparation method of the above-mentioned ultrafine grouting material for repairing concrete cracks in cold environments includes the following specific steps:

[0112] First, ordinary silicate cement is stirred evenly to obtain component A. Then, lithium carbonate, boric acid, polycarboxylate superplasticizer, and hydroxypropyl methylcellulose are mixed to obtain component B. Component A is placed in a mixer and stirred at low speed for 1-3 minutes until evenly mixed. While stirring, component B is evenly added to the mixing pot. After mixing is complete, the mixer is kept at low speed, and water is slowly poured into the mixing pot at a uniform speed and stirred for 30 seconds before stopping. The slurry deposited at the bottom of the mixing pot is scraped off with a scraper to ensure that there are no lumps deposited or attached to the surface of the mixing pot. Finally, the mixture is stirred rapidly for 1-2 minutes to ensure that the slurry is fully mixed and homogeneous, thus obtaining the grouting material.

[0113] The performance of the grouting materials obtained in each embodiment and comparative example was tested under environmental conditions of -3 to 3℃. Flowability was tested according to "GB / T 8077-2012 'Test Method for Homogeneity of Concrete Admixtures'", strength according to "GB / T 17671-2021 'Test Method for Strength of Cement Mortar (ISO Method)'", and expansion rate according to "JC / T 313-2009 'Test Method for Expansion Rate of Expansive Cement'". The test results for strength and flowability are shown in Table 1.

[0114] Table 1. Performance test results of grouting materials under environmental conditions of -3 to 3℃

[0115]

[0116]

[0117] As shown in Table 1, Examples 1-5 of the present invention provide ultrafine grouting materials for repairing concrete cracks in cold environments with different contents of calcium formate, which are the mix proportions described in the present invention; Comparative Example 1 is the mix proportion without early strength agent; Comparative Examples 2-5 are mix proportions with different contents of triethanolamine; Comparative Examples 6-9 are mix proportions with different contents of aluminum sulfate; Comparative Example 10 is the mix proportion containing only ordinary Portland cement;

[0118] Figure 4 The initial flowability and flexural and compressive strength properties of the grouting materials in Examples 1-4 and Comparative Example 1 are demonstrated. A comparison of Examples 1-4 and Comparative Example 1 shows that the amount of calcium formate has a significant impact on the performance of the grouting material, with Example 2 exhibiting the best results.

[0119] Comparing Example 2 with Comparative Example 10, it can be seen that the curing performance of the grouting material of the present invention is significantly different from that of the grouting material made of ordinary silicate cement under low temperature conditions.

[0120] Comparing Example 2 with Comparative Examples 2-5 and Comparative Examples 6-9, it can be found that triethanolamine and aluminum sulfate have no beneficial effect on improving early strength, while calcium formate can improve the early strength of the grouting material.

[0121] Figure 2 and Figure 3 This indicates that grouting materials prepared with ordinary silicate cement cannot solidify under low-temperature conditions, while the grouting material provided by this invention can solidify and be demolded normally.

[0122] Figure 4 The paper demonstrates the loss of fluidity of the grouting material provided by the present invention over 1 hour, indicating that the ability of grouting materials with different calcium formate contents to maintain fluidity is different. As the amount of calcium formate increases, the ability of the grouting material to maintain fluidity first increases and then decreases.

[0123] Figure 5 The expansion rate development curve of the grouting material specimens during the 28-day standard age period is shown, indicating that the expansion rate of grouting materials with different calcium formate contents is different. As the calcium formate content increases, the expansion rate of the specimens in the stable stage shows a pattern of first increasing and then decreasing.

[0124] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A type of ultrafine grouting material for repairing narrow cracks in concrete in high-altitude and cold environments, characterized in that: The ultrafine grouting material for repairing narrow cracks in concrete in cold environments is composed of the following raw materials in parts by weight: 4000-8000 parts of sulfoaluminate cement clinker, 500-1000 parts of dihydrate gypsum, 500-1000 parts of ordinary silicate cement, 200-1000 parts of silica fume, 200-1000 parts of limestone powder, 1000-2000 parts of slag, 1-5 parts of lithium carbonate, 20-30 parts of boric acid, 20-30 parts of polycarboxylate superplasticizer, 1-10 parts of thickener, 10-80 parts of calcium formate, and 3500-4000 parts of water at a temperature of 1-5℃.

2. The ultrafine grouting material for repairing narrow cracks in concrete in cold environments according to claim 1, characterized in that: The water-cement ratio of the ultrafine grouting material for repairing concrete cracks in cold environments is 0.3~0.

4.

3. The ultrafine grouting material for repairing narrow cracks in concrete in cold environments according to claim 2, characterized in that: The water-cement ratio of the ultrafine grouting material for repairing concrete cracks in cold environments is 0.

35.

4. The ultrafine grouting material for repairing narrow cracks in concrete in cold environments according to claim 1, characterized in that: The content of calcium formate is 50 parts.

5. The ultrafine grouting material for repairing narrow cracks in concrete in cold environments according to claim 1, characterized in that: The Fe2O3 content in the sulfoaluminate cement clinker is not less than 5 wt%; and / or, The CaO content in the slag is not less than 40 wt%; and / or, The ordinary Portland cement is graded PO 42.5; and / or, The CaSO4·2H2O content in the dihydrate gypsum is not less than 97%; and / or, The limestone powder contains no less than 95% CaCO3; and / or The specific surface area of ​​the silica fume is not less than 21000 m². 2 / kg; and / or, The thickener is hydroxypropyl methylcellulose.

6. A method for repairing narrow cracks in concrete in cold environments, characterized in that, include: Under extremely cold temperatures, the ultrafine grouting material for repairing concrete cracks in frigid environments as described in any one of claims 1 to 5 is mixed into a grout. The grout is injected into cracks in concrete or rock and left to cure naturally for one day.

7. The method for repairing narrow concrete cracks in cold environments according to claim 6, characterized in that: The extreme cold temperature ranges from -5 to 5℃.

8. The method for repairing narrow cracks in concrete in cold environments according to claim 6, characterized in that: The width of the crack is less than 1 mm.

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