A chloride-penetrating resistant concrete and a method for preparing the same

Abstract

The application discloses a kind of anti-chloride ion permeable concrete, raw materials and the weight percentage it occupies include: cement 200-400 parts, fly ash 60-100 parts, modified composite silica mortar 50-80 parts, modified lithium slag powder 40-60 parts, gravel 950-1050 parts, sand 700-960 parts, water reducing agent 5-10 parts, water 110-130 parts;The modified lithium slag powder is modified by crown ether and barium acetate to lithium slag;Modified composite silica mortar includes silane coupling agent modified unencrypted silica fume and citric acid modified encrypted silica mortar.The anti-chloride ion permeable concrete can greatly improve the anti-chloride ion permeability of concrete, effectively reduce the phenomenon of steel corrosion, and has wide applicability under the premise of ensuring the design strength requirement.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building materials, and particularly relates to a chloride ion permeation resistant concrete and a preparation method thereof. BACKGROUND

[0002] Compared with engineering projects on land, island engineering projects are far away from the mainland and have a harsh environment, and thus more problems and challenges are faced in the process of infrastructure construction and use. Concrete is the most widely used engineering material due to its strong versatility and relatively low cost. Even in a harsh marine environment, concrete materials are often the first choice of engineering personnel.

[0003] At present, a large number of investigations on concrete structures in marine environments show that the causes of structural damage are rarely due to the fact that the structure reaches the ultimate state of bearing capacity under the action of external loads, and most of the time, the durability of the structure is continuously deteriorated under the action of marine erosion environment, thereby causing the bearing capacity to decrease and leading to structural damage. A large number of studies have shown that the corrosion of chloride ions on steel bars in a chloride salt environment is the main cause of the durability damage of marine concrete structures.

[0004] In order to improve the chloride ion permeation resistance of concrete during the design of existing chloride ion permeation resistant concrete, high-performance admixtures and additives or external corrosion-resistant and impermeable materials are usually used, which greatly increases the cost of concrete. In addition, during long-term use, especially for concrete exposed to humid and salt spray environments, there are still severe challenges of chloride ion permeation, which leads to steel corrosion and further affects the durability of the structure. Therefore, it is necessary to develop a chloride ion permeation resistant concrete to further effectively improve the durability and service life of marine concrete structures. SUMMARY

[0005] The main purpose of the present application is to provide a chloride ion permeation resistant concrete that has excellent chloride ion permeation resistance and can effectively prevent the corrosion of steel bars in concrete.

[0006] To achieve the above-mentioned purposes, the technical scheme adopted by the present application is as follows:

[0007] A chloride ion permeation resistant concrete, raw materials and their weight fractions include: cement 200-400 parts, fly ash 60-100 parts, modified composite silica fume paste 50-80 parts, modified lithium slag powder 40-60 parts, crushed stone 950-1050 parts, sand 700-960 parts, water reducing agent 5-10 parts, and water 110-130 parts; the modified lithium slag powder is obtained by modifying lithium slag with crown ether and barium acetate.

[0008] Further, the modified lithium slag powder is obtained by mixing, homogenizing, drying and grinding lithium slag, crown ether, barium acetate and water to form a lithium slag slurry, wherein the 45μm square hole sieve residue is not more than 15%.

[0009] Further, the mass ratio of lithium slag, crown ether, barium acetate and water is 1:0.03-0.05:0.05-0.08:1-1.5.

[0010] In the above scheme, the homogenization (room temperature standing) time is 20-30min.

[0011] Further, in the lithium slag, the SO3 content is not higher than 5wt%, the Li content is 1.5-2.0wt%, and the specific surface area of the lithium slag is 400-450kg / m 3 .

[0012] Further, the crown ether is 2-crown-4.

[0013] In the above scheme, the modified composite silica ash slurry comprises silane coupling agent modified non-encrypted silica ash and citric acid modified encrypted silica ash slurry, and the silica ash slurry particle D50 is less than 1.5μm.

[0014] Further, the silane coupling agent modified non-encrypted silica ash is obtained by uniformly stirring non-encrypted silica ash and an alcohol solvent (anhydrous ethanol, etc.), adding a silane coupling agent for stirring treatment, centrifugal separation and drying.

[0015] In the above scheme, the silane coupling agent is β-(3,4-epoxycyclohexyl) ethyl trimethoxysilane.

[0016] Further, the amount of the silane coupling agent is 2-4% of the mass of the non-encrypted silica ash.

[0017] Further, the bulk density of the non-encrypted silica ash is 180-200kg / m 3 .

[0018] In the above scheme, the citric acid modified encrypted silica ash slurry is obtained by mixing encrypted silica ash, water and citric acid and high-speed shearing.

[0019] In the above scheme, the mass ratio of the encrypted silica ash, water and citric acid is 1:3-4:0.01-0.02.

[0020] In the above scheme, the shear rate for high-speed shearing is 700-900r / min, and the time is 25-35min.

[0021] Further, the bulk density of the encrypted silica ash is 680-710kg / m 3 , the SiO2 content is not less than 85%, and the activity index is not less than 105%

[0022] In the above scheme, the mass ratio of the silane coupling agent modified unencrypted silica ash to the citric acid modified encrypted silica ash paste is 1:2-4.

[0023] In the above scheme, the cement is one of Portland cement, ordinary Portland cement, and slag Portland cement, and the strength grade is not less than 42.5.

[0024] In the above scheme, the fly ash is I-grade fly ash, the SiO2 content is not less than 60wt%, the water demand ratio is not higher than 92%, and the loss on ignition is not higher than 3%.

[0025] In the above scheme, the crushed stone is a continuous gradation crushed stone with a size of 5-31.5mm; and the sand is siliceous machine-made sand with a fineness of 2.5-2.8.

[0026] In the above scheme, the water reducing agent is a high-performance polycarboxylic acid water reducing agent.

[0027] The preparation method of the anti-chloride ion permeation concrete comprises the following steps:

[0028] 1) weighing of raw materials, the raw materials and the weight percentage thereof include: cement 200-400 parts, fly ash 60-100 parts, modified composite silica ash paste 50-80 parts, modified lithium slag powder 40-60 parts, crushed stone 950-1050 parts, sand 700-960 parts, water reducing agent 5-10 parts, and water 110-130 parts;

[0029] 2) mixing and stirring the weighed raw materials uniformly to obtain the anti-chloride ion permeation concrete.

[0030] The anti-chloride ion permeation concrete prepared according to the above scheme has a permeation resistance grade of P12 or more, and has excellent anti-chloride ion erosion performance.

[0031] The main principle of the present application is as follows:

[0032] (1) The lithium slag is modified in the present application, on the one hand, barium acetate is used to react with calcium sulfate in the lithium slag to generate barium sulfate and calcium acetate, wherein the barium sulfate is a difficultly soluble precipitate, which can solidify sulfate ions in the lithium slag, and the calcium acetate has a certain early strength effect on the concrete; on the other hand, crown ether 2-crown-4 can react with Li + in the lithium slag in a complex form to generate [2-crown-4·Li + ], which is conducive to competitive adsorption of chloride ions, and the released Li + can inhibit the alkali-silicon reaction of the concrete.

[0033] (2) The modified composite silica slurry used in this invention contains undensed silica slurry modified by silane coupling agent and densified silica slurry modified by citric acid. On the one hand, the silane coupling agent modifies some silica slurry particles to make them hydrophobic, and at the same time, it disperses them in the silica slurry to form steric hindrance for the remaining silica slurry particles. Citric acid is used to further disperse and stabilize the composite silica slurry. This can solve the problem of the significant increase in concrete water consumption caused by traditional silica slurry particles. It can also greatly increase the impermeability of concrete by using nano-sized silica slurry particles and their high activity. It can effectively block chloride ions from the outside of the concrete structure.

[0034] (3) In this invention, by modifying lithium slag powder, the resulting calcium acetate can effectively promote the early strength development of concrete and improve the density of concrete; in addition, when Cl - When it seeps into the concrete, it will interact with Li + Competition replaces it to form a more stable complex [2-crown-4·Cl] - ], reduce Cl - The degree of ionization prevents Cl - Further infiltration; on the other hand, Li + It can inhibit the alkali-silica reaction in concrete and form a passivation protective film on the surface of steel bars, further inhibiting the corrosion of steel bars.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) This invention uses silane coupling agent to modify undensed silica fume and combines it with citric acid modified densified silica fume-based silica fume slurry, so that the modified undensed silica fume particles and the modified densified silica fume particles fill each other, further improving the dispersibility of silica fume particles in the slurry. At the same time, it can significantly reduce the adsorption of water by silica fume particles, which is beneficial to significantly reduce the water consumption of concrete, improve the density of concrete structure, and enhance the impermeability of concrete.

[0037] (2) The incorporation of modified lithium slag powder can enhance the penetration of Cl... - Forming stable complexes reduces their ionization, while Li + It can protect the steel bars from corrosion;

[0038] (3) The concrete described in this invention effectively blocks the migration of Cl- into the interior of the concrete structure with a triple effect of high impermeability, high adsorption and strong protection; under the premise of ensuring the design strength requirements, it can greatly improve the resistance of concrete to chloride ion penetration and effectively reduce the phenomenon of steel corrosion. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to embodiments, so as to facilitate a clearer understanding of the present invention, but these embodiments do not constitute a limitation on the present invention.

[0040] In the following embodiments, the unrefined silica fume packing density is 200 kg / m³. 3 The bulk density of the encrypted silica fume is 690 kg / m³. 3 The SiO2 content is 90%, and the activity index is 108%.

[0041] The lithium slag contains 4.5 wt% SO3, 1.8 wt% Li, and has a specific surface area of ​​400 kg / m². 3 .

[0042] Example 1

[0043] A C30 chloride ion-resistant concrete, the raw materials used are, by weight, 200 parts of ordinary Portland cement, 60 parts of fly ash, 50 parts of modified composite silica mortar, 40 parts of modified lithium slag powder, 990 parts of crushed stone, 960 parts of sand, 6 parts of water-reducing agent, and 125 parts of water (excluding the water in the modified composite silica mortar).

[0044] The ordinary Portland cement used is P·O 42.5 grade, with a specific surface area of ​​340 m². 2 / kg; the fly ash is Grade I fly ash, with SiO2 content of 65wt%, water requirement ratio of 92%, and loss on ignition of 2.1%;

[0045] The crushed stone is continuously graded crushed stone ranging from 5 to 31.5 mm; the sand is siliceous manufactured sand with a fineness of 2.5.

[0046] The water-reducing agent used is a high-performance polycarboxylate water-reducing agent with a water reduction rate of 25%.

[0047] The preparation steps of the modified composite silica paste are as follows:

[0048] 1) Mix uncontaminated silica fume and anhydrous ethanol at a mass ratio of 1:2.5 and stir evenly. Then add silane coupling agent (3% of silica fume mass) and continue stirring for 2 hours. After centrifugation, dry at 50°C to obtain modified silica fume powder.

[0049] 2) Mix the silica fume, water, and citric acid in a mass ratio of 1:3:0.01, and stir for 30 minutes using a high-speed dispersing shear machine (shearing rate of 800 r / min) to obtain silica fume slurry;

[0050] 3) Mix the obtained modified silica fume powder and silica fume slurry at a mass ratio of 1:3 to obtain modified composite silica fume slurry, with its solid content controlled at 40%.

[0051] The preparation steps of the modified lithium slag powder are as follows: lithium slag, water, crown ether, and barium acetate are homogenized for 25 minutes at a mass ratio of 1:1:0.05:0.06 to form a lithium slag slurry. The slurry is then dried and ground at 60°C (the residue on a 45μm square hole sieve is 10%) to obtain the modified lithium slag powder.

[0052] The above raw materials are mixed and stirred to obtain chloride ion-resistant concrete.

[0053] Example 2

[0054] A C40 chloride ion-resistant concrete, the raw materials used are, by weight, 230 parts of ordinary Portland cement, 80 parts of fly ash, 50 parts of modified composite silica ash slurry, 55 parts of modified lithium slag powder, 1000 parts of crushed stone, 880 parts of sand, 7 parts of water-reducing agent, and 130 parts of water (excluding the water in the modified composite silica ash slurry).

[0055] The ordinary Portland cement used is P·O 42.5 grade, with a specific surface area of ​​345 m². 2 / kg; the fly ash is Grade I fly ash, with SiO2 content of 66wt%, water requirement ratio of 93%, and loss on ignition of 2.5%;

[0056] The crushed stone is continuously graded crushed stone ranging from 5 to 31.5 mm; the sand is siliceous manufactured sand with a fineness of 2.6.

[0057] The water-reducing agent used is a high-performance polycarboxylate water-reducing agent with a water reduction rate of 25%.

[0058] The preparation steps of the modified composite silica paste are as follows:

[0059] 1) Mix uncontaminated silica fume and anhydrous ethanol at a mass ratio of 1:2 and stir until homogeneous. Then add silane coupling agent (2% of silica fume mass) and continue stirring for 2 hours. After centrifugation, dry at 50°C to obtain modified silica fume powder.

[0060] 2) Mix the silica fume, water, and citric acid in a mass ratio of 1:3:0.01, and stir for 30 minutes using a high-speed dispersing shear machine (shear rate of 850 r / min) to obtain silica fume slurry;

[0061] 3) Mix the obtained modified silica fume powder and silica fume slurry at a mass ratio of 1:2 to obtain modified composite silica fume slurry, with its solid content controlled at 50%.

[0062] The preparation steps of the modified lithium slag powder are as follows: lithium slag, water, crown ether, and barium acetate are homogenized for 20 minutes at a mass ratio of 1:1.5:0.03:0.05 to form lithium slag slurry, which is then dried and ground at 55°C (the residue on a 45μm square hole sieve is 12%) to obtain modified lithium slag powder.

[0063] The above raw materials are mixed and stirred to obtain chloride ion-resistant concrete.

[0064] Example 3

[0065] A C40 chloride ion-resistant concrete, the raw materials used are, by weight, 260 parts slag silicate cement, 60 parts fly ash, 60 parts modified composite silica mortar, 40 parts modified lithium slag powder, 1000 parts crushed stone, 880 parts sand, 7 parts water-reducing agent, and 125 parts water (excluding water in the modified composite silica mortar).

[0066] The ordinary Portland cement used is P·S·A 42.5 grade, with a specific surface area of ​​360 m². 2 / kg; The fly ash is Grade I fly ash with a SiO2 content of 68wt%, a water requirement of 95%, and a loss on ignition of 2.0%;

[0067] The crushed stone is continuously graded crushed stone ranging from 5 to 31.5 mm; the sand is siliceous manufactured sand with a fineness of 2.6.

[0068] The water-reducing agent used is a high-performance polycarboxylate water-reducing agent with a water reduction rate of 25%.

[0069] The preparation steps of the modified composite silica paste are as follows:

[0070] 1) Mix uncontaminated silica fume and anhydrous ethanol at a mass ratio of 1:3 and stir until homogeneous. Then add silane coupling agent (accounting for 2.5% of the silica fume mass) and continue stirring for 2.5 hours. After centrifugation, dry at 50°C to obtain modified silica fume powder.

[0071] 2) Mix the silica fume, water, and citric acid in a mass ratio of 1:3:0.01, and stir for 30 minutes using a high-speed dispersing shear machine (shear rate of 750 r / min) to obtain silica fume slurry;

[0072] 3) Mix the obtained modified silica fume powder and silica fume slurry at a mass ratio of 1:2 to obtain modified composite silica fume slurry, with its solid content controlled at 50%.

[0073] The preparation steps of the modified lithium slag powder are as follows: lithium slag, water, crown ether, and barium acetate are homogenized in a mass ratio of 1:1.5:0.03:0.05 for 20 minutes to form a lithium slag slurry. After drying and grinding at 60°C (the residue on a 45μm square hole sieve is 8%), the modified lithium slag powder is obtained.

[0074] The above raw materials are mixed and stirred to obtain chloride ion-resistant concrete.

[0075] Example 4

[0076] A C50 chloride ion-resistant concrete, the raw materials used are, by weight, 300 parts of silicate cement, 80 parts of fly ash, 50 parts of modified composite silica ash slurry, 60 parts of modified lithium slag powder, 1030 parts of crushed stone, 780 parts of sand, 8 parts of water-reducing agent, and 120 parts of water (excluding the water in the modified composite silica ash slurry).

[0077] The silicate cement used is P·I 52.5 grade, with a specific surface area of ​​345 m². 2 / kg; The fly ash is Grade I fly ash, with a SiO2 content of 68wt%, a water requirement ratio of 93%, and a loss on ignition of 2.0%;

[0078] The crushed stone is continuously graded crushed stone ranging from 5 to 31.5 mm; the sand is siliceous manufactured sand with a fineness of 2.7.

[0079] The water-reducing agent used is a high-performance polycarboxylate water-reducing agent with a water reduction rate of 28%.

[0080] The preparation steps of the modified composite silica paste are as follows:

[0081] 1) Mix uncontaminated silica fume and anhydrous ethanol at a mass ratio of 1:2 and stir until homogeneous. Then add silane coupling agent (2% of silica fume mass) and continue stirring for 2 hours. After centrifugation, dry at 50°C to obtain modified silica fume powder.

[0082] 2) Mix the silica fume, water, and citric acid in a mass ratio of 1:4:0.01, and stir for 30 minutes using a high-speed dispersing shear machine (shear rate of 750 r / min) to obtain silica fume slurry;

[0083] 3) Mix the obtained modified silica fume powder and silica fume slurry at a mass ratio of 1:3 to obtain modified composite silica fume slurry, with its solid content controlled at 40%.

[0084] The modified lithium slag powder is prepared by the following steps: lithium slag, water, crown ether, and barium acetate are homogenized at a mass ratio of 1:1.5:0.04:0.08 for 20 minutes to form a lithium slag slurry, which is then dried and ground at 60°C (the residue on a 45μm square hole sieve is 6%) to obtain the modified lithium slag powder.

[0085] The above raw materials are mixed and stirred to obtain chloride ion-resistant concrete.

[0086] Example 5

[0087] A C60 chloride ion-resistant concrete, the raw materials used are, by weight, 340 parts of ordinary Portland cement, 80 parts of fly ash, 60 parts of modified composite silica mortar, 50 parts of modified lithium slag powder, 1050 parts of crushed stone, 720 parts of sand, 9 parts of water-reducing agent, and 115 parts of water (excluding water in the modified composite silica mortar).

[0088] The ordinary Portland cement used is P·O 42.5 grade, with a specific surface area of ​​345 m². 2 / kg; the fly ash is Grade I fly ash, with SiO2 content of 66wt%, water requirement ratio of 91%, and loss on ignition of 1.8%;

[0089] The crushed stone is continuously graded crushed stone ranging from 5 to 31.5 mm; the sand is siliceous manufactured sand with a fineness of 2.8.

[0090] The water-reducing agent used is a high-performance polycarboxylate water-reducing agent with a water reduction rate of 28%.

[0091] The preparation steps of the modified composite silica paste are as follows:

[0092] 1) Mix uncontaminated silica fume and anhydrous ethanol at a mass ratio of 1:3 and stir until homogeneous. Then add silane coupling agent (3% of silica fume mass) and continue stirring for 3 hours. After centrifugation, dry at 50°C to obtain modified silica fume powder.

[0093] 2) Mix the silica fume, water, and citric acid in a mass ratio of 1:3:0.01, and stir for 25 minutes using a high-speed dispersing shear machine (shear rate of 800 r / min) to obtain silica fume slurry;

[0094] 3) Mix the obtained modified silica fume powder and silica fume slurry at a mass ratio of 1:2 to obtain modified composite silica fume slurry, with its solid content controlled at 50%.

[0095] The preparation steps of the modified lithium slag powder are as follows: lithium slag, water, crown ether, and barium acetate are homogenized for 25 minutes at a mass ratio of 1:1.3:0.04:0.06 to form lithium slag slurry. After drying and grinding at 60°C (the residue on a 45μm square hole sieve is 9%), the modified lithium slag powder is obtained.

[0096] The above raw materials are mixed and stirred to obtain chloride ion-resistant concrete.

[0097] Comparative Example 1

[0098] A C30 chloride ion-resistant concrete is prepared in a manner similar to that of Example 1, except that the raw materials used are, by weight, 220 parts of ordinary Portland cement, 60 parts of Grade I fly ash, 50 parts of S95 slag powder, 990 parts of crushed stone, 950 parts of sand, 6 parts of water-reducing agent, and 155 parts of water.

[0099] Comparative Example 2

[0100] A C40 chloride ion-resistant concrete is prepared in a manner similar to that of Example 2, except that the raw materials used are, by weight, 250 parts of ordinary silicate cement, 80 parts of fly ash, 25 parts of dense silica fume, 55 parts of modified lithium slag powder, 1000 parts of crushed stone, 880 parts of sand, 8 parts of water-reducing agent, and 155 parts of water.

[0101] Comparative Example 3

[0102] A C50 chloride ion-resistant concrete is prepared in a manner similar to that of Example 4, except that the raw materials used, by weight, are: 300 parts silicate cement, 80 parts fly ash, 50 parts modified composite silica fume slurry, 55 parts slag powder, 1030 parts crushed stone, 760 parts sand, 8 parts water-reducing agent, and 125 parts water.

[0103] Comparative Example 4

[0104] A C60 chloride ion-resistant concrete is prepared in a manner similar to that of Example 5, except that the raw materials used, by weight, are: 340 parts ordinary silicate cement, 80 parts fly ash, 30 parts dense silica fume, 50 parts S95 slag powder, 1050 parts crushed stone, 720 parts sand, 10 parts water-reducing agent, and 155 parts water.

[0105] Comparative Example 5

[0106] A C60 chloride ion-resistant concrete is prepared in a manner similar to that of Example 5, except that the raw materials used, by weight, are: 340 parts ordinary Portland cement, 80 parts fly ash, 60 parts modified silica fume slurry, 50 parts modified lithium slag powder, 1050 parts crushed stone, 720 parts sand, 9 parts water-reducing agent, and 130 parts water (excluding water in the modified silica fume slurry).

[0107] The preparation steps of the modified silica fume slurry are as follows: mix the silica fume, water and sodium hexametaphosphate in a mass ratio of 1:3:0.01, and stir for 25 minutes using a high-speed dispersing shear machine (shear rate of 800 r / min) to obtain the modified silica fume slurry.

[0108] Comparative Example 6

[0109] A C60 chloride ion-resistant concrete is prepared in a manner similar to that of Example 5, except that the raw materials used, by weight, are: 340 parts ordinary Portland cement, 80 parts fly ash, 60 parts modified silica fume slurry, 50 parts modified lithium slag powder, 1050 parts crushed stone, 720 parts sand, 9 parts water-reducing agent, and 115 parts water (excluding water in the modified silica fume slurry).

[0110] The preparation steps of the modified lithium slag powder are as follows: lithium slag, water, sodium secondary alkyl sulfonate and coconut oil diethanolamide are homogenized for 25 minutes at a mass ratio of 1:1.3:0.1:0.08 to form lithium slag slurry. After drying and grinding at 60°C, the modified lithium slag powder is obtained (its 45μm square hole sieve residue is 9%).

[0111] The concrete samples from the above embodiments and comparative examples were subjected to 28-day compressive strength, electrical conductivity, impermeability, and steel reinforcement corrosion tests. The compressive strength tests were conducted according to GB / T50081 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete," while the electrical conductivity, impermeability, and steel reinforcement corrosion tests were conducted according to GB / T50082 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete." The test results are shown in Table 1.

[0112] Table 1. Test results of chloride ion penetration resistant concrete.

[0113]

[0114]

[0115] As can be seen from Examples 1 to 5, the 28-day strength of the prepared concrete all meets the design requirements of each strength grade and all reaches the P12 impermeability grade, indicating that the concrete has good impermeability. The 28-day electrical flux of the concrete in the examples is significantly lower than that of the concrete in the comparative example, indicating that the concrete of the present invention has excellent resistance to chloride ion penetration. There is no steel reinforcement corrosion in the concrete of the examples.

[0116] Comparative Example 1 lacks the modified composite silica fume slurry and modified lithium slag powder of the present invention. Although the strength is similar to that of Example 1, the impermeability grade is significantly reduced, the electrical flux is significantly increased, and the steel bars are severely corroded.

[0117] Comparative Example 2 uses densified silica fume to replace the modified composite silica fume slurry in Example 2 of this invention. The amount of water and admixture used in concrete is significantly increased. The concrete obtained in Example 2 has a strength grade one grade higher than that in Comparative Example 2. The modified composite silica fume slurry of this invention helps increase the strength of concrete, and at the same time, its impermeability, chloride ion penetration resistance and steel corrosion resistance are greatly improved.

[0118] In Comparative Example 3, slag powder was used to replace the modified lithium slag powder in Example 4 of this invention. The 28-day strength and impermeability grade of the concrete were basically the same, but the electrical flux was significantly increased. The steel bars still showed slight corrosion, indicating that the modified lithium slag powder of this invention is beneficial to weakening chloride ion penetration and can effectively prevent steel bars from being corroded.

[0119] Comparative Example 4 used slag powder to replace the modified lithium slag powder in Example 5 of this invention, and used dense silica fume to replace the modified composite silica fume slurry. The test results showed that the concrete water consumption and admixtures increased, the strength decreased, the electrical flux increased, and the steel bars still showed signs of corrosion, which further verified the excellent performance of the chloride ion penetration resistant concrete created by this invention.

[0120] Comparative Example 5 uses sodium hexametaphosphate to modify silica fume. The test results show that the water content of the concrete increases significantly, the concrete strength is low, the concrete still has a certain anti-seepage effect, but the steel bars in the concrete show slight corrosion.

[0121] The concrete obtained in Comparative Example 6 had low strength and some impermeability, but the steel bars in the concrete showed slight corrosion.

[0122] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It should be understood that the above are merely some embodiments of the present invention and are not intended to limit the invention. Therefore, any changes and improvements to the above embodiments should be included within the scope of protection of the claims of this invention.

Claims

1. A chloride ion-resistant concrete, characterized in that, The raw materials and their respective weight percentages include: 200-400 parts cement, 60-100 parts fly ash, 50-80 parts modified composite silica fume slurry, 40-60 parts modified lithium slag powder, 950-1050 parts crushed stone, 700-960 parts sand, 5-10 parts water-reducing agent, and 110-130 parts water; the modified lithium slag powder is obtained by modifying lithium slag with crown ether and barium acetate. The modified composite silica slurry comprises undensed silica slurry modified with silane coupling agent and dense silica slurry modified with citric acid; The citric acid modified densifying silica slurry is obtained by mixing densifying silica ash, water, and citric acid, and then subjecting it to high-speed shearing. The modified lithium slag powder is obtained by mixing and homogenizing lithium slag, crown ether, barium acetate and water to form a lithium slag slurry, and then drying and grinding it; its residue on a 45μm square hole sieve is no more than 15%.

2. The chloride ion-resistant concrete according to claim 1, characterized in that, The mass ratio of lithium slag, crown ether, barium acetate and water is 1:0.03~0.05:0.05~0.08:1~1.

5.

3. The chloride ion-resistant concrete according to claim 1, characterized in that, The lithium slag contains no more than 5 wt% SO3, 1.5-2.0 wt% Li, and has a specific surface area of ​​400-450 kg / m². 3 .

4. The chloride ion-resistant concrete according to claim 1, characterized in that, The silane coupling agent modified undensed silica fume is obtained by mixing undensed silica fume and alcohol solvent evenly, adding silane coupling agent and stirring, centrifuging and drying.

5. The chloride ion-resistant concrete according to claim 1, characterized in that, The mass ratio of the silane coupling agent-modified undensed silica fume to the citric acid-modified densified silica fume slurry is 1:2~4.

6. The chloride ion-resistant concrete according to claim 1, characterized in that, The cement is one of silicate cement, ordinary silicate cement, and slag silicate cement, with a strength grade of not less than 42.5; the fly ash is Grade I fly ash, with a SiO2 content of not less than 60wt%, a water requirement ratio of not more than 92%, and a loss on ignition of not more than 3%.

7. The method for preparing chloride ion-resistant concrete according to any one of claims 1 to 6, characterized in that, Includes the following steps: 1) Weighing of raw materials: The raw materials and their weight percentages include: 200-400 parts cement, 60-100 parts fly ash, 50-80 parts modified composite silica fume slurry, 40-60 parts modified lithium slag powder, 950-1050 parts crushed stone, 700-960 parts sand, 5-10 parts water-reducing agent, and 110-130 parts water. 2) Mix and stir the weighed raw materials evenly to obtain the chloride ion-resistant concrete.

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