A kind of concrete with C80 grade for improving low-temperature toughness and its preparation method

Abstract

The present invention provides a concrete with improved low-temperature toughness at C80 grade and a preparation method thereof, comprising the following raw materials in parts by weight: 330-380 parts of cement, 100-150 parts of admixture, 600-700 parts of fine aggregate, 850-1000 parts of coarse aggregate, 7-10 parts of air-entraining polycarboxylate water reducer, 25-35 parts of toughening agent and water, and the water-binder ratio is 1:0.2-0.28; the air-entraining polycarboxylate water reducer is copolymerized from an alkenyl polyether macromonomer, a monoalkenyl polyol, a monoalkenyl acid compound, and an alkenyl aromatic compound in a mass ratio of 100:10-20:5-10:5-10, and the monoalkenyl polyol is prepared by reacting a glycidyl acrylate compound with a monoamino polyol compound at an epoxy group to amino group molar ratio of 1:1.0-1.05; the toughening agent is an inorganic filler coated with carboxyl-terminated polybutadiene liquid rubber. The concrete provided by the present invention has excellent mechanical properties, especially low-temperature toughness.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete, and particularly relates to a concrete with improved low-temperature toughness at C80 grade and a preparation method thereof. Background Art

[0002] With the continuous development of the construction industry, modern engineering structures are developing towards large-span, super-high-rise, and heavy-load directions. At the same time, special engineering fields such as ocean engineering and nuclear power engineering are emerging continuously. These projects put more stringent requirements on the performance of concrete, and high-strength concrete has emerged and has been widely studied and applied.

[0003] Due to its high strength, high-strength concrete can effectively reduce the size of structural members, thereby increasing the usable space of buildings, reducing the structural self-weight, and improving the stability of the foundation. Improving the strength of concrete is mainly achieved by increasing the amount of cementitious materials and reducing the water-binder ratio. However, a low water-binder ratio will cause the hydration heat of concrete to be released concentratedly in the early stage, while the tensile strength and ultimate tensile strain of concrete are relatively low at this time, which is easy to cause early shrinkage micro-cracks and segregation cracks in concrete, such as the high-performance water reducer for C80 concrete and its preparation method and usage method disclosed in Patent CN103922637B.

[0004] Research shows that adding an appropriate amount of mineral admixture can make the concrete more dense, improve the interfacial transition zone, and also has the function of reducing hydration heat, which can overcome the problems of many early cracks and poor toughness in high-strength concrete. However, its toughness is still not enough to support this high-strength concrete to work in cold and extremely cold regions for a long time. Under the action of low temperature and impact load, the interfacial transition zone is the weak link for crack propagation, and the interfacial transition zone between aggregates and cement paste is still easily damaged, such as a C80 ultra-high pumping concrete and its preparation method disclosed in Patent CN111454033B, including the following raw materials in parts by weight: 270-310 parts of cement; 690-720 parts of sand; 950-990 parts of gravel; 240-260 parts of mineral admixture; 8.5-10.5 parts of polycarboxylate water reducer; 25-56 parts of graphite powder; 10-20 parts of superfine coal gangue powder; 0.0145-0.145 parts of air-entraining agent; 2.4-2.6 parts of activator; and 135-147 parts of water.

[0005] Therefore, it is necessary to further improve the low-temperature toughness of high-strength concrete using mineral admixtures to expand the application of high-strength concrete in different climate regions. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a concrete for improving low-temperature toughness at C80 grade and a preparation method thereof, including an air-entraining polycarboxylate water reducer copolymerized from an alkenyl polyether macromonomer, a monoalkenyl polyol, a monoalkenyl acid compound, and an alkenyl aromatic compound. By controlling the relative proportion of the monoalkenyl polyol with strong hydrophilic action and the alkenyl aromatic compound with lipophilicity in the air-entraining polycarboxylate water reducer, its ability to generate new interfaces is improved, a large number of tiny, uniform, and stable bubbles are introduced during the concrete mixing process, the pore structure of the concrete is adjusted, and the low-temperature toughness is improved; in addition, the toughening agent is an inorganic filler coated with carboxyl-terminated polybutadiene liquid rubber that can produce elastic deformation. When the concrete is subjected to external force or temperature change, the toughening agent can absorb part of the energy and avoid the rapid expansion of cracks, playing a role in synergistically improving the toughness of the concrete.

[0007] To achieve the above object, the following technical solutions are adopted:

[0008] A concrete for improving low-temperature toughness at C80 grade includes the following raw materials: 330-380 parts by weight of cement, 100-150 parts by weight of admixture, 600-700 parts by weight of fine aggregate, 850-1000 parts by weight of coarse aggregate, 7-10 parts by weight of air-entraining polycarboxylate water reducer, 25-35 parts by weight of toughening agent, and water. The mass ratio of the total mass of cement and admixture to the mass of water is 1:0.2-0.28; the air-entraining polycarboxylate water reducer is copolymerized from an alkenyl polyether macromonomer, a monoalkenyl polyol, a monoalkenyl acid compound, and an alkenyl aromatic compound in a mass ratio of 100:10-20:5-10:5-10. The monoalkenyl polyol is prepared by reacting a glycidyl acrylate compound with a monoamino polyol compound at an epoxy group to amino group molar ratio of 1:1.0-1.05; the toughening agent is an inorganic filler coated with carboxyl-terminated polybutadiene liquid rubber.

[0009] The glycidyl acrylate compound is selected from one or a combination of two of glycidyl acrylate and glycidyl methacrylate; the monoamino polyol compound is selected from one or a combination of two or more of tromethamine, 3-amino-1,2-propanediol, 2-aminobutane-1,3-diol, 2-(aminomethyl)-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, and 2-amino-2-ethyl-1,3-propanediol; preferably tromethamine.

[0010] The air-entraining polycarboxylate water reducer is prepared by a method including the following steps:

[0011] 1) Under an inert atmosphere, dissolve the glycidyl acrylate compound and the monoamino polyol compound in an organic solvent, control the temperature for reaction, distill off the organic solvent after the reaction, and separate by column chromatography to obtain the monoalkenyl polyol;

[0012] 2) Under an inert atmosphere, add the alkenyl polyether macromonomer, monoalkenyl polyol, monoalkenyl acid compound, alkenyl aromatic compound, initiator, and chain transfer agent into a reaction kettle, mix evenly, raise the temperature for reaction, cool down after the reaction ends, add water to adjust the solid content, and adjust the pH to obtain an air-entraining polycarboxylate water reducer.

[0013] In step 1), the organic solvent is selected from one or a combination of two or more of methanol, ethanol, and isopropanol. The temperature control is to control the temperature at 25 - 50 °C. The reaction time is 24 - 48 h. The eluent for column chromatography is a mixture of chloroform and methanol with a volume ratio of 1:1 - 10.

[0014] In step 2), the alkenyl aromatic compound is selected from one or a combination of two or more of styrene, allylbenzene, and 3-methylstyrene.

[0015] The number-average molecular weight of the alkenyl polyether macromonomer is 1000 - 1500, and it is selected from one or a combination of two or more of isopentenyl polyoxyethylene ether, methallyl polyoxyethylene ether, ethylene glycol mono vinyl polyethylene glycol ether, and allyl polyoxyethylene ether.

[0016] The monoalkenyl acid compound is selected from one or a combination of two or more of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, allylsulfonic acid sodium salt, methallylsulfonic acid sodium salt, vinylsulfonic acid sodium salt, propenylsulfonic acid sodium salt, methallyl sulfonic acid sodium salt, styrenesulfonic acid sodium salt, p-styrenesulfonic acid sodium salt, and 2-acrylamido-2-methylpropanesulfonic acid.

[0017] In step 2), the initiator is selected from one or a combination of two or more of BPO, cumene hydroperoxide, and tert-butyl hydroperoxide; the dosage of the initiator is 1 - 3 wt% of the total mass of the alkenyl polyether macromonomer, monoalkenyl polyol, monoalkenyl acid compound, and alkenyl aromatic compound. The chain transfer agent is selected from one or a combination of two of mercaptoethanol and dodecyl mercaptan. The dosage of the chain transfer agent is 0.5 - 0.8 wt% of the total mass of the alkenyl polyether macromonomer, monoalkenyl polyol, monoalkenyl acid compound, and alkenyl aromatic compound. The temperature is raised to 60 - 80 °C, and the reaction time is 3 - 5 h. The pH is adjusted to 7 - 9 with an alkali solution, and the alkali solution is selected from one or a combination of two or more of sodium hydroxide solution, sodium carbonate solution, and sodium bicarbonate solution. The solid content is adjusted to 35 - 45 wt% by adding water.

[0018] The air-entraining polycarboxylate water reducer can introduce a large number of tiny, uniform and stable air bubbles during the concrete mixing process. However, a large number of small air bubbles will coalesce or rupture, forming weak points and reducing the compressive strength of the concrete. The use of a toughening agent composed of inorganic filler coated with liquid carboxyl-terminated polybutadiene rubber can synergistically improve the low-temperature toughness of the concrete with the air-entraining polycarboxylate water reducer without reducing the compressive strength.

[0019] The toughening agent is inorganic filler coated with liquid carboxyl-terminated polybutadiene rubber and is prepared by a method including the following steps:

[0020] Add the inorganic filler, liquid carboxyl-terminated polybutadiene rubber, organic solvent, and ball-milling medium into a ball mill, ball-mill to obtain a ball-milled slurry, and filter and dry to obtain the toughening agent.

[0021] The ball-milling medium is zirconia beads with a particle size of 0.1 mm - 0.5 mm. The rotation speed of the ball-milling is 200 - 800 r / min. The ball-milling time is 3 - 5 h. The mass ratio of the sum of the masses of the inorganic filler and the liquid carboxyl-terminated polybutadiene rubber to the mass of the ball-milling medium is 1:20 - 25. The mass ratio of the inorganic filler, liquid carboxyl-terminated polybutadiene rubber, and organic solvent is 5:0.4 - 0.5:10 - 15. The organic solvent is selected from one or a combination of two or more of toluene, benzene, dichloromethane, methyl ethyl ketone, and ethyl acetate. The temperature of the ball-milling is 25 - 50 °C. The drying is carried out at 60 - 80 °C and a vacuum degree of 0.01 - 0.1 MPa for 1 - 3 h.

[0022] The number-average molecular weight of the liquid carboxyl-terminated polybutadiene rubber is 3000 - 5000.

[0023] The average particle size of the inorganic filler is 50 - 100 nm, and it is selected from one or a combination of two or more of silica, calcium carbonate, talcum powder, and magnesium carbonate.

[0024] The admixture is selected from one or a combination of two of fly ash and mineral powder.

[0025] The admixture is a mixture of fly ash and mineral powder with a mass ratio of 1:2 - 5.

[0026] The fly ash is selected from one or a combination of two of Class I fly ash and Class II fly ash.

[0027] The mineral powder is selected from one or a combination of two of S105 grade mineral powder, S95 grade mineral powder, and S75 grade mineral powder.

[0028] The cement is Portland cement with a strength grade of 42.5 to 52.5.

[0029] The fine aggregate is quartz sand with a fineness modulus of 3.0 - 2.3.

[0030] The coarse aggregate is continuously graded gravel with a particle size of 5-20 mm.

[0031] The present invention also provides a method for preparing the above-mentioned C80 grade concrete with improved low-temperature toughness, which includes the following steps:

[0032] Mix cement, admixture, air-entraining polycarboxylate water reducer, toughening agent, and water evenly to obtain a slurry, and then add the coarse aggregate and fine aggregate to the slurry and mix evenly to obtain the C80 grade concrete with improved low-temperature toughness.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The concrete of the present invention includes an air-entraining polycarboxylate water reducer copolymerized from an alkenyl polyether macromonomer, a monoalkenyl polyol, a monoalkenyl acid compound, and an alkenyl aromatic compound. By controlling the relative proportion of the monoalkenyl polyol with strong hydrophilicity and the alkenyl aromatic compound with lipophilicity in the air-entraining polycarboxylate water reducer, the ability to generate new interfaces is improved, and a large number of tiny, uniform, and stable bubbles are introduced during the concrete mixing process to adjust the pore structure of the concrete and improve the low-temperature toughness. In addition, the toughening agent is an inorganic filler coated with a carboxyl-terminated polybutadiene liquid rubber capable of generating elastic deformation. When the concrete is subjected to external impact or temperature change, the toughening agent can absorb part of the energy and prevent the rapid expansion of cracks, playing a role in synergistically improving the toughness of the concrete. Specific Embodiments

[0035] The following further illustrates the present invention with specific embodiments, but it is not limited to the content in the specification. Unless otherwise specified, the "parts" mentioned in the embodiments of the present invention are all parts by weight. The reagents used are all commercially available reagents in the art.

[0036] The number average molecular weight of type I carboxyl-terminated polybutadiene liquid rubber is 5000, purchased from Tianyuan Aviation Materials.

[0037] The number average molecular weight of type II carboxyl-terminated polybutadiene liquid rubber is 3500, purchased from Tianyuan Aviation Materials.

[0038] Allyl polyoxyethylene ether with a number average molecular weight of APEG1500, purchased from Wuhan Xinxin Jiali Biotechnology Co., Ltd.

[0039] Continuously graded gravel with a particle size of 5-20 mm is purchased from Huzhou Xinkaiyuan Gravel Co., Ltd.

[0040] Quartz sand with a fineness modulus of 2.6 is purchased from Fengyang Jihui Quartz Sand Co., Ltd.

[0041] Nano-silica DK-SiO2-60 with an average particle size of 60 nm, purchased from Zhongke Jinyan (Beijing) Technology Co., Ltd.

[0042] Example 1

[0043] 1) Under a nitrogen atmosphere, 1 mol of glycidyl methacrylate and 1 mol of tromethamine were dissolved in ethanol, and the temperature was controlled at 25 °C for reaction. After 48 h of reaction, ethanol was removed by distillation, and column chromatography separation was carried out on a silica gel column. The eluent was a mixture of chloroform and methanol with a volume ratio of 1:3 to obtain a mono-vinyl polyol.

[0044] 2) Under a nitrogen atmosphere, 100 g of APEG1500, 20 g of mono-vinyl polyol, 10 g of acrylic acid, 10 g of styrene, 4.2 g of BPO, and 0.7 g of mercaptoethanol were added to a reaction kettle and mixed evenly. The temperature was raised to 80 °C for reaction for 5 h. After the reaction was completed, the temperature was lowered to room temperature, and water was added to adjust the solid content to 45 wt%. The pH was adjusted to 7 with a 32 wt% sodium hydroxide solution to obtain an air-entraining polycarboxylate superplasticizer.

[0045] 3) 50 g of DK-SiO2-60, 5 g of type I carboxyl-terminated polybutadiene liquid rubber, 150 g of toluene, and zirconia beads with a particle size of 0.2 mm were added to a ball mill. The ball-to-material ratio was 20:1, and ball milling was carried out at 30 °C for 5 h to obtain a ball-milled slurry. After filtration, it was dried at 60 °C and a vacuum degree of 0.08 MPa to obtain a toughening agent.

[0046] 4) 330 parts by mass of Portland cement with a strength grade of 52.5, 150 parts by mass of a blend of class I fly ash and S95 grade blast furnace slag powder mixed at a mass ratio of 1:3, 10 parts by mass of an air-entraining polycarboxylate superplasticizer, 35 parts by mass of a toughening agent, and water accounting for 28 wt% of the sum of the mass of Portland cement and the blend were mixed evenly to obtain a slurry. 1000 parts by mass of continuously graded gravel and 600 parts by mass of quartz sand with a fineness modulus of 2.6 were added to the slurry and mixed evenly to obtain C80 grade concrete with improved low-temperature toughness.

[0047] Example 2

[0048] The rest was the same as in Example 1, except that in step 4), the dosage of the air-entraining polycarboxylate superplasticizer was 7 parts by mass.

[0049] Example 3

[0050] The rest was the same as in Example 1, except that in step 2), the dosage of the mono-vinyl polyol was 10 g.

[0051] Example 4

[0052] The rest was the same as in Example 1, except that in step 2), the dosage of styrene was 5 g.

[0053] Example 5

[0054] The rest is the same as in Example 1, except that in step 4), the amount of the toughening agent is 25 parts by mass.

[0055] Example 6

[0056] The rest is the same as in Example 1, except that in step 1), 3-amino-1,2-propanediol in an equimolar amount is used to replace tromethamine.

[0057] Example 7

[0058] The rest is the same as in Example 1, except that in step 3), type II carboxyl-terminated polybutadiene liquid rubber with the same mass is used to replace type I carboxyl-terminated polybutadiene liquid rubber.

[0059] Example 8

[0060] 1) Under a nitrogen atmosphere, 1 mol of glycidyl methacrylate and 1.05 mol of tromethamine are dissolved in ethanol, and the temperature is controlled at 25 °C for reaction. After 48 h of reaction, ethanol is removed by distillation, and column chromatography separation is carried out on a silica gel column. The eluent is a mixture of chloroform and methanol with a volume ratio of 1:3 to obtain monoalkenyl polyol.

[0061] 2) Under a nitrogen atmosphere, 100 g of APEG1500, 10 g of monoalkenyl polyol, 5 g of acrylic acid, 10 g of allylbenzene, 3.75 g of BPO, and 0.625 g of mercaptoethanol are added to a reaction kettle and mixed evenly. The temperature is raised to 80 °C for reaction for 5 h. After the reaction is completed, the temperature is lowered to room temperature, water is added to adjust the solid content to 45 wt%, and the pH is adjusted to 7 with 32 wt% sodium hydroxide solution to obtain an air-entraining polycarboxylate superplasticizer.

[0062] 3) 50 g of DK-SiO2-60, 4 g of type I carboxyl-terminated polybutadiene liquid rubber, 100 g of toluene, and 1080 g of zirconia beads with a particle size of 0.3 mm are added to a ball mill, and ball milling is carried out at 30 °C for 5 h to obtain a ball-milled slurry. After filtration, drying is carried out at 60 °C and a vacuum degree of 0.08 MPa to obtain a toughening agent.

[0063] 4) 380 parts by mass of Portland cement with a strength grade of 52.5, 100 parts by mass of a admixture composed of class I fly ash and S95 grade blast furnace slag mixed at a mass ratio of 1:2, 10 parts by mass of the air-entraining polycarboxylate superplasticizer, 35 parts by mass of the toughening agent, and water accounting for 28 wt% of the sum of the mass of Portland cement and the admixture are mixed evenly to obtain a slurry. 850 parts by mass of continuously graded crushed stone and 700 parts by mass of quartz sand with a fineness modulus of 2.6 are added to the slurry and mixed evenly to obtain C80 grade concrete with improved low-temperature toughness.

[0064] Comparative Example 1

[0065] The rest is the same as in Example 1, except that in step 2), hydroxyethyl acrylate of equal mass is used to replace the mono-vinyl polyol.

[0066] After the concrete prepared in the above examples and comparative examples was cured under standard conditions for 28 days, the following performance tests were carried out:

[0067] Compressive strength and flexural strength: The tests were carried out with reference to the Standard Test Method for Mechanical Properties of Ordinary Concrete GB / T50081-2002.

[0068] Low-temperature toughness: The tests were carried out with reference to the Standard Test Method for Long-term Performance and Durability of Ordinary Concrete GB / T50082-2009. Freeze-thaw cycles (rapid freezing method) were carried out at -20°C / 2 h and 20°C / 2 h, and repeated 200 times. After the freeze-thaw cycles, heat treatment was carried out in an oven at 40°C for 24 h, and then the flexural strength test was carried out again, and the strength loss rate was calculated.

[0069] Table 1 Test results of performance

[0070]

[0071] It can be seen from the flexural strength test in Table 1 that the concrete prepared by the present invention has good low-temperature toughness. The air-entraining polycarboxylate water reducer has a great influence on the room-temperature toughness of the concrete, and the toughening agent has a great influence on the low-temperature toughness of the concrete. The two have an obvious synergistic effect in improving toughness.

[0072] It can be seen from the test results of compressive strength performance that the toughening agent can improve the toughness of the concrete on the premise that the air-entraining water reducer does not excessively reduce the compressive strength.

[0073] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification without departing from the present invention shall be included within the scope of the technical solution of the present invention.

Claims

1. A concrete of C80 grade with improved low-temperature toughness, characterized in that, It includes the following raw materials in parts by weight: 330 - 380 parts of cement, 100 - 150 parts of admixture, 600 - 700 parts of fine aggregate, 850 - 1000 parts of coarse aggregate, 7 - 10 parts of air-entraining polycarboxylate superplasticizer, 25 - 35 parts of toughening agent and water. The mass ratio of the total mass of cement and admixture to the mass of water is 1:0.2 - 0.28; the toughening agent is inorganic filler coated with carboxyl-terminated polybutadiene liquid rubber; The air-entraining polycarboxylate superplasticizer is prepared by the following method steps: 1) Under an inert atmosphere, glycidyl acrylate compounds and monoamino polyol compounds are dissolved in an organic solvent according to a molar ratio of epoxy group to amino group of 1:1.0 - 1.05, the temperature is controlled for reaction, after the reaction is completed, the organic solvent is removed by distillation, and column chromatography separation is carried out to obtain monoalkenyl polyol; 2) Under an inert atmosphere, alkenyl polyether macromonomer, monoalkenyl polyol, monoalkenoic acid compounds, alkenyl aromatic compounds, initiator, and chain transfer agent with a mass ratio of 100:10 - 20:5 - 10:5 - 10 are added to the reaction kettle and mixed evenly, the temperature is raised for reaction, after the reaction is completed, the temperature is lowered, water is added to adjust the solid content, and the pH is adjusted to obtain the air-entraining polycarboxylate superplasticizer; The glycidyl acrylate compounds are selected from one or a combination of two of glycidyl acrylate and glycidyl methacrylate; The monoamino polyol compounds are selected from one or a combination of two or more of tromethamine, 3-amino-1,2-propanediol, 2-aminobutane-1,3-diol, 2-(aminomethyl)-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol; The alkenyl aromatic compounds are selected from one or a combination of two or more of styrene, allylbenzene, 3-methylstyrene; The number-average molecular weight of the alkenyl polyether macromonomer is 1000 - 1500, and it is selected from one or a combination of two or more of isopentenyl polyoxyethylene ether, methyl allyl polyoxyethylene ether, ethylene glycol mono vinyl polyethylene glycol ether, allyl polyoxyethylene ether; The monoalkenoic acid compounds are selected from one or a combination of two or more of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, sodium allylsulfonate, sodium methallylsulfonate, sodium vinylsulfonate, sodium propenylsulfonate, sodium methallylsulfonate, sodium styrenesulfonate, sodium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid; 2. The C80 grade concrete with improved low-temperature toughness according to claim 1, characterized in that, In step 1), the organic solvent is selected from one or a combination of two or more of methanol, ethanol, and isopropanol; the temperature control is to control the temperature at 25 - 50 °C; the reaction time is 24 - 48 h.

3. The concrete for improving low-temperature toughness of C80 grade according to claim 1, characterized in that, The toughening agent is inorganic filler coated with carboxyl-terminated polybutadiene liquid rubber, and is prepared by a method including the following steps: The inorganic filler, carboxyl-terminated polybutadiene liquid rubber, organic solvent, and ball milling medium are added to a ball mill, and ball milling is carried out to obtain a ball milling slurry, which is filtered and dried to obtain the toughening agent.

4. The concrete for improving low-temperature toughness at C80 level according to claim 3, wherein The rotation speed of the ball milling is 200 - 800 r / min; the time of the ball milling is 3 - 5 h; the mass ratio of the inorganic filler, the carboxyl-terminated polybutadiene liquid rubber, and the organic solvent is 5: 0.4 - 0.5: 10 - 15.

5. The concrete with improved low-temperature toughness of C80 grade according to claim 1, wherein The number average molecular weight of the carboxyl-terminated polybutadiene liquid rubber is 3000 - 5000; the average particle size of the inorganic filler is 50 - 100 nm, and it is selected from one or a combination of two or more of silica, calcium carbonate, talcum powder, and magnesium carbonate.

6. The C80 grade concrete with improved low-temperature toughness according to claim 1, wherein The admixture is selected from one or a combination of two of fly ash and mineral powder; the cement is Portland cement with a strength grade of 42.5 to 52.

5.

7. The preparation method of the concrete with improved low-temperature toughness of C80 grade according to any one of claims 1-6, characterized in that, It includes the following steps: Mix the cement, the admixture, the air-entraining polycarboxylate water reducer, the toughening agent, and water evenly to obtain a slurry, and add the coarse aggregate and the fine aggregate to the slurry and mix evenly to obtain C80 grade concrete with improved low-temperature toughness.

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