Cement-based composite material and preparation method thereof

Abstract

The invention discloses a cement-based composite material which comprises the following components in parts by weight: 50-70 parts of Portland cement, 30-50 parts of a mineral admixture, 0.5-5 parts of modified bamboo fibers, 0.5-2 parts of a water reducing agent and 20-40 parts of water, the preparation method of the modified bamboo fiber comprises the following steps: step 1, taking 3-20mm bamboo fiber, soaking the bamboo fiber in a sodium hydroxide solution, and soaking after stirring; 2, cleaning with clear water, and drying to obtain alkali-treated bamboo fibers; step 3, putting the alkali-treated bamboo fibers into a solvent, adding diethylene glycol monovinyl ether and a catalyst, and reacting while stirring under a low-temperature condition; 4, diethylene glycol divinyl ether and glycerol are added for continuous reaction; 5, finally, a silane coupling agent is added for a reaction, and the modified bamboo fibers are obtained. The prepared modified bamboo fiber has good hydrophilicity and is connected with silane, the mechanical property of cement can be improved, and meanwhile better dispersing performance is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cement, more particularly to a cement-based composite material and a preparation method thereof. BACKGROUND

[0002] High ductility cement-based composite material (ECC) can significantly improve the toughness and crack resistance of concrete by adding high-performance fibers in the cement matrix. However, traditional ECCs mostly use polyvinyl alcohol (PVA) fibers, which are less environmentally friendly and require strict dispersion. Some studies have used waste materials to replace natural aggregates to reduce costs and environmental burden. For example, Southeast University replaced river sand with wind-blown sand to prepare ECCs and introduced PE fibers, achieving the green goal of "waste into treasure". However, there is less development of environmentally friendly fibers in existing technologies, especially lacking systematic research on renewable or degradable fibers.

[0003] Meanwhile, natural fibers such as bamboo fibers are also added to cement to improve performance. In order to pursue better performance, the bamboo fibers are often modified, and the general modification process is to modify the bamboo fibers with organosilicon coupling agents and then add them to the cement to improve performance. However, organosilicon is not hydrophilic, and water is a very important factor in the curing and mixing process of cement. The modification of bamboo fibers will lead to a decrease in hydrophilicity, resulting in uneven dispersion of bamboo fibers, thus causing local reinforcement, and the overall cement material is not completely reinforced. The mechanical properties of the part with less bamboo fiber are poor, leading to poor performance of the entire material. SUMMARY

[0004] In view of the deficiencies in the prior art, the purpose of the present application is to provide a cement-based composite material.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A cement-based composite material, including the following weight parts: portland cement: 50-70 parts mineral admixture: 30-50 parts modified bamboo fiber: 0.5-5 parts water reducing agent: 0.5-2 parts water: 20-40 parts; The preparation method of the modified bamboo fiber is: Step 1: Take 3-20 mm bamboo fibers, soak the bamboo fibers in a sodium hydroxide solution, and stir and soak after stirring; Step 2: Wash with clean water and dry to obtain alkali-treated bamboo fibers; Step 3: Put the alkali-treated bamboo fibers into a solvent, add diethylene glycol monovinyl ether and a catalyst, and react under low degree conditions with stirring. Step 4: then add diethylene glycol divinyl ether, glycerol to continue the reaction; Step 5: finally add silane coupling agent to react to obtain the modified bamboo fiber.

[0006] As a further improvement of the present application, The mineral admixture is fly ash or slag.

[0007] As a further improvement of the present application, The water reducing agent is a polycarboxylic acid type high efficiency water reducing agent.

[0008] As a further improvement of the present application, The sodium hydroxide solution in step 1 is a 5w% sodium hydroxide aqueous solution.

[0009] Here, the sodium hydroxide aqueous solution is selected as a 5w% sodium hydroxide aqueous solution, which is a moderate concentration and will not cause excessive corrosion to the bamboo fiber, and can better preserve the structure of the bamboo fiber to ensure the strength of the bamboo fiber.

[0010] As a further improvement of the present application, The solvent in step 3 is dichloromethane.

[0011] In the selection of the solvent, dichloromethane is selected because dichloromethane has good solubility for ethylene glycol monovinyl ether and diethylene glycol divinyl ether, making it easy to dissolve and repeat the reaction.

[0012] As a further improvement of the present application, The catalyst in step 3 is p-toluenesulfonic acid.

[0013] The catalyst is selected as p-toluenesulfonic acid, which mainly catalyzes the reaction of double bond and hydroxyl group.

[0014] As a further improvement of the present application, The reaction temperature of step 3 and step 4 is 5℃.

[0015] The reaction of step 3 and step 4 is controlled as low as possible, which can effectively control the reaction progress and reduce the occurrence of side reactions.

[0016] The temperature in step 5 can be appropriately increased to room temperature for reaction, and as a further improvement, the silane coupling agent is first mixed with water in step 5, and then added to the reaction container for reaction, and the addition of water is beneficial to speed up the reaction; As a further improvement, acetic acid is added to the silane coupling agent and water in step 5, and the silane coupling agent is more easily involved in the reaction under acidic conditions.

[0017] As a further improvement of the present application, The silane coupling agent in step 3 is silane coupling agent KH560.

[0018] As another object of the present application, a preparation method of a cement-based composite material is provided, Step A: take the Portland cement, mineral admixtures, mix and stir, then add water reducing agent and part of water, continue to stir, then add modified bamboo fiber, continue to stir to make the modified bamboo fiber uniformly dispersed, continue to add the remaining water to complete the stirring; Step B: put the stirred material into a mold, then demold, and continue to maintain to obtain the cement-based composite material.

[0019] As a further improvement of the present application, In step B, after the stirred material is put into the mold, it is demolded after 24 hours, and the maintenance time is 28 days.

[0020] The present application mainly improves the mechanical properties of cement by adding modified bamboo fiber to cement. The main method is to first alkali treat the bamboo fiber to expose more hydroxyl groups on the surface, then react the hydroxyl groups on the surface of the bamboo fiber with diethylene glycol monovinyl ether under the action of a catalyst, and a polydiethylene glycol monovinyl ether compound is generated in the reaction. The double bond at one end of the diethylene glycol monovinyl ether reacts with the hydroxyl group, and the hydroxyl group at the other end reacts with another diethylene glycol monovinyl ether molecule to form a polydiethylene glycol monovinyl ether compound, while retaining a hydroxyl group on the outside.

[0021] Then, by adding diethylene glycol divinyl ether, one double bond of the diethylene glycol divinyl ether continues to polymerize with the hydroxyl group of the polydiethylene glycol monovinyl ether compound, so that the final terminal group is a double bond. The addition of the hydroxyl group on glycerol will continue to react with the double bond on the diethylene glycol divinyl ether, so that more terminal hydroxyl groups are exposed.

[0022] Finally, the silane coupling agent is added to react with the terminal hydroxyl group, completing the modification process of the bamboo fiber. Due to the large number of ether bonds on the surface of the polydiethylene glycol monovinyl ether compound and the diethylene glycol divinyl ether polymerized later, the hydrophilic property of the modified bamboo fiber is greatly enhanced. The addition of glycerol here also increases the content of hydroxyl groups, which can also improve the hydrophilic property. At the same time, the grafting of the polymer also makes the silane coupling agent away from the bamboo fiber body. The modified bamboo fiber obtained finally has good hydrophilicity and also has the groups of the silane coupling agent, which can improve the mechanical properties of cement. It not only has the ability to improve the performance, but also has better hydrophilicity. When the modified bamboo fiber is added to cement, it has better dispersion performance, so that the modified bamboo fiber is more uniformly dispersed, thereby improving the overall mechanical properties of the cement material. DETAILED DESCRIPTION

[0023] Example 1: Preparation of Modified Bamboo Fiber Step 1: Take 100 parts by weight of bamboo fiber with a thickness of about 15mm, immerse the bamboo fiber in a 5w% sodium hydroxide solution, stir magnetically at 1200 r / min for 15 min, and soak for 8 h; Step 2: Rinse with clean water until the pH of the rinse water is around 7 to complete the rinsing process, and then dry in a drying oven at 70℃ for 7 hours to obtain alkali-treated bamboo fiber. Step 3: Place the alkali-treated bamboo fiber into dichloromethane, and add 14 parts by weight of diethylene glycol monovinyl ether and 0.1 parts by weight of p-toluenesulfonic acid. React at 5°C and 1800 r / min for 30 min. Step 4: Then add 7 parts by weight of diethylene glycol divinyl ether and 5 parts by weight of glycerol and continue the reaction at 5°C and 1800 r / min for 30 min. Step 5: Mix 12 parts KH560 and 10 parts water, then add the mixture to the reaction vessel. Heat the mixture to room temperature and stir at 1500 r / min for 20 min. Dry the mixture in a drying oven at 70℃ for 7 h to obtain modified bamboo fiber.

[0024] The bamboo fiber here is a bundle of natural yellow bamboo fiber purchased from Sichuan Changsheng New Material Technology Co., Ltd. During the experiment, the yellow bamboo fiber was manually combed and trimmed to a length of about 15cm.

[0025] A cement-based composite material, Includes the following parts by weight: Silicate cement (grade 42.5): 70 parts Slag: 30 portions The modified bamboo fiber prepared above: 3 parts Polycarboxylate superplasticizer: 1 part Water: 30 parts; Step A: Take silicate cement (grade 42.5) and slag and mix them in a cement mixer at 100 rpm for 30 seconds. Then add polycarboxylate superplasticizer and 20 parts of water, continue mixing, add modified bamboo fiber, continue mixing to make the modified bamboo fiber evenly dispersed, and then add the remaining 10 parts of water to complete the mixing. Step B: After the mixed material is placed into the mold, it is demolded after 24 hours and cured for 28 days to obtain the cement-based composite material.

[0026] Example 2: Preparation of modified bamboo fiber Step 1: Take 100 parts by weight of bamboo fiber with a thickness of about 15mm, immerse the bamboo fiber in a 5w% sodium hydroxide solution, stir magnetically at 1200 r / min for 15 min, and soak for 8 h; Step 2: Rinse with clean water until the pH of the rinse water is around 7 to complete the rinsing process, and then dry in a drying oven at 70℃ for 7 hours to obtain alkali-treated bamboo fiber. Step 3: Place the alkali-treated bamboo fiber into dichloromethane, and add 14 parts by weight of diethylene glycol monovinyl ether and 0.1 parts by weight of p-toluenesulfonic acid. React at 5°C and 1800 r / min for 30 min. Step 4: Then add 7 parts by weight of diethylene glycol divinyl ether and 5 parts by weight of glycerol and continue the reaction at 5°C and 1800 r / min for 30 min. Step 5: Mix 12 parts KH560, 10 parts water, and 0.5 parts acetic acid, then add the mixture to the reaction vessel. Heat the mixture to room temperature and stir at 1500 r / min for 20 min. Dry the mixture in a drying oven at 70℃ for 7 h to obtain modified bamboo fiber.

[0027] The bamboo fiber here is a bundle of natural yellow bamboo fiber purchased from Sichuan Changsheng New Material Technology Co., Ltd. During the experiment, the yellow bamboo fiber was manually combed and trimmed to a length of about 15cm.

[0028] A cement-based composite material, Includes the following parts by weight: Silicate cement (grade 42.5): 70 parts Slag: 30 portions The modified bamboo fiber prepared above: 3 parts Polycarboxylate superplasticizer: 1 part Water: 30 parts; Step A: Take silicate cement (grade 42.5) and slag and mix them in a cement mixer at 100 rpm for 30 seconds. Then add polycarboxylate superplasticizer and 20 parts of water, continue mixing, add modified bamboo fiber, continue mixing to make the modified bamboo fiber evenly dispersed, and then add the remaining 10 parts of water to complete the mixing. Step B: After the mixed material is placed into the mold, it is demolded after 24 hours and cured for 28 days to obtain the cement-based composite material.

[0029] Example 3: Preparation of Modified Bamboo Fiber Step 1: Take 100 parts by weight of bamboo fiber with a thickness of about 15mm, immerse the bamboo fiber in a 5w% sodium hydroxide solution, stir magnetically at 1200 r / min for 15 min, and soak for 8 h; Step 2: Rinse with clean water until the pH of the rinse water is around 7 to complete the rinsing process, and then dry in a drying oven at 70℃ for 7 hours to obtain alkali-treated bamboo fiber. Step 3: Place the alkali-treated bamboo fiber into dichloromethane, and add 14 parts by weight of diethylene glycol monovinyl ether and 0.1 parts by weight of p-toluenesulfonic acid. React at 5°C and 1800 r / min for 30 min. Step 4: Then add 7 parts by weight of diethylene glycol divinyl ether and 5 parts by weight of glycerol and continue the reaction at 5°C and 1800 r / min for 30 min. Step 5: Mix 12 parts KH560 and 10 parts water, then add the mixture to the reaction vessel. Heat the mixture to room temperature and stir at 1500 r / min for 20 min. Dry the mixture in a drying oven at 70℃ for 7 h to obtain modified bamboo fiber.

[0030] The bamboo fiber here is a bundle of natural yellow bamboo fiber purchased from Sichuan Changsheng New Material Technology Co., Ltd. During the experiment, the yellow bamboo fiber was manually combed and trimmed to a length of about 15cm.

[0031] A cement-based composite material, Includes the following parts by weight: Silicate cement (grade 42.5): 70 parts Fly ash: 30 parts The modified bamboo fiber prepared above: 3 parts Polycarboxylate superplasticizer: 1 part Water: 30 parts; Step A: Take silicate cement (grade 42.5) and slag and mix them in a cement mixer at 100 rpm for 30 seconds. Then add polycarboxylate superplasticizer and 20 parts of water, continue mixing, add modified bamboo fiber, continue mixing to make the modified bamboo fiber evenly dispersed, and then add the remaining 10 parts of water to complete the mixing. Step B: After the mixed material is placed into the mold, it is demolded after 24 hours and cured for 28 days to obtain the cement-based composite material.

[0032] Example 4: Preparation of Modified Bamboo Fiber Step 1: Take 100 parts by weight of bamboo fiber with a thickness of about 15mm, immerse the bamboo fiber in a 5w% sodium hydroxide solution, stir magnetically at 1200 r / min for 15 min, and soak for 8 h; Step 2: Rinse with clean water until the pH of the rinse water is around 7 to complete the rinsing process, and then dry in a drying oven at 70℃ for 7 hours to obtain alkali-treated bamboo fiber. Step 3: Place the alkali-treated bamboo fiber into dichloromethane, and add 14 parts by weight of diethylene glycol monovinyl ether and 0.1 parts by weight of p-toluenesulfonic acid. React at 5°C and 1800 r / min for 30 min. Step 4: Then add 7 parts by weight of diethylene glycol divinyl ether and 5 parts by weight of glycerol and continue the reaction at 5°C and 1800 r / min for 30 min. Step 5: Mix 12 parts KH560, 10 parts water, and 0.5 parts acetic acid, then add the mixture to the reaction vessel. Heat the mixture to room temperature and stir at 1500 r / min for 20 min. Dry the mixture in a drying oven at 70℃ for 7 h to obtain modified bamboo fiber.

[0033] The bamboo fiber here is a bundle of natural yellow bamboo fiber purchased from Sichuan Changsheng New Material Technology Co., Ltd. During the experiment, the yellow bamboo fiber was manually combed and trimmed to a length of about 15cm.

[0034] A cement-based composite material, Includes the following parts by weight: Silicate cement (grade 42.5): 70 parts Fly ash: 30 parts The modified bamboo fiber prepared above: 3 parts Polycarboxylate superplasticizer: 1 part Water: 30 parts; Step A: Take silicate cement (grade 42.5) and slag and mix them in a cement mixer at 100 rpm for 30 seconds. Then add polycarboxylate superplasticizer and 20 parts of water, continue mixing, add modified bamboo fiber, continue mixing to make the modified bamboo fiber evenly dispersed, and then add the remaining 10 parts of water to complete the mixing. Step B: After the mixed material is placed into the mold, it is demolded after 24 hours and cured for 28 days to obtain the cement-based composite material.

[0035] Comparative Example 1: A cement-based composite material, Includes the following parts by weight: Silicate cement (grade 42.5): 70 parts Slag: 30 portions 15mm bamboo fiber: 3 parts Polycarboxylate superplasticizer: 1 part Water: 30 parts; Step A: Take silicate cement (grade 42.5) and slag and mix them in a cement mixer at 100 rpm for 30 seconds. Then add polycarboxylate superplasticizer and 20 parts of water, continue mixing, add modified bamboo fiber, continue mixing to make the modified bamboo fiber evenly dispersed, and then add the remaining 10 parts of water to complete the mixing. Step B: After the mixed material is placed into the mold, it is demolded after 24 hours and cured for 28 days to obtain the cement-based composite material.

[0036] Comparative Example 2: Preparation of modified bamboo fiber Step 1: Take 100 parts by weight of bamboo fiber with a thickness of about 15mm, immerse the bamboo fiber in a 5w% sodium hydroxide solution, stir magnetically at 1200 r / min for 15 min, and soak for 8 h; Step 2: Rinse with clean water until the pH of the rinse water is around 7 to complete the rinsing process, and then dry in a drying oven at 70℃ for 7 hours to obtain alkali-treated bamboo fiber. A cement-based composite material, Includes the following parts by weight: Silicate cement (grade 42.5): 70 parts Slag: 30 portions The above-mentioned alkali-treated bamboo fiber: 3 parts Polycarboxylate superplasticizer: 1 part Water: 30 parts; Step A: Take silicate cement (grade 42.5) and slag and mix them in a cement mixer at 100 rpm for 30 seconds. Then add polycarboxylate superplasticizer and 20 parts of water, continue mixing, add modified bamboo fiber, continue mixing to make the modified bamboo fiber evenly dispersed, and then add the remaining 10 parts of water to complete the mixing. Step B: After the mixed material is placed into the mold, it is demolded after 24 hours and cured for 28 days to obtain the cement-based composite material.

[0037] Comparative Example 3: A cement-based composite material, Includes the following parts by weight: Silicate cement (grade 42.5): 70 parts Fly ash: 30 parts 15mm bamboo fiber: 3 parts Polycarboxylate superplasticizer: 1 part Water: 30 parts; Step A: Take silicate cement (grade 42.5) and slag and mix them in a cement mixer at 100 rpm for 30 seconds. Then add polycarboxylate superplasticizer and 20 parts of water, continue mixing, add modified bamboo fiber, continue mixing to make the modified bamboo fiber evenly dispersed, and then add the remaining 10 parts of water to complete the mixing. Step B: After the mixed material is placed into the mold, it is demolded after 24 hours and cured for 28 days to obtain the cement-based composite material.

[0038] Comparative Example 4: Preparation of modified bamboo fiber Step 1: Take 100 parts by weight of bamboo fiber with a thickness of about 15mm, immerse the bamboo fiber in a 5w% sodium hydroxide solution, stir magnetically at 1200 r / min for 15 min, and soak for 8 h; Step 2: Rinse with clean water until the pH of the rinse water is around 7 to complete the rinsing process, and then dry in a drying oven at 70℃ for 7 hours to obtain alkali-treated bamboo fiber. A cement-based composite material, Includes the following parts by weight: Silicate cement (grade 42.5): 70 parts Fly ash: 30 parts The above-mentioned alkali-treated bamboo fiber: 3 parts Polycarboxylate superplasticizer: 1 part Water: 30 parts; Step A: Take silicate cement (grade 42.5) and slag and mix them in a cement mixer at 100 rpm for 30 seconds. Then add polycarboxylate superplasticizer and 20 parts of water, continue mixing, add modified bamboo fiber, continue mixing to make the modified bamboo fiber evenly dispersed, and then add the remaining 10 parts of water to complete the mixing. Step B: After the mixed material is placed into the mold, it is demolded after 24 hours and cured for 28 days to obtain the cement-based composite material.

[0039] Comparative Example 5: I. Modified bamboo fiber Step 1: Take 100 parts by weight of bamboo fiber with a thickness of about 15mm, immerse the bamboo fiber in a 5w% sodium hydroxide solution, stir magnetically at 1200 r / min for 15 min, and soak for 8 h; Step 2: Rinse with clean water until the pH of the rinse water is around 7 to complete the rinsing process, and then dry in a drying oven at 70℃ for 7 hours to obtain alkali-treated bamboo fiber. Step 3: Place the alkali-treated bamboo fiber into dichloromethane and stir for 60 minutes at 1800 r / min and 5°C. Step 4: Mix 12 parts KH560, 10 parts water, and 0.5 parts acetic acid, then add the mixture to the reaction vessel. Heat the mixture to room temperature and stir at 1500 r / min for 20 min. Dry the mixture in a drying oven at 70℃ for 7 h to obtain modified bamboo fiber.

[0040] The bamboo fiber here is a bundle of natural yellow bamboo fiber purchased from Sichuan Changsheng New Material Technology Co., Ltd. During the experiment, the yellow bamboo fiber was manually combed and trimmed to a length of about 15cm.

[0041] A cement-based composite material, Includes the following parts by weight: Silicate cement (grade 42.5): 70 parts Slag: 30 portions The above modified bamboo fiber: 3 parts Polycarboxylate superplasticizer: 1 part Water: 30 parts; Step A: Take silicate cement (grade 42.5) and slag and mix them in a cement mixer at 100 rpm for 30 seconds. Then add polycarboxylate superplasticizer and 20 parts of water, continue mixing, add modified bamboo fiber, continue mixing to make the modified bamboo fiber evenly dispersed, and then add the remaining 10 parts of water to complete the mixing. Step B: After the mixed material is placed into the mold, it is demolded after 24 hours and cured for 28 days to obtain the cement-based composite material.

[0042] Comparative Example 6: I. Modified bamboo fiber Step 1: Take 100 parts by weight of bamboo fiber with a thickness of about 15mm, immerse the bamboo fiber in a 5w% sodium hydroxide solution, stir magnetically at 1200 r / min for 15 min, and soak for 8 h; Step 2: Rinse with clean water until the pH of the rinse water is around 7 to complete the rinsing process, and then dry in a drying oven at 70℃ for 7 hours to obtain alkali-treated bamboo fiber. Step 3: Place the alkali-treated bamboo fiber into dichloromethane and stir for 60 minutes at 1800 r / min and 5°C. Step 4: Mix 12 parts KH560, 10 parts water, and 0.5 parts acetic acid, then add the mixture to the reaction vessel. Heat the mixture to room temperature and stir at 1500 r / min for 20 min. Dry the mixture in a drying oven at 70℃ for 7 h to obtain modified bamboo fiber.

[0043] The bamboo fiber here is a bundle of natural yellow bamboo fiber purchased from Sichuan Changsheng New Material Technology Co., Ltd. During the experiment, the yellow bamboo fiber was manually combed and trimmed to a length of about 15cm.

[0044] A cement-based composite material, Includes the following parts by weight: Silicate cement (grade 42.5): 70 parts Fly ash: 30 parts The above modified bamboo fiber: 3 parts Polycarboxylate superplasticizer: 1 part Water: 30 parts; Step A: Take silicate cement (grade 42.5) and slag and mix them in a cement mixer at 100 rpm for 30 seconds. Then add polycarboxylate superplasticizer and 20 parts of water, continue mixing, add modified bamboo fiber, continue mixing to make the modified bamboo fiber evenly dispersed, and then add the remaining 10 parts of water to complete the mixing. Step B: After the mixed material is placed into the mold, it is demolded after 24 hours and cured for 28 days to obtain the cement-based composite material.

[0045] Raw material list:

[0046] test: Compressive strength test, flexural strength test, ultimate tensile strain

[0047] By comparing Examples 1 and 2 with Comparative Examples 1, 2, and 5, all five schemes used slag as a mineral admixture. It can be clearly seen that the compressive strength, flexural strength, and ultimate tensile strain of Examples 1 and 2 are significantly improved. Example 1, compared to Example 2, lacks the addition of acetic acid in the preparation of modified bamboo fiber. This indicates that in Example 2, the addition of acetic acid, through pH adjustment, allowed the silane coupling agent to react fully, thereby improving the mechanical properties.

[0048] By comparing Examples 3 and 4 with Comparative Examples 3, 4, and 6, it can be seen that all three schemes used fly ash as the mineral admixture. Specifically, Examples 3 and 4 showed significant improvements in compressive strength, flexural strength, and ultimate tensile strain. Example 3, compared to Example 4, lacked the addition of acetic acid during the preparation of the modified bamboo fiber. This indicates that in Example 2, the addition of acetic acid, through pH adjustment, allowed the silane coupling agent to react fully, thereby improving the mechanical properties.

[0049] This invention primarily improves the mechanical properties of cement by adding modified bamboo fiber. The main method involves first treating the bamboo fiber with alkali to expose more hydroxyl groups on its surface. Then, under the action of a catalyst, diethylene glycol monovinyl ether (DGE) reacts with the hydroxyl groups on the bamboo fiber surface, generating a DGE compound. One end of the DGE compound's double bond reacts with a hydroxyl group, while the other end reacts with another DGE molecule, forming a DGE compound while retaining one hydroxyl group externally. Further addition of DGE divinyl ether allows one of the double bonds on the DGE compound to polymerize with the hydroxyl group of the DGE compound, resulting in a final double bond at the end. Adding glycerol further reacts the hydroxyl groups on the DGE divinyl ether, exposing more terminal hydroxyl groups. Finally, a silane coupling agent is added to react with the terminal hydroxyl groups, completing the bamboo fiber modification process. Because the surface of the polyethylene glycol monovinyl ether compound has a large number of ether bonds, and the diethylene glycol divinyl ether polymerized later also has a large number of ether bonds, the hydrophilicity of the modified bamboo fiber is greatly enhanced. Furthermore, the addition of glycerol increases the hydroxyl content, which also improves hydrophilicity. Simultaneously, the grafting of the polymer keeps the silane coupling agent away from the bamboo fiber body. The resulting modified bamboo fiber has good hydrophilicity and also possesses silane coupling agent groups, which can improve the mechanical properties of cement. It possesses both the ability to improve performance and better hydrophilicity. When the modified bamboo fiber is added to cement, it exhibits better dispersion performance, resulting in more uniform dispersion of the modified bamboo fiber, thereby improving the overall mechanical properties of the cement material.

[0050] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A cement-based composite material, characterized in that: Includes the following parts by weight: Silicate cement: 50-70 parts Mineral admixtures: 30-50 parts Modified bamboo fiber: 0.5~5 parts Water-reducing agent: 0.5~2 parts Water: 20-40 parts; The method for preparing the modified bamboo fiber is as follows: Step 1: Take 3-20mm bamboo fiber, soak the bamboo fiber in sodium hydroxide solution, stir and soak. Step 2: Wash with clean water and dry to obtain alkali-treated bamboo fiber; Step 3: Place the alkali-treated bamboo fiber into a solvent, add diethylene glycol monovinyl ether and a catalyst, and react with stirring under low temperature conditions; Step 4: Then add diethylene glycol divinyl ether and glycerol to continue the reaction; Step 5: Finally, add a silane coupling agent to react and obtain modified bamboo fiber.

2. The cement-based composite material according to claim 1, characterized in that: The mineral admixture is fly ash or slag.

3. The cement-based composite material according to claim 1, characterized in that: The water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent.

4. The cement-based composite material according to claim 1, characterized in that: In step 1, the sodium hydroxide solution is a 5w% sodium hydroxide aqueous solution.

5. The cement-based composite material according to claim 1, characterized in that: The solvent in step 3 is dichloromethane.

6. The cement-based composite material according to claim 1, characterized in that: The catalyst in step 3 is p-toluenesulfonic acid.

7. A cement-based composite material according to claim 1, characterized in that: The reaction temperature for steps 3 and 4 is 5°C.

8. The cement-based composite material according to claim 1, characterized in that: In step 3, the silane coupling agent is silane coupling agent KH560.

9. A method for preparing a cement-based composite material according to any one of claims 1 to 8, characterized in that: Step A: Mix silicate cement and mineral admixtures, then add water-reducing agent and some water, continue mixing, then add modified bamboo fiber, continue mixing until the modified bamboo fiber is evenly dispersed, and then add the remaining water to complete the mixing. Step B: Place the mixed material into the mold, then demold and continue curing to obtain the cement-based composite material.

10. The method for preparing a cement-based composite material according to claim 9, characterized in that: In step B, after the mixed material is placed into the mold, it is demolded after 24 hours, and the curing time is 28 days.

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