High-strength long-life marine engineering concrete and preparation method thereof

Abstract

The application belongs to the technical field of concrete and specifically relates to high-strength long-life marine engineering concrete and a preparation method thereof. The high-strength long-life marine engineering concrete comprises the following components in parts by weight: Portland cement 200-300 parts, fly ash 50-100 parts, mineral powder 50-80 parts, silicon powder 20-50 parts, aggregate 1500-2000 parts, stainless steel fiber 30-40 parts, synergist 5-10 parts, water reducing agent 5-10 parts, and anti-cracking agent 5-10 parts. The synergist comprises aromatic polyamide fiber 50-60%, zirconium oxide 15-30%, anionic surfactant 5-10%, and water 20-30%. The water reducing agent comprises polycarboxylic acid water reducing agent 30-55%, lignin sulfonate 20-30%, film forming agent 5-10%, and water 20-30%. The concrete has improved strength, durability and service life in the marine environment.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology, specifically relating to a high-strength, long-life marine engineering concrete and its preparation method. Background Technology

[0002] Concrete is a general term for engineering composite materials in which aggregates are bound together by cementing materials. While concrete used in marine engineering requires high workability and durability, its structure is highly susceptible to damage due to long-term exposure to marine organisms, inorganic salts, atmosphere, water, and temperature. Research indicates that marine forces causing damage to concrete structures include: freeze-thaw cycles, steel reinforcement corrosion, carbonation, alkali-aggregate reactions, acid-alkali corrosion, and mechanical damage from impact abrasion. Among these, steel reinforcement corrosion and salt erosion are the most significant causes. Seawater contains approximately 3.5% dissolved salts, including sodium (Na₂O₃). + Mg 2+ Ca 2+ K + Cl - SO4 2- Plasma, with Cl being the most abundant. - These ions can easily penetrate the pores of concrete, reacting adversely with alkaline aggregates, weakening the concrete's strength, causing steel corrosion, and ultimately damaging the overall structure. Under alternating wet and dry conditions such as wave erosion, these ions can also form expanding crystals in the capillary pores of the concrete, leading to cracking. The combined effect of these two processes accelerates the erosion and damage of the concrete structure; in cold regions, freezing damage may also occur.

[0003] Concrete structures in my country's coastal and near-shore areas suffer severe damage from the marine environment, particularly those located in areas of fluctuating water levels or exposed to water. This leads to steel corrosion and premature structural failure, resulting in significant damage and substantial losses. Concrete cracking, especially early-stage cracking, is a major factor affecting structural durability. Cracking in marine concrete is a highly complex systemic problem, currently focusing on four main aspects: material selection, environmental conditions and constraints, structural design, and construction techniques. Concrete crack prevention can be approached from two angles: first, controlling temperature, improving constraints, and reducing temperature stress; second, maximizing the crack resistance of concrete and improving its inherent properties.

[0004] In addition, large-volume concrete in marine engineering is generally poured in place. Before pouring, steel caskets, bamboo plywood and other materials are often used as structural formwork, which can easily cause problems such as slow heat dissipation and excessively high temperature peaks. When selecting temperature control measures, attention should be paid to the influence of the formwork. At the same time, excessive water consumption in concrete will directly reduce its strength and density, seriously affecting the quality of the project and endangering the safety of the project. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned technical problems by providing a high-strength, long-life marine engineering concrete. Through appropriate ingredient composition and preparation methods, the strength, durability, and service life of the concrete in the marine environment are improved.

[0006] The high-strength, long-life marine engineering concrete of this invention comprises the following components in parts by weight: 200-300 parts silicate cement, 50-100 parts fly ash, 50-80 parts mineral powder, 20-50 parts silica fume, 1500-2000 parts aggregate, 30-40 parts stainless steel fiber, 5-10 parts synergist, 5-10 parts water-reducing agent, and 5-10 parts crack-resistant agent.

[0007] Furthermore, the density of the mineral powder is 2.8–2.9 g / cm³. 3 Specific surface area is 350-500 m² 2 / kg.

[0008] Furthermore, the aggregate is a mixture of large stones, small stones, and sand, with the mass percentages of large stones, small stones, and sand being 40-50%, 15-20%, and 35-45%, respectively. This combination of three stone sizes results in a lower porosity and requires less cement, which helps improve the strength of the concrete.

[0009] Furthermore, the particle sizes of the large stones and small stones are 10–15 mm and 1–5 mm, respectively.

[0010] Furthermore, the fineness modulus of the sand is 2.2 to 1.6.

[0011] Furthermore, the synergist comprises the following components in weight percentage: 50-60% aromatic polyamide fiber, 15-30% zirconium oxide, 5-10% anionic surfactant, and 20-30% water.

[0012] Aromatic polyamide fibers have extremely high mechanical strength and elastic modulus, which can increase the strength of concrete. Zirconia dispersed inside the aromatic polyamide fibers can react with harmful ions to form insoluble compound crystals. The combination of the two can not only prevent further intrusion of chloride ions, but also enhance the strength and durability of concrete structures.

[0013] Furthermore, the synergist is obtained by mixing aromatic polyamide fibers, zirconium oxide, and water, and then adding anionic surfactants and stirring.

[0014] Preferably, the anionic surfactant may be one or more of sodium dioctyl succinate sulfonate, sodium dodecylbenzene sulfonate, sodium glycocholate, sodium dodecyl sulfate, stearic acid, and oleic acid.

[0015] Furthermore, the water-reducing agent comprises the following components by weight percentage: 30-55% polycarboxylate water-reducing agent, 20-30% lignin sulfonate, 5-10% film-forming agent, and 20-30% water.

[0016] Polycarboxylate superplasticizers have a water reduction rate of up to 45%, minimal slump loss, and significant reinforcing effect, which helps improve the strength of concrete. Lignosulfonates can promote the dispersion of the superplasticizer in the concrete system, synergistically inhibit slump loss, and maintain concrete strength. Film-forming agents make it easy for the superplasticizer to form a film on its surface during dispersion, slowing down the release and diffusion of the superplasticizer, prolonging the dispersion and action time of the superplasticizer, and helping to delay the setting time of concrete, thereby effectively improving concrete strength.

[0017] Furthermore, the film-forming agent is one or both of polyurethane emulsion and polyester emulsion.

[0018] Furthermore, the water-reducing agent is obtained by mixing polycarboxylate water-reducing agent, lignin sulfonate and water, and then adding a film-forming agent.

[0019] Furthermore, the aforementioned high-strength, long-life marine engineering concrete also includes 100 to 200 parts water.

[0020] The present invention also provides a method for preparing the above-mentioned high-strength long-life marine engineering concrete, which includes mixing silicate cement, fly ash, mineral powder, silica fume, aggregate, stainless steel fiber and water for 40-60 seconds, then adding synergist, water-reducing agent and crack-resistant agent and mixing for 90-120 seconds, pouring the resulting mixture into a mold, vibrating and molding, and curing with the mold after demolding.

[0021] Furthermore, during vibration molding, a vibrator with a diameter of 20-30mm is used to vibrate between the formwork and the reinforcing bars to remove air bubbles from the edges of the formwork, reduce internal defects in the concrete, and improve the concrete strength.

[0022] Furthermore, the mold should be removed after vibrating and compacting for more than 3 days.

[0023] Furthermore, curing with the mold for at least 5 days can effectively prevent cracks from forming.

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0025] (1) By selecting appropriate mineral powder and aggregate, adding additives such as synergists, and combining effective preparation and curing methods, the strength, durability and service life of concrete in marine environment have been improved.

[0026] (2) The aggregate is a combination of three sizes of stone, which has a small porosity and requires less cement, which helps to improve the strength of concrete.

[0027] (3) The aromatic polyamide fiber in the synergist has extremely high mechanical strength and elastic modulus, which can increase the strength of concrete. Zirconia is dispersed inside the aromatic polyamide fiber, which can react with harmful ions to generate insoluble compound crystals. The combination of the two can prevent further intrusion of chloride ions and enhance the strength and durability of concrete buildings.

[0028] (4) The water-reducing agent combines polycarboxylate water-reducing agent and lignin sulfonate, resulting in small slump loss and significant strengthening effect. The film-forming agent slows down the release and diffusion of the water-reducing agent, prolongs the dispersion and action time of the water-reducing agent, and can effectively delay the setting time of concrete and improve the concrete strength.

[0029] (5) When vibrating and molding, a vibrator with a diameter of 20-30mm is used to vibrate between the formwork and the reinforcing bars to remove air bubbles at the edge of the formwork, reduce internal defects in the concrete, and improve the strength of the concrete. Detailed Implementation

[0030] The technical solution of the present invention will be further described and illustrated below through specific embodiments. It should be understood that the specific embodiments described herein are only for the purpose of helping to understand the present invention and are not intended to limit the present invention. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0031] The film-forming agent used in the following examples and comparative examples is a polyurethane emulsion from Shandong Aokai Waterproof Materials Co., Ltd., and the crack-resistant agent is an HME type crack-resistant agent.

[0032] Example 1

[0033] The preparation method of high-strength, long-life marine engineering concrete in this embodiment includes the following steps:

[0034] (1) Mix 52 parts of aromatic polyamide fiber, 20 parts of zirconium oxide and 20 parts of water, and then add 8 parts of sodium dodecyl sulfate and stir to obtain a synergist;

[0035] (2) Mix 40 parts of polycarboxylate superplasticizer, 25 parts of lignin sulfonate and 25 parts of water, and then add 10 parts of polyurethane emulsion to obtain the superplasticizer.

[0036] (3) Mix 250 parts silicate cement, 54 parts fly ash, 55 parts mineral powder, 30 parts silica fume, 790 parts large stone, 320 parts small stone, 745 parts sand, 30 parts stainless steel fiber and 140 parts water for 60 seconds, then add 7 parts synergist, 7 parts water-reducing agent and 7 parts crack-resistant agent and mix for 100 seconds. Pour the resulting mixture into a mold and vibrate it to form the shape. Use a 30mm diameter vibrator to vibrate between the template and the reinforcing bar to remove air bubbles from the edges of the template. Remove the template after 5 days and cure it with the template for 10 days.

[0037] Example 2

[0038] The preparation method of high-strength, long-life marine engineering concrete in this embodiment includes the following steps:

[0039] (1) Mix 55 parts of aromatic polyamide fiber, 18 parts of zirconium oxide and 22 parts of water, and then add 5 parts of sodium dodecyl sulfate and stir to obtain a synergist;

[0040] (2) Mix 40 parts of polycarboxylate superplasticizer, 25 parts of lignin sulfonate and 25 parts of water, and then add 10 parts of polyester emulsion to obtain the superplasticizer.

[0041] (3) Mix 250 parts silicate cement, 85 parts fly ash, 55 parts mineral powder, 35 parts silica fume, 800 parts large stone, 320 parts small stone, 750 parts sand, 30 parts stainless steel fiber and 140 parts water for 60 seconds, then add 7 parts synergist, 7 parts water-reducing agent and 8 parts crack-resistant agent and mix for 100 seconds. Pour the resulting mixture into a mold and vibrate it to form the shape. Use a 30mm diameter vibrator to vibrate between the template and the reinforcing bar to remove air bubbles from the edges of the template. Remove the template after 5 days and cure it with the template for 10 days.

[0042] Example 3

[0043] The preparation method of high-strength, long-life marine engineering concrete in this embodiment includes the following steps:

[0044] (1) Mix 52 parts of aromatic polyamide fiber, 20 parts of zirconium oxide and 20 parts of water, then add 8 parts of sodium cholate and stir to obtain a synergist;

[0045] (2) Mix 45 parts of polycarboxylate superplasticizer, 23 parts of lignin sulfonate and 22 parts of water, and then add 8 parts of polyurethane emulsion to obtain the superplasticizer.

[0046] (3) Mix 280 parts silicate cement, 80 parts fly ash, 80 parts mineral powder, 30 parts silica fume, 790 parts large stone, 320 parts small stone, 745 parts sand, 32 parts stainless steel fiber and 140 parts water for 60 seconds, then add 8 parts synergist, 8 parts water-reducing agent and 7 parts crack-resistant agent and mix for 120 seconds. Pour the resulting mixture into a mold and vibrate it to form the shape. Use a 30mm diameter vibrator to vibrate between the template and the reinforcing steel to remove air bubbles from the edges of the template. Remove the template after 5 days and cure it with the template for 10 days.

[0047] Example 4

[0048] The difference between this embodiment and Embodiment 1 is only that in step (1), 65 parts of aromatic polyamide fiber, 10 parts of zirconium oxide and 17 parts of water are mixed and then 8 parts of sodium dodecyl sulfate are added and stirred to obtain an synergist.

[0049] Example 5

[0050] The difference between this embodiment and Embodiment 1 is only in step (1) after mixing 43 parts of aromatic polyamide fiber, 32 parts of zirconium oxide and 20 parts of water, 5 parts of sodium dodecyl sulfate are added and stirred to obtain a synergist.

[0051] Example 6

[0052] The difference between this embodiment and embodiment 1 is only that in step (2), 40 parts of polycarboxylate superplasticizer are mixed with 25 parts of water, and then 10 parts of polyurethane emulsion are added to obtain the superplasticizer.

[0053] Example 7

[0054] The difference between this embodiment and embodiment 1 is only in step (2) after mixing 42 parts of polycarboxylate superplasticizer, 25 parts of lignin sulfonate and 30 parts of water, 3 parts of polyurethane emulsion are added to obtain the superplasticizer.

[0055] Example 8

[0056] The only difference between this embodiment and embodiment 1 is that in step (2), 40 parts of polycarboxylate superplasticizer, 25 parts of lignin sulfonate and 23 parts of water are mixed and then 12 parts of polyurethane emulsion are added to obtain the superplasticizer.

[0057] Example 9

[0058] The difference between this embodiment and embodiment 1 is only in step (3): 250 parts silicate cement, 54 parts fly ash, 55 parts mineral powder, 30 parts silica fume, 790 parts large stone, 320 parts small stone, 30 parts stainless steel fiber and 140 parts water are mixed for 60 seconds, and then 7 parts synergist, 7 parts water-reducing agent and 7 parts crack-resistant agent are added and mixed for 100 seconds. The resulting mixture is poured into a mold, vibrated and shaped, and a 30mm diameter vibrator is used to vibrate between the template and the reinforcing steel to remove air bubbles at the edge of the template. The template is removed after 5 days and cured with the template for 10 days.

[0059] Example 10

[0060] The difference between this embodiment and embodiment 1 is only in step (3): 250 parts silicate cement, 54 parts fly ash, 55 parts mineral powder, 30 parts silica fume, 790 parts large stone, 745 parts sand, 30 parts stainless steel fiber and 140 parts water are mixed for 60 seconds, and then 7 parts synergist, 7 parts water-reducing agent and 7 parts crack-resistant agent are added and mixed for 100 seconds. The resulting mixture is poured into a mold, vibrated and shaped, and a 30mm diameter vibrator is used to vibrate between the template and the reinforcing steel to remove air bubbles from the edges of the template. The template is removed after 5 days and cured with the template for 10 days.

[0061] Example 11

[0062] The difference between this embodiment and embodiment 1 is only in step (3): 250 parts silicate cement, 54 parts fly ash, 55 parts mineral powder, 30 parts silica fume, 320 parts small stone, 745 parts sand, 30 parts stainless steel fiber and 140 parts water are mixed for 60 seconds, and then 7 parts synergist, 7 parts water-reducing agent and 7 parts crack-resistant agent are added and mixed for 100 seconds. The resulting mixture is poured into a mold, vibrated and shaped, and a 30mm diameter vibrator is used to vibrate between the template and the reinforcing steel to remove air bubbles from the edges of the template. The template is removed after 5 days and cured with the template for 10 days.

[0063] Comparative Example 1

[0064] The comparative method for preparing marine engineering concrete includes the following steps:

[0065] (1) Mix 40 parts of polycarboxylate superplasticizer, 25 parts of lignin sulfonate and 25 parts of water, and then add 10 parts of polyurethane emulsion to obtain superplasticizer.

[0066] (2) Mix 250 parts silicate cement, 54 parts fly ash, 55 parts mineral powder, 30 parts silica fume, 790 parts large stone, 320 parts small stone, 745 parts sand, 30 parts stainless steel fiber and 140 parts water for 60 seconds, then add 7 parts water-reducing agent and 7 parts crack-resistant agent and mix for 100 seconds. Pour the resulting mixture into a mold and vibrate it to form the shape. Use a 30mm diameter vibrator to vibrate between the template and the reinforcing steel to remove air bubbles from the edges of the template. Remove the template after 5 days and cure it with the template for 10 days.

[0067] Comparative Example 2

[0068] The comparative method for preparing marine engineering concrete includes the following steps:

[0069] (1) Mix 52 parts of aromatic polyamide fiber, 20 parts of zirconium oxide and 20 parts of water, and then add 8 parts of anionic surfactant and stir to obtain a synergist;

[0070] (2) Mix 250 parts silicate cement, 54 parts fly ash, 55 parts mineral powder, 30 parts silica fume, 790 parts large stone, 320 parts small stone, 745 parts sand, 30 parts stainless steel fiber and 140 parts water for 60 seconds, then add 7 parts synergist, 7 parts polycarboxylate superplasticizer and 7 parts crack-resistant agent and mix for 100 seconds. Pour the resulting mixture into a mold and vibrate it to form the shape. Use a 30mm diameter vibrator to vibrate between the template and the reinforcing steel to remove air bubbles from the edges of the template. Remove the template after 5 days and cure it with the template for 10 days.

[0071] The mechanical properties and impermeability of the concrete obtained in the above embodiments and comparative examples were tested, and the test results are shown in Table 1.

[0072] Table 1. Concrete performance test results

[0073]

[0074] The concrete obtained in Examples 1-3 exhibits high strength, durability, and service life in marine environments. In Example 4, the synergist contains more aromatic polyamide fibers and less zirconium oxide, weakening the interaction between zirconium oxide and harmful ions, resulting in increased harmful ions in the concrete and decreased durability. In Example 5, the synergist contains less aromatic polyamide fibers and more zirconium oxide, weakening its reinforcing effect on the concrete and reducing its strength. In Example 6, the water-reducing agent does not contain lignin sulfonate, weakening its dispersion ability in concrete and reducing its strength. In Example 7, the water-reducing agent contains less film-forming agent, shortening its action time. The shorter the time, the worse the effect, and the lower the concrete strength and impermeability. In Example 8, the water-reducing agent contained more film-forming agents, which increased the difficulty of the release and diffusion of the water-reducing agent, weakened its effect, and reduced the concrete strength. In Examples 9-11, the concrete aggregate used a mixture of sand and gravel with two particle sizes, which increased the internal porosity of the concrete, and reduced the concrete strength and impermeability. The concrete in Comparative Example 1 did not contain any synergist, and the concrete strength and impermeability were reduced. The water-reducing agent in Comparative Example 2 was only polycarboxylate water-reducing agent and did not contain lignin sulfonate and film-forming agents, so the effect of the water-reducing agent was weakened, and the concrete strength and impermeability were reduced.

[0075] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the spirit of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various modifications or additions to the described embodiments or use similar methods to replace them; it is neither necessary nor possible to exemplify all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the invention still fall within the scope of protection of the invention, and interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A high-strength, long-life marine engineering concrete, characterized in that, The components include the following parts by weight: 200-300 parts silicate cement, 50-100 parts fly ash, 50-80 parts mineral powder, 20-50 parts silica fume, 1500-2000 parts aggregate, 30-40 parts stainless steel fiber, 5-10 parts synergist, 5-10 parts water-reducing agent, and 5-10 parts crack-resistant agent. The synergist comprises the following components by weight percentage: 50-60% aromatic polyamide fiber, 15-30% zirconium oxide, 5-10% anionic surfactant, and 20-30% water; the total amount of the above components in the synergist is 100%. The water-reducing agent comprises the following components in parts by weight: 30-55% polycarboxylate water-reducing agent, 20-30% lignin sulfonate, 5-10% film-forming agent, and 20-30% water.

2. The high-strength, long-life marine engineering concrete according to claim 1, characterized in that, The density of the mineral powder is 2.8–2.9 g / cm³, and the specific surface area is 350–500 m² / kg.

3. The high-strength, long-life marine engineering concrete according to claim 1, characterized in that, The aggregate is a mixture of large stones, small stones, and sand, wherein the mass percentages of large stones, small stones, and sand are 40-50%, 15-20%, and 35-45%, respectively.

4. The high-strength, long-life marine engineering concrete according to claim 3, characterized in that, The fineness modulus of the sand is 2.2 to 1.

6.

5. The high-strength, long-life marine engineering concrete according to claim 1, characterized in that, The synergist is obtained by mixing aromatic polyamide fibers, zirconium oxide and water, and then adding anionic surfactants and stirring.

6. The high-strength, long-life marine engineering concrete according to claim 1, characterized in that, The film-forming agent is one or both of polyurethane emulsion and polyester emulsion.

7. The high-strength, long-life marine engineering concrete according to claim 1, characterized in that, Water-reducing agents are obtained by mixing polycarboxylate water-reducing agents, lignin sulfonate and water, and then adding a film-forming agent.

8. A method for preparing high-strength, long-life marine engineering concrete as described in claim 1, characterized in that, The preparation method includes mixing silicate cement, fly ash, mineral powder, silica fume, aggregate, stainless steel fiber and water for 40-60 seconds, then adding synergist, water-reducing agent and crack-resistant agent and mixing for 90-120 seconds. The resulting mixture is poured into a mold, vibrated and shaped, and then cured in the mold after demolding.

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