Concrete anti-cracking, anti-seepage and corrosion-resistant construction material and application thereof

Abstract

This application relates to concrete crack-resistant, seepage-proof, and corrosion-resistant construction materials and their applications. The concrete crack-resistant, seepage-proof, and corrosion-resistant construction materials, by weight percentage, include: modified calcium-magnesium composite expansive agent: 35-60%; waterproofing component: 10-30%; anti-corrosion and rust-inhibiting component: 10-20%; viscosity-reducing component: 5-15%. The preparation steps of the modified calcium-magnesium composite expansive agent include: S1: [The text abruptly ends here, so the translation stops.] 2 / kg of calcium-based expansive agent is reacted under a hydrogen fluoride atmosphere to obtain a modified calcium-based expansive agent with calcium fluoride on its surface; S2: The modified calcium-based expansive agent and magnesium-based expansive agent are mixed, and then stirred and mixed with an epoxy silane solution at 30-40°C, dried, and ground to obtain a modified calcium-magnesium composite expansive agent. This invention, through the coating of a calcium fluoride layer with calcium-based expansive agent and the coating of modified calcium-based and magnesium-based expansive agents with epoxy silane solution, can reduce early expansion loss, increase mid-term expansion, raise the water absorption threshold to avoid late-stage expansion, compensate for concrete shrinkage, and improve crack resistance and structural stability.

Description

Technical Field

[0001] This invention relates to the field of concrete construction materials, and more particularly to concrete crack-resistant, seepage-proof, and corrosion-resistant construction materials and their applications. Background Technology

[0002] Concrete is a man-made stone composed of cementitious materials, coarse aggregate, fine aggregate, and water, widely used in construction projects and infrastructure. Concrete admixtures are widely used in concrete because they can improve its performance.

[0003] Existing concrete admixtures mainly include expanding agents, waterproofing agents, corrosion inhibitors, and pumping agents. These admixtures have limited functions, and their combined effect is poor when used in combination. Expanding agents are widely used to compensate for concrete shrinkage by producing an expansion effect within the concrete. Commonly used expanding agents are calcium-based or magnesium-based. Calcium-based expanding agents have a larger expansion energy, but over 80% is released within 1-3 days, and almost all is released within 1-4 days. This results in excessive early expansion energy, significant loss during the plastic stage of concrete, and no expansion in the middle stage. Magnesium oxide expanding agents have a milder expansion performance, producing expansion in the early, middle, and late stages of concrete formation. However, their expansion energy is relatively small, and inevitably, in the later stages of concrete hardening, the continued expansion of magnesium oxide expands, causing micro-expansion in the concrete structure, which threatens the stability and durability of the engineering structure.

[0004] Based on the aforementioned problems with concrete, there is an urgent need for a concrete admixture to address the issues of large early expansion energy loss, poor mid-term expansion effect, and continued expansion leading to instability in concrete structures caused by conventional expansive agents. The aim is to improve the volume stability of concrete structures and comprehensively enhance their crack resistance, impermeability, and corrosion resistance, thereby ensuring the durability of concrete structures. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a concrete crack-resistant, waterproof, and corrosion-resistant construction material, solving the problem of concrete cracking and subsequent volume instability caused by the mismatch between the expansion energy of concrete expansion agents and concrete shrinkage, thereby improving the overall crack resistance, waterproofing, and corrosion resistance of concrete. Another objective of this invention is to provide the application of this concrete crack-resistant, waterproof, and corrosion-resistant construction material.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] According to a first aspect of the present invention, a concrete crack-resistant, seepage-proof, and corrosion-resistant construction material is provided, comprising, by weight percentage: a modified calcium-magnesium composite expansive agent: 35-60%; a waterproof component: 10-30%; an anti-corrosion and rust-inhibiting component: 10-20%; and a viscosity-reducing component: 5-15%; wherein the preparation step of the modified calcium-magnesium composite expansive agent includes: S1: [The text abruptly ends here, so the translation stops.] 2 / kg of calcium expanding agent is reacted under a hydrogen fluoride atmosphere to obtain a modified calcium expanding agent with calcium fluoride on the surface; S2: The modified calcium expanding agent and magnesium expanding agent are mixed evenly, and then stirred and mixed with epoxy silane solution at 30-40℃ for 4-8h, dried, and ground to obtain the modified calcium-magnesium composite expanding agent.

[0008] Further, in step S1, the amount of calcium fluoride coating on the surface of the calcium expanding agent is 0.5-5 wt% of the mass of the calcium expanding agent.

[0009] Furthermore, the amount of epoxy silane on the surface of the modified calcium and magnesium expansion agent mixture in step S2 is 5-15 wt% of the mass of the mixture.

[0010] According to one embodiment, the concentration of hydrogen fluoride in the hydrogen fluoride atmosphere is not less than 20 wt%.

[0011] Furthermore, the reaction temperature of the calcium-based expanding agent under a hydrogen fluoride atmosphere can be 50-150℃, and the reaction time can be 2-3 h.

[0012] Furthermore, the hydrogen fluoride atmosphere can be industrial waste gas containing hydrogen fluoride gas.

[0013] Furthermore, the calcium-based expanding agent described in step S1 can be in a flat, suspended, or rolling state when reacting under a hydrogen fluoride atmosphere.

[0014] According to one embodiment, the epoxy silane solution is a solution of epoxy silane dissolved in ethanol, and the concentration of epoxy silane is 20-40 wt%.

[0015] Furthermore, the mass ratio of the mixture of the modified calcium expanding agent and the magnesium expanding agent to the epoxy silane solution is (94:6)-(97:3).

[0016] Furthermore, the epoxy silane may be one or more of trimethylepoxyethyl silane, triethylepoxyethyl silane, octafluoropropylepoxypropyltrimethoxysilane, and octadecylepoxypropyltrimethoxysilane.

[0017] According to one embodiment, the mass ratio of the modified calcium expanding agent to the magnesium expanding agent is between (3:7) and (6:4).

[0018] According to one embodiment, the waterproofing component includes at least one of calcium silicate and calcium stearate.

[0019] According to one embodiment, the anti-corrosion and rust-inhibiting component includes at least one of ultrafine mineral powder, ultrafine fly ash, and ultrafine silica fume, and at least one of polyphosphate, sodium hexametaphosphate, zinc oxide, sodium sulfite, aluminum sulfate, and sodium carbonate.

[0020] According to one embodiment, the viscosity-reducing component includes at least one of polyacrylic acid, polymethacrylic acid, maleic anhydride, sodium lignin sulfonate, and trisodium phosphate.

[0021] According to a second aspect of the present invention, an application of a concrete crack-resistant, seepage-proof, and corrosion-resistant construction material is provided, wherein the concrete crack-resistant, seepage-proof, and corrosion-resistant construction material is mixed with a concrete mixture and applied to a concrete structure.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) In the embodiments of the present invention, the calcium expansion agent is reacted under a hydrogen fluoride atmosphere to generate a calcium fluoride coating layer on the surface of the calcium expansion agent. The formation of the calcium fluoride coating layer slows down the rapid reaction of the calcium expansion agent in concrete, and plays a certain role in slow-release hydration and slow-release expansion energy, thereby reducing the expansion loss in the plastic stage of concrete and increasing the mid-term expansion in the shrinkage stage of concrete.

[0024] (2) The calcium-based expansive agent coated with calcium fluoride was mixed with the magnesium-based expansive agent and stirred with an epoxy silane solution. The hydrophilic groups of the epoxy silane reacted with the calcium fluoride and magnesium oxide, strengthening the adhesion of the epoxy silane coating layer. At the same time, the hydrophobic groups of the epoxy silane were exposed, forming a hydrophobic surface for the modified calcium-based and magnesium oxide expansive agents. This increased the water absorption threshold of the expansive agents, requiring higher humidity or longer soaking time before they could begin to absorb water and expand. The epoxy silane coating on the surface of the modified calcium-based and magnesium-based expansive agents slowed down the early reaction, effectively delaying the expansion performance to the middle stage. On the other hand, the hydrophilic groups adhered tightly to the expansive agents, and the hydrophobic outer surface formed by the hydrophobic groups increased the water absorption threshold of the expansive agents, preventing the expansive agents from threatening the structural stability due to expansion in the later stages of concrete.

[0025] (3) By adjusting the concentration of hydrogen fluoride in the hydrogen fluoride atmosphere, the reaction temperature and time, the thickness and density of the calcium fluoride coating layer can be adjusted. By adjusting the mass ratio of modified calcium expansion agent and magnesium expansion agent, as well as the concentration of epoxy silane solution and the reaction temperature and time, the coating layer thickness, internal adhesion and external surface hydrophobicity can be adjusted. The expansion effect can be controlled to a certain extent. Based on the shrinkage characteristics of concrete itself and the characteristics of the environment, the shrinkage of concrete can be more accurately compensated and the structural stability can be guaranteed, thereby improving the crack resistance and durability of concrete.

[0026] (4) Modified calcium-magnesium composite expansion agent can improve crack resistance and ensure structural stability. It can also be combined with waterproofing components and anti-corrosion and rust-inhibiting components to improve waterproofing and anti-corrosion and rust-inhibiting capabilities. However, it reduces the concrete discharge condition to a certain extent. The viscosity-reducing component compensates for the loss of condition and improves the discharge condition and pumpability of concrete. Modified calcium-magnesium composite expansion agent can be well combined with waterproofing components, anti-corrosion and rust-inhibiting components and viscosity-reducing components, which comprehensively improves the crack resistance, seepage prevention and corrosion resistance of concrete. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0028] In engineering applications, concrete often suffers from problems such as cracking, water seepage, and internal steel reinforcement corrosion. Adding concrete admixtures can improve these properties. Concrete admixtures containing expansive agents can compensate for concrete shrinkage and prevent cracking. However, the inventors have discovered that conventional expansive agents cannot adequately address the shrinkage and structural characteristics of concrete. For example, calcium-based expansive agents have a rapid reaction rate, leading to significant early expansion energy loss and insufficient mid-term expansion, while magnesium-based expansive agents exhibit expansion in the early, middle, and late stages, with insufficient mid-term expansion and late-term expansion threatening the volumetric stability of the concrete structure.

[0029] Based on this, the inventors have studied concrete crack-resistant, seepage-proof, and corrosion-resistant construction materials. The modified calcium-magnesium composite expansion agent in the admixture is modified through process and combined with waterproof components, anti-corrosion and rust-inhibiting components and viscosity-reducing components, which comprehensively improves the crack resistance, seepage prevention, and corrosion resistance of concrete, and has good application prospects in the field of concrete materials.

[0030] Example 1:

[0031] The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material of this embodiment includes 50% modified calcium-magnesium composite expansive agent, 17% calcium silicate, 5% calcium stearate, 13% ultrafine fly ash, 5% sodium hexametaphosphate, and 10% polyacrylic acid; wherein, the preparation steps of the modified calcium-magnesium composite expansive agent include:

[0032] S1: A surface area of ​​500 m² 2 / kg of calcium-based expanding agent was reacted in an atmosphere with a hydrogen fluoride concentration of 50wt%, the reaction vessel temperature was 150℃, and the reaction time was 3h, to obtain a modified calcium-based expanding agent with calcium fluoride generated on the surface.

[0033] S2: The modified calcium expanding agent and magnesium expanding agent are mixed evenly at a mass ratio of 6:4 to obtain a solid powder. Epoxy silane is dissolved in ethanol to prepare an epoxy silane solution with a concentration of 40%. The solid powder is then placed in the epoxy silane solution at a mass ratio of 94:6. The mixture is stirred and mixed at 40°C for 8 hours, dried, and ground to obtain the modified calcium-magnesium composite expanding agent of this embodiment.

[0034] Specifically, in step S1, the mass of the calcium expanding agent is 1000g, the volume of the reaction vessel is 1L, the calcium expanding agent is placed in the vessel in a flat state, and the content of hydrogen fluoride gas in the reaction vessel is 0.02 L / min.

[0035] In this embodiment, the calcium-magnesium composite expansive agent forms a calcium fluoride coating layer of a certain thickness on the surface of the calcium expansive agent, which slows down the rapid reaction of the calcium expansive agent in concrete, and plays a certain role in slow-release hydration and slow-release expansion energy, reducing the expansion loss in the plastic stage of concrete and increasing the mid-term expansion in the shrinkage stage of concrete. Furthermore, an epoxy silane solution is chemically bonded to the surface of the calcium expansive agent coated with calcium fluoride and the surface of the magnesium expansive agent. The hydrophilic groups of the epoxy silane react with calcium fluoride and magnesium oxide to enhance the adhesion of the epoxy silane coating layer. At the same time, the hydrophobic groups of the epoxy silane are exposed, making the modified calcium expansive agent and magnesium oxide expansive agent form a hydrophobic surface, increasing the water absorption threshold of the expansive agent, so that the expansive agent needs a higher humidity or a longer soaking time before it can begin to absorb water and expand. Epoxysilane coating on the surface of modified calcium and magnesium expansive agents slows down the early reaction and effectively delays the expansion performance to the middle stage. On the other hand, the hydrophilic groups are tightly bonded to the expansive agent, and the hydrophobic groups form a hydrophobic outer surface that increases the water absorption threshold of the expansive agent, thus preventing the expansive agent from threatening the structural stability in the later stage of concrete expansion.

[0036] Specifically, by controlling the hydrogen fluoride concentration to 50 wt%, the calcium-based expansive agent was reacted in a hydrogen fluoride atmosphere at 150°C for 3 hours. This controlled the thickness and density of the calcium fluoride coating formed on the surface of the calcium-based expansive agent. An excessively thin or low-density calcium fluoride coating resulted in poor slow-release effect of the calcium-based expansive agent, leading to greater early expansion and losses, and less mid-term expansion energy, thus failing to adequately compensate for concrete shrinkage. Conversely, an excessively thick or high-density calcium fluoride coating resulted in insufficient expansion energy release not only in the early stages but also in the mid-term.

[0037] Furthermore, controlling the epoxy silane solution concentration to 40% and the mass ratio to 94:6, and mixing at 40℃ for 8 hours, controlled the thickness of the epoxy silane coating layer, as well as the adhesion of epoxy silane to calcium fluoride and calcium oxide expansion agents, and the hydrophobicity of the outer surface. To a certain extent, a higher solution concentration, a smaller mass ratio, and a longer mixing time resulted in a thicker epoxy silane coating layer and stronger hydrophobicity of the outer surface, preventing micro-expansion of the concrete in the later stages that could lead to structural safety issues. However, this also reduced the release of expansion energy to some extent, resulting in poor mid-term expansion. Conversely, a thinner epoxy silane coating layer and weaker hydrophobicity of the outer surface allowed expansion energy to still be released in the later stages, thus affecting the stability of the concrete structure to some extent.

[0038] By controlling the mass ratio of modified calcium expansion agent to magnesium expansion agent to 6:4, the expansion effect of modified calcium expansion agent during slow release to the middle stage and the high middle stage expansion effect of magnesium expansion agent can be better utilized.

[0039] Example 2:

[0040] The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material of this embodiment includes 50% modified calcium-magnesium composite expansive agent, 17% calcium silicate, 5% calcium stearate, 13% ultrafine fly ash, 5% sodium hexametaphosphate, and 10% polyacrylic acid; wherein, the preparation steps of the modified calcium-magnesium composite expansive agent include:

[0041] S1: A surface area of ​​350 m² 2 / kg of calcium-based expanding agent was reacted in an atmosphere with a hydrogen fluoride concentration of 20 wt% at a reaction temperature of 50℃ for 2 hours to obtain a modified calcium-based expanding agent with calcium fluoride on its surface.

[0042] S2: The modified calcium expanding agent and magnesium expanding agent are mixed evenly at a mass ratio of 3:7 to obtain a solid powder. Epoxy silane is dissolved in ethanol to prepare an epoxy silane solution with a concentration of 20%. The solid powder is then placed in the epoxy silane solution at a mass ratio of 94:6. The mixture is stirred and mixed at 30°C for 4 hours, dried, and ground to obtain the modified calcium-magnesium composite expanding agent of this embodiment.

[0043] Specifically, in step S1, the mass of the calcium expanding agent is 1000g, the volume of the reaction vessel is 1L, the calcium expanding agent is placed in the vessel in a flat state, and the content of hydrogen fluoride gas in the reaction vessel is 0.02 L / min.

[0044] Example 3:

[0045] The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material of this embodiment includes 50% modified calcium-magnesium composite expansive agent, 17% calcium silicate, 5% calcium stearate, 13% ultrafine fly ash, 5% sodium hexametaphosphate, and 10% polyacrylic acid; wherein, the preparation steps of the modified calcium-magnesium composite expansive agent include:

[0046] S1: A surface area of ​​500 m² 2 / kg of calcium-based expanding agent was reacted in an atmosphere with a hydrogen fluoride concentration of 50wt% at a reaction temperature of 150℃ for 3h to obtain a modified calcium-based expanding agent with calcium fluoride on its surface.

[0047] S2: The modified calcium expanding agent and magnesium expanding agent are mixed evenly at a mass ratio of 3:7 to obtain a solid powder. Epoxy silane is dissolved in ethanol to prepare an epoxy silane solution with a concentration of 20%. The solid powder is then placed in the epoxy silane solution at a mass ratio of 94:6. The mixture is stirred and mixed at 30°C for 4 hours, dried, and ground to obtain the modified calcium-magnesium composite expanding agent of this embodiment.

[0048] Specifically, in step S1, the mass of the calcium expanding agent is 1000g, the volume of the reaction vessel is 1L, the calcium expanding agent is placed in the vessel in a flat state, and the content of hydrogen fluoride gas in the reaction vessel is 0.02 L / min.

[0049] Example 4:

[0050] The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material of this embodiment includes 50% modified calcium-magnesium composite expansive agent, 17% calcium silicate, 5% calcium stearate, 13% ultrafine fly ash, 5% sodium hexametaphosphate, and 10% polyacrylic acid; wherein, the preparation steps of the modified calcium-magnesium composite expansive agent include:

[0051] S1: A surface area of ​​350 m² 2 / kg of calcium-based expanding agent was reacted in an atmosphere with a hydrogen fluoride concentration of 20 wt% at a reaction temperature of 50℃ for 2 hours to obtain a modified calcium-based expanding agent with calcium fluoride on its surface.

[0052] S2: The modified calcium expanding agent and magnesium expanding agent are mixed evenly at a mass ratio of 6:4 to obtain a solid powder. Epoxy silane is dissolved in ethanol to prepare an epoxy silane solution with a concentration of 40%. The solid powder is then placed in the epoxy silane solution at a mass ratio of 94:6. The mixture is stirred and mixed at 40°C for 8 hours, dried, and ground to obtain the modified calcium-magnesium composite expanding agent of this embodiment.

[0053] Specifically, in step S1, the mass of the calcium expanding agent is 1000g, the volume of the reaction vessel is 1L, the calcium expanding agent is placed in the vessel in a flat state, and the content of hydrogen fluoride gas in the reaction vessel is 0.02 L / min.

[0054] Example 5:

[0055] The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material of this embodiment includes 50% modified calcium-magnesium composite expansive agent, 17% calcium silicate, 5% calcium stearate, 13% ultrafine fly ash, 5% sodium hexametaphosphate, and 10% polyacrylic acid; wherein, the preparation steps of the modified calcium-magnesium composite expansive agent include:

[0056] S1: A surface area of ​​350 m² 2 While stirring, industrial waste gas containing hydrogen fluoride (20 wt%) is introduced into the container at a reaction temperature of 50°C for 2 hours. The industrial waste gas is then discharged to the next collection and treatment device after the reaction. The reaction of the calcium-based expanding agent with the hydrogen fluoride-containing industrial waste gas yields a modified calcium-based expanding agent with calcium fluoride formed on its surface.

[0057] S2: The modified calcium expanding agent and magnesium expanding agent are mixed evenly at a mass ratio of 3:7 to obtain a solid powder. Epoxy silane is dissolved in ethanol to prepare an epoxy silane solution with a concentration of 20%. The solid powder is then placed in the epoxy silane solution at a mass ratio of 94:6. The mixture is stirred and mixed at 30°C for 4 hours, dried, and ground to obtain the modified calcium-magnesium composite expanding agent of this embodiment.

[0058] Specifically, in step S1, the mass of the calcium expanding agent is 10 kg, the volume of the reaction vessel is 10 L, and the content of hydrogen fluoride gas in the reaction vessel is 0.2 L / min.

[0059] Example 6:

[0060] The difference between this implementation and Example 1 is that the mass ratio of modified calcium expansion agent to magnesium expansion agent is 3:7.

[0061] Example 7:

[0062] The difference between this embodiment and Embodiment 1 lies in the different proportions of the components in the concrete crack-resistant, seepage-proof, and corrosion-resistant construction material, as well as the different compositions of the waterproofing component, anti-corrosion and rust-inhibiting component, and viscosity-reducing component. Specifically, the concrete crack-resistant, seepage-proof, and corrosion-resistant construction material includes 35% modified calcium-magnesium composite expansion agent, 25% calcium silicate, 5% calcium stearate, 15% ultrafine mineral powder, 5% zinc oxide, 10% polyacrylic acid, and 5% sodium lignosulfonate.

[0063] Comparative Example 1: The difference between this comparative example and Example 1 is that no modified calcium-magnesium composite expansion agent was added to the concrete crack-resistant, seepage-proof and corrosion-resistant construction material. The dosage of the concrete crack-resistant, seepage-proof and corrosion-resistant construction material in the concrete is the total amount of cementitious material × 6% × (the proportion of waterproof component in Example 1 + the proportion of anti-corrosion and rust-inhibiting component in Example 1 + the proportion of viscosity-reducing component in Example 1).

[0064] Comparative Example 2: The difference between this comparative example and Example 1 is that a calcium-based expansion agent is used instead of a modified calcium-magnesium composite expansion agent in the concrete crack-resistant, seepage-proof, and corrosion-resistant construction material.

[0065] Comparative Example 3: The difference between this comparative example and Example 1 is that a magnesium-based expansion agent is used instead of a modified calcium-magnesium composite expansion agent in the concrete crack-resistant, seepage-proof, and corrosion-resistant construction material.

[0066] Comparative Example 4: The difference between this comparative example and Example 1 is that a modified calcium-based expansion agent is used instead of a modified calcium-magnesium composite expansion agent in the concrete crack-resistant, seepage-proof, and corrosion-resistant construction material.

[0067] Comparative Example 5: The difference between this comparative example and Example 1 is that the modified calcium-magnesium composite expansion agent is replaced by a mixture of calcium-based expansion agent and magnesium oxide expansion agent coated with epoxy silane in the concrete crack-resistant, seepage-proof and corrosion-resistant construction material.

[0068] Comparative Example 6: The difference between this comparative example and Example 1 is that the concrete crack-resistant, seepage-proof and corrosion-resistant construction material is a calcium-magnesium composite expansion agent, which is a mixture of calcium expansion agent and magnesium expansion agent. It has not been modified and no waterproofing components, anti-corrosion and rust-inhibiting components or viscosity-reducing components have been added. The dosage in the concrete is the total amount of cementitious materials × 6% × (the proportion of modified calcium-magnesium composite expansion agent in Example 1).

[0069] The chemical analysis results of the calcium-based and magnesium-based expanding agents of this invention are shown in Table 1.

[0070]

[0071] Encapsulation amount tests of modified calcium-based expanding agent and modified calcium-magnesium composite expanding agent in Examples 1-5:

[0072] (1) The method for testing the amount of modified calcium expansion agent is as follows: weigh the mass M1 of the calcium expansion agent before coating in a dry state, and after reaction in a hydrogen fluoride atmosphere, weigh the mass M2 of the modified calcium expansion agent after coating with calcium fluoride. The amount of coating M3 is obtained by calculating M3=(M2-M1) / M1*100%.

[0073] (2) The coating amount test of the modified calcium-magnesium composite expansion agent is as follows: weigh the mass Ma of the modified calcium expansion agent and magnesium expansion agent in the dry state, weigh the mass Mb of the modified calcium-magnesium composite expansion agent after epoxy silane coating and drying, and calculate Mc=(Mb-Ma) / Ma*100% to obtain the coating amount Mc.

[0074] The coating amounts of the modified calcium-based expanding agent and the modified calcium-magnesium composite expanding agent are shown in Table 2.

[0075]

[0076] Concrete specimen molding:

[0077] Concrete specimens were prepared using C40 strength grade concrete for testing. The concrete mix design for the baseline group is shown in Table 3. In Examples 1-7 and Comparative Examples 1-6 of this invention, the construction materials were prepared by replacing part of the cementitious material, fly ash, with a cement content of 6%, as shown in Table 4.

[0078]

[0079]

[0080] In the above benchmark group, examples, and comparative examples, for raw materials, the cement used was ordinary Portland cement with a strength grade of PO 42.5, the crushed stone used was a continuous gradation of 5-31.5mm, the crushed stone and sand were all from the same warehouse where they were uniformly mixed, the tap water was from the same water source, and the water-reducing agent was the same polycarboxylate water-reducing agent from the same container. During the test, the construction materials, tap water, and water-reducing agent were all weighed using a weighing tool with an accuracy of 0.001g, and the sand and stone were weighed using a weighing tool with an accuracy of 0.01g. All tests were conducted and completed on the same day. During the specimen curing process, the molded specimens were all in the same curing environment. During the testing process, the same staff member used the same testing tool to test different specimens at different ages.

[0081] Concrete performance testing:

[0082] Slump testing

[0083] The slump of concrete was tested according to GB / T50080-2002 "Test Methods for Performance of Ordinary Concrete Mixtures".

[0084] Concrete restricted expansion rate test

[0085] The restricted expansion rate of concrete was tested according to GB / T 23439-2017 "Concrete Expansion Agent". Three concrete specimens were formed for each group, and the average value of the two closest specimens was taken as the measurement value. The restricted expansion rate of concrete was tested for specimens cured in water for 3 days and 14 days. After 14 days of water curing, the specimens were transferred to a constant temperature and humidity chamber (temperature 20℃±2℃, humidity 60%±5%) for curing. The restricted expansion rate of concrete was tested for specimens cured in water for 14 days and then transferred to constant temperature and humidity chamber for 60 days. The restricted expansion rate of concrete was tested for specimens cured in constant temperature and humidity chamber for 180 days. The structural volume stability was determined by Δε(180d-60d).

[0086] Penetration height detection

[0087] The penetration height of concrete test blocks was tested according to standard JC / T 474-2008 "Waterproofing Agents for Mortar and Concrete".

[0088] Corrosion resistance coefficient test

[0089] The corrosion resistance coefficient of concrete was tested according to GB / T 50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete".

[0090] Chloride ion permeability detection

[0091] The chloride ion diffusion coefficients of the concrete samples in the blank group, Examples 1-6, and Comparative Examples 1-6 were tested at 28 days according to GB / T 50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete".

[0092] Crack resistance area per unit area testing

[0093] According to GB / T 50081-2016 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", concrete samples of the reference group, Examples 1-7 and Comparative Examples 1-6 were made into test blocks with a size of 500mm×500mm×500mm. The cracking area of ​​the five sides other than the bottom surface was measured, and the cracking area per unit area was calculated.

[0094] The performance of concrete specimens formed by the test benchmark group, Examples 1-7 of the present invention and Comparative Examples 1-6 is shown in Table 5.

[0095]

[0096] As shown in Table 5, the limiting expansion rate of the baseline group after 3 days of water curing is negative, indicating that the concrete is in a shrinking state relative to its initial length, and this shrinkage continues with increasing age. However, the limiting expansion rate of the group after 14 days of water curing followed by 60 days of constant temperature and humidity curing is -0.069%, indicating significant shrinkage. The limiting expansion rate between 60 and 180 days is essentially zero, indicating that the concrete volume no longer changes after shrinking to a certain extent, demonstrating strong volume stability. The significant shrinkage of the concrete at 60 days leads to severe cracking. Furthermore, the large permeability height, low corrosion resistance coefficient, and high 28-day chloride ion permeability coefficient indicate that the concrete has water seepage and corrosion problems.

[0097] In Example 1 of this invention, the early expansion after 3 days of water curing is small, while the mid-term expansion after 14 days of water curing is large. The Δε(180d-60d) is 0.006%, indicating minimal expansion after concrete hardening. This example demonstrates minimal early expansion energy loss, significant mid-term expansion energy, and minimal late-term expansion, exhibiting excellent expansion energy release, compensating for concrete shrinkage, and ensuring structural stability to a certain extent. The crack area per unit area is small, indicating good crack resistance. The penetration height is zero, and the corrosion resistance coefficient is high. The chloride ion penetration coefficient at 28 days is low, indicating good impermeability and corrosion resistance.

[0098] Compared with Example 1, Examples 2-6 of this invention modify the calcareous expansive agent and the modified calcareous and magnesium expansive agents, resulting in different coating thicknesses and densities of calcium fluoride in the calcareous expansive agent. They also alter the coating thickness, internal adhesion, and external hydrophobicity of epoxy silane in the modified calcareous and magnesium expansive agents, leading to variations in the restricted expansion rate of concrete at different ages. Within this modification range, the concrete exhibits superior crack resistance. Furthermore, when combined with waterproofing, anti-corrosion, and viscosity-reducing components, it simultaneously demonstrates excellent workability, impermeability, and corrosion resistance.

[0099] Compared with Comparative Example 1, Example 7 of the present invention has a smaller mass ratio of modified calcium-magnesium composite expansion agent, resulting in a slight loss of expansion energy in the 14-day mid-term and a lower crack resistance than Example 1. However, it still has better crack resistance than the benchmark group.

[0100] Compared with Example 1, Comparative Example 1, without the addition of modified calcium-magnesium composite expansive agent, resulted in a concrete mortar restricted expansion rate similar to the baseline group and a larger crack area, indicating that the modified calcium-magnesium composite expansive agent plays a key role in releasing expansion energy to compensate for concrete shrinkage and thus reduce cracks; the weakened waterproof and corrosion-resistant properties compared with Example 1 indicate that the modified calcium-magnesium composite expansive agent has a promoting effect on waterproof and corrosion-resistant properties.

[0101] Compared to Example 1, Comparative Example 2, where the calcium-based expansive agent replaced the modified calcium-magnesium composite expansive agent, showed a larger limited expansion rate in the concrete during the early stage (3 days of water curing), virtually no increase during the middle stage (14 days of water curing), and greater shrinkage and crack area during the transition from water curing to constant temperature and humidity curing. This indicates that the calcium-based expansive agent reacts too quickly, resulting in significant early expansion energy loss, and also negatively impacts waterproofing and corrosion resistance. This demonstrates that the calcium-based expansive agent, when coated with calcium fluoride, has a good slow-release effect.

[0102] Compared with Example 1, in Comparative Example 3, the magnesium expansive agent replaced the modified calcium-magnesium composite expansive agent. The mid-term expansion rate of the concrete after 14 days of water curing was not high, and the Δε (180d-60d) was relatively large. This indicates that the expansion of the magnesium expansive agent in the later stage poses a threat to the volume stability of the structure. The crack area per unit area was large at 14d, and the crack area increased significantly at 180d.

[0103] Compared with Example 1, Comparative Example 4 showed insufficient mid-term expansion rate of concrete after 14 days of water curing, larger crack area per unit area after 14 days, and a significantly larger crack area after 180 days.

[0104] Compared to Example 1, Comparative Example 5, where the calcium-based expansive agent was not coated with calcium fluoride, showed greater early-stage restricted expansion in the concrete after 3 days of water curing, but a lower mid-stage restricted expansion rate. It also exhibited greater shrinkage during the transition from water curing to constant temperature and humidity curing, and larger crack areas per unit area at 14 days and 180 days. This demonstrates that the calcium-based expansive agent coating with calcium fluoride effectively reduces early-stage expansion energy loss and increases mid-stage expansion.

[0105] Compared with Example 1, Comparative Example 6, which only contains calcium and magnesium expansive agents, exhibited a large early expansion rate in the concrete after 3 days of water curing, resulting in a low mid-term expansion rate after 14 days of water curing. This led to a large Δε (180d-60d) in the concrete, posing a threat to the structure's volume stability. Furthermore, the absence of waterproofing, corrosion-inhibiting, and viscosity-reducing components resulted in poor workability, impermeability, and corrosion resistance. This indicates that the unmodified calcium-magnesium composite expansive agent was ineffective. Modified calcium-magnesium composite expansive agents play a crucial role in controlling concrete expansion, compensating for concrete shrinkage, and resisting cracking. Waterproofing, corrosion-inhibiting, and viscosity-reducing components also play important roles in improving concrete workability, impermeability, and corrosion resistance.

[0106] It should be noted that, in this document, terms such as "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 limitation, 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.

[0107] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A concrete crack-resistant, seepage-proof, and corrosion-resistant construction material, characterized in that: The concrete crack-resistant, seepage-proof, and corrosion-resistant construction materials, by weight percentage, include: Modified calcium-magnesium composite expander: 35-60%; Waterproofing component: 10-30%; Corrosion and rust inhibitor components: 10-20%; And viscosity-reducing components 5-15%; The preparation steps of the modified calcium-magnesium composite expanding agent include: S1: A specific surface area of ​​350-500 m² 2 / kg of calcium-based expanding agent was reacted under a hydrogen fluoride atmosphere to obtain a modified calcium-based expanding agent with calcium fluoride on the surface; S2: Mix the modified calcium-based expansion agent and magnesium-based expansion agent evenly, then stir and mix with epoxy silane solution at 30-40℃ for 4-8 hours, dry, and grind to obtain modified calcium-magnesium composite expansion agent.

2. The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material according to claim 1, characterized in that: The concentration of hydrogen fluoride in the hydrogen fluoride atmosphere is not less than 20 wt%.

3. The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material according to claim 2, characterized in that: The reaction temperature of the calcium-based expanding agent under a hydrogen fluoride atmosphere is 50-150℃, and the reaction time is 2-3 h.

4. The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material according to claim 1, characterized in that: The epoxy silane solution is a solution of epoxy silane dissolved in ethanol, and the concentration of epoxy silane is 20-40 wt%.

5. The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material according to claim 4, characterized in that: The mass ratio of the mixture of the modified calcium expansion agent and the magnesium expansion agent to the epoxy silane solution is (94:6)-(97:3).

6. The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material according to claim 1, characterized in that: The mass ratio of the modified calcium expanding agent to the magnesium expanding agent is between (3:7) and (6:4).

7. The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material according to claim 1, characterized in that: The waterproofing component includes at least one of calcium silicate and calcium stearate.

8. The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material according to claim 1, characterized in that, The corrosion-resistant and rust-inhibiting components include at least one of ultrafine mineral powder, ultrafine fly ash, and ultrafine silica fume, and at least one of polyphosphate, sodium hexametaphosphate, zinc oxide, sodium sulfite, aluminum sulfate, and sodium carbonate.

9. The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material according to claim 1, characterized in that: The viscosity-reducing component includes at least one of polyacrylic acid, polymethacrylic acid, maleic anhydride, sodium lignin sulfonate, and trisodium phosphate.

10. The application of a concrete crack-resistant, seepage-proof, and corrosion-resistant construction material, characterized in that: The concrete crack-resistant, seepage-proof, and corrosion-resistant construction material according to any one of claims 1-9 is mixed with concrete mixture and applied to concrete structures.

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