Early-strength high-strength repairing material in extremely cold environment and preparation method thereof

Abstract

The application discloses a kind of early-strength high-strength repair materials and preparation methods in severe cold environment, by mass fraction including: A. cementitious component: 100 parts, wherein low temperature modified sulphoaluminate cement 35-50 parts, high belite Portland cement 25-40 parts, superfine calcined aluminosilicate activator 20-30 parts;B. aggregate component: 80-110 parts, wherein graded rigid aggregate: 75-105 parts, lightweight insulation micro aggregate: 5-15 parts;C. core functional component includes pre-hydrated nano composite crystal nucleus: 1.5-3.5% of the mass of cementitious component, organic-inorganic low-temperature composite activator, 4.0-7.0% of the mass of cementitious component;Water: the mass ratio of water and cementitious component is 0.16-0.22, to realize self, rapid hydration in severe cold environment, realize 4 hours ultra-high early strength;And finally have excellent long-term strength and durability;When construction, no external heat source, simplify process, reduce energy consumption and cost characteristics.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to an early-strength and high-strength repair material for extremely cold environments, its preparation method, and its application. Background Technology

[0002] Emergency repairs and continuous winter construction of infrastructure in extremely cold regions (Level 2 "Extreme Cold", -30℃ to -39.9℃) face enormous challenges. At these temperatures, the hydration reaction of traditional cement-based materials essentially halts, preventing strength development. Existing research and patents on low-temperature repair materials primarily focus on "Extreme Cold" (above -20℃) or "Very Cold" (above -10℃) environments, and their technical solutions cannot meet the stringent requirements of extremely cold environments. Specific shortcomings are as follows: Insufficient applicable temperature: Existing technical solutions (such as CN112811871A) typically claim a lower limit of applicable low temperature between -10℃ and -20℃, with performance rapidly declining or failing below -30℃. For example, a novel inorganic cementitious material, while possessing high early strength (3h>35MPa), has a defined environmental adaptability range of -20℃ to 5℃. Another patent discloses a methyl methacrylate-based organic repair material that can cure at -30℃, but as an organic resin system, its long-term durability, weather resistance, and compatibility with old concrete are generally inferior to cement-based materials.

[0003] Early strength and ultra-high strength are difficult to achieve simultaneously: some solutions improve early strength by adding sulfoaluminate cement or large amounts of early strength agents, but this often leads to weak strength growth in later stages (28-day strength is often below 80 MPa) or poor volume stability. For example, an ultra-early strength high ductility material has a strength greater than 30 MPa at room temperature after 2 hours, but its performance in extremely cold environments is not mentioned.

[0004] Technical limitations: Existing technologies mostly rely on single or combined chemical additives (such as antifreeze and early-strength agents) to lower the freezing point and promote hydration, or simply introduce nanomaterials (such as nano-SiO2) as crystal nuclei. These methods have limited effectiveness in extremely cold environments and fail to systematically solve the problem from the root causes of hydration kinetics and microstructure formation. For example, research indicates that the effect of conventional nano-SiO2 crystal nuclei at low temperatures is only significant after 3 days, which cannot meet the requirement of ultra-early strength within 4 hours.

[0005] Lack of systematic solutions: Existing technologies focus on improving single components or simply recombining existing materials. There is a lack of collaborative innovation solutions across the entire chain, from the design of the gelation system and the precise activation of the hydration process to the optimization of the microstructure, specifically tailored to the characteristics of extremely cold environments.

[0006] Therefore, developing an inorganic repair material that can simultaneously achieve "ultra-early strength" (4h>30MPa) and "ultra-high strength" (28d>80MPa) at temperatures ranging from -30℃ to -39.9℃ is a technical bottleneck that urgently needs to be overcome. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide an early-strength and high-strength repair material and preparation method for extremely cold environments. It has the characteristics of being able to autonomously and rapidly hydrate in extremely cold environments, achieving ultra-high early strength (>30MPa) in 4 hours, and ultimately developing excellent long-term strength and durability. It does not require an external heat source during construction, simplifies the process, and reduces energy consumption and costs.

[0008] This application provides an early-strength, high-strength repair material for harsh environments, comprising, by weight: A. Cementitious component: 100 parts, including 35-50 parts of low-temperature modified sulfoaluminate cement, 25-40 parts of high belite silicate cement, and 20-30 parts of ultrafine calcined aluminosilicate activator. B. Aggregate composition: 80-110 parts Graded rigid aggregate: 75-105 parts Lightweight thermal insulation micro-aggregate: 5-15 parts C. Core functional components: Prehydrated nanocomposite nuclei: accounting for 1.5-3.5% of the mass of the cementitious components.

[0009] Organic-inorganic low-temperature composite activator: accounting for 4.0-7.0% of the mass of the gelling component.

[0010] Water: The mass ratio of water to the cementitious components is 0.16-0.22.

[0011] Preferably, the preparation method of the low-temperature modified sulfoaluminate cement includes the following steps: 1. Mixing limestone, bauxite, gypsum, boron source, and phosphorus source evenly, with the following mass percentages: limestone 38-42%, bauxite 28-32%, gypsum 28-32%, boron source 0.3%-0.8%, and phosphorus source 0.1%-0.4%; 2. Low-temperature rapid calcination and controlled quenching: The residence time in the rotary kiln is 20-30 minutes, the maximum calcination temperature is 1250℃-1280℃, the residence time at 1250℃-1280℃ is 5-8 minutes, and the clinker exiting the kiln enters the cooler, using high airflow for rapid cooling, cooling to 800℃ at a rate of 150-180℃ / second, and then cooling to room temperature at a rate of 50-80℃ / second; 3. Micronization and surface passivation treatment: After cooling, it is fed into a closed-circuit ball milling system together with anhydrite, and ball milled to a specific surface area of ​​450-500 m². 2 / kg, at the end of the grinding process, spray 0.01%-0.05% of a composite organic surface treatment agent into the mill.

[0012] Preferably, the high-belite silicate cement has a specific surface area ≥450m² / kg, an initial setting time ≥15min, and a final setting time ≤45min; the ultrafine calcined aluminosilicate activator has an average particle size ≤5μm.

[0013] Preferably, the method for preparing the prehydrated nanocomposite crystal nuclei involves prehydrating 40-50% low-temperature modified sulfoaluminate cement, 30-40% high-belite silicate cement, 5-10% organic lithium reinforcing agent, and 30-40% water at 5-15°C with high-speed stirring for 2-4 hours to form a slurry rich in nano-CSH and AFt; subsequently, it is rapidly freeze-dried below -40°C and then subjected to air jet milling under inert gas protection to obtain dry powder with a particle size D50≤500nm.

[0014] Preferably, the organic-inorganic low-temperature composite activator is an aqueous solution composed of a low-temperature polycarboxylate superplasticizer, a diethanolamine isopropanolamine complex, lithium nitrate and calcium formate, wherein the mass ratio of the low-temperature polycarboxylate superplasticizer, the diethanolamine isopropanolamine complex, lithium nitrate and calcium formate is (3-5):0.5:(5-20):(10-30).

[0015] A method for preparing an early-strength and high-strength repair material for extremely cold environments includes the following steps: S1 is prepared by uniformly mixing an organic-inorganic low-temperature composite activator, mixing water and prehydrated nanocomposite crystal nuclei at 0-5℃ to obtain a functional mother liquor. S2 Dry Mix: Mix the A cementitious component and the B aggregate component in a forced mixer cooled to about -5°C for 2-3 minutes until homogeneous to obtain a dry mix. S3 activation mixing involves adding the functional mother liquor to the dry mix all at once, stirring at low speed for 1 minute, then switching to high speed for 3-5 minutes until the slurry is uniform, dense, and exhibits excellent fluidity. Preferably, in step S3, the stirring speed of the low-speed stirring is 60 rpm, the stirring speed of the high-speed stirring is 180-220 rpm, and the outlet temperature after high-speed stirring is -3℃ to 2℃.

[0016] A construction method for an early-strength and high-strength repair material in extremely cold environments, which involves direct pouring, spraying, or troweling in environments ranging from -30℃ to -39.9℃.

[0017] Compared with related technologies, the present invention has the following advantages: Prehydrated nanocomposite crystal nuclei (PHNCS) technology differs from directly adding inert crystal nuclei such as nano-SiO2 or nano-calcium carbonate. This crystal nucleus is produced by pre-hydrating some core cementing materials (such as highly active aluminates and silicates) with specific activators under controlled conditions to generate a slurry with high surface activity, mainly composed of hydrated calcium silicate (CSH) and ettringite (AFt) nanocrystal nuclei. The slurry is then dried at low temperature and depolymerized to form an ultrafine powder.

[0018] Mechanism of action: When mixed in a frigid environment, PHNCS is directly introduced as a "mature seed," providing a massive number of nucleation sites with crystal structures completely consistent with the final product for the newly formed hydration products at low temperatures. This bypasses the bottleneck of high nucleation energy barriers at low temperatures, directly initiating and dominating the hydration process, thereby achieving a "leapfrog" initial development of strength (satisfying the 4-hour ultra-early strength requirement), rather than the "accelerating" effect of traditional crystal nuclei.

[0019] Low-Temperature Active Mineral Composite (LAMC) System: This invention abandons the conventional simple binary compounding model of "sulfoaluminate cement + silicate cement". It adopts a ternary composite system composed of low-temperature modified sulfoaluminate cement (L-SAC), high belite silicate cement (H-BC), and ultrafine calcined aluminosilicate activator (UFA).

[0020] Mechanism of action and differences: L-SAC: Through mineral doping modification, its early hydration exothermic curve at -30℃ is optimized to avoid excessive instantaneous exothermic heat leading to microcracks, while ensuring sufficient early strength contribution.

[0021] H-BC: Its dominant mineral, belite (C2S), hydrates slowly at low temperatures, but exhibits high strength and mild exothermic reaction in the later stages. This invention utilizes the strong inducing effect of PHNCS to activate its low-temperature hydration in advance, solving the problem of belite materials "dormant" at sub-zero temperatures in traditional technologies.

[0022] UFA: Under the combined action of PHNCS and low-temperature activator, it can undergo volcanic ash reaction in the early stage, consume calcium hydroxide, and promote the formation of denser CSH gel.

[0023] Through ratio optimization, the three components, in the series connection of PHNCS, achieve temporal complementarity and exothermic synergy of low-temperature hydration reactions: L-SAC provides the initial structure and early strength; the reactions of H-BC and UFA are seamlessly connected, continuously filling the pores and ensuring a continuous and stable increase in strength from the ultra-early stage to the ultra-high late stage.

[0024] Organic-Inorganic Low-Temperature Composite Initiator (OILE): This is not a simple compound of inorganic salts such as calcium nitrate and calcium formate, or commercial antifreeze agents. The OILE in this invention comprises a composite liquid of low-temperature polycarboxylic acid molecules (PCE), small molecule organic alcohol amine chelates (OA), and a specific inorganic salt (IS).

[0025] Its core components and functions are as follows: Low-temperature polycarboxylate superplasticizer (PCE): responsible for ensuring particle dispersion and workability at low temperatures.

[0026] Diethanolamine isopropanolamine complex (OA): The core functional component, which significantly enhances the ion migration rate at low temperatures through complexation.

[0027] Specific inorganic salts (IS), such as lithium nitrate and calcium formate, work synergistically with OA to further lower the freezing point of the liquid phase and provide an early strengthening phase.

[0028] Mechanism of action and differences: Low-temperature PCE: Its molecular side chains are designed to effectively disperse particles even in extreme cold and have a certain air-entraining function to alleviate frost heave pressure.

[0029] OA chelates: preferentially bind with Ca 2+ Plasma bonding forms soluble complexes at low temperatures, significantly increasing the migration rate of ions in the liquid phase and continuously delivering "nutrients" to the PHNCS surface, maintaining high-speed hydration.

[0030] Specific IS: In synergy with OA, it further lowers the solution freezing point to below -50°C and participates in the formation of the early strengthening phase.

[0031] OILE, in collaboration with PHNCS and LAMC systems, has constructed a three-pronged mechanism to ensure hydration in extreme cold conditions: lowering the freezing point to protect the reaction environment, enhancing ion migration to protect the reaction dynamics, and providing structured crystal nuclei to protect the reaction pathway. Detailed Implementation

[0032] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0033] Modification process of low-temperature modified sulfoaluminate cement (L-SAC): The main problem with ordinary sulfoaluminate cement at low temperatures (such as -30℃) is that the early hydration reaction is too intense and concentrated, resulting in a large but short-lived instantaneous heat release. In extremely cold environments, this heat is quickly dissipated and cannot maintain a continuous "positive temperature microenvironment" inside the paste. At the same time, the loose structure of the large amount of ettringite (AFt) generated in the early stage leads to weak strength growth in the later stage.

[0034] The hydration exothermic kinetics, early hydration product morphology, and long-term strength development of sulfoaluminate cement were systematically "regulated" to make it an ideal component for use in extremely cold environments. The main objectives were to induce low-temperature activity, regulate the exothermic process, and optimize the product structure.

[0035] Modification process of low-temperature modified sulfoaluminate cement (L-SAC): Step 1: Mineral composite doping and raw material preparation 1. Basic raw materials: High-quality limestone, bauxite and gypsum are selected as the main raw materials for preparing sulfoaluminate cement clinker, of which limestone accounts for 38-42% by mass, bauxite accounts for 28-32% and gypsum accounts for 28-32%.

[0036] 2. Key Modifier Doping: Two key modifiers are uniformly incorporated during the raw material grinding stage: Boron source modifier: The dosage is 0.3%-0.8% of the total mass of raw material (calculated as B2O3), which can be replaced by borax (Na2B4O7·10H2O) or boric acid (H3BO3).

[0037] Mechanism of action: B 3+ Ions can dissolve into the calcium sulfoaluminate (C4A3Š) mineral lattice, causing lattice distortion and defects, reducing its hydration activation energy at low temperatures, and refining the size of early-formed AFt crystals, making its structure more compact.

[0038] Phosphorus source modifier: The dosage is 0.1%-0.4% of the total mass of raw materials (calculated as P2O5), which can be replaced by calcium dihydrogen phosphate or industrial phosphoric acid.

[0039] Mechanism of action: trace amounts of PO4 3- It can adsorb onto the surface of cement minerals, forming an extremely thin soluble phosphate film in the very early stages. This film provides an "instantaneous slow release" effect on the initial contact between cement particles and water, preventing heat loss due to an excessively large reaction interface in extremely cold environments. Simultaneously, it promotes the formation of more stable monosulfide calcium aluminate (AFm) in the later stages, which is beneficial for long-term strength growth.

[0040] 3. Raw material homogenization: The doped raw material is fully homogenized in a homogenization chamber to ensure the microscopic uniformity of the modifier distribution.

[0041] Step 2: Low-temperature rapid calcination and controlled quenching 1. Calcination: A "moderately low temperature, rapid passage" calcination scheme is adopted in the rotary kiln. The residence time in the rotary kiln is 20-30 minutes, the maximum calcination temperature is 1250℃-1280℃ (about 50℃ lower than the approximately 1300-1350℃ of traditional sulfoaluminate cement clinker), the residence time at 1250℃-1280℃ is 5-8 minutes, and the residence time of the material in the high temperature zone is shortened.

[0042] The method employs a 1250℃-1280℃, rapid pass-through temperature to generate C4A3Š minerals with higher specific surface area and more crystal defects. Lower calcination temperatures inhibit overly complete crystal growth, thus preserving higher chemical potential and reactivity, making it particularly suitable for activation at low temperatures.

[0043] 2. Cooling: The clinker exiting the kiln immediately enters a dedicated multi-stage controllable air quenching cooler for rapid cooling.

[0044] The first stage (high temperature stage, >1000℃): High-volume rapid cooling is used, with a cooling rate of 150-180℃ / s, to reduce the clinker temperature from the kiln outlet temperature to below 800℃ within seconds. The purpose is to preserve the high-temperature mineral phases (such as C4A3Š) in a metastable state and fix their highly active structure.

[0045] The second stage (medium-low temperature stage, <800℃): Controlled medium-speed cooling is employed, with a cooling rate of 50-80℃ / s, and a small amount of water mist is introduced for humidification. This process intentionally induces trace surface hydration of some β-C2S (belite) minerals, forming a nanoscale pre-hydrated calcium silicate (CSH) gel thin layer on their surface. This is one of the key innovations of this process: these pre-hydrated layers become "built-in nuclei" after subsequent grinding, which can preferentially and rapidly initiate the hydration of the silicate phase during cold mixing, forming a "synergistic nucleation effect between the inside and outside" with PHNCS.

[0046] Step 3: Micronization and Surface Passivation Treatment 1. Selective micro-grinding: Cooled clinker is fed together with an appropriate amount of anhydrite (to provide a stable sulfate source for later processing) into a closed-circuit ball mill system. The grinding objective is to control the specific surface area of ​​the finished cement to 450-500 m². 2 The concentration is at a relatively high level of / kg, with a focus on ensuring that the C4A3Š mineral phase particles are finer (achieved through adjustment by a classifier), so that they can be more uniformly and rapidly dispersed and reacted in the mixture.

[0047] 2. In-situ passivation treatment: At the end of the grinding process, a small amount of composite organic surface treatment agent (e.g., a mixture of glycolic acid and triethanolamine at 0.01%-0.05% of the cement mass) is sprayed into the mill.

[0048] Mechanism of action: These organic molecules can selectively adsorb onto the surface of newly formed, highly active cement particles (especially C4A3Š), forming a monomolecular adsorption layer. This film has minimal effect at room temperature, but in extremely cold environments (such as -30℃), it can moderately slow down the initial contact rate between water molecules and the mineral surface, preventing uncontrolled and inefficient "cold shock" hydration from occurring before the slurry temperature has risen due to the activator. This allows limited chemical energy to be used more effectively to build the early strength framework.

[0049] III. The role of modified L-SAC in the LAMC system After undergoing the above-mentioned process modification, L-SAC has undergone a fundamental transformation in performance, becoming a "smart" gelling component specifically designed for extremely cold environments: 1. Mild and long-lasting early exothermic properties: Modifiers and surface treatments broaden and reduce the peak value of hydration exothermics under extreme cold conditions, enabling better coupling with the exothermics of H-BC and UFA, and maintaining a positive temperature microenvironment inside the slurry for a longer period of time.

[0050] 2. Optimized product structure: The introduction of boron and phosphorus elements makes the early-generated AFt crystals smaller and more tightly interwoven, forming a denser early structure together with the CSH gel induced by PHNCS.

[0051] 3. Deep Synergy with PHNCS and OILE: Its surface's "built-in nucleus" and "controlled release" characteristics achieve perfect synergy with the added PHNCS (main nucleus) and OILE (ion transporter). L-SAC is no longer a "lone wolf" violent reaction, but rather an orderly and efficient material deposition on the fully integrated framework provided by PHNCS, thereby achieving ultra-high strength in a very short time (4 hours).

[0052] Example 1: Rapid repair of road and bridge decks in extremely cold regions It balances ultra-early strength, ultra-high strength and excellent construction fluidity, and is suitable for large-area thin-layer repair.

[0053] Raw material formulation (by weight) for a high-strength, early-strength repair material for extremely cold environments: A. Gelation component: 100 parts Low-temperature modified sulfoaluminate cement (L-SAC): 40 parts High Belite Portland Cement (H-BC): 35 parts Ultrafine calcined aluminosilicate activator (UFA): 25 parts B aggregate component: 95 parts Graded quartz sand (0.08-1.18mm): 85 parts Hollow glass microspheres (0.05-0.15mm): 10 parts C functional components: Prehydrated nanocomposite crystal nuclei (PHNCS): accounting for 2.5% of the mass of the gelling components.

[0054] Organic-inorganic low-temperature composite activator (OILE): accounts for 5.5% of the mass of the gelling component.

[0055] Water: Water-to-binder ratio 0.18.

[0056] Preparation of prehydrated nanocomposite nuclei: 40-50% low-temperature modified sulfoaluminate cement, 30-40% high belite silicate cement, 5-10% organic lithium reinforcing agent and 30-40% water are stirred at high speed at 5-15℃ for 2-4 hours to form a slurry rich in nano-CSH and AFt; then it is rapidly freeze-dried below -40℃ and air-jet pulverized under inert gas protection to obtain dry powder with a particle size D50≤500nm.

[0057] Preparation of organic-inorganic low-temperature composite activator: An aqueous solution is prepared by compounding low-temperature polycarboxylate superplasticizer, diethanolamine isopropanolamine complex, lithium nitrate and calcium formate, wherein the mass ratio of low-temperature polycarboxylate superplasticizer, diethanolamine isopropanolamine complex, lithium nitrate and calcium formate is (3-5):0.5:(5-20):(10-30).

[0058] A method for preparing an early-strength and high-strength repair material for extremely cold environments includes the following steps: S1 is prepared by uniformly mixing an organic-inorganic low-temperature composite activator, mixing water and prehydrated nanocomposite crystal nuclei at 0-5℃ to obtain a functional mother liquor. S2 dry mix: A cementitious component and B aggregate component are dry mixed in a forced mixer cooled to about -5°C for 2-3 minutes until uniform to obtain a dry mix. S3 activation mixing involves adding the functional mother liquor to the dry mix all at once, stirring at low speed for 1 minute, then switching to high speed for 3-5 minutes until the slurry is uniform, dense, and exhibits excellent fluidity. The slurry temperature at the outlet is -1℃, and the initial fluidity reaches 280mm (jump table method).

[0059] A construction method for an early-strength and high-strength repair material in extremely cold environments involves pouring it onto a pre-treated concrete substrate at -30℃.

[0060] Performance test results: Mechanical properties (compressive strength, MPa): 4 hours: 36.5 24 hours: 52.8 28 days: 103.7 Workability and durability: Initial setting / final setting time (-30℃): 28 minutes / 41 minutes.

[0061] 28-day bond strength: 4.2 MPa.

[0062] Relative dynamic elastic modulus after 300 freeze-thaw cycles: 96.5%.

[0063] 90-day drying shrinkage value: 328×10 -6 .

[0064] Example 2: Grouting and structural reinforcement for cracks in high-altitude hydropower projects (ultra-high strength, low shrinkage formula) With its ultimate strength and dimensional stability, it is suitable for the reinforcement and repair of critical load-bearing components.

[0065] Raw material formulation (by weight) for a high-strength, early-strength repair material for extremely cold environments: A. Gelation component: 100 parts L-SAC: 35 copies H-BC: 40 copies UFA: 25 copies B. Aggregate composition: 85 parts Graded corundum sand (0.1-0.8mm): 80 parts Ceramic microspheres (0.02-0.1mm): 5 parts C. Functional components: PHNCS: accounts for 3.0% of the mass of the gelling components.

[0066] OILE: accounts for 6.0% of the mass of the gelling components.

[0067] Water: Water-to-binder ratio 0.17.

[0068] The rest is the same as in Example 1. The preparation method is the same as in Example 1. After preparation, the fluidity of the slurry is 250 mm, which is suitable for pressure grouting.

[0069] Construction method: Simulate cracks by injecting them at -32℃.

[0070] Performance test results: Mechanical properties (compressive strength, MPa): 4 hours: 34.2 (Note: Due to the decrease in water-cement ratio and the increase in aggregate hardness, the 4-hour strength is slightly lower than that of Example 1, but still far exceeds 30 MPa) 24 hours: 55.1 28 days: 112.4 Workability and durability: 28-day flexural strength: 14.8 MPa.

[0071] 28-day bond strength: 4.5 MPa.

[0072] Permeability grade: >P20.

[0073] 90-day drying shrinkage value: 298×10 -6 (Significantly low shrinkage characteristics).

[0074] Comparative Example 1: A comparative formulation without PHNCS but containing an equal amount of conventional nanomaterials. Based on Example 1, PHNCS was completely removed, and 2.5% of commercially available hydrophilic nano silica powder (particle size ~30nm) was added by mass of the gelling component, while the remaining components and amounts remained unchanged.

[0075] 1.3 Performance Test Results Comparison: Mechanical properties (compressive strength, MPa): Mechanism analysis: At -30℃, ordinary nano-SiO2 mainly acts as a microfiller and a late-stage pozzolanic effect, failing to provide effective nucleation sites with hydrated product crystal structures, resulting in the slurry's inability to form a sufficiently strong framework in the very early stages. This comparison strongly demonstrates that PHNCS is the core innovation for achieving the breakthrough indicator of ">30MPa in 4 hours," which can be expected through the replacement of conventional nanomaterials.

[0076] Comparative Example 2: Comparative formulations using common material systems from existing technologies Simulate a publicly available repair mortar suitable for -20℃: Rapid-hardening sulfoaluminate cement (R·SAC): 70 parts Ordinary Portland cement (P·O 42.5): 30 parts Silica fume: 10 parts Same aggregate composition (same as Example 1): 95 parts Commercially available composite antifreeze and early-strength agent (calcium nitrate based): 7.0% (percentage of cementitious material mass) Common polycarboxylate superplasticizer: 1.0% Water: Water-to-binder ratio 0.20.

[0077] (Note: This does not include PHNCS and OILE) 2.3 Performance Test Results Comparison: Mechanical properties (compressive strength, MPa): Overall performance: The paste of Comparative Example 2 exhibits rapid loss of fluidity at -30℃, a long initial setting time of up to 65 minutes, and slow strength gain in the later stages. Its 28-day drying shrinkage value reaches as high as 450 × 10⁻⁶. -6.

[0078] This comparison demonstrates that even combining materials considered effective in existing technologies fails to function in "extremely cold" environments. This invention, through the synergistic effect of PHNCS (solving nucleation issues), the LAMC system (optimizing the reaction process), and OILE (ensuring a safe reaction environment), forms a novel system solution for extremely cold environments, achieving unexpected technical results and possessing outstanding substantive features and significant progress.

[0079] The above description is merely a specific embodiment of this application. However, the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A high-strength, early-strength repair material for extremely cold environments, characterized in that, Included by weight parts: B. Gelation component: 100 parts, of which 35-50 parts of low-temperature modified sulfoaluminate cement 25-40 parts of high-belite silicate cement 20-30 parts of ultrafine calcined aluminosilicate activator; B. Aggregate composition: 80-110 parts, of which Graded rigid aggregate: 75-105 parts Lightweight thermal insulation micro-aggregate: 5-15 parts; C. Core functional components: Prehydrated nanocomposite crystal nuclei account for 1.5-3.5% of the mass of the cementitious components. Organic-inorganic low-temperature composite activator, accounting for 4.0-7.0% of the mass of the gelling component; Water: The mass ratio of water to the cementitious components is 0.16-0.

22.

2. The early-strength and high-strength repair material for extremely cold environments according to claim 1, characterized in that, The preparation method of the low-temperature modified sulfoaluminate cement includes the following steps:

1. Mixing limestone, bauxite, gypsum, boron source, and phosphorus source evenly, with the following mass percentages: limestone 38-42%, bauxite 28-32%, gypsum 28-32%, boron source 0.3%-0.8%, and phosphorus source 0.1%-0.4%; 2. Low-temperature rapid calcination and controlled quenching: The residence time in the rotary kiln is 20-30 minutes, the maximum calcination temperature is 1250℃-1280℃, the residence time at 1250℃-1280℃ is 5-8 minutes, and the clinker exiting the kiln enters the cooler, using high airflow for rapid cooling, cooling to 800℃ at a rate of 150-180℃ / second, and then cooling to room temperature at a rate of 50-80℃ / second; 3. Micronization and surface passivation treatment: After cooling, it is fed into a closed-circuit ball milling system together with anhydrite, and ball milled to a specific surface area of ​​450-500 m². 2 / kg, at the end of the grinding process, spray 0.01%-0.05% of a composite organic surface treatment agent into the mill.

3. The early-strength and high-strength repair material for extremely cold environments according to claim 1, characterized in that, The high-belite silicate cement has a specific surface area ≥450m². 2 / kg, initial setting time ≥15min, final setting time ≤45min; the average particle size of the ultrafine calcined aluminosilicate activator is ≤5μm.

4. The early-strength and high-strength repair material for extremely cold environments according to claim 1, characterized in that, The preparation method of the prehydrated nanocomposite crystal nucleus is as follows: 40-50% low-temperature modified sulfoaluminate cement, 30-40% high belite silicate cement, 5-10% organic lithium reinforcing agent and 30-40% water are stirred at high speed at 5-15℃ for 2-4 hours to form a slurry rich in nano-CSH and AFt; then it is rapidly freeze-dried below -40℃ and pulverized by airflow under inert gas protection to obtain dry powder with a particle size D50≤500nm.

5. The early-strength and high-strength repair material for extremely cold environments according to claim 1, characterized in that, The organic-inorganic low-temperature composite activator is an aqueous solution composed of low-temperature polycarboxylate superplasticizer, diethanolamine isopropanolamine complex, lithium nitrate and calcium formate, wherein the mass ratio of low-temperature polycarboxylate superplasticizer, diethanolamine isopropanolamine complex, lithium nitrate and calcium formate is (3-5):0.5:(5-20):(10-30).

6. The method for preparing an early-strength, high-strength repair material under extremely cold environments as described in claims 1-5, characterized in that, Includes the following steps: S1 is prepared by uniformly mixing an organic-inorganic low-temperature composite activator, mixing water and prehydrated nanocomposite crystal nuclei at 0-5℃ to obtain a functional mother liquor. S2 Dry Mix: Mix the A cementitious component and the B aggregate component in a forced mixer cooled to about -5°C for 2-3 minutes until homogeneous to obtain a dry mix. S3 activation mixing involves adding the functional mother liquor to the dry mix all at once, stirring at low speed for 1 minute, then switching to high speed for 3-5 minutes until the slurry is uniform, dense, and exhibits excellent fluidity.

7. The method for preparing an early-strength, high-strength repair material for extremely cold environments according to claim 1, characterized in that, In step S3, the stirring speed of the low-speed stirring is 60 rpm, the stirring speed of the high-speed stirring is 180-220 rpm, and the outlet temperature after high-speed stirring is -3℃ to 2℃.

8. A construction method for an early-strength, high-strength repair material in extremely cold environments as described in any one of claims 6-7, characterized in that, Direct pouring, spraying or troweling can be performed in environments ranging from -30℃ to -39.9℃.

Images