Carbonated water erosion resistant concrete, method for preparing the same, and use thereof

Abstract

The application belongs to the technical field of material concrete, and particularly relates to a carbonic acid water erosion resistant concrete and a preparation method and application thereof. The carbonic acid water erosion resistant concrete is made of the following raw materials: ordinary Portland cement, sulphoaluminate cement, fly ash, slag powder, machine-made sand, gravel, water, water reducing agent, retarder, stabilizer, wherein the stabilizer is prepared by compounding a water-soluble polymer and an organic silane hydrophobic agent. The carbonic acid water erosion resistant concrete provided by the application can maintain excellent mechanical properties, anti-permeability and carbonic acid water erosion resistance in a carbonic acid water environment. The application is suitable for engineering application in a karst area or a carbonic acid water environment containing erosive CO2, and can effectively solve the technical problems that the performance of concrete in a carbonic acid water environment is degraded, and the safety and durability of the concrete structure and material cannot be guaranteed.

Description

Technical Field

[0001] This invention relates to the field of materials and concrete technology, and in particular to a concrete resistant to carbonated water erosion, its preparation method, and its application. Background Technology

[0002] Current research both domestically and internationally on improving the corrosion resistance of concrete mainly focuses on sulfate attack resistance, while less attention has been paid to the destructive effects of carbonated water on concrete materials in karst areas or groundwater environments containing corrosive CO2. In these areas, CO2-rich ambient water can further react with the hydration products of cementitious materials, such as calcium hydroxide (Ca(OH)2) and calcium silicate hydrate gel (CSH), to generate soluble substances that compromise the service life of concrete.

[0003] The erosion and damage of concrete by carbonated water is a complex process involving chemical carbonation and acid corrosion, accompanied by physical hydrolytic dissolution. Under prolonged carbonated water erosion, the mortar on the concrete surface peels off, and even black, eroded surfaces appear. This is because Ca(OH)2 in the concrete is initially eroded by carbonated water, transforming into calcium carbonate (CaCO3), and then continuously generating water-soluble calcium bicarbonate which is carried away by the flowing water. As Ca(OH)2 decomposes, CSH gel, ettringite, and other substances continuously decompose and release calcium ions into the pore solution. When the alkalinity inside the concrete decreases, the CSH gel can no longer exist stably, transforming into silica gel and poorly crystallized CaCO3, causing the concrete to lose its bonding strength. Simultaneously, when the pH value of the concrete pore solution drops to between 9.4 and 10, the reinforcing steel is prone to depassivation and corrosion, endangering the safety of the concrete structure. A prolonged carbonated water environment will cause degradation of various concrete properties, leading to problems such as the inability to guarantee the safety and durability of engineering concrete structures and materials. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a carbonate-resistant concrete, its preparation method, and its applications. The carbonate-resistant concrete provided by this invention maintains excellent mechanical properties, impermeability, and resistance to carbonate erosion in a carbonated water environment.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a concrete resistant to carbonic acid water erosion, the raw materials comprising, by weight: 145-160 parts of ordinary silicate cement; 110-120 parts of sulfoaluminate cement; 55-60 parts of fly ash; 55-60 parts of slag powder; 820-850 parts of manufactured sand; 1000-1100 parts of crushed stone; 145-160 parts of water; 3-8 parts of water-reducing agent; 0.4-0.6 parts of retarder; and 0.3-2 parts of stabilizer; wherein the stabilizer is a composite formulation of a water-soluble polymer and an organosilane water-repellent agent.

[0007] The ball-bearing effect of fly ash reduces the unit water consumption of concrete, while slag powder delays and reduces the isolation effect of early hydration products, improving the workability of concrete. The combined use of fly ash and slag powder fully utilizes the filling effect of micro-aggregates, generating dense potential energy, strengthening the interfacial bond between aggregates, and effectively improving the compactness of concrete. Simultaneously, the addition of water-reducing agents and a reduced water-cement ratio can decrease the proportion of harmful pores in concrete, increasing its density and thus improving its corrosion resistance.

[0008] The incorporation of sulfoaluminate cement shortens the setting time of concrete and improves its early-stage impermeability. Simultaneously, combined with the sustained strength development of ordinary Portland cement, this allows the concrete to maintain excellent mechanical properties throughout its long service life.

[0009] The secondary hydration process of fly ash and slag powder can consume the Ca(OH)2 content in concrete, increase effective hydration products, and reduce the total calcium content and Ca(OH)2 content. The main hydration products of sulfoaluminate cement, such as ettringite, low-sulfur hydrated calcium sulfoaluminate, and aluminum glue, have low reactivity with carbonated water, reducing the loss of calcium-containing hydration products and the formation of soluble products in concrete. A stabilizer formulated from water-soluble polymers and organosilane water-repellent agents can significantly improve the segregation resistance of concrete mixtures, ensuring a slump of at least 160 mm. When used in conjunction with a retarder, it can control the cement hydration rate and improve impermeability and erosion resistance. The concrete preparation method provided by this invention can improve the concrete's resistance to carbonated water erosion.

[0010] Based on the properties of each of the above-mentioned raw materials and their combination at specific dosages, the carbonate-resistant concrete provided by the present invention has excellent resistance to carbonate erosion.

[0011] Furthermore, the stabilizer is composed of hydroxypropyl methylcellulose ether, diethylene glycol, and calcium stearate; the weight ratio of the hydroxypropyl methylcellulose ether, diethylene glycol, and calcium stearate is 1-2:1.5-3:5-9.

[0012] The hydroxyl groups and ether bonds on the molecular chain of hydroxypropyl methylcellulose ether can combine with free water through hydrogen bonds, playing a role in water retention, thickening, anti-precipitation, and anti-segregation. Diethylene glycol is adsorbed on the surface of cement particles, increasing the stability and dispersibility of the gel suspension, which is conducive to the formation of a dense structure in the early stage of hardened paste. After calcium stearate is incorporated, it forms a hydrophobic film on the surface of hydration products, preventing water penetration and internal water diffusion, and can also regulate the hydration rate and improve the pore structure.

[0013] As a further improvement to concrete resistant to carbonated water erosion:

[0014] Furthermore, the carbonic acid water erosion resistant concrete, by weight, comprises: 156 parts of ordinary Portland cement; 117 parts of sulfoaluminate cement; 59 parts of fly ash; 59 parts of slag powder; 840 parts of manufactured sand; 1018 parts of crushed stone; 149 parts of water; 7.2 parts of water-reducing agent; 0.16 parts of retarder; and 1.6 parts of stabilizer.

[0015] Concrete made using the above-mentioned technical solution and its raw material ratio has superior mechanical properties, impermeability, and resistance to carbonated water erosion.

[0016] Furthermore, the ordinary silicate cement is grade 42.5 ordinary silicate cement with a 28-day mortar strength ≥ 48 MPa.

[0017] Furthermore, the sulfoaluminate cement is R·SAC 42·5 rapid-hardening sulfoaluminate cement, with an initial setting time ≤25min and a final setting time ≥180min.

[0018] By adopting the above technical solution, the use of R·SAC 42·5 rapid-hardening sulfoaluminate cement can improve the early-stage impermeability of concrete.

[0019] Furthermore, the fly ash is Grade I or Grade II ground fly ash with a specific surface area ≥310 m². 2 / kg.

[0020] Furthermore, the slag powder is S95 grade or S105 grade ground slag powder.

[0021] Grade I or II finely ground fly ash and S95 or S105 finely ground slag powder can influence the pore structure of cement paste through particle filling, better altering the particle distribution of the cement paste and reducing the effective porosity. Among them, Grade I fly ash is preferred, and S95 grade slag powder is preferred.

[0022] Furthermore, the manufactured sand is medium sand with a fineness modulus of 2.5 to 3.0, a stone powder content of less than 3%, and a mud content of less than 0.8%.

[0023] Furthermore, the crushed stone has a particle size range of 5–25 mm and a mud content of less than 0.3%.

[0024] Furthermore, the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent with a water reduction rate of ≥20%.

[0025] Furthermore, the retarder is one or a mixture of two or more of sodium citrate, sodium gluconate, and borax.

[0026] Sodium citrate and sodium gluconate are hydroxycarboxylic acids and their salts that act as retarder. They have a strong active effect on the surface of cement particles and new phases of hydration products. They can be adsorbed onto the surface of solid particles, thus delaying the hydration of cement and the formation of the paste structure.

[0027] The borax is an inorganic salt retarder that can form a thin, insoluble film on the surface of cement particles, acting as a barrier to the hydration of cement particles and hindering the normal hydration of cement.

[0028] The above-mentioned preferred retarders show better adaptability to the retarding effect of the carbonate water erosion resistant concrete provided by the present invention.

[0029] Secondly, the present invention also provides a method for preparing the above-mentioned resistant concrete to carbonated water erosion, comprising at least the following steps performed in sequence:

[0030] Step a: Add the manufactured sand and crushed stone to the concrete mixer in sequence and dry mix for 30-60 seconds;

[0031] Step b: Add ordinary Portland cement, sulfoaluminate cement, slag powder, fly ash, retarder and stabilizer to the concrete mixer in sequence and continue dry mixing for 30-60 seconds;

[0032] Step c: Add water and water-reducing agent, and stir thoroughly until homogeneous to obtain concrete mixture;

[0033] Step d: Fill the concrete mixture obtained in step c into the mold, demold after 1 day, and cure for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity to obtain concrete resistant to carbonated water erosion.

[0034] The preparation method of this invention first involves dry-mixing manufactured sand and crushed stone, then adding powdered materials such as ordinary silicate cement, sulfoaluminate cement, slag powder, fly ash, retarders, and stabilizers. This dry-mixing is performed without adding water to prevent the agglomeration of fine particles and improve the dispersibility of the raw materials. Subsequently, mixing water containing a water-reducing agent is added, and the mixture is stirred until homogeneous to obtain the concrete. This method is simple, easy to operate, ensures thorough mixing of the concrete, effectively reduces the proportion of harmful pores, and improves its impermeability.

[0035] Thirdly, the present invention also provides applications of the above-mentioned anti-carbonic acid water erosion concrete, including at least engineering applications in karst areas or groundwater environments containing corrosive CO2.

[0036] Karst areas, also known as karst regions, rely on flowing water rich in CO2 and other acidic substances for their development. Furthermore, the construction environments of some underground projects (underground buildings and structures, subways, highway tunnels, underwater tunnels, underground utility tunnels, and pedestrian underpasses, etc.) generate groundwater containing corrosive CO2. For example, groundwater rich in corrosive CO2 has been detected along the water quality of underground projects in Guangzhou and Nanning. This corrosive carbonated water can further react with the hydration products of concrete, calcium hydroxide and calcium silicate hydrate gel, to generate soluble substances, damaging the concrete structure. The carbonated water-resistant concrete provided by this invention exhibits excellent resistance to carbonated water erosion in engineering applications in karst areas or groundwater environments containing corrosive CO2. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0038] In the following examples and comparative examples, the polycarboxylate-based high-performance water-reducing agent used was Subote, with a water reduction rate of 25%-30%. -Series I polycarboxylate high-performance water-reducing agent; retarders sodium citrate, borax, and sodium gluconate are analytical grade reagents; stabilizers are industrial-grade hydroxypropyl methylcellulose ether produced by Xi'an Longmao Biotechnology Co., Ltd., industrial-grade diethylene glycol produced by Jinan Qihang Chemical Technology Co., Ltd., and calcium stearate produced by Shijiazhuang Mayue Building Materials Co., Ltd. Other similar products can also be used for each of the above components.

[0039] Example 1

[0040] A type of concrete resistant to carbonated water erosion comprises the following raw material components in parts by weight: 152 parts of PO42.5 grade ordinary Portland cement; 114 parts of R·SAC 42.5 rapid-hardening sulfoaluminate cement; 57 parts of S95 grade ground blast furnace slag powder; 57 parts of Grade II ground fly ash; 840 parts of manufactured sand; 1018 parts of crushed stone; 5.6 parts of polycarboxylate-based high-performance water-reducing agent; 0.13 parts of sodium gluconate retarder; 1.2 parts of stabilizer; and 152 parts of water. The stabilizer is formulated by compounding hydroxypropyl methylcellulose ether, diethylene glycol, and calcium stearate in a weight ratio of 1:1.5:5.

[0041] Prepare according to the following steps:

[0042] (1) Add the above-mentioned manufactured sand and crushed stone to the concrete mixer and dry mix for 50 seconds;

[0043] (2) Mix the above-mentioned ordinary silicate cement, sulfoaluminate cement, slag powder, fly ash, retarder and stabilizer into a concrete mixer and continue mixing for 50 seconds.

[0044] (3) Add the remaining water and water-reducing agent to the concrete mixer and mix thoroughly for 5 minutes. Fill the prepared concrete mixture into the mold, demold after 1 day, and cure for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity.

[0045] This yields C1 concrete resistant to carbonated water erosion.

[0046] Example 2

[0047] A type of concrete resistant to carbonated water erosion comprises the following raw material components in parts by weight: 148 parts of PO42.5 grade ordinary Portland cement; 111 parts of R·SAC 42.5 rapid-hardening sulfoaluminate cement; 56 parts of S105 grade ground blast furnace slag powder; 56 parts of Grade I ground fly ash; 850 parts of manufactured sand; 1020 parts of crushed stone; 4.6 parts of polycarboxylate-based high-performance water-reducing agent; 0.11 parts of borax; 0.8 parts of stabilizer; and 140 parts of water. The stabilizer is formulated by compounding hydroxypropyl methylcellulose ether, diethylene glycol, and calcium stearate in a weight ratio of 2:2:5.

[0048] Following the preparation steps of Example 1, C2 concrete resistant to carbonated water erosion was prepared.

[0049] Example 3

[0050] A type of concrete resistant to carbonated water erosion comprises the following raw material components in parts by weight: 156 parts of PO42.5 grade ordinary Portland cement; 117 parts of R·SAC 42.5 rapid-hardening sulfoaluminate cement; 59 parts of S95 grade ground blast furnace slag powder; 59 parts of Grade II ground fly ash; 820 parts of manufactured sand; 1010 parts of crushed stone; 7.2 parts of polycarboxylate-based high-performance water-reducing agent; 0.16 parts of sodium citrate; 1.6 parts of stabilizer; and 160 parts of water. The stabilizer is formulated by compounding hydroxypropyl methylcellulose ether, diethylene glycol, and calcium stearate in a weight ratio of 2:3:9.

[0051] Following the preparation steps of Example 1, C3 concrete resistant to carbonated water erosion was prepared.

[0052] Example 4

[0053] A type of concrete resistant to carbonated water erosion comprises the following raw material components in parts by weight: 156 parts of PO42.5 grade ordinary Portland cement; 110 parts of R·SAC 42.5 rapid-hardening sulfoaluminate cement; 57 parts of S105 grade ground blast furnace slag powder; 57 parts of Grade I ground fly ash; 845 parts of manufactured sand; 1022 parts of crushed stone; 5.8 parts of polycarboxylate-based high-performance water-reducing agent; 0.10 parts of borax; 0.3 parts of stabilizer; and 152 parts of water. The stabilizer is formulated by compounding hydroxypropyl methylcellulose ether, diethylene glycol, and calcium stearate in a weight ratio of 1.4:2.3:6.

[0054] Following the preparation steps of Example 1, C4 concrete resistant to carbonated water erosion was prepared.

[0055] Example 5

[0056] A type of concrete resistant to carbonated water erosion comprises the following raw material components in parts by weight: 146 parts of PO42.5 grade ordinary Portland cement; 120 parts of R·SAC 42.5 rapid-hardening sulfoaluminate cement; 57 parts of S105 grade ground blast furnace slag powder; 57 parts of Grade I ground fly ash; 848 parts of manufactured sand; 1015 parts of crushed stone; 5.1 parts of polycarboxylate-based high-performance water-reducing agent; 0.18 parts of borax; 2.0 parts of stabilizer; and 152 parts of water. The stabilizer is formulated by compounding hydroxypropyl methylcellulose ether, diethylene glycol, and calcium stearate in a weight ratio of 1.8:2.8:5.4.

[0057] Following the preparation steps of Example 1, C5 concrete resistant to carbonated water erosion was prepared.

[0058] Comparative Example 1

[0059] Based on Example 1, without adding sulfoaluminate cement, retarders and stabilizers, the amount of PO42.5 grade ordinary Portland cement was increased to 266 parts, and the remaining components were the same as in Example 1.

[0060] Prepare according to the following steps:

[0061] (1) Add the above-mentioned manufactured sand and crushed stone to the concrete mixer and dry mix for 50 seconds;

[0062] (2) Add the above-mentioned ordinary silicate cement, slag powder and fly ash into the concrete mixer and continue mixing for 50 seconds;

[0063] (3) Add the remaining water and water-reducing agent to the concrete mixer and mix thoroughly for 5 minutes. Fill the prepared concrete mixture into the mold, demold after 1 day, and cure for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity.

[0064] This yields concrete D1.

[0065] Comparative Example 2

[0066] Based on Example 1, without adding sulfoaluminate cement and retarder, the amount of PO42.5 grade ordinary Portland cement was increased to 266 parts, and the remaining components were the same as in Example 1.

[0067] Prepare according to the following steps:

[0068] (1) Add the above-mentioned manufactured sand and crushed stone to the concrete mixer and dry mix for 50 seconds;

[0069] (2) Mix the above-mentioned ordinary silicate water, slag powder, fly ash and stabilizer into a concrete mixer and continue mixing for 50 seconds;

[0070] (3) Add the remaining water and water-reducing agent to the concrete mixer and mix thoroughly for 5 minutes. Fill the prepared concrete mixture into the mold, demold after 1 day, and cure for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity.

[0071] This yields concrete D2.

[0072] Comparative Example 3

[0073] The stabilizer was not added in Example 1, and the remaining components were the same as in Example 1.

[0074] Prepare according to the following steps:

[0075] (1) Add the above-mentioned manufactured sand and crushed stone to the concrete mixer and dry mix for 50 seconds;

[0076] (2) Mix the above-mentioned ordinary silicate cement, sulfoaluminate cement, slag powder, fly ash and retarder into a concrete mixer and continue mixing for 50 seconds.

[0077] (3) Add the remaining water and water-reducing agent to the concrete mixer and mix thoroughly for 5 minutes. Fill the prepared concrete mixture into the mold, demold after 1 day, and cure for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity.

[0078] This yields concrete D3.

[0079] To better illustrate the properties of the carbonate-resistant concrete provided in the embodiments of the present invention, concrete specimens prepared in Examples 1-5 and Comparative Examples 1-3 were placed in a high-temperature, high-pressure, sealed container at 50°C and 5 MPa. The container was filled with an aqueous solution, and CO2 was introduced until saturation. At this point, the solubility of CO2 was 17.25 dm³. 3 / kg. The specimen rack in the container rotates around the central axis to achieve relative flow between the corrosive solution and the specimen. The solution in the container is changed every 2 days to facilitate the migration of the corrosive solution. After 28 days of corrosion in the flowing and migrating carbonated water environment, the specimen is removed and its various performance indicators are tested. The test results, according to GB / T50081 2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" and GB / T50082 2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete", are shown in Table 1.

[0080] Table 1 Test Results

[0081]

[0082] The test results in the table show that the compressive strength of the carbonate-resistant concrete specimens in Examples 1-5 before and after erosion all exceeded 40 MPa, indicating that they possess excellent mechanical properties. The concrete mass loss rate was -0.15% to -0.34%, and the linear expansion rate was -0.13% to -0.25% (negative numbers represent a decrease in mass and linear expansion). The changes in mass and volume are negligible, indicating excellent resistance to carbonate erosion and stability. The carbonate-resistant concrete provided in the embodiments of this invention can all achieve a permeability grade of P12. Therefore, the chloride ion diffusion coefficient (ASTM C1202 DC charge method) is used to more accurately evaluate the permeability of the concrete. The lower the electrical flux, the higher the concrete density and the better the permeability resistance. The total conductivity of the concrete specimens provided in the embodiments of this invention was between 100 and 1000 ohms 6 hours before and after erosion, and the permeability evaluation was very low, indicating that they have good permeability resistance. Therefore, the carbonic acid water erosion resistant concrete provided in this embodiment of the invention still maintains excellent mechanical properties and impermeability after being eroded by flowing and migrating carbonic acid water for 28 days, and is suitable for the construction of concrete structures in a carbonic acid water environment.

[0083] The results of three comparative experiments show that the 7-day strength of concrete without sulfoaluminate cement is relatively low, making it difficult to meet the requirements for early-stage impermeability; furthermore, the mass loss after erosion is increased, with calcium hydration products in the concrete being lost. The strength and impermeability of concrete without stabilizers are both reduced to some extent, and the impermeability grade cannot reach P12. Therefore, only by partially replacing ordinary Portland cement with sulfoaluminate cement and combining it with a stabilizer can the mechanical properties, impermeability, and resistance to carbonated water erosion of concrete be simultaneously improved, thus producing high-performance concrete suitable for carbonated water environments.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A type of concrete resistant to carbonated water erosion, characterized in that, The raw materials, by weight, include: 145-160 parts of ordinary Portland cement; 110-120 parts of sulfoaluminate cement; 55-60 parts of fly ash; 55-60 parts of slag powder; 820-850 parts of manufactured sand; 1000-1100 parts of crushed stone; 145-160 parts of water; 3-8 parts of water-reducing agent; 0.1-0.2 parts of retarder; and 0.3-2 parts of stabilizer. The stabilizer is composed of hydroxypropyl methylcellulose ether, diethylene glycol, and calcium stearate. The weight ratio of hydroxypropyl methylcellulose ether, diethylene glycol, and calcium stearate is 1-2:1.5-3:5-9.

2. The carbonic acid-resistant concrete according to claim 1, characterized in that, The raw materials, by weight, include: 156 parts ordinary Portland cement; 117 parts sulfoaluminate cement; 59 parts fly ash; 59 parts slag powder; 840 parts manufactured sand; 1018 parts crushed stone; 149 parts water; 7.2 parts water-reducing agent; 0.16 parts retarder; and 1.6 parts stabilizer.

3. The carbonic acid-resistant concrete according to claim 1, characterized in that, The ordinary silicate cement is grade 42.5 ordinary silicate cement with a 28-day mortar strength ≥ 48 MPa; and / or the sulfoaluminate cement is R·SAC 42·5 rapid-hardening sulfoaluminate cement with an initial setting time ≤ 25 min and a final setting time ≥ 180 min.

4. The carbonic acid-resistant concrete according to claim 1, characterized in that, The fly ash is Grade I or Grade II ground fly ash with a specific surface area ≥ 310 m². 2 / kg; and / or The slag powder is S95 or S105 grade ground slag powder.

5. The carbonic acid-resistant concrete according to claim 4, characterized in that, The fly ash is Class I fly ash; and / or The slag powder is S95 grade slag powder.

6. The carbonic acid-resistant concrete according to claim 1, characterized in that, The manufactured sand is medium sand with a fineness modulus of 2.5 to 3.0, a stone powder content of less than 3%, and a mud content of less than 0.8%; and / or The crushed stone has a particle size range of 5 to 25 mm and a mud content of less than 0.3%.

7. The carbonic acid-resistant concrete according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate-based high-performance water-reducing agent with a water reduction rate ≥20%; and / or The retarder is one or a mixture of two or more of sodium citrate, sodium gluconate, and borax.

8. A method for preparing the carbonate-resistant concrete according to any one of claims 1-7, characterized in that, It should include at least the following steps performed in sequence: Step a: Add the manufactured sand and crushed stone to the concrete mixer in sequence and dry mix for 30-60 seconds; Step b: Add ordinary Portland cement, sulfoaluminate cement, slag powder, fly ash, retarder and stabilizer to the concrete mixer in sequence and continue dry mixing for 30 to 60 seconds; Step c: Add water and water-reducing agent, and stir thoroughly until homogeneous to obtain concrete mixture; Step d: Fill the concrete mixture obtained in step c into the mold, demold after 1 day, and cure for 28 days under standard curing conditions of 20±2 ℃ and relative humidity above 95% to obtain concrete resistant to carbonic acid water erosion.

9. The engineering application of the carbonic acid erosion-resistant concrete according to any one of claims 1-7 in a carbonic acid water environment.

Images