Chloride ion permeation resistant concrete and preparation method thereof

Abstract

The invention discloses chloride ion permeation resistant concrete, which is prepared from the following raw materials in parts by weight: 200 to 400 parts of cement, 60 to 100 parts of fly ash, 50 to 80 parts of modified composite silica mortar, 40 to 60 parts of modified lithium slag powder, 950 to 1050 parts of gravel, 700 to 960 parts of sand, 5 to 10 parts of water reducing agent and 110 to 130 parts of water, the modified lithium slag powder is obtained by modifying lithium slag with crown ether and barium acetate; the modified composite silica mortar contains silane coupling agent modified unencrypted silica fume and citric acid modified encrypted silica mortar. According to the chloride ion permeation resistant concrete, on the premise of ensuring the design strength requirement, the chloride ion permeation resistance of the concrete can be greatly improved, the corrosion phenomenon of steel bars is effectively reduced, and the applicability is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to chloride ion penetration resistant concrete and a preparation method thereof. Background Art

[0002] Marine engineering is different from land-based engineering projects. Islands are far away from the mainland and have harsh environments. Infrastructure construction and use will face more problems and challenges. Concrete has become the most widely used engineering material due to its strong versatility and relatively low price. Even in harsh marine environments, concrete materials are often the first choice of engineers.

[0003] At present, a large number of investigations on concrete structures in marine environments have shown that the cause of structural damage is rarely due to external loads that cause the structure to reach the limit state of bearing capacity. Most of the time, the durability of the structure continues to deteriorate under the influence of the marine erosion environment, 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 chloride salt environments is the main cause of marine concrete structures and their durability damage.

[0004] In order to improve the concrete's resistance to chloride ion penetration, the existing chloride ion penetration resistant concrete design usually requires the use of some high-performance admixtures and additives, or the application of anti-corrosion and anti-seepage materials. These measures greatly increase the cost of concrete. In addition, during long-term use, especially when exposed to a humid and salt spray environment, concrete will still face severe challenges of chloride ion penetration, leading to steel corrosion, which in turn affects the durability of the structure. For this reason, it is necessary to develop a chloride ion penetration resistant concrete to further effectively improve the durability and service life of marine concrete structures. Summary of the invention

[0005] The main purpose of the present invention is to provide a chloride ion penetration resistant concrete with excellent chloride ion penetration resistance to effectively prevent steel bars in concrete from rusting in view of the problems and shortcomings of the prior art.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

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

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

[0009] Furthermore, the mass ratio of the 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 (standing at room temperature) time is 20 to 30 minutes.

[0011] Furthermore, 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] Furthermore, the crown ether is 2-crown-4.

[0013] In the above scheme, the modified composite silica mortar comprises undensified silica mortar modified by a silane coupling agent and densified silica mortar modified by citric acid, and the D50 of the silica mortar particles is less than 1.5 μm.

[0014] Furthermore, the silane coupling agent-modified undenatured silica ash is prepared by uniformly stirring undenatured silica ash and an alcohol solvent (such as anhydrous ethanol), adding a silane coupling agent, stirring, centrifuging, and drying.

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

[0016] Furthermore, the dosage of the silane coupling agent is 2-4% of the mass of the undensified silica ash.

[0017] Furthermore, the bulk density of the undensified silica fume is 180-200 kg / m 3 .

[0018] In the above scheme, the citric acid modified densified silica ash slurry is obtained by mixing densified silica ash, water and citric acid and subjecting them to 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 adopted by the high-speed shearing is 700-900 r / min and the time is 25-35 min.

[0021] Furthermore, the bulk density of the densified silica fume is 680-710 kg / m 3 , SiO2 content is not less than 85%, activity index is not less than 105%

[0022] In the above scheme, the mass ratio of the undensified silica ash modified by the silane coupling agent to the densified silica ash mortar modified by citric acid is 1:2-4.

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

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

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

[0026] In the above scheme, the water reducer is a high-performance polycarboxylate water reducer.

[0027] The method for preparing the above-mentioned chloride ion penetration resistant concrete comprises the following steps:

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

[0029] 2) The weighed raw materials are mixed and stirred evenly to obtain the chloride ion penetration resistant concrete.

[0030] The chloride ion penetration-resistant concrete prepared according to the above scheme has an impermeability grade of P12 or above and has excellent chloride ion corrosion resistance.

[0031] The main principles of the present invention are:

[0032] (1) The present invention modifies lithium slag. On the one hand, barium acetate is used to react with calcium sulfate in lithium slag to generate barium sulfate and calcium acetate, wherein barium sulfate is a poorly soluble precipitate, which can solidify sulfate ions in lithium slag, and calcium acetate plays a certain role in early strength of concrete; on the other hand, crown ether 2-crown-4 is used to react with Li + The complex reaction generates [2-crown-4·Li + ], which is conducive to the competitive adsorption of chloride ions, while the released Li + It can inhibit the alkali-silica reaction of concrete.

[0033] (2) The modified composite silica ash mortar used in the present invention comprises undensified silica ash modified by a silane coupling agent and densified silica ash mortar modified by citric acid. On the one hand, part of the silica ash particles are modified by a silane coupling agent to make them hydrophobic, and at the same time, they are dispersed in the silica ash mortar to form a steric hindrance to the remaining silica ash particles, and citric acid is used to further disperse and stabilize the composite silica ash mortar. This can not only solve the problem of a significant increase in the water consumption of concrete caused by traditional silica ash particles, but also greatly increase the anti-permeability performance of concrete by using nano-scale silica ash particles and their high activity, and can effectively block chloride ions outside the concrete structure.

[0034] (3) In the present invention, the lithium slag powder is modified and the obtained calcium acetate can be used to effectively promote the early strength development of concrete and improve the density of concrete; in addition, when Cl - When it penetrates into the concrete, it will react with Li + Competitive substitution to form a more stable complex [2-crown-4·Cl - ], reducing Cl - The degree of ionization of Cl - On the other hand, Li + It can inhibit the alkali-silica reaction of 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) The present invention uses a silane coupling agent to modify the undensified silica fume, and composites it with a densified silica fume-based silica fume mortar modified with citric acid, so that the modified undensified silica fume particles and the modified densified silica fume particles are mutually filled, further improving the dispersibility of the silica fume particles in the slurry, and at the same time greatly reducing the adsorption of water by the silica fume particles, which is beneficial to significantly reduce the water consumption of concrete, improve the density of the concrete structure, and enhance the anti-seepage effect of the concrete;

[0037] (2) The addition of modified lithium slag powder can make the infiltrated Cl - Form a stable complex, reduce its ionization, and Li + It can protect the steel bars from rust;

[0038] (3) The concrete of the present invention effectively blocks the migration of Cl- into the interior of the concrete structure with the triple effects of high impermeability, high adsorption and strong protection; while ensuring the design strength requirements, the concrete's resistance to chloride ion penetration can be greatly improved, effectively reducing the corrosion of steel bars. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below in conjunction with the embodiments to facilitate a clearer understanding of the present invention, but they do not limit the present invention.

[0040] In the following examples, the bulk density of the undensified silica fume used is 200 kg / m 3 ; The bulk density of the dense silica fume is 690kg / m 3 , SiO2 content 90%, activity index 108%;

[0041] The SO3 content in the lithium slag is 4.5wt%, the Li content is 1.8wt%, and the specific surface area of ​​the lithium slag is 400kg / m 3 .

[0042] Example 1

[0043] A C30 chloride ion penetration 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 reducer, and 125 parts of water (excluding 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 ​​340m 2 / kg; the fly ash is Class I fly ash, with SiO2 content of 65wt%, water requirement of 92%, and loss on ignition of 2.1%;

[0045] The crushed stone is 5-31.5mm continuously graded crushed stone; the sand is siliceous machine-made sand with a fineness of 2.5;

[0046] The water reducer used is a high-performance polycarboxylate water reducer with a water reduction rate of 25%;

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

[0048] 1) Undensified silica fume and anhydrous ethanol were mixed and stirred in a mass ratio of 1:2.5, and then a silane coupling agent (accounting for 3% of the mass of silica fume) was added and stirred for 2 hours. After centrifugation, the modified silica fume powder was dried at 50°C to obtain the modified silica fume powder;

[0049] 2) Mix the densified 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 shearing machine (shear rate of 800 r / min) to obtain silica fume slurry;

[0050] 3) The obtained modified silica fume powder and silica ash slurry are stirred and mixed uniformly in a mass ratio of 1:3 to obtain a modified composite silica ash slurry, the solid content of which is adjusted to 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 according to a mass ratio of 1:1:0.05:0.06 to form a lithium slag slurry, and the slurry is dried and ground at 60° C. (the residue on a 45 μm 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 penetration resistant concrete.

[0053] Example 2

[0054] A C40 chloride ion penetration 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 mortar, 55 parts of modified lithium slag powder, 1000 parts of crushed stone, 880 parts of sand, 7 parts of water reducer, and 130 parts of water (excluding water in the modified composite silica mortar);

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

[0056] The crushed stone is 5-31.5mm continuously graded crushed stone; the sand is siliceous machine-made sand with a fineness of 2.6;

[0057] The water reducer used is a high-performance polycarboxylate water reducer with a water reduction rate of 25%;

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

[0059] 1) Undensified silica fume and anhydrous ethanol were mixed and stirred in a mass ratio of 1:2, and then a silane coupling agent (accounting for 2% of the mass of silica fume) was added and stirred for 2 hours. After centrifugation, the modified silica fume powder was dried at 50°C to obtain the modified silica fume powder;

[0060] 2) Mix the densified 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 shearing machine (shear rate of 850 r / min) to obtain silica fume slurry;

[0061] 3) The obtained modified silica fume powder and silica ash slurry are stirred and mixed uniformly in a mass ratio of 1:2 to obtain a modified composite silica ash slurry, the solid content of which is adjusted to 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 according to a mass ratio of 1:1.5:0.03:0.05 to form a lithium slag slurry, and the slurry is dried and ground at 55° C. (the residue on a 45 μm square hole sieve is 12%) to obtain the modified lithium slag powder;

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

[0064] Example 3

[0065] A C40 chloride ion penetration resistant concrete, the raw materials used are, by weight, 260 parts of slag silicate cement, 60 parts of fly ash, 60 parts of modified composite silica mortar, 40 parts of modified lithium slag powder, 1000 parts of crushed stone, 880 parts of sand, 7 parts of water reducer, and 125 parts of 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 ​​360m 2 / kg; the fly ash is Class I fly ash, with SiO2 content of 68wt%, water requirement of 95%, and loss on ignition of 2.0%;

[0067] The crushed stone is 5-31.5mm continuously graded crushed stone; the sand is siliceous machine-made sand with a fineness of 2.6;

[0068] The water reducer used is a high-performance polycarboxylate water reducer with a water reduction rate of 25%;

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

[0070] 1) Undensified silica fume and anhydrous ethanol were mixed and stirred in a mass ratio of 1:3, and then a silane coupling agent (accounting for 2.5% of the mass of silica fume) was added and stirred for 2.5 hours. After centrifugation, the modified silica fume powder was dried at 50°C to obtain the modified silica fume powder;

[0071] 2) Mix the densified 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 shearing machine (shear rate of 750 r / min) to obtain silica fume slurry;

[0072] 3) The obtained modified silica fume powder and silica ash slurry are stirred and mixed uniformly in a mass ratio of 1:2 to obtain a modified composite silica ash slurry, the solid content of which is adjusted to 50%;

[0073] 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 according to a mass ratio of 1:1.5:0.03:0.05 to form a lithium slag slurry, and the slurry is dried and ground at 60° C. (the residue on a 45 μm square hole sieve is 8%) to obtain the modified lithium slag powder;

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

[0075] Example 4

[0076] A C50 chloride ion penetration 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 mortar, 60 parts of modified lithium slag powder, 1030 parts of crushed stone, 780 parts of sand, 8 parts of water reducer, and 120 parts of water (excluding water in the modified composite silica mortar);

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

[0078] The crushed stone is 5-31.5mm continuously graded crushed stone; the sand is siliceous machine-made sand with a fineness of 2.7;

[0079] The water reducer used is a high-performance polycarboxylate water reducer with a water reduction rate of 28%;

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

[0081] 1) Undensified silica fume and anhydrous ethanol were mixed and stirred in a mass ratio of 1:2, and then a silane coupling agent (accounting for 2% of the mass of silica fume) was added and stirred for 2 hours. After centrifugation, the modified silica fume powder was dried at 50°C to obtain the modified silica fume powder;

[0082] 2) Mix the densified 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 shearing machine (shear rate of 750 r / min) to obtain silica fume slurry;

[0083] 3) The obtained modified silica fume powder and silica ash slurry are stirred and mixed uniformly in a mass ratio of 1:3 to obtain a modified composite silica ash slurry, the solid content of which is adjusted to 40%;

[0084] 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 according to a mass ratio of 1:1.5:0.04:0.08 to form lithium slag slurry, and the slurry is dried and ground at 60° C. (the residue on a 45 μm 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 penetration resistant concrete.

[0086] Example 5

[0087] A C60 chloride ion penetration 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 ash mortar, 50 parts of modified lithium slag powder, 1050 parts of crushed stone, 720 parts of sand, 9 parts of water reducer, and 115 parts of water (excluding water in the modified composite silica ash mortar);

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

[0089] The crushed stone is 5-31.5mm continuously graded crushed stone; the sand is siliceous machine-made sand with a fineness of 2.8;

[0090] The water reducer used is a high-performance polycarboxylate water reducer with a water reduction rate of 28%;

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

[0092] 1) Undensified silica fume and anhydrous ethanol were mixed and stirred in a mass ratio of 1:3, and then a silane coupling agent (accounting for 3% of the mass of silica fume) was added and stirred for 3 hours. After centrifugation, the modified silica fume powder was dried at 50°C to obtain the modified silica fume powder;

[0093] 2) Mix the densified 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 shearing machine (shear rate of 800 r / min) to obtain silica fume slurry;

[0094] 3) The obtained modified silica fume powder and silica ash slurry are stirred and mixed uniformly in a mass ratio of 1:2 to obtain a modified composite silica ash slurry, the solid content of which is adjusted to 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 according to a mass ratio of 1:1.3:0.04:0.06 to form a lithium slag slurry, and the slurry is dried and ground at 60° C. (the residue on a 45 μm square hole sieve is 9%) to obtain the modified lithium slag powder;

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

[0097] Comparative Example 1

[0098] A C30 chloride ion penetration resistant concrete, the preparation method of which is substantially the same as 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 reducer, and 155 parts of water.

[0099] Comparative Example 2

[0100] A C40 chloride ion penetration resistant concrete, the preparation method of which is substantially the same as that of Example 2, except that the raw materials used are, by mass, 250 parts of ordinary Portland cement, 80 parts of fly ash, 25 parts of densified silica fume, 55 parts of modified lithium slag powder, 1000 parts of crushed stone, 880 parts of sand, 8 parts of water reducer, and 155 parts of water.

[0101] Comparative Example 3

[0102] A C50 chloride ion penetration resistant concrete, the preparation method of which is substantially the same as that of Example 4, except that the raw materials used are, by mass, 300 parts of silicate cement, 80 parts of fly ash, 50 parts of modified composite silica mortar, 55 parts of slag powder, 1030 parts of crushed stone, 760 parts of sand, 8 parts of water reducer, and 125 parts of water.

[0103] Comparative Example 4

[0104] A C60 chloride ion penetration resistant concrete, the preparation method of which is substantially the same as that of Example 5, except that the raw materials used are, by mass, 340 parts of ordinary Portland cement, 80 parts of fly ash, 30 parts of densified silica fume, 50 parts of S95 slag powder, 1050 parts of crushed stone, 720 parts of sand, 10 parts of water reducer, and 155 parts of water.

[0105] Comparative Example 5

[0106] A C60 chloride ion penetration resistant concrete, the preparation method of which is substantially the same as that of Example 5, except that the raw materials used are, by mass, 340 parts of ordinary Portland cement, 80 parts of fly ash, 60 parts of modified silica mortar, 50 parts of modified lithium slag powder, 1050 parts of crushed stone, 720 parts of sand, 9 parts of water reducer, and 130 parts of water (excluding water in the modified silica mortar);

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

[0108] Comparative Example 6

[0109] A C60 chloride ion penetration resistant concrete, the preparation method of which is substantially the same as that of Example 5, except that the raw materials used are, by mass, 340 parts of ordinary Portland cement, 80 parts of fly ash, 60 parts of modified silica mortar, 50 parts of modified lithium slag powder, 1050 parts of crushed stone, 720 parts of sand, 9 parts of water reducer, and 115 parts of water (excluding water in the modified silica mortar).

[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 a lithium slag slurry, and the modified lithium slag powder is obtained after drying and grinding at 60° C. (the residue on a 45 μm square hole sieve is 9%);

[0111] The concrete of the above-mentioned embodiment and comparative example was subjected to 28d compressive strength, electric flux, impermeability test and steel corrosion test; the compressive strength was tested in accordance with GB / T50081 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", and the electric flux, impermeability test and steel corrosion test were tested in accordance with 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 concrete performance against chloride ion penetration

[0113]

[0114]

[0115] It can be seen from Examples 1 to 5 that the 28d strength of the prepared concrete meets the design requirements of each strength grade and reaches the P12 anti-seepage grade, indicating that the concrete has good anti-seepage performance. The 28d electrical flux of the example concrete 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, and the example concrete has no steel bar corrosion.

[0116] Comparative Example 1 lacks the modified composite silicon ash mortar 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 electric 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 ash mortar in Example 2 of the present invention. The water consumption and admixture consumption of concrete are significantly improved. The concrete obtained in Example 2 is one strength grade higher than that of Comparative Example 2. The modified composite silica ash mortar of the present invention helps to increase the strength of concrete. At the same time, the impermeability, resistance to chloride ion penetration, and resistance to steel bar corrosion are greatly improved.

[0118] In Comparative Example 3, slag powder is used to replace the modified lithium slag powder in Example 4 of the present invention. The 28d strength and impermeability grade of the concrete are basically the same, but the electric flux is significantly increased, and the steel bars are still slightly corroded, indicating that the modified lithium slag powder of the present invention is beneficial to weaken the penetration of chloride ions and can effectively prevent the steel bars from being corroded.

[0119] In Comparative Example 4, slag powder is used to replace the modified lithium slag powder in Example 5 of the present invention, and densified silica fume is used to replace the modified composite silica ash mortar. The test results show that the water consumption and admixture of concrete are increased, the strength is reduced, the electric flux is increased, and the steel bars are still rusted, which further verifies the excellent performance of the chloride ion penetration-resistant concrete created by the present invention.

[0120] Comparative Example 5 uses sodium hexametaphosphate to modify silica mortar. The test results show that the water consumption of concrete is significantly increased, the strength of concrete is low, the concrete still has a certain anti-seepage effect, but the steel bars in the concrete are slightly rusted.

[0121] The concrete obtained in Comparative Example 6 has a relatively low strength, and the concrete has a certain anti-seepage effect, but the steel bars in the concrete are slightly corroded.

[0122] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood that the above are only some implementation cases of the present invention and are not intended to limit the present invention. Therefore, any changes and improvements to the above implementation cases should be included in the protection scope of the claims of the present invention.

Claims

1. A chloride ion penetration resistant concrete, characterized in that: The raw materials and their weight proportions include: 200-400 parts of cement, 60-100 parts of fly ash, 50-80 parts of modified composite silica ash slurry, 40-60 parts of modified lithium slag powder, 950-1050 parts of crushed stone, 700-960 parts of sand, 5-10 parts of water reducing agent and 110-130 parts of water; the modified lithium slag powder is obtained by modifying lithium slag with crown ether and barium acetate.

2. The chloride ion penetration resistant concrete according to claim 1, characterized in that: The modified lithium slag powder is obtained by mixing lithium slag, crown ether, barium acetate and water, homogenizing to form lithium slag slurry, and then drying and grinding; the residue on a 45μm square hole sieve is not more than 15%.

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

5.

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

5. The chloride ion penetration resistant concrete according to claim 1, characterized in that: The modified composite silica ash mortar comprises undensified silica ash modified by a silane coupling agent and densified silica ash mortar modified by citric acid.

6. The chloride ion penetration resistant concrete according to claim 5, characterized in that: The silane coupling agent-modified undensified silica ash is prepared by uniformly stirring undensified silica ash and an alcohol solvent, adding a silane coupling agent, stirring, centrifugally separating, and drying.

7. The chloride ion penetration resistant concrete according to claim 5, characterized in that: The citric acid modified densified silica ash mortar is obtained by mixing densified silica ash, water and citric acid and subjecting the mixture to high-speed shearing.

8. The chloride ion penetration resistant concrete according to claim 5, characterized in that: The mass ratio of the undensified silica ash modified by the silane coupling agent to the densified silica ash mortar modified by citric acid is 1:2-4.

9. The chloride ion penetration resistant concrete according to claim 5, characterized in that: The cement is one of silicate cement, ordinary silicate cement and slag silicate cement, and its strength grade is not less than 42.5; the fly ash is Class I fly ash, and its SiO2 content is not less than 60wt%, its water requirement ratio is not higher than 92%, and its loss on ignition is not higher than 3%.

10. The method for preparing chloride ion penetration resistant concrete according to any one of claims 1 to 9, characterized in that: The steps include: 1) Weighing of raw materials, the raw materials and their weight proportions include: 200-400 parts of cement, 60-100 parts of fly ash, 50-80 parts of modified composite silica ash mortar, 40-60 parts of modified lithium slag powder, 950-1050 parts of crushed stone, 700-960 parts of sand, 5-10 parts of water reducer, and 110-130 parts of water; 2) The weighed raw materials are mixed and stirred evenly to obtain the chloride ion penetration resistant concrete.

Images