Low-alkali, high-strength, anti-crack, anti-freezing and cold-resistant concrete suitable for plateau regions and preparation method thereof

Abstract

The invention relates to the field of building materials, in particular to low-alkali, high-strength, anti-crack, anti-freezing and cold-resistant concrete suitable for plateau areas and a preparation method of the low-alkali, high-strength, anti-crack and anti-freezing and cold-resistant concrete. Comprising 140 to 180 parts of low-alkali reinforced Portland cement, 275 to 360 parts of coarse aggregate, 450 to 580 parts of fine aggregate, 40 to 60 parts of silica powder, 15 to 35 parts of lignin fiber, 1.8 to 3.6 parts of a superplasticizer and 100 parts of water. The concrete suitable for the plateau area is prepared by taking the low-alkali reinforced Portland cement as a main material, and compared with traditional low-alkali cement, the low-alkali reinforced Portland cement prepared by the preparation method disclosed by the invention is applied to the concrete, so that the strength is higher, the crack resistance is stronger, and the cold resistance and freezing resistance are better.

Description

Technical Field

[0001] The invention relates to the field of building materials, and in particular to a low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas and a preparation method thereof. Background Art

[0002] Concrete is a composite material made of cement, aggregate and water in appropriate proportions and hardened after a certain period of time. It is the world's most widely used artificial civil construction material. Concrete has a wide range of raw materials, low cost and good use effect. It is widely used in structures such as houses, roads, military projects, and nuclear power plants. Concrete has the characteristics of abundant raw materials, low price and simple production process, which makes it widely used. At the same time, concrete also has the characteristics of high compressive strength, good durability and a wide range of strength grades. These characteristics make it widely used. It is not only used in various civil engineering projects, but also in the fields of machinery industry, marine development, geothermal engineering, etc., where concrete is also an important material.

[0003] In the plateau areas of western my country, the climate conditions are very harsh, the terrain, landform and hydrogeological conditions are complex, and the fragile ecological environment has brought great challenges to highway construction. The high-quality raw materials that can be used to build asphalt pavements are relatively scarce, which has brought great constraints to local highway construction. In the plateau areas, concrete is mostly in an extremely low temperature environment in the early stage. In this low temperature environment, concrete will solidify and harden slowly. During the hardening process, the internal temperature will be lower than the freezing point, and the liquid water will easily form ice crystals to expand, increase the volume, increase the porosity, and reduce the mechanical properties; the hydration rate is reduced, and the heat released by hydration is reduced, resulting in incomplete hydration of concrete, slow growth of various properties, and failure of concrete to reach the critical strength of antifreeze in the early stage; and the dry environment will aggravate the loss of water inside the concrete, causing concrete shrinkage and crack expansion, resulting in the deterioration of the internal structure of the concrete, reducing the mechanical and durability properties of the concrete, and seriously affecting the quality and service life of the concrete structure. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas and a preparation method thereof.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] In a first aspect, the present invention provides a low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas, which comprises, calculated by weight:

[0007] 140-180 parts of low-alkali reinforced silicate cement, 275-360 parts of coarse aggregate, 450-580 parts of fine aggregate, 40-60 parts of silica powder, 15-35 parts of lignin fiber, 1.8-3.6 parts of high-efficiency water reducer and 100 parts of water.

[0008] Preferably, the coarse aggregate is crushed stone or pebbles with a particle size between 5-10 mm, and the fine aggregate is river sand or sea sand with a particle size between 0.16-4.5 mm.

[0009] Preferably, the density of the silicon powder is 2.65 g / cm 3 , particle size is 100±10μm.

[0010] Preferably, the density of the lignin fiber is 1.3 g / cm 3 , length 6±1mm, diameter 10±2μm.

[0011] Preferably, the high-efficiency water reducer is Type I PCA-DS1 or Type II PCA-DS2 produced by Chongqing Sansheng Industrial Co., Ltd.

[0012] Preferably, the method for preparing the low-alkali reinforced silicate cement comprises:

[0013] S1. Preparation of grinding aid enhancer:

[0014] Weigh p-aminobenzyl alcohol and add it to anhydrous ethanol. After fully stirring to dissolve, add epoxy-polyethylene glycol-acrylamide (EPO-PEG-ACA), heat to reflux, stir and react for 2-5 hours. After the reaction is completed, remove the solvent by vacuum distillation to obtain a grinding enhancer.

[0015] S2. Grinding preparation:

[0016] Weigh low-alkali cement clinker, fly ash and gypsum and mix them into a ball mill. After mixing evenly, add a grinding enhancer and grind them at a speed of 40-80r / min for 20-40min. After the ball milling is completed, sieve to obtain low-alkali enhanced silicate cement.

[0017] Preferably, in S1, the weight average molecular weight (Mw) of epoxy-polyethylene glycol-acrylamide (EPO-PEG-ACA) is 500-2000.

[0018] Preferably, in S1, the mass ratio of p-aminobenzyl alcohol, epoxy-polyethylene glycol-acrylamide and anhydrous ethanol is 0.12-0.36:0.9-2.7:10-20.

[0019] Preferably, in S2, the mass ratio of low-alkali cement clinker, fly ash, gypsum and grinding aid enhancer is 100:8-12:5-10:0.1-0.5.

[0020] Preferably, in the S2, the components of the low-alkali cement clinker, calculated by weight percentage, include: SiO2: 22.67%, CaO: 64.56%, Al2O3: 5.25%, Fe2O3: 3.65%, MgO: 1.59%, K2O: 0.32%, Na2O: 0.22%, SO3: 0.33% and other impurities.

[0021] Preferably, in the S2, the components of gypsum, calculated by weight percentage, include: CaO: 32.32%, SiO2: 0.86%, Al2O3: 0.32%, MgO: 2.07%, SO3: 42.34%, H2O: 18.24% and other impurities.

[0022] Preferably, in S2, the fly ash is Class I fly ash or Class II fly ash.

[0023] Preferably, in S2, the sieving is through a 45 μm square hole sieve, and the sieving residue rate is less than 5%.

[0024] In a second aspect, the present invention provides a method for preparing low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas, comprising the following steps:

[0025] (1) Weigh low-alkali reinforced silicate cement, coarse aggregate, fine aggregate, and silica powder according to weight parts, mix them into a mixer, and mix them evenly to obtain a mixed dry material;

[0026] (2) adding water to the mixed dry material, stirring evenly, then adding lignin fiber and high-efficiency water reducing agent, stirring evenly again, to obtain a mixed wet material;

[0027] (3) After the mixed wet material is passed through a mold or directly laid, it is sprinkled with water and cured for at least 7 days to obtain concrete.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention prepares a concrete suitable for plateau areas, which is prepared by using low-alkali reinforced silicate cement as the main ingredient. Compared with traditional low-alkali cement, the low-alkali reinforced silicate cement prepared by the present invention is applied to concrete, which not only has higher strength, but also has stronger crack resistance and better cold and frost resistance.

[0030] 2. In the preparation process of low-alkali cement, an appropriate amount of alcohol amine is used as a cement additive to improve the fluidity of cement, reduce the heat release of cement, and prolong the setting time of concrete. However, the stability of small molecule alcohol amine is poor, and when the dosage is not well controlled, it will greatly affect the hydration process of cement, resulting in a significant decrease in the strength of concrete, as well as a decrease in performance such as crack resistance and cold resistance. The present invention prepares low-alkali enhanced silicate cement, which is prepared by grinding low-alkali cement clinker, fly ash, and calcium sulfate hydrate as raw materials, adding a grinding aid enhancer as a grinding aid material. Compared with traditional technology, the present invention improves the grinding aid material, and replaces the traditional alcohol amine grinding aid with the reaction product of p-aminobenzyl alcohol and EPO-PEG-ACA. It is found that not only the strength of concrete is enhanced, but also the crack resistance, frost resistance and cold resistance are greatly improved. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. The change or adjustment of the relative relationship thereof shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0032] In order to better understand the above technical scheme, the exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0033] The components of the low-alkali cement clinker used in the embodiment of the present invention, calculated by weight percentage, include: SiO2: 22.67%, CaO: 64.56%, Al2O3: 5.25%, Fe2O3: 3.65%, MgO: 1.59%, K2O: 0.32%, Na2O: 0.22%, SO3: 0.33% and other impurities.

[0034] The components of the gypsum used in the embodiment of the present invention, calculated by weight percentage, include: CaO: 32.32%, SiO2: 0.86%, Al2O3: 0.32%, MgO: 2.07%, SO3: 42.34%, H2O: 18.24% and other impurities.

[0035] The present invention will be further described below in conjunction with the following examples.

[0036] Example 1

[0037] A low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas, calculated by weight, comprising:

[0038] 160 parts of low-alkali reinforced silicate cement, 325 parts of coarse aggregate, 510 parts of fine aggregate, 50 parts of silica powder, 25 parts of lignin fiber, 2.5 parts of high-efficiency water reducer and 100 parts of water.

[0039] Among them, coarse aggregate is crushed stone or pebbles with a particle size between 5-10mm; fine aggregate is river sand or sea sand with a particle size between 0.16-4.5mm; the density of silica powder is 2.65g / cm 3 , particle size is 100±10μm; density of lignin fiber is 1.3g / cm 3 , length is 6±1mm, diameter is 10±2μm; the high-efficiency water reducer is Type I PCA-DS1 of Chongqing Sansheng Industrial Co., Ltd.

[0040] The preparation method of low-alkali reinforced silicate cement comprises:

[0041] S1. Preparation of grinding aid enhancer:

[0042] Weigh p-aminobenzyl alcohol and add it to anhydrous ethanol. After fully stirring and dissolving, add epoxy-polyethylene glycol-acrylamide (EPO-PEG-ACA, Mw is 1000), the mass ratio of p-aminobenzyl alcohol, epoxy-polyethylene glycol-acrylamide and anhydrous ethanol is 0.24:1.8:15, heat to reflux, stir and react for 3 hours, and after the reaction is completed, remove the solvent by reduced pressure distillation to obtain a grinding enhancer;

[0043] S2. Grinding preparation:

[0044] Weigh low-alkali cement clinker, grade I fly ash and gypsum, mix them into a ball mill, mix them evenly, then add a grinding enhancer, the mass ratio of low-alkali cement clinker, fly ash, gypsum and grinding enhancer is 100:10:8:0.3, grind them, the speed is 60r / min, the grinding time is 30min, after the ball milling is completed, pass through a 45μm square hole sieve with a sieve residue rate of less than 5%, and obtain low-alkali enhanced silicate cement.

[0045] The method for preparing the low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas comprises the following steps:

[0046] (1) Weigh low-alkali reinforced silicate cement, coarse aggregate, fine aggregate, and silica powder according to weight parts, mix them into a mixer, and mix them evenly to obtain a mixed dry material;

[0047] (2) adding water to the mixed dry material, stirring evenly, then adding lignin fiber and high-efficiency water reducing agent, stirring evenly again, to obtain a mixed wet material;

[0048] (3) After the mixed wet material is laid on the ground and watered and cured for at least 7 days, the required concrete is obtained.

[0049] Example 2

[0050] A low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas, calculated by weight, comprising:

[0051] 140 parts of low-alkali reinforced silicate cement, 275 parts of coarse aggregate, 450 parts of fine aggregate, 40 parts of silica powder, 15 parts of lignin fiber, 1.8 parts of high-efficiency water reducer and 100 parts of water.

[0052] Among them, the coarse aggregate is crushed stone or pebbles with a particle size between 5-10mm, the fine aggregate is river sand or sea sand with a particle size between 0.16-4.5mm, and the density of silica powder is 2.65g / cm 3 , particle size is 100±10μm, and the density of lignin fiber is 1.3g / cm 3 , length is 6±1mm, diameter is 10±2μm, and the high-efficiency water reducer is Type II PCA-DS2 produced by Chongqing Sansheng Industrial Co., Ltd.

[0053] The preparation method of low-alkali reinforced silicate cement comprises:

[0054] S1. Preparation of grinding aid enhancer:

[0055] Weigh p-aminobenzyl alcohol and add it to anhydrous ethanol. After fully stirring and dissolving, add epoxy-polyethylene glycol-acrylamide (EPO-PEG-ACA, Mw is 500), the mass ratio of p-aminobenzyl alcohol, epoxy-polyethylene glycol-acrylamide and anhydrous ethanol is 0.12:0.9:10, heat to reflux, stir and react for 2 hours, and after the reaction is completed, remove the solvent by reduced pressure distillation to obtain a grinding enhancer;

[0056] S2. Grinding preparation:

[0057] Weigh low-alkali cement clinker, grade II fly ash, and gypsum, mix them into a ball mill, mix them evenly, then add a grinding enhancer, the mass ratio of low-alkali cement clinker, fly ash, gypsum and grinding enhancer is 100:8:5:0.1, grind them, the speed is 40r / min, the grinding time is 20min, after the ball milling is completed, pass through a 45μm square hole sieve with a sieve residue rate of less than 5%, and obtain low-alkali enhanced silicate cement;

[0058] The method for preparing the low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas comprises the following steps:

[0059] (1) Weigh low-alkali reinforced silicate cement, coarse aggregate, fine aggregate, and silica powder according to weight parts, mix them into a mixer, and mix them evenly to obtain a mixed dry material;

[0060] (2) adding water to the mixed dry material, stirring evenly, then adding lignin fiber and high-efficiency water reducing agent, stirring evenly again, to obtain a mixed wet material;

[0061] (3) After the mixed wet material is passed through a mold or directly laid, it is sprinkled with water and cured for at least 7 days to obtain concrete.

[0062] Example 3

[0063] A low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas, calculated by weight, comprising:

[0064] 180 parts of low-alkali reinforced silicate cement, 360 parts of coarse aggregate, 580 parts of fine aggregate, 60 parts of silica powder, 35 parts of lignin fiber, 3.6 parts of high-efficiency water reducer and 100 parts of water.

[0065] Among them, the coarse aggregate is crushed stone or pebbles with a particle size between 5-10mm, the fine aggregate is river sand or sea sand with a particle size between 0.16-4.5mm, and the density of silica powder is 2.65g / cm 3 , particle size is 100±10μm, and the density of lignin fiber is 1.3g / cm 3 , length is 6±1mm, diameter is 10±2μm, and the high-efficiency water reducer is Type I PCA-DS1 of Chongqing Sansheng Industrial Co., Ltd.

[0066] The preparation method of low-alkali reinforced silicate cement comprises:

[0067] S1. Preparation of grinding aid enhancer:

[0068] Weigh p-aminobenzyl alcohol and add it to anhydrous ethanol. After fully stirring and dissolving, add epoxy-polyethylene glycol-acrylamide (EPO-PEG-ACA, Mw is 2000), the mass ratio of p-aminobenzyl alcohol, epoxy-polyethylene glycol-acrylamide and anhydrous ethanol is 0.36:2.7:20, heat to reflux, stir and react for 5 hours, and after the reaction is completed, remove the solvent by reduced pressure distillation to obtain a grinding enhancer;

[0069] S2. Grinding preparation:

[0070] Weigh low-alkali cement clinker, grade I fly ash, and gypsum, mix them into a ball mill, mix them evenly, then add a grinding enhancer, the mass ratio of low-alkali cement clinker, fly ash, gypsum and grinding enhancer is 100:12:10:0.5, grind them, the speed is 80r / min, the grinding time is 40min, after the ball milling is completed, pass through a 45μm square hole sieve with a sieve residue rate of less than 5%, and obtain low-alkali enhanced silicate cement;

[0071] The method for preparing the low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas comprises the following steps:

[0072] (1) Weigh low-alkali reinforced silicate cement, coarse aggregate, fine aggregate, and silica powder according to weight parts, mix them into a mixer, and mix them evenly to obtain a mixed dry material;

[0073] (2) adding water to the mixed dry material, stirring evenly, then adding lignin fiber and high-efficiency water reducing agent, stirring evenly again, to obtain a mixed wet material;

[0074] (3) After the mixed wet material is passed through a mold or directly laid, it is sprinkled with water and cured for at least 7 days to obtain concrete.

[0075] Comparative Example 1

[0076] A concrete, which is different from Example 1 in that the cement used is low-alkali silicate cement, and the grinding aid enhancer used in the preparation of the low-alkali silicate cement is triethanolamine (traditional small molecule alcohol amine), and the rest is the same as Example 1.

[0077] That is, the preparation method of low-alkali silicate cement comprises:

[0078] Weigh low-alkali cement clinker, grade I fly ash and gypsum, mix them into a ball mill, mix them evenly, then add triethanolamine, the mass ratio of low-alkali cement clinker, fly ash, gypsum and triethanolamine is 100:10:8:0.3, grind them, the speed is 60r / min, the grinding time is 30min, after the ball milling is completed, pass through a 45μm square hole sieve with a sieve residue rate of less than 5%, to obtain low-alkali silicate cement.

[0079] Comparative Example 2

[0080] A concrete, which is different from Example 1 in that the cement used is low-alkali silicate cement, the grinding aid and enhancer used in the preparation of the low-alkali silicate cement is p-aminobenzyl alcohol, and the rest is the same as Example 1.

[0081] That is, the preparation method of low-alkali silicate cement comprises:

[0082] Weigh low-alkali cement clinker, grade I fly ash and gypsum, mix them into a ball mill, mix them evenly, then add p-aminobenzyl alcohol, the mass ratio of low-alkali cement clinker, fly ash, gypsum and p-aminobenzyl alcohol is 100:10:8:0.3, grind them, the speed is 60r / min, the grinding time is 30min, after the ball milling, pass through a 45μm square hole sieve with a sieve residue rate of less than 5%, to obtain low-alkali silicate cement.

[0083] Comparative Example 3

[0084] A concrete, which is different from Example 1 in that the cement used is low-alkali silicate cement, and the grinding aid enhancer used in the preparation of the low-alkali silicate cement is epoxy-polyethylene glycol-acrylamide (EPO-PEG-ACA, Mw is 1000), and the rest is the same as Example 1.

[0085] That is, the preparation method of low-alkali silicate cement comprises:

[0086] Weigh low-alkali cement clinker, grade I fly ash and gypsum, mix them into a ball mill, mix them evenly, then add epoxy-polyethylene glycol-acrylamide, the mass ratio of low-alkali cement clinker, fly ash, gypsum and epoxy-polyethylene glycol-acrylamide is 100:10:8:0.3, grind them, the speed is 60r / min, the grinding time is 30min, after the ball milling is completed, pass through a 45μm square hole sieve with a sieve residue rate of less than 5%, and obtain low-alkali silicate cement.

[0087] Experimental testing

[0088] The concrete prepared in Example 1 and Comparative Examples 1-3 was tested for performance, wherein the test standards refer to:

[0089] (1) Compressive strength: GB / T 50081-2016, testing includes 7d and 28d strength;

[0090] (2) Crack resistance (crack resistance grade): JGJ / T 193-2009, the grades are divided into LI, L-II, L-III, L-IV, and LV. The higher the grade, the better the crack resistance.

[0091] (3) Antifreeze property (quick freezing method, antifreeze grade): GB / T 50164-2009, antifreeze grades are divided into nine grades: F50, F100, F150, F200, F250, F300, F350, F400, and >F400. The higher the grade, the better the antifreeze property.

[0092] The experimental test results are shown in Table 1.

[0093] Table 1 Performance of different concrete

[0094] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 7d compressive strength (MPa) 38.7 35.3 33.1 36.5 28d compressive strength (MPa) 52.1 45.7 42.6 49.3 Crack resistance grade L-IV L-III L-Ⅱ L-III Frost resistance level F350 F250 F200 F300

[0095] It can be seen from Table 1 that, compared with Comparative Examples 1-3, the concrete prepared in Example 1 of the present invention not only has high compressive strength in the early stage (7d), but also has better compressive strength in the later stage (28d). In addition, the concrete prepared in Example 1 has better crack resistance and frost resistance, and is more suitable for use in plateau areas.

[0096] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0097] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas, characterized in that: Calculated by weight, including: 140-180 parts of low-alkali reinforced silicate cement, 275-360 parts of coarse aggregate, 450-580 parts of fine aggregate, 40-60 parts of silica powder, 15-35 parts of lignin fiber, 1.8-3.6 parts of high-efficiency water reducer and 100 parts of water.

2. The low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas according to claim 1, characterized in that: The coarse aggregate is crushed stone or pebble with a particle size between 5-10 mm, and the fine aggregate is river sand or sea sand with a particle size between 0.16-4.5 mm.

3. The low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas according to claim 1, characterized in that: The density of the silicon powder is 2.65 g / cm 3 , particle size is 100±10μm; the density of the lignin fiber is 1.3g / cm 3 , length 6±1mm, diameter 10±2μm.

4. The low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas according to claim 1, characterized in that: The high-efficiency water reducing agent is type I PCA-DS1 or type II PCA-DS2.

5. The low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas according to claim 1, characterized in that: The preparation method of the low-alkali reinforced silicate cement comprises: S1. Preparation of grinding aid enhancer: Weigh p-aminobenzyl alcohol and add it to anhydrous ethanol. After fully stirring and dissolving, add epoxy-polyethylene glycol-acrylamide, raise the temperature to reflux, and stir to react for 2-5 hours. After the reaction is completed, remove the solvent by vacuum distillation to obtain a grinding enhancer; S2. Grinding preparation: Weigh low-alkali cement clinker, fly ash and gypsum and mix them into a ball mill. After mixing evenly, add a grinding enhancer and grind them at a speed of 40-80r / min for 20-40min. After the ball milling is completed, sieve to obtain low-alkali enhanced silicate cement.

6. The low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas according to claim 5, characterized in that: In the S1, the weight average molecular weight of epoxy-polyethylene glycol-acrylamide is 500-2000; the mass ratio of p-aminobenzyl alcohol, epoxy-polyethylene glycol-acrylamide and anhydrous ethanol is 0.12-0.36:0.9-2.7:10-20.

7. The low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas according to claim 5, characterized in that: In the S2, the mass ratio of low-alkali cement clinker, fly ash, gypsum and grinding aid enhancer is 100:8-12:5-10:0.1-0.

5.

8. The low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas according to claim 5, characterized in that: In the S2, the components of the low-alkali cement clinker, calculated by weight percentage, include: SiO2: 22.67%, CaO: 64.56%, Al2O3: 5.25%, Fe2O3: 3.65%, MgO: 1.59%, K2O: 0.32%, Na2O: 0.22%, SO3: 0.33% and other impurities.

9. The low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas according to claim 5, characterized in that: In the S2, the components of gypsum, calculated by weight percentage, include: CaO: 32.32%, SiO2: 0.86%, Al2O3: 0.32%, MgO: 2.07%, SO3: 42.34%, H2O: 18.24% and other impurities.

10. A method for preparing low-alkali, high-strength, crack-resistant, frost-resistant and cold-resistant concrete suitable for plateau areas as claimed in claim 1, characterized in that: The following steps are involved: (1) Weigh low-alkali reinforced silicate cement, coarse aggregate, fine aggregate, and silica powder according to weight parts, mix them into a mixer, and mix them evenly to obtain a mixed dry material; (2) adding water to the mixed dry material, stirring evenly, then adding lignin fiber and high-efficiency water reducing agent, stirring evenly again, to obtain a mixed wet material; (3) After the mixed wet material is passed through a mold or directly laid, it is sprinkled with water and cured for at least 7 days to obtain concrete.