Low temperature resistant concrete composite material and preparation method thereof

Abstract

The application relates to the technical field of concrete materials, and discloses a low-temperature-resistant concrete composite material and a preparation method thereof. The low-temperature-resistant concrete material is prepared by mixing ordinary Portland cement, an asphalt base material, fine aggregate, coarse aggregate, modified lignin, a water reducing agent, a retarder and water, and then adding polypropylene fibers; the concrete material can still maintain excellent compressive strength, crack resistance and anti-freezing performance at low temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete materials, and particularly relates to a low-temperature-resistant concrete composite material and a preparation method thereof. BACKGROUND

[0002] As the most widely used building material in the world, the durability of concrete material directly determines the service life and safety of the structure. In cold regions, high-altitude areas and polar scientific research, concrete structures are long-term or periodic exposed to low-temperature environment, one of the most severe challenges they face is freeze-thaw cycle damage. The essence of the damage of concrete at low temperature is the phase change of water. The free water in the capillary pores and gel pores of concrete freezes and expands by about 9% at low temperature, and the expansion pressure will cause microcracks in the pore wall. After multiple freeze-thaw cycles, these microcracks continuously expand and connect, leading to concrete surface spalling, strength loss and even structure collapse.

[0003] In order to achieve excellent compressive strength, crack resistance and freeze-thaw resistance at low temperature, traditional concrete materials generally use methods such as adding air entraining agent, reducing water-binder ratio or using antifreeze to achieve the above-mentioned properties. However, there are some shortcomings, such as: the addition of a large amount of air entraining agent reduces the compressive strength of the concrete material; the introduction of inorganic salt antifreeze has corrosion hazards to steel bars (such as chloride salt), and excessive use will cause salt crystallization, leading to surface powdering, and its effect is diluted with hydration, and has limited contribution to long-term frost resistance. Therefore, researchers need to develop a new type of concrete composite material to provide a new and efficient solution for the long-term durability of concrete in low-temperature environment, effectively making up for the defects of the prior art. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a low-temperature-resistant concrete composite material and a preparation method thereof.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] A low-temperature-resistant concrete composite material comprises the following raw materials by weight: 100-120 parts of ordinary Portland cement, 25-35 parts of asphalt base, 70-100 parts of fine aggregate, 35-55 parts of coarse aggregate, 10-16 parts of polypropylene fiber, 8-13 parts of modified lignin, 0.1-0.3 parts of retarder, 0.1-0.3 parts of water reducing agent, and 35-45 parts of water.

[0007] Further, the particle size of the fine aggregate is 0.2mm-2mm, and the particle size of the coarse aggregate is 4.5mm-5.5mm.

[0008] Further, the retarder is sodium citrate.

[0009] Furthermore, the water-reducing agent is a polycarboxylate water-reducing agent;

[0010] The modified lignin is prepared by the following steps:

[0011] Step A1: Mix cyanuric chloride and acetonitrile and stir in an ice-water bath for 30 min, denoted as solution A; disperse perfluorohexylethyl alcohol and sodium hydroxide in acetonitrile by ultrasonication for 30 min, denoted as solution B; slowly add solution B to solution A, keeping the pH of the system at 7-8, with a dropwise addition time of 30 min; after the dropwise addition is complete, continue stirring in an ice-water bath for 4 h; filter, wash, and dry to obtain intermediate product 1.

[0012] Furthermore, in step A1, the ratio of cyanuric chloride to acetonitrile in solution A is 0.1-0.2 mol: 100 mL;

[0013] Furthermore, in step A1, the ratio of perfluorohexylethyl alcohol, sodium hydroxide, and acetonitrile in solution B is 0.1-0.2 mol: 4-8 g: 100 mL;

[0014] Step A2: Mix intermediate product 1 with acetonitrile and stir until homogeneous, then heat to 45-55℃, and label this as solution C; ultrasonically disperse sodium 3-hydroxy-1-propanesulfonate and sodium hydroxide in acetonitrile until homogeneous, and label this as solution D; add solution D dropwise to solution C within 30 min, maintain the pH of the system at 7-8, maintain the temperature for 4-6 h, filter, wash, and dry to obtain intermediate product 2;

[0015] Furthermore, in step A2, the ratio of intermediate product 1 to acetonitrile in solution C is 0.1-0.2 mol: 100 mL;

[0016] Furthermore, in step A2, the ratio of sodium 3-hydroxy-1-propanesulfonate, sodium hydroxide, and acetonitrile in solution D is 0.1-0.2 mol: 4-8 g: 100 mL;

[0017] Step A3: Mix intermediate product 2 in acetonitrile and stir until homogeneous, then heat to reflux temperature, denoted as solution E; mix lignin in 0.1 mol / L sodium hydroxide solution and stir for 30 min, denoted as alkali lignin solution; add alkali lignin solution to solution E, then heat to 90℃ and reflux for 12 h, filter, wash, and dry to obtain modified lignin;

[0018] Furthermore, in step A3, the ratio of intermediate product 2 to acetonitrile in solution E is 0.1-0.3 mol: 100 mL;

[0019] Furthermore, in step A3, the ratio of lignin to sodium hydroxide solution in the alkaline lignin solution is 5g:20mL.

[0020] A method for preparing a low-temperature resistant concrete composite material includes the following steps:

[0021] Step S1: Weigh the raw materials according to the weight parts, and mix the ordinary silicate cement, asphalt base material, fine aggregate, coarse aggregate, modified lignin, water-reducing agent and retarder evenly to obtain the concrete base material.

[0022] Step S2: After mixing the concrete base material and water, add polypropylene fiber and stir evenly. Discharge the material, pour it into a mold for molding, demold, and cure to obtain the low-temperature resistant concrete composite material.

[0023] The beneficial effects of this invention are:

[0024] The low-temperature resistant concrete material of the present invention is prepared by mixing ordinary silicate cement, asphalt base material, fine aggregate, coarse aggregate, modified lignin, water-reducing agent and retarder as base materials, and then adding polypropylene fiber after mixing with water; the concrete material can still maintain excellent compressive strength, crack resistance and antifreeze performance at low temperatures.

[0025] The low-temperature resistant concrete material prepared in this invention incorporates modified lignin. The addition of modified lignin improves the low-temperature resistance of the concrete material and enables it to maintain excellent crack resistance and freeze-thaw resistance even at low temperatures. The modified lignin uses lignin as a base and a triazine structure as a "bridge," grafting long-chain fluoroalkanes and sulfonates onto the lignin. The lignin matrix itself possesses good low-temperature resistance and remains stable at low temperatures. The grafting of sulfonates allows the modified lignin to utilize the strong negative charge of the sulfonate group to adsorb onto the surface of cement particles, generating a strong electrostatic repulsion force that disperses the cement particles, releasing the trapped free water. This significantly reduces the amount of water used in the mixing process, thus drastically reducing the total amount of "freezing water" inside the concrete. This process weakens the destructive power of low temperatures at the source. Simultaneously, the combined action of hydrophilic sulfonate groups and hydrophobic long-chain fluorocarbons produces a surfactant-like effect, reducing the surface tension of water. During mixing, a large number of tiny, independent, and uniformly distributed spherical bubbles are introduced. These microbubbles are dry, air-filled cavities. When water in the surrounding capillaries freezes and expands at low temperatures, the pressure forces unfrozen water or ice crystals into these bubbles, thus absorbing the expansion stress and preventing the concrete structure from bursting. This improves the crack resistance and compressive strength of the concrete material. Furthermore, the hydrophobic long-chain fluorocarbons accumulate on the inner walls of the concrete capillaries and the membrane walls of the microbubbles during mixing and setting, forming a permanent hydrophobic layer. This protective film significantly hinders the intrusion of external liquid water into the concrete, substantially reducing its water absorption in aquatic environments. Even at low temperatures, the internal moisture content of the concrete material remains at a low level, effectively cutting off the source of freezeable water. In addition, the triazine ring acts as a strong bridge, effectively linking lignin, sulfonate, and fluoroalkane chains into a stable macromolecule, ensuring that the additive will not easily decompose in strongly alkaline cement paste and can maintain its function for a long time. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The following are the sources of some of the raw materials used in the examples:

[0028] Polypropylene fiber, purchased from Shandong Yuyite New Material Co., Ltd., with a fiber length of 3mm;

[0029] Ordinary Portland cement, purchased from Taizhou Yigao E-commerce Co., Ltd., PO42.5 grade;

[0030] Carboxylic acid water-reducing agent, purchased from Shandong Jinrong Chemical Technology Co., Ltd.;

[0031] Sodium citrate, a retarder, was purchased from Jinan Shengda Chemical Co., Ltd.

[0032] Fine aggregate uses fine quartz sand with a particle size in the range of 0.2mm-2mm, and coarse aggregate uses coarse quartz sand with a particle size in the range of 4.5mm-5.5mm.

[0033] The asphalt base material is No. 10 flake petroleum asphalt, with a softening point of 105-110℃, a flash point of 240℃, and a needle diameter of 30mm. It was purchased from Hengshui Zehao Rubber & Chemical Co., Ltd.

[0034] Example 1: Modified lignin was prepared by the following steps:

[0035] Step A1: Mix 0.1 mol cyanuric chloride and 100 mL acetonitrile, and stir in an ice-water bath for 30 min, denoted as solution A; disperse 0.1 mol perfluorohexylethyl alcohol and 4 g sodium hydroxide in 100 mL acetonitrile by ultrasonication for 30 min, denoted as solution B; slowly add solution B to solution A, keeping the pH of the system at 7, with a dropwise addition time of 30 min; after the dropwise addition is complete, continue stirring in an ice-water bath for 4 h; filter, wash, and dry to obtain intermediate product 1.

[0036] Step A2: Mix 0.1 mol of intermediate product 1 with 100 mL of acetonitrile and stir until homogeneous. Heat the mixture to 45 °C and label it as solution C. Disperse 0.1 mol of sodium 3-hydroxy-1-propanesulfonate and 4 g of sodium hydroxide in 100 mL of acetonitrile using ultrasonication until homogeneous and label it as solution D. Add solution D dropwise to solution C over 30 min, maintaining the pH of the system at 7.5 and maintaining the temperature for 4 h. Filter, wash, and dry the mixture to obtain intermediate product 2.

[0037] Step A3: Mix 0.1 mol of intermediate product 2 in 100 mL of acetonitrile and stir until homogeneous, then heat to reflux temperature, denoted as solution E; mix 5 g of lignin in 20 mL of 0.1 mol / L sodium hydroxide solution and stir for 30 min, denoted as alkali lignin solution; add alkali lignin solution to solution E, then heat to 90 °C and reflux for 12 h, filter, wash, and dry to obtain modified lignin.

[0038] Example 2: Modified lignin was prepared by the following steps:

[0039] Step A1: Mix 0.15 mol cyanuric chloride and 100 mL acetonitrile, and stir in an ice-water bath for 30 min, denoted as solution A; disperse 0.15 mol perfluorohexylethyl alcohol and 6 g sodium hydroxide in 100 mL acetonitrile by ultrasonication for 30 min, denoted as solution B; slowly add solution B to solution A, keeping the pH of the system at 7.5, with a dropwise addition time of 30 min; after the dropwise addition is complete, continue stirring in an ice-water bath for 4 h; filter, wash, and dry to obtain intermediate product 1.

[0040] Step A2: Mix 0.15 mol of intermediate product 1 with 100 mL of acetonitrile and stir until homogeneous. Heat the mixture to 50 °C and label it as solution C. Disperse 0.15 mol of sodium 3-hydroxy-1-propanesulfonate and 6 g of sodium hydroxide in 100 mL of acetonitrile using ultrasonication until homogeneous and label it as solution D. Add solution D dropwise to solution C over 30 min, maintaining the pH of the system at 7 and maintaining the temperature for 5 h. Filter, wash, and dry the mixture to obtain intermediate product 2.

[0041] Step A3: Mix 0.2 mol of intermediate product 2 in 100 mL of acetonitrile and stir until homogeneous, then heat to reflux temperature, denoted as solution E; mix 5 g of lignin in 20 mL of 0.1 mol / L sodium hydroxide solution and stir for 30 min, denoted as alkali lignin solution; add alkali lignin solution to solution E, then heat to 90 °C and reflux and stir for 12 h, filter, wash, and dry to obtain modified lignin.

[0042] Example 3: Modified lignin was prepared by the following steps:

[0043] Step A1: Mix 0.2 mol cyanuric chloride and 100 mL acetonitrile, and stir in an ice-water bath for 30 min, denoted as solution A; disperse 0.2 mol perfluorohexylethyl alcohol and 8 g sodium hydroxide in 100 mL acetonitrile by ultrasonication for 30 min, denoted as solution B; slowly add solution B to solution A, keeping the pH of the system at 8, with a dropwise addition time of 30 min; after the dropwise addition is complete, continue stirring in an ice-water bath for 4 h; filter, wash, and dry to obtain intermediate product 1;

[0044] Step A2: Mix 0.2 mol of intermediate product 1 with 100 mL of acetonitrile and stir until homogeneous. Heat the mixture to 55 °C and label it as solution C. Disperse 0.2 mol of sodium 3-hydroxy-1-propanesulfonate and 8 g of sodium hydroxide in 100 mL of acetonitrile using ultrasonication until homogeneous and label it as solution D. Add solution D dropwise to solution C over 30 min, maintain the pH of the system at 8, and maintain the temperature for 6 h. Filter, wash, and dry the mixture to obtain intermediate product 2.

[0045] Step A3: Mix 0.3 mol of intermediate product 2 in 100 mL of acetonitrile and stir until homogeneous, then heat to reflux temperature, denoted as solution E; mix 5 g of lignin in 20 mL of 0.1 mol / L sodium hydroxide solution and stir for 30 min, denoted as alkali lignin solution; add alkali lignin solution to solution E, then heat to 90 °C and reflux for 12 h, filter, wash, and dry to obtain modified lignin.

[0046] Example 4: A method for preparing a low-temperature resistant concrete composite material includes the following steps:

[0047] 100 parts of ordinary silicate cement, 25 parts of asphalt base, 70 parts of fine aggregate, 35 parts of coarse aggregate, 10 parts of polypropylene fiber, 8 parts of modified lignin prepared in Example 1, 0.1 parts of retarder, 0.1 parts of water-reducing agent, and 35 parts of water.

[0048] Step S1: Weigh the raw materials according to the weight parts, and mix and stir the ordinary silicate cement, asphalt base material, fine aggregate, coarse aggregate, modified lignin prepared in Example 1, water-reducing agent and retarder evenly to obtain concrete base material.

[0049] Step S2: After mixing the concrete base material and water, add polypropylene fiber and stir evenly. Discharge the material, pour it into a mold for molding, demold, and cure to obtain the low-temperature resistant concrete composite material.

[0050] Example 5: A method for preparing a low-temperature resistant concrete composite material includes the following steps:

[0051] 110 parts of ordinary silicate cement, 30 parts of asphalt base, 85 parts of fine aggregate, 45 parts of coarse aggregate, 13 parts of polypropylene fiber, 10 parts of modified lignin prepared in Example 2, 0.2 parts of retarder, 0.2 parts of water-reducing agent, and 40 parts of water.

[0052] Step S1: Weigh the raw materials according to the weight parts, and mix and stir the ordinary silicate cement, asphalt base material, fine aggregate, coarse aggregate, modified lignin prepared in Example 2, water-reducing agent and retarder evenly to obtain concrete base material.

[0053] Step S2: After mixing the concrete base material and water, add polypropylene fiber and stir evenly. Discharge the material, pour it into a mold for molding, demold, and cure to obtain the low-temperature resistant concrete composite material.

[0054] Example 6: A method for preparing a low-temperature resistant concrete composite material includes the following steps:

[0055] 120 parts of ordinary silicate cement, 35 parts of asphalt base, 100 parts of fine aggregate, 55 parts of coarse aggregate, 16 parts of polypropylene fiber, 13 parts of modified lignin prepared in Example 3, 0.3 parts of retarder, 0.3 parts of water-reducing agent, and 45 parts of water.

[0056] Step S1: Weigh the raw materials according to the weight parts, and mix and stir the ordinary silicate cement, asphalt base material, fine aggregate, coarse aggregate, modified lignin prepared in Example 3, water-reducing agent and retarder evenly to obtain concrete base material.

[0057] Step S2: After mixing the concrete base material and water, add polypropylene fiber and stir evenly. Discharge the material, pour it into a mold for molding, demold, and cure to obtain the low-temperature resistant concrete composite material.

[0058] Comparative Example 1: This comparative example is a concrete composite material. The difference between this example and Example 6 is that unmodified lignin is used instead of the modified lignin prepared in Example 3. All other aspects are the same.

[0059] Comparative Example 2: This comparative example is a concrete composite material. The difference between this example and Example 6 is that the intermediate product 2 prepared in Example 3 is used instead of the modified lignin prepared in Example 3. All other aspects are the same.

[0060] The concrete composite materials prepared in Examples 4-6 and Comparative Examples 1-2 were made into 100mm×100mm×100mm cubic specimens for performance testing:

[0061] Compressive strength test: According to GB / T 50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", the compressive strength of each specimen at 7d and 28d was tested;

[0062] Low temperature performance test:

[0063] (1) Crack resistance: The failure tensile strain was measured in accordance with the T0716-1993 splitting test of asphalt mixture in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering (JIT052 2000)".

[0064] (2) Freeze-thaw resistance: Each specimen was subjected to 100 freeze-thaw cycles according to the slow freezing method of GB / T 50082-2009 Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete. After the freeze-thaw treatment, the mass loss rate and compressive strength loss rate of each specimen were tested.

[0065] The test results are shown in Table 1:

[0066] Table 1: Performance Test Results

[0067]

[0068] As can be seen from Table 1, the concrete material prepared by this invention still maintains excellent compressive strength, crack resistance and freeze-thaw resistance at low temperatures.

[0069] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. A low-temperature resistant concrete composite material, characterized in that, The raw materials include the following parts by weight: 100-120 parts of ordinary Portland cement, 25-35 parts of asphalt base, 70-100 parts of fine aggregate, 35-55 parts of coarse aggregate, 10-16 parts of polypropylene fiber, 8-13 parts of modified lignin, 0.1-0.3 parts of retarder, 0.1-0.3 parts of water-reducing agent, and 35-45 parts of water. The modified lignin is prepared by the following steps: Step A1: Mix cyanuric chloride and acetonitrile and stir in an ice-water bath for 30 min, denoted as solution A; disperse perfluorohexylethyl alcohol and sodium hydroxide in acetonitrile by ultrasonication for 30 min, denoted as solution B; slowly add solution B to solution A, keeping the pH of the system at 7-8, with a dropwise addition time of 30 min; after the dropwise addition is complete, continue stirring in an ice-water bath for 4 h; filter, wash, and dry to obtain intermediate product 1. Step A2: Mix intermediate product 1 with acetonitrile and stir until homogeneous, then heat to 45-55℃, and label this as solution C; ultrasonically disperse sodium 3-hydroxy-1-propanesulfonate and sodium hydroxide in acetonitrile until homogeneous, and label this as solution D; add solution D dropwise to solution C within 30 min, maintain the pH of the system at 7-8, maintain the temperature for 4-6 h, filter, wash, and dry to obtain intermediate product 2; Step A3: Mix intermediate product 2 in acetonitrile and stir until homogeneous, then heat to reflux temperature, denoted as solution E; mix lignin in 0.1 mol / L sodium hydroxide solution and stir for 30 min, denoted as alkali lignin solution; Add the alkali lignin solution to solution E, then heat to 90℃ and reflux with stirring for 12 hours. Filter, wash, and dry to obtain modified lignin.

2. The low-temperature resistant concrete composite material according to claim 1, characterized in that, In step A1, the ratio of cyanuric chloride to acetonitrile in solution A is 0.1-0.2 mol: 100 mL.

3. The low-temperature resistant concrete composite material according to claim 1, characterized in that, In step A1, the ratio of perfluorohexylethyl alcohol, sodium hydroxide, and acetonitrile in solution B is 0.1-0.2 mol: 4-8 g: 100 mL.

4. The low-temperature resistant concrete composite material according to claim 1, characterized in that, In step A2, the ratio of intermediate product 1 to acetonitrile in solution C is 0.1-0.2 mol: 100 mL.

5. The low-temperature resistant concrete composite material according to claim 1, characterized in that, In step A2, the ratio of sodium 3-hydroxy-1-propanesulfonate, sodium hydroxide, and acetonitrile in solution D is 0.1-0.2 mol: 4-8 g: 100 mL.

6. The low-temperature resistant concrete composite material according to claim 1, characterized in that, In step A3, the ratio of intermediate product 2 to acetonitrile in solution E is 0.1-0.3 mol: 100 mL.

7. The low-temperature resistant concrete composite material according to claim 1, characterized in that, In step A3, the ratio of lignin to sodium hydroxide solution in the alkaline lignin solution is 5g:20mL.

8. The low-temperature resistant concrete composite material according to claim 1, characterized in that, The fine aggregate has a particle size of 0.2mm-2mm, and the coarse aggregate has a particle size of 4.5mm-5.5mm.

9. The low-temperature resistant concrete composite material according to claim 1, characterized in that, The retarder is sodium citrate, and the water-reducing agent is polycarboxylate superplasticizer.

10. A method for preparing the low-temperature resistant concrete composite material according to any one of claims 1-9, characterized in that, Includes the following steps: Step S1: Weigh the raw materials according to the weight parts, and mix the ordinary silicate cement, asphalt base material, fine aggregate, coarse aggregate, modified lignin, water-reducing agent and retarder evenly to obtain the concrete base material. Step S2: After mixing the concrete base material and water, add polypropylene fiber and stir evenly. Discharge the material, pour it into a mold for molding, demold, and cure to obtain the low-temperature resistant concrete composite material.

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