Early strength admixture for ballastless track concrete sleeper and preparation method thereof

Abstract

The invention specifically discloses an early strength admixture for a ballastless track concrete sleeper, which comprises 20-50 wt% of an early strength guarantee component A, 15-40 wt% of a later strength guarantee component B, 5-15 wt% of an industrial solid waste component C, 15-25 wt% of a high temperature activity guarantee component D, 0-5 wt% of an expansion component E and 0-5 wt% of an excitation component F. The industrial solid waste component C comprises modified lithium slag. According to the method, the industrial solid waste component C is used for modifying the lithium slag, the potential negative effect of the lithium slag is eliminated in a manner of adding the modified material and autoclaving, and a new manner is provided for consumption of the industrial solid waste. On the basis of a traditional admixture, early strength, later strength, high-temperature activity guarantee, expansion and excitation components are effectively integrated together, the respective effects of the components are exerted, and the prepared product meets the requirements in TBT 3397-2015 CRTS double-block ballastless track concrete sleepers.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to an early strength admixture for ballastless track concrete sleepers and a preparation method thereof. Background Art

[0002] Ballastless track concrete sleepers are important components of high-speed railway track structures. Due to their use environment and conditions, they are not only subjected to continuous impact loads from trains, but also to rain, freeze-thaw and chemical corrosion, making them one of the most vulnerable components in the track structure. Replacing part of the cement with mineral admixtures such as fly ash and slag powder is a common method in the current sleeper concrete mix design process. However, in order to compensate for the early strength loss, the amount of cementitious materials will be appropriately increased, which not only increases the production cost, but also increases the risk of product cracking.

[0003] To this end, the use of liquid early-strength admixtures as a means of regulation has been promoted and applied to a certain extent. It can compensate for the loss of early strength of sleeper concrete to a certain extent. However, on the one hand, the performance of mineral admixtures such as slag powder and fly ash fluctuates, and the concrete formulas of various sleeper manufacturers are different, resulting in unstable early-strength effects in concrete, and may even cause the concrete's later strength to shrink. On the other hand, the liquid properties of early-strength admixtures force companies to add additional equipment modification costs when using them, so their application has strong limitations.

[0004] Therefore, research on powder early-strength admixtures that meet the requirements of sleeper production standards and have both early strength and stable admixture performance is of great significance for improving the quality of sleeper products, reducing production costs and increasing the recognition of sleeper companies. Summary of the invention

[0005] The purpose of the present invention is to provide an early-strength admixture for ballastless track concrete sleepers and a preparation method thereof. The prepared early-strength admixture has stable product performance and early-strength effect, can significantly reduce the production cost of sleeper enterprises, improve product quality and the product is easy to industrialize and promote.

[0006] The early strength admixture for ballastless track concrete sleepers provided by the present invention adopts the following technical solution: An early strength admixture for ballastless track concrete sleepers comprises 20% to 50wt% of an early strength guarantee component A, 15% to 40wt% of a later strength guarantee component B, 5% to 15wt% of an industrial solid waste component C, 15% to 25wt% of a high temperature activity guarantee component D, 0 to 5wt% of an expansion component E and 0 to 5wt% of an excitation component F, wherein the industrial solid waste component comprises modified lithium slag.

[0007] Preferably, the early strength guarantee component A comprises silicate cement with a specific surface area of ​​≧500m 2 / kg, D50≦8μm, the silicate cement is obtained by grinding PO 52.5 cement, and 0.1%wt~0.5wt% of alcoholamines are added during the grinding process, and the alcoholamines include one or more of triethanolamine, methyldiethanolamine, diethanol monoisopropanolamine, and triisopropanolamine; further, the alcoholamines include one or more of triethanolamine and methyldiethanolamine, and further, the alcoholamines include methyldiethanolamine, and the amount thereof is 0.3wt%. Compared with ordinary admixtures, cement has poor grindability, especially when the specific surface area exceeds 350m 2 / kg, further grinding becomes more difficult. Alcoholamines can reduce the electrostatic adsorption and agglomeration phenomenon in the cement grinding process, increase the repulsion between particles, prevent the agglomeration of fine cement particles, and effectively improve the grinding efficiency. At the same time, since alcoholamines have the effect of complexing metal cations and dissolving clinker particles, they also promote the formation of early hydration products to a certain extent and improve the early strength.

[0008] Preferably, the late strength guarantee component B comprises slag powder, the specific surface area of ​​which is ≥ 700 m 2 / kg, D50≦6μm, 28d mortar activity (50% dosage)≧140%; slag powder as a traditional admixture has high activity in the later period but low strength in the early period due to its high calcium content and volcanic ash effect; the present invention improves the contact area between slag powder and the reaction product through ultra-fine grinding, which can weaken the disadvantage of reduced early strength while ensuring improved strength in the later period.

[0009] Preferably, the modified lithium slag comprises 85% to 96wt% of lepidolite slag, 0 to 5wt% of quicklime, 0 to 5wt% of surfactant, and 0 to 5wt% of drag reducer, wherein the lepidolite slag is the residue after lithium extraction from lepidolite ore by acid method, and the specific surface area of ​​the modified lithium slag is ≥750m 2 / kg, 28d mortar activity (30% dosage) ≥ 90%, the specific surface area of ​​quicklime ≥ 300m 2 / kg.

[0010] Preferably, the surfactant includes one or more of dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and dioctadecyltrimethylammonium chloride, and the drag reducer includes one or more of polylauryl acrylate, polytetradecyl acrylate, polyhexadecyl acrylate, and polyoctadecyl acrylate.

[0011] Lepidolite slag is the residue after roasting, grinding, soaking and washing of lepidolite ore. It contains trace amounts of LiCO3, which can increase the contact probability between liquid phase ions, shorten the hydration induction period, accelerate the hydration process of clinker minerals, promote the formation of hydration products, and improve early strength. In the modification process, quicklime is added as an alkaline activator, so that the lepidolite slag can further react to generate tobermorite under high temperature and high pressure conditions, increase the non-crystalline phase content of the lepidolite slag, and improve its volcanic ash activity. At the same time, the generated product can also play a role as a crystal nucleus after ultrafine grinding to improve early activity. Due to acid melting, the lepidolite slag has a large number of pores inside, resulting in a high water demand. Generally, surfactants are added to improve the condition. However, under traditional methods, surfactants cannot be well adsorbed with the lepidolite slag. Under high temperature and high pressure conditions, the compatibility between the two is well improved, and the surface modifier can be well adsorbed and penetrated, and the improvement effect is greatly improved. At the same time, the drag reducer is used together, and the synergistic effect of the two effectively reduces the water demand of the lepidolite slag.

[0012] Further preferably, the modified lithium slag comprises: 90-96wt% lepidolite slag, 4wt% quicklime, 0-3wt% surfactant, 0-3wt% drag reducer, wherein the hexadecyl surfactant comprises trimethylammonium chloride, and the drag reducer comprises hexadecyl polyacrylate.

[0013] Preferably, the method for preparing the modified lithium slag comprises the following steps: Step 1, adding lithium mica slag, quicklime, surfactant and drag reducer into a mixer according to the proportion, and then adding an appropriate amount of water to stir the mixture evenly, and filtering to obtain a modified lithium slag intermediate; Step 2: placing the modified lithium slag intermediate obtained in step 1 in an autoclave device, autoclave reaction for 4 to 6 hours, to obtain a modified lithium slag solid body; the autoclave reaction temperature is 180° C. to 210° C., and the autoclave reaction pressure is 0.7 to 1.2 MPa; Step 3: crush and grind the modified lithium slag solid body after the autoclave in step 2 to D50≦7μm to obtain the modified lithium slag.

[0014] Preferably, in the above modified lithium slag preparation method, step 2 is to place the modified lithium slag intermediate obtained in step 1 in an autoclave device, autoclave for 5 hours to obtain a modified lithium slag solid body; the autoclave reaction temperature is 190° C., and the autoclave reaction pressure is 1.0 MPa; Preferably, the high temperature activity guarantee component D comprises semi-densified silica fume with a purity greater than 98% and a specific surface area of ​​not less than 200m 2 / g, particle size is not more than 200nm; nano-scale silica fume can act as a crystal nucleus in the cement hydration process, reduce the nucleation barrier of hydration products, and promote the hydration reaction. At the same time, its high-temperature activity can also ensure that the strength of ballastless track concrete sleepers is effectively increased after steam curing.

[0015] Preferably, the expansion component E includes one or more of calcium oxide or magnesium oxide; further, the expansion component E is a mixture of calcium oxide and magnesium oxide at a mass ratio of 1:0.2-0.4; ballastless track concrete sleepers are generally cured by steam. Due to the rapid development of early concrete strength, cracks will inevitably occur inside and outside the sleepers. Magnesium oxide and calcium oxide, two expansion agents, can react with cement hydration products to generate expansion products, effectively reducing the risk of cracks. Calcium oxide mainly works in the early stage of hydration, while magnesium oxide works in the late stage of hydration. The combination of the two can better inhibit the generation of cracks in ballastless track concrete sleepers.

[0016] Preferably, the exciting component F includes one or more of sodium sulfate, sodium thiocyanate, and calcium formate; further, the exciting component is sodium thiocyanate; after the hydrolysis of sodium thiocyanate, the lone pair electron atomic volume of the thiocyanate group is large, the electronegativity is small, the constraint on the valence electrons is small, and the polarizability is large. Its polarization effect can promote the rupture of the hydration product coating film on the surface of the clinker particles, thereby shortening the cement hydration induction period, and also accelerates the dissolution of the clinker particles, generating more hydration products such as hydrated calcium silicate (CSH) and high-sulfur hydrated calcium sulfoaluminate (AFt) within the same hydration time, thereby improving the early strength of cement.

[0017] The present invention also provides a method for preparing the above-mentioned early strength admixture for ballastless track concrete sleepers: early strength guarantee component A, late strength guarantee component B, industrial solid waste component C, high temperature activity guarantee component D, expansion component E, and excitation component F are mixed and stirred evenly to obtain the early strength admixture for ballastless track concrete sleepers.

[0018] In summary, the present invention includes at least one of the following beneficial technical effects: 1. On the basis of traditional admixtures, the early strength, late strength, high temperature activity guarantee, expansion and excitation components are effectively integrated together to give full play to their respective functions. The prepared products meet the requirements of TBT 3397-2015 "CRTS Double-Block Ballastless Track Concrete Sleepers"; 2. The present invention adds alcohol amines during the grinding process of silicate cement, the early strength guarantee component A, and sodium thiocyanate, the stimulating component F. Both substances have a significant stimulating effect on early strength. The invention adopts an organic and inorganic combination method to avoid the problems of steel bar corrosion, later strength reduction, poor compatibility with cement, and frost on the concrete surface caused by the use of traditional chloride early strength agents and sulfate early strength agents. 3. The present invention uses industrial solid waste component C to modify lithium slag, and eliminates the potential negative effects of lithium slag by adding modified materials and pressure steaming, thus providing a new way for the disposal of such industrial solid waste; 4. The early strength agent and admixture are effectively integrated into one product, so that sleeper companies can obtain products with excellent performance and avoid the cost of equipment transformation, which has a high degree of corporate recognition. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In the following examples and comparative examples, unless otherwise specified, the early strength admixture for ballastless track concrete sleepers is prepared according to the following raw materials and preparation methods.

[0021] Preparation method of industrial solid waste component C modified lithium slag: Step 1, adding lithium mica slag, quicklime, surfactant and drag reducer into a mixer according to the proportion, and then adding an appropriate amount of water to stir the mixture evenly, and filtering to obtain a modified lithium slag intermediate; Step 2: placing the modified lithium slag intermediate obtained in step 1 in an autoclave device, autoclave reaction for 4 to 6 hours, to obtain a modified lithium slag solid body; the autoclave reaction temperature is 180° C. to 210° C., and the autoclave reaction pressure is 0.7 to 1.2 MPa; Step 3: crush and grind the modified lithium slag solid body after the autoclave in step 2 to D50≦7μm to obtain the modified lithium slag.

[0022] Ballastless track concrete sleeper preparation method: The early strength guarantee component A, the later strength guarantee component B, the industrial solid waste component C, the high temperature activity guarantee component D, the expansion component E, and the excitation component F are mixed and stirred evenly to obtain the early strength admixture for ballastless track concrete sleepers. The early strength guarantee component A used is ultrafine silicate cement with a specific surface area of ​​≧500m 2 / kg, D50≦8μm; the late strength guarantee component B is ultra-fine slag powder, with a specific surface area of ​​​​≥700m 2 / kg, D50≦6μm, 28d mortar activity (50% dosage)≧140%; industrial solid waste component C is prepared according to the above method; high temperature activity guarantee component D is semi-densified silica fume, with a purity greater than 98% and a specific surface area of ​​not less than 200m 2 / g, particle size is not greater than 200nm; expansion component E is one or more of calcium oxide or magnesium oxide; excitation component F is one or more of sodium sulfate, sodium thiocyanate, and calcium formate. Different embodiments and comparative examples use different specific proportions.

[0023] Example 1 The early strength admixture for ballastless track concrete sleepers provided in this embodiment is prepared by mixing and stirring 25wt% of early strength guarantee component A ultrafine silicate cement, 40wt% of late strength guarantee component B ultrafine slag powder, 10wt% of industrial solid waste component C modified lithium slag, 15wt% of high temperature activity guarantee component D semi-densified silica fume, 5wt% expansion component E, and 5wt% of exciting component F sodium thiocyanate. 0.3wt% methyldiethanolamine is added during the grinding process of early strength guarantee component A, the expansion component E is a mixture of calcium oxide and magnesium oxide at a mass ratio of 1:0.3, and the exciting component F is sodium thiocyanate.

[0024] The proportion of each raw material of the industrial solid waste component C modified lithium slag is: 90wt% lithium mica slag, 4wt% quicklime, 3wt% hexadecyltrimethylammonium chloride, 3wt% polyacrylate hexadecyl. In the preparation process of industrial solid waste component C, in step 2, the modified lithium slag intermediate obtained in step 1 is placed in an autoclave device, autoclaved for 5 hours, and a modified lithium slag solid body is obtained; the autoclave reaction temperature is 190°C, and the autoclave reaction pressure is 1.0Mpa. It is recorded as FH1.

[0025] Example 2 The early strength guarantee component A, ultrafine silicate cement, is changed to 40wt%, and the late strength guarantee component B, ultrafine slag powder, is changed to 25wt%. The rest is the same as in Example 1, and is denoted as FH2.

[0026] Example 3 The weight of hexadecyltrimethylammonium chloride, hexadecyl polyacrylate and lepidolite residue were changed to 0 wt %, 96 wt % and the rest were the same as in Example 1, and were recorded as FH3.

[0027] Example 4 The high temperature activity guarantee component D, semi-densified silica fume, is changed to 25wt%, the early strength guarantee component A, ultrafine silicate cement, is changed to 20wt%, and the late strength guarantee component B, ultrafine slag powder, is changed to 35wt%. The rest is the same as in Example 1, and is recorded as FH4.

[0028] Example 5 The expansion component E was changed to 0wt%, the industrial solid waste component C modified lithium slag was changed to 15wt%, and the rest was the same as in Example 1, recorded as FH5.

[0029] Example 6 The exciting component F, sodium thiocyanate, was changed to 0 wt %, the industrial solid waste component C, modified lithium slag, was changed to 15 wt %, and the rest was the same as in Example 1, recorded as FH6.

[0030] Example 7 The early strength admixture for ballastless track concrete sleepers provided in this embodiment is prepared by mixing and stirring 30wt% of early strength guarantee component A ultrafine silicate cement, 40wt% of late strength guarantee component B ultrafine slag powder, 5wt% of industrial solid waste component C modified lithium slag, 20wt% of high temperature activity guarantee component D semi-densified silica fume, 2.5wt% expansion component E, and 2.5wt% of exciting component F sodium thiocyanate. 0.1wt% triethanolamine is added during the grinding process of early strength guarantee component A, the expansion component E is calcium oxide, and the exciting component F is sodium sulfate.

[0031] The proportion of each raw material of the industrial solid waste component C modified lithium slag is: 85wt% lithium mica slag, 5wt% quicklime, 5wt% dodecyltrimethylammonium chloride, 5wt% polyacrylate. In the preparation process of industrial solid waste component C, in step 2, the modified lithium slag intermediate obtained in step 1 is placed in an autoclave, autoclaved for 4 hours to obtain a modified lithium slag solid; the autoclave reaction temperature is 180°C, and the autoclave reaction pressure is 0.7Mpa. It is recorded as FH7.

[0032] Example 8 The early strength admixture for ballastless track concrete sleepers provided in this embodiment is prepared by mixing and stirring 50wt% of early strength guarantee component A ultrafine silicate cement, 15wt% of late strength guarantee component B ultrafine slag powder, 15wt% of industrial solid waste component C modified lithium slag, 18wt% of high temperature activity guarantee component D semi-densified silica fume, 1wt% expansion component E, and 1wt% of excitation component F calcium formate. 0.5wt% diethanol monoisopropanolamine is added during the grinding process of early strength guarantee component A, the expansion component E is magnesium oxide, and the excitation component F is calcium formate.

[0033] The proportion of each raw material of the industrial solid waste component C modified lithium slag is: 90wt% lithium mica slag, 4wt% quicklime, 3wt% dioctadecyltrimethylammonium chloride, 3wt% polytetradecyl acrylate. In the preparation process of industrial solid waste component C, in step 2, the modified lithium slag intermediate obtained in step 1 is placed in an autoclave, autoclaved for 6 hours to obtain a modified lithium slag solid; the autoclave reaction temperature is 210°C, and the autoclave reaction pressure is 1.2Mpa. It is denoted as FH8.

[0034] Example 9 The early strength admixture for ballastless track concrete sleepers provided in this embodiment is prepared by mixing and stirring 35wt% of early strength guarantee component A ultrafine silicate cement, 35wt% of late strength guarantee component B ultrafine slag powder, 8wt% of industrial solid waste component C modified lithium slag, 15wt% of high temperature activity guarantee component D semi-densified silica fume, 3wt% expansion component E, and 4wt% of exciting component F sodium thiocyanate. 0.3wt% triisopropanolamine is added during the grinding process of early strength guarantee component A, the expansion component E is a mixture of calcium oxide: magnesium oxide at a mass ratio of 1:0.2, and the exciting component F is a mixture of sodium thiocyanate and sodium sulfate.

[0035] The proportion of each raw material of the industrial solid waste component C modified lithium slag is: 90wt% lithium mica slag, 4wt% quicklime, 3wt% mixture of hexadecyltrimethylammonium chloride and dodecyltrimethylammonium chloride, 3wt% polyacrylate octadecyl. In the preparation process of industrial solid waste component C, in step 2, the modified lithium slag intermediate obtained in step 1 is placed in an autoclave, autoclaved for 5 hours, and a modified lithium slag solid is obtained; the autoclave reaction temperature is 200°C, and the autoclave reaction pressure is 1.1Mpa. It is denoted as FH9.

[0036] Example 10 The early strength admixture for ballastless track concrete sleepers provided in this embodiment is prepared by mixing and stirring 25wt% of early strength guarantee component A ultrafine silicate cement, 40wt% of late strength guarantee component B ultrafine slag powder, 10wt% of industrial solid waste component C modified lithium slag, 15wt% of high temperature activity guarantee component D semi-densified silica fume, 5wt% expansion component E, and 5wt% of exciting component F sodium thiocyanate. During the grinding process of early strength guarantee component A, a mixture of 0.3wt% methyldiethanolamine and triethanolamine is added, wherein the expansion component E is a mixture of calcium oxide: magnesium oxide at a mass ratio of 1:0.4, and the exciting component F is sodium thiocyanate.

[0037] The proportion of each raw material of the industrial solid waste component C modified lithium slag is: 90wt% lithium mica slag, 4wt% quicklime, 3wt% hexadecyltrimethylammonium chloride, 3wt% polyacrylate hexadecyl and polyacrylate dodecyl mixture. In the preparation process of industrial solid waste component C, in step 2, the modified lithium slag intermediate obtained in step 1 is placed in an autoclave device, autoclaved for 5 hours, and a modified lithium slag solid body is obtained; the autoclave reaction temperature is 190°C, and the autoclave reaction pressure is 1.0Mpa. It is denoted as FH10.

[0038] The early-strength admixture for ballastless track concrete sleepers obtained in Examples 1-6 was tested using the GB / T17671-2021 cement mortar strength test method and the GBT2419-2005 cement mortar fluidity determination method, wherein an equal amount of the early-strength admixture replaced 10% of the benchmark cement, and the benchmark cement without the early-strength admixture was used for comparison. The measurement results are shown in Table 1:

[0039] Table 1 Properties of cement mortar after adding early strength admixtures

[0040] It can be seen from Table 1 that after the early strength admixtures of Examples 1 to 6 are used to replace the benchmark cement, the 1d mortar activity is greater than 125%, the 28d% mortar activity is higher than 100%, and the mortar fluidity ratio is less than 105%, which meets the requirements of TB / T 3397-2015 "CRTS Double-Block Ballastless Track Concrete Sleeper"; and it can be seen from the data of Examples 1 and 2 that after changing the ratio of the early strength guarantee component to the later strength guarantee component in the early strength admixture, the corresponding mortar activity also changes significantly; Example 3 adds surfactants and drag reducers when modifying industrial solid waste, so its water demand is relatively high compared with other examples; No activator is added in Example 6, so its 1d mortar activity is only 115%, which is lower than the standard (≧125%).

[0041] The early strength admixture for the ballastless track concrete sleeper obtained in Example 1-6 was added to C60 concrete at 10% of the mass of the cementitious material for trial preparation, and the concrete was mixed at a temperature of 20°C. The corresponding concrete formula is shown in Table 2. The mixed concrete was formed into a test piece with a size of 150 mm × 150 mm × 150 mm. After molding, it was stopped for 3 hours, heated for 2 hours, kept at a constant temperature of 50°C for 4 hours, and cooled for 3 hours. The 12h demolding strength was tested with reference to GB\T50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete", and the remaining test blocks were continued to be cured under standard curing conditions to the 28d test strength.

[0042] Table 2C60 concrete mix ratio

[0043] The data units in Table 2 are all kg / m 3 The strength data of concrete of each formula and the relevant data of the occurrence of surface cracks in a batch of ballastless track concrete sleepers produced by using the early strength admixture produced by the present invention are shown in Table 3: Table 3 Concrete strength data and sleeper surface cracking data of the experimental group

[0044] It can be seen from Table 1 that after the early strength admixtures of Examples 1 to 6 were used to replace the benchmark cement, the 28d concrete compressive strength far exceeded the design requirements. Except for Example 6 in which no exciting component was added, the 12h strength of the other five examples increased significantly, with the highest increase reaching 15.3%; and Example 3 had the highest 12h strength because of the highest high-temperature active component; the surface of the comparative sleeper was 4 / 100, which was lower than that of the control group in all examples, and the examples with the addition of expansion agent were all 0.

[0045] The above data prove that the concrete early strength agent for ballastless track provided by the present invention meets the relevant requirements of "CRTS double-block ballastless track concrete sleeper". Through the combination of organic and inorganic early strength components, compounding of various guarantee components, targeted stimulation and use of modified components, the early strength is significantly increased without reducing the later strength, and part of the industrial solid waste is consumed, thus avoiding waste of resources and environmental pollution. At the same time, the product is easy to use and has high corporate recognition.

[0046] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An early strength admixture for ballastless track concrete sleepers, characterized in that: The invention comprises 20% to 50wt% of early strength guarantee component A, 15% to 40wt% of late strength guarantee component B, 5% to 15wt% of industrial solid waste component C, 15% to 25wt% of high temperature activity guarantee component D, 0 to 5wt% of expansion component E and 0 to 5wt% of excitation component F, wherein the industrial solid waste component C comprises modified lithium slag.

2. The early strength admixture for ballastless track concrete sleeper according to claim 1, characterized in that: The early strength guarantee component A comprises silicate cement, with a specific surface area of ​​≧500m 2 / kg, D50≦8μm, the silicate cement is prepared by grinding PO 52.5 cement, and 0.1%wt~0.5wt% of alcoholamine substances are added during the grinding process. The alcoholamine substances include one or more of triethanolamine, methyldiethanolamine, diethanol monoisopropanolamine, and triisopropanolamine.

3. The early strength admixture for ballastless track concrete sleeper according to claim 1, characterized in that: The later strength guarantee component B includes slag powder with a specific surface area of ​​≧700m 2 / kg, D50≦6μm, 28d mortar activity (50% dosage)≧140%.

4. The early strength admixture for ballastless track concrete sleeper according to claim 1, characterized in that: The modified lithium slag comprises 85% to 96wt% of lithium mica slag, 0 to 5wt% of quicklime, 0 to 5wt% of a surfactant and 0 to 5wt% of a drag reducer. The specific surface area of ​​the modified lithium slag is ≥ 750m 2 / kg, 28d mortar activity (30% dosage) ≥ 90%, the specific surface area of ​​quicklime ≥ 300m 2 / kg.

5. The early strength admixture for ballastless track concrete sleeper according to claim 4, characterized in that: The surfactant includes one or more of dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and dioctadecyltrimethylammonium chloride, and the drag reducer includes one or more of polylauryl acrylate, polytetradecyl acrylate, polyhexadecyl acrylate, and polyoctadecyl acrylate.

6. The early strength admixture for ballastless track concrete sleeper according to claim 5, characterized in that: The preparation method of the modified lithium slag comprises the following steps: Step 1, adding lithium mica slag, quicklime, surfactant and drag reducer into a mixer according to the proportion, and then adding an appropriate amount of water to stir the mixture evenly, and filtering to obtain a modified lithium slag intermediate; Step 2: placing the modified lithium slag intermediate obtained in step 1 in an autoclave device, autoclave reaction for 4 to 6 hours, to obtain a modified lithium slag solid body; the autoclave reaction temperature is 180° C. to 210° C., and the autoclave reaction pressure is 0.7 to 1.2 MPa; Step 3: crush and grind the modified lithium slag solid body after the autoclave in step 2 to D50≦7μm to obtain the modified lithium slag.

7. The early strength admixture for ballastless track concrete sleeper according to claim 1, characterized in that: The high temperature activity guarantee component D comprises semi-densified silica fume with a purity greater than 98% and a specific surface area of ​​not less than 200m 2 / g, particle size is no more than 200nm.

8. The early strength admixture for ballastless track concrete sleepers according to claim 1, characterized in that: The expansion component E includes one or more of calcium oxide and magnesium oxide.

9. The early strength admixture for ballastless track concrete sleeper according to claim 1, characterized in that: The exciting component F includes one or more of sodium sulfate, sodium thiocyanate and calcium formate.

10. A method for preparing the early strength admixture for ballastless track concrete sleepers according to any one of claims 1 to 9, characterized in that: The method comprises uniformly mixing an early strength guarantee component A, a later strength guarantee component B, an industrial solid waste component C, a high temperature activity guarantee component D, an expansion component E and an excitation component F to prepare an early strength admixture for ballastless track concrete sleepers.

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