A low-carbon gel material for concrete roads and a preparation method and application thereof

Abstract

The application belongs to the technical field of resource recycling, and discloses a low-carbon gel material for concrete roads and a preparation method and application thereof. The low-carbon gel material for concrete roads is mainly prepared from the following raw materials in parts by mass: mineral powder 50-65 parts; electrolytic aluminum red mud 15-20 parts; steel slag micro powder 10-15 parts; waste concrete powder 5-10 parts; and composite activator 1-3 parts. The composite activator is composed of Na2SO4 solution, CaSO4, triethanolamine, monoethanolamine and N-methyl diethanolamine. A preparation method of the low-carbon gel material for concrete roads is also provided. The low-carbon gel material is prepared through the synergistic effect of multiple solid wastes, and the resource utilization of multiple solid wastes is realized. Through the synergistic effect of gradient alkali activation and ultrasonic activation, the activation of solid waste is realized, the low-carbon gel material is prepared, and the performance of the low-carbon gel material and the mechanical properties and durability in concrete are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resource recycling, and particularly relates to a low-carbon gel material for concrete highways and a preparation method and application thereof. BACKGROUND

[0002] Low-carbon cementitious materials have become an important type of cementitious material for replacing cement applications. Compared with traditional cementitious materials (such as Portland cement), the production process of low-carbon cementitious materials mainly uses solid waste and other alternative raw materials, which can significantly reduce carbon dioxide emissions and help reduce the environmental impact of the construction industry. Moreover, the production and use processes usually require less energy, so they can reduce energy consumption and improve the energy utilization efficiency of the construction industry. However, there are still some problems in the development of low-carbon cementitious materials. On the one hand, the composition differences of different industrial wastes may cause large fluctuations in the performance of low-carbon cementitious materials. On the other hand, the technology of low-carbon cementitious materials is not mature enough, and there are still some technical problems to be solved. For example, there are still some problems in improving the strength, durability and stability of low-carbon cementitious materials. At present, low-carbon cementitious materials also face the problems of low strength and poor durability in concrete highway engineering. SUMMARY

[0003] In view of the problems and deficiencies in the prior art, the application aims to provide a low-carbon cementitious material for concrete highways and a preparation method and application thereof.

[0004] To achieve the purpose of the application, the technical scheme adopted by the application is as follows:

[0005] The application protects, in a first aspect, a low-carbon cementitious material for concrete highways, which is mainly made of the following raw materials by mass:

[0006] 50-65 parts of mineral powder;

[0007] 15-20 parts of electrolytic aluminum red mud;

[0008] 10-15 parts of steel slag micro-powder;

[0009] 5-10 parts of waste concrete powder;

[0010] 1-3 parts of a composite activator;

[0011] The composite activator is composed of Na2SO4 solution, CaSO4, triethanolamine, monoethanolamine and N-methyl diethanolamine.

[0012] Preferably, the mass ratio of Na2SO4 solution, CaSO4, triethanolamine, monoethanolamine and N-methyl diethanol in the composite activator is 1:(1-3):(2-4):(1-3):(1-3).

[0013] Preferably, the concentration of the Na2SO4 solution is 1%-2%.

[0014] Preferably, the specific surface area of the mineral powder is 400-600 m 2 / kg.

[0015] Preferably, the mineral powder is the mineral powder in GB / T 18046-2017 Granulated Blast Furnace Slag for Use in Cement, Mortar and Concrete.

[0016] Preferably, the specific surface area of the electrolytic aluminum red mud is 350-500 m 2 / kg.

[0017] Preferably, the specific surface area of the steel slag micro-powder is 500-800 m 2 / kg.

[0018] Preferably, the steel slag is a by-product generated in the steelmaking process, mainly composed of various oxides formed by the oxidation of impurities such as silicon, manganese, phosphorus and sulfur in pig iron in the smelting process, and salts generated by the reaction of these oxides with solvents, and the steel slag micro-powder is a powder obtained by grinding the steel slag.

[0019] Preferably, the specific surface area of the waste concrete powder is 300-500 m 2 / kg of particles.

[0020] The second aspect of the present application protects a preparation method of the low-carbon cementitious material for concrete roads according to any one of the first aspect, comprising the following steps:

[0021] (1) The above raw materials are placed in a sealed ammonia gas at the same time with 5-10 parts by mass of ammonia water with a concentration of 25%-28%, and the gas pressure is controlled at 0.2-0.4 MPa, and the stirring starts at a speed of 5-20 r / min;

[0022] (2) High-frequency ultrasonic waves of 60-100 kHz are applied to the materials in step (1) for continuous stirring for 2-3 h;

[0023] (3) The ammonia gas is evacuated, and the materials in step (2) are taken out and dried at 80-120 DEG C to obtain the low-carbon cementitious material.

[0024] The third aspect of the present application protects the application of the low-carbon cementitious material according to any one of the first aspect in the preparation of concrete.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] (1) The present application realizes the resource utilization of various solid wastes by the synergistic effect of the various solid wastes in the preparation of low-carbon cementitious materials. Through the synergistic effect of gradient alkali activation and ultrasonic excitation, the activation of solid wastes is realized, low-carbon cementitious materials are prepared, and the performance of low-carbon cementitious materials and the mechanical properties and durability in concrete are improved.

[0027] (2) In the raw materials for preparing low-carbon cementitious materials, slag provides silicon-aluminum activity, red mud contains alkali metals (Na / K) which can reduce the dosage of activator, steel slag powder supplements iron phase to enhance wear resistance, and waste concrete powder optimizes particle size distribution while providing alkaline substances and hydrated calcium silicate.

[0028] (3) The present application controls the proportion of each component in the composite activator to ensure the persistence of the activation effect. In the early stage, the sulfate promotes the dissolution of calcium ions and accelerates hydration, while the solubility of calcium sulfate is low, and its dissolution is slow, effectively controlling the generation of active substances. At the same time, the alkalinity of triethanolamine, monoethanolamine and N-methyldiethanolamine is different, the alkalinity of triethanolamine is weak, and the early stage is mainly dispersed, the alkalinity of monoethanolamine is strong, and the early stage is mainly to promote the dissolution of calcium-silicon active substances in slag, steel slag and other substances, and the alkalinity of N-methyldiethanolamine is moderate, which can effectively control the reaction alkalinity and play an emulsifying role, avoiding material agglomeration and affecting active excitation.

[0029] (4) The present application controls the specific surface area of each raw material to ensure better dissolution of active substances during the activation process. If the particle size is too small, the active excitation effect is poor. If the particle size is too large, the active excitation effect is not obviously improved, and the grinding is difficult.

[0030] (5) In the preparation process of the low-carbon cementitious material of the present application, the raw materials are mixed with ammonia water, placed in a sealed ammonia gas environment and pressurized, mainly to ensure that the material is fully eroded by the alkaline environment. Under this condition, the ultrasonic wave breaks the particles of the volcanic ash, increases the specific surface area, and accelerates the contact between the alkaline substances and the mineral surface. At the same time, the shock wave generated by the collapse of the cavitation bubble promotes the expansion of the crystal lattice defects and the directional stripping of the inert ingredients. The local high temperature generated by the ultrasonic wave promotes the rapid cooling of the dissolved silicate, forming a high-activity amorphous structure.

[0031] (6) In the preparation process of the low-carbon cementitious material of the present application, the material is dried at 80-120℃, because under this temperature condition, the material can further promote the activation of the active excitation, which is beneficial to the continuous process of the active excitation, and at the same time, the residual ammonia gas is removed. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below through examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0033] Example 1

[0034] A low-carbon cementitious material for concrete highway is mainly made of the following raw materials by mass fraction:

[0035] 50 parts of mineral powder (specific surface area of 600 m 2 / kg);

[0036] 20 parts of red mud of electrolytic aluminum (specific surface area of 350 m 2 / kg);

[0037] 10 parts of steel slag micro powder (specific surface area of 800 m 2 / kg);

[0038] 10 parts of waste concrete powder;

[0039] 1 part of composite activator;

[0040] The mineral powder is the mineral powder in GB / T 18046-2017 “Ground Granulated Blast Furnace Slag for Use in Cement, Mortar and Concrete”;

[0041] The steel slag is a by-product generated in the steelmaking process, mainly composed of various oxides formed by the oxidation of impurities such as silicon, manganese, phosphorus and sulfur in pig iron during the smelting process, and salts generated by the reaction of these oxides with solvents, and the steel slag micro powder is a powder obtained by grinding the steel slag;

[0042] The waste concrete powder is the powder left after the preparation of recycled aggregate from crushed concrete, and the specific surface area of the powder reaches 300 m 2 / kg after grinding;

[0043] The composite activator is composed of a 2% Na2SO4 solution, CaSO4, triethanolamine, monoethanolamine, N-methyl diethanolamine, and mixed uniformly in a mass ratio of 1:1:2:1:1.

[0044] The preparation method of the low-carbon cementitious material for concrete highway includes the following specific steps:

[0045] (1) The above raw materials by mass fraction and 10 parts of 25% ammonia water by mass fraction are simultaneously added to a closed ammonia gas stirring tank, the gas pressure of the closed ammonia gas tank is controlled at 0.4 MPa, and the stirring starts at a speed of 5 r / min;

[0046] (2) High-frequency ultrasonic waves of 60 kHz are applied to the materials in step (1) for continuous stirring for 3 hours;

[0047] (3) After the material in step (2) is taken out, it is dried at 80°C to obtain a low-carbon cementitious material.

[0048] Example 2

[0049] A low-carbon cementitious material for concrete roads is mainly made of the following raw materials by mass fraction:

[0050] 65 parts of mineral powder (specific surface area 400 m 2 / kg);

[0051] 15 parts of electrolytic aluminum red mud (specific surface area 500 m 2 / kg);

[0052] 15 parts of steel slag micro powder (specific surface area 500 m 2 / kg);

[0053] 5 parts of waste concrete powder;

[0054] 3 parts of composite activator;

[0055] The mineral powder is the mineral powder in GB / T 18046-2017 “Ground Granulated Blast Furnace Slag for Use in Cement, Mortar and Concrete”;

[0056] The steel slag is a byproduct produced during the steelmaking process, mainly composed of various oxides formed by the oxidation of impurities such as silicon, manganese, phosphorus, sulfur, etc. in pig iron during the smelting process, and salts generated by the reaction of these oxides with solvents. Steel slag micro powder is a powder obtained by grinding steel slag;

[0057] The waste concrete powder is the powder left after the preparation of recycled aggregate from crushed concrete, with a specific surface area of 500 m 2 / kg of particles after grinding;

[0058] The composite activator is composed of a 1% Na2SO4 solution, CaSO4, triethanolamine, monoethanolamine, and N-methyl diethanolamine in a mass ratio of 1:3:4:3:3.

[0059] The preparation method of the low-carbon cementitious material for concrete roads includes the following specific steps:

[0060] (1) The above raw materials and 5 parts of 28% ammonia water by mass fraction are simultaneously added to a sealed ammonia gas stirring tank, the gas pressure of the sealed ammonia gas tank is controlled at 0.2 MPa, and stirring is started at a speed of 20 r / min;

[0061] (2) High-frequency ultrasound of 100 kHz is applied to the material in step (1) for continuous stirring for 2 hours.

[0062] (3) After the material in step (2) is taken out, it is dried at 120℃ under vacuum to obtain a low-carbon cementitious material.

[0063] Example 3

[0064] A low-carbon cementitious material for concrete roads is mainly made of the following raw materials by mass fraction:

[0065] 60 parts of mineral powder (specific surface area 450 m 2 / kg) ;

[0066] 18 parts of red mud from electrolytic aluminum (specific surface area 420 m 2 / kg) ;

[0067] 12 parts of steel slag micro-powder (specific surface area 600 m 2 / kg) ;

[0068] 7 parts of waste concrete powder;

[0069] 2 parts of composite activator;

[0070] The mineral powder is the mineral powder in GB / T 18046-2017 “Ground Granulated Blast Furnace Slag for Use in Cement, Mortar and Concrete”;

[0071] The steel slag is a byproduct generated during the steelmaking process, mainly composed of various oxides formed by the oxidation of impurities such as silicon, manganese, phosphorus, sulfur, etc. in pig iron during the smelting process, and salts generated by the reaction of these oxides with solvents. Steel slag micro-powder is a powder obtained by grinding steel slag;

[0072] The waste concrete powder is the powder left after the preparation of recycled aggregate from crushed concrete, with a specific surface area of 400 m 2 / kg of particles after grinding;

[0073] The composite activator is composed of a 1.4% Na2SO4 solution, CaSO4, triethanolamine, monoethanolamine, and N-methyl diethanolamine in a mass ratio of 1:2:3:2:2.

[0074] The preparation method of the low-carbon cementitious material for concrete roads includes the following specific steps:

[0075] (1) The above raw materials by mass fraction and 6 parts of 28% ammonia water are simultaneously added to a sealed ammonia gas stirring tank, the gas pressure in the sealed ammonia gas tank is controlled at 0.3 MPa, and the stirring is started at 10 r / min;

[0076] (2) High-frequency ultrasound of 80 kHz is applied to the material in step (1) for continuous stirring for 2.5 hours;

[0077] (3) After the material in step (2) is taken out, it is dried at 100°C under the condition of ammonia gas being evacuated to obtain a low-carbon cementitious material.

[0078] Performance detection: low-carbon cementitious materials of examples 1-3 are used to replace cement to prepare concrete respectively, and the concrete mix proportion is 360 kg / m 3 of cementitious material, sand ratio 45%, water-cement ratio 0.45, and polycarboxylic acid water reducer is the recommended dosage (1% of the cementitious material). The compressive strength of the concrete is detected according to the provisions of GB / T 50081-2019 "Standard Test Methods for Physical and Mechanical Properties of Concrete", and the performance indicators of frost resistance (mass loss rate of freeze-thaw cycle), carbonation depth and shrinkage rate of the concrete are detected according to GB / T 50082-2024 "Standard Test Methods for Long-term Performance and Durability of Concrete".

[0079] The performance of the concrete prepared by the low-carbon cementitious materials of examples 1-3 is shown in table 1.

[0080] Table 1 Performance indicators of the concrete prepared by the low-carbon cementitious materials of examples 1-3

[0081]

[0082] As can be seen from table 1, the performance of the concrete prepared by the low-carbon cementitious materials of examples 1-3 is better than that of the concrete prepared by cement-based materials, the compressive strength is higher, the mass loss rate after 100 freeze-thaw cycles is lower, and the carbonation depth and 28d shrinkage rate are smaller.

[0083] Comparative example 1

[0084] The difference from example 3 is that the specific surface area of the mineral powder is 300 m 2 / kg.

[0085] Comparative example 2

[0086] The difference from example 3 is that the specific surface area of the electrolytic aluminum red mud is 300 m 2 / kg.

[0087] Comparative example 3

[0088] The difference from example 3 is that the specific surface area of the steel slag micro-powder is 400 m 2 / kg.

[0089] Comparative example 4

[0090] The difference from example 3 is that the specific surface area of the waste concrete powder is 200 m 2 / kg.

[0091] The low-carbon gel materials of Comparative Examples 1-4 were used to prepare concrete, and the concrete mix ratio was the same as above. The performance of the concrete prepared by the low-carbon gel materials of Comparative Examples 1-4 was detected, and the results are shown in Table 2.

[0092] Table 2 Performance index of concrete prepared by low-carbon gel materials of Comparative Examples 1-4

[0093]

[0094] As shown in Table 2, when the specific surface area of the raw materials used in the preparation of the low-carbon gel material is small and the particle size is large, the compressive strength, frost resistance, durability, and volume stability of the concrete prepared by the low-carbon gel material decrease.

[0095] Comparative Example 5

[0096] The difference from Example 3 is that no monoethanolamine is added to the composite activator.

[0097] Comparative Example 6

[0098] The difference from Example 3 is that no N-methyldiethanolamine is added to the composite activator.

[0099] Comparative Example 7

[0100] The difference from Example 3 is that the composite activator is composed of Na2SO4 solution, CaSO4, triethanolamine, monoethanolamine, and N-methyldiethanolamine, which are uniformly mixed in a mass ratio of 1:2:3:5:5.

[0101] The low-carbon gel materials of Comparative Examples 5-7 were used to prepare concrete, and the concrete mix ratio was the same as above. The performance of the concrete prepared by Comparative Examples 5-7 was detected, and the results are shown in Table 3.

[0102] Table 3 Performance index of concrete prepared by low-carbon gel materials of Comparative Examples 5-7

[0103]

[0104] As shown in Table 3, Comparative Examples 5-6 lack monoethanolamine and N-methyldiethanolamine, and the mechanical properties of the concrete prepared by the gel material decrease, and the durability such as frost resistance and carbonation resistance decreases. This is mainly because the lack of different alcohol amine components makes it impossible to form a stable alkalinity during the alkaline activation and high-frequency ultrasonic activation process, resulting in a decrease in the synergistic effect of alkaline activation and high-frequency ultrasonic activation, and a decrease in the performance of the low-carbon gel material. The excessive amount of monoethanolamine and N-methyldiethanolamine in Comparative Example 7 also causes a decrease in the synergistic effect, although the mechanical properties do not decrease much, but the shrinkage rate increases.

[0105] Comparative Example 8

[0106] The difference from Example 3 is that the preparation method step (1) does not use ammonia water soaking and does not use an ammonia gas sealed environment.

[0107] The low-carbon cementing material of Comparative Example 8 is used to prepare concrete, and the concrete mix ratio is the same as above. The performance of the concrete prepared by Comparative Example 8 is detected, and Table 4 shows the results.

[0108] Table 4 Performance index of concrete prepared by low-carbon cementing material of Comparative Example 8

[0109]

[0110] As can be seen from Table 4, the preparation method of Comparative Example 8 lacks ammonia water soaking and ammonia gas environment, resulting in a decrease in the mechanical properties and durability of the cementing material. Because the purpose of mixing the material with ammonia water and placing it in a sealed ammonia gas environment with pressure during the preparation process is to ensure that the material is fully eroded by the alkaline environment, under this condition, the ultrasonic wave is used to break the particles of the pozzolan, increase the specific surface area, and accelerate the contact between the alkaline substances and the mineral surface. At the same time, the shock wave generated by the collapse of the cavitation bubble promotes the expansion of the crystal lattice defects and the directional stripping of the inert ingredients. In addition, the local high temperature generated by the ultrasonic wave promotes the rapid cooling of the dissolved silicate and aluminate, forming a high-activity amorphous structure.

[0111] Comparative Example 9

[0112] The difference from Example 3 is that the preparation method step (2) does not apply high-frequency ultrasonic waves.

[0113] The low-carbon cementing material of Comparative Example 9 is used to prepare concrete, and the concrete mix ratio is the same as above. The performance of the concrete prepared by Comparative Example 9 is detected, and Table 5 shows the results.

[0114] Table 5 Performance index of concrete prepared by low-carbon cementing material of Comparative Example 9

[0115]

[0116] As can be seen from Table 5, the lack of high-frequency ultrasonic excitation in Comparative Example 9 results in a decrease in the mechanical properties and durability of the concrete prepared by the cementing material.

[0117] Comparative Example 10

[0118] The difference from Example 3 is that the preparation method step (3) is air-dried at room temperature.

[0119] The low-carbon cementing material of Comparative Example 10 is used to prepare concrete, and the concrete mix ratio is the same as above. The performance of the concrete prepared by Comparative Example 10 is detected, and Table 6 shows the results.

[0120] Table 6 Performance index of concrete prepared by low-carbon cementing material of Comparative Example 10

[0121]

[0122] As can be seen from Table 6, the low-carbon gel material of Comparative Example 10 is dried at room temperature, and the mechanical properties and durability of the gel material decrease. This is because under this temperature condition, the activation of the material activity can be further promoted, which is conducive to the continuous progress of the activation process, and at the same time, the residual ammonia gas is removed.

Claims

1. A low-carbon cementitious material for concrete roads, characterized by, It is mainly made of the following raw materials by mass fraction: 50-65 parts of mineral powder; 15-20 parts of electrolytic aluminum red mud; 10-15 parts of steel slag micro powder; 5-10 parts of waste concrete powder; 1-3 parts of composite activator; The composite activator is composed of Na2SO4 solution, CaSO4, triethanolamine, monoethanolamine and N-methyl diethanolamine according to 1:(1-3):(2-4):(1-3):(1-3).

2. The low carbon gel material of claim 1, wherein, The concentration of the Na2SO4 solution is 1%-2%.

3. The low carbon gel material of claim 1, wherein, The specific surface area of the mineral powder is 400-600 m 2 / kg.

4. The low carbon gel material of claim 1, wherein, The specific surface area of the electrolytic aluminium red mud is 350-500 m 2 / kg.

5. The low carbon gel material of claim 1, wherein, The specific surface area of the steel slag micropowder is 500-800 m 2 / kg.

6. The low carbon gel material of claim 1, wherein, The specific surface area of the waste concrete powder is 300-500 m 2 / kg.

7. A method for producing the low-carbon gel material for concrete roads according to any one of claims 1 to 6, characterized by, It comprises the following steps: (1) Put the above raw materials by mass fraction and 5-10 mass fraction of ammonia water with a concentration of 25%-28% into a sealed ammonia gas at the same time, control the gas pressure at 0.2-0.4 MPa, and start stirring at a speed of 5-20 r / min; (2) Apply high-frequency ultrasonic waves of 60-100 kHz to the materials in step (1) for continuous stirring for 2-3 h; (3) Evacuate the ammonia gas, take out the materials in step (2), and dry them at 80-120 ℃ to obtain a low-carbon cementitious material.

8. Use of the low-carbon cementitious material according to any one of claims 1-6 in the preparation of concrete.

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