CN115286301A - Multi-scale fiber reinforcement alkali-activated cementing material and preparation method thereof - Google Patents

Abstract

The invention provides a method for preparing a multi-scale fiber-reinforced alkali-excited gelling material, comprising the following steps: first, dissolving filter paper fibers to obtain a nanofiber solution; secondly, adding sodium hydroxide to obtain a nanofiber alkali-excited solution; The mixture of the precursor powder of the gelling material and the fine sand is added to the nanofiber alkali-excited solution; finally, the micro-fiber is added, mixed well, and the mold is installed and vibrated to obtain a multi-scale fiber-reinforced alkali-excited gelling material after curing. The gelling material contains a woven network of nanofibers with self-assembly properties, and forms a unique "mace" multi-scale structure with microfibers. The interaction of two different scale fibers improves the compactness of the microstructure and enhances the crack resistance of the matrix. The hydrophilic groups on the surface of the nanofibers improve the interface bonding between the microfibers and the matrix of the alkali-excited gelling material, and improve the mechanical properties of the alkali-excited gelling material. The obtained gelling material has the advantages of high bending resistance and high shrinkage resistance.

Description

A multi-scale fiber-reinforced alkali-activated gelling material and its preparation method

technical field

The invention belongs to the field of inorganic non-metallic materials, and in particular relates to a multi-scale fiber-reinforced alkali-activated gelling material and a preparation method thereof.

Background technique

Alkali-activated gelling materials are inorganic, non-metallic gelling materials composed of aluminosilicates, which are produced by mixing waste or natural aluminosilicate sources with high concentrations of alkali metal hydroxides. After mixing, the alkali activator dissolves the aluminosilicate precursor, releasing the aluminate and silicate monomers, followed by polycondensation reaction to form a unique three-dimensional network structure of silicon and aluminum. Therefore, the production process has a potentially low _CO2 footprint. Depending on the mix design and processing conditions, the excited cementitious materials can exhibit different properties, such as high early-stage compressive strength, acid resistance, and fire resistance. In addition, alkali-activated gelling materials also have the characteristics of consolidating heavy metals, stabilizing harmful chemicals and purifying water quality.

However, there are obvious brittle defects in alkali-activated gelled materials, and low tensile strength and cracks will appear under unfavorable mechanical loads. At present, fibers are usually used to toughen alkali-activated gelling materials, but there are uneven distribution and agglomeration of fibers during the doping process; at the same time, the multi-scale fiber-toughened alkali-activated gelling materials involved in other patents, nanofibers and The micro-fibers cannot interact with each other, and the multi-scale toughening effect cannot be exerted to the greatest extent, which affects the interfacial bonding between the fiber and the matrix, and affects the mechanical properties of the alkali-activated gelled material.

In addition, the drying shrinkage of alkali-induced gelling materials is serious, and surface cracks and even cracks will appear under the shrinkage force. At present, internal curing agents such as water-absorbing resins are commonly used to slow down drying shrinkage and cracking by absorbing water in advance before mixing, but there is no fiber that can take care of both internal curing and bridging cracks, and the existing internal curing agents have no effect on the interface between micron fibers and the matrix. Lifting doesn't do much.

Based on this, on the basis of high durability and high compressive strength of alkali-activated gelling materials, solve the problems of high drying shrinkage and low toughness, and provide a high-shrinkage-resistant and high-bending performance inorganic material with uniform distribution of fibers. Materials, so that it can better meet the application requirements in the restoration of hydraulic building structures, is a technical problem that needs to be solved urgently.

Contents of the invention

One of the objectives of the present invention is to provide a method for preparing a multi-scale fiber-reinforced alkali-activated gelling material that can improve the shrinkage resistance and high bending resistance of the product.

The second object of the present invention is to provide a multi-scale fiber-reinforced alkali-activated gelling material with uniform distribution of fibers, high shrinkage resistance and high bending resistance.

One of the purposes of the present invention is achieved by adopting a technical solution that provides a method for preparing a multi-scale fiber-reinforced alkali-activated gelling material, comprising the following steps:

S1. Put the filter paper fibers in a mixed solvent of sodium hydroxide, urea, and deionized water, freeze at -45 to -35°C for 6 to 12 hours, and then thaw to obtain a nanofiber solution;

S2, adding sodium hydroxide to the nanofiber solution to adjust the concentration to obtain a nanofiber alkali excitation solution;

S3, dry-mixing the geopolymer precursor powder and fine sand to obtain a mixture, adding the nanofiber alkali excitation solution to the mixture, and mixing to obtain the first product;

S4. Add micron fibers to the first product, and mix to obtain the second product. After the second product is molded and vibrated, it is maintained at 55-65°C for 6-8 days to obtain a multi-scale fiber-reinforced alkali Excite the gelling material.

The present invention adopts the above-mentioned preparation method to carry out the general train of thought of the preparation of multi-scale fiber-reinforced alkali-excited gelling material as follows:

First of all, suitable nanofibers are selected to be dispersed in the alkali-activated solution to ensure that the nanofibers can be evenly distributed on the alkali-activated gelling material. Secondly, according to the type and amount of the precursor powder of the gelling material, the alkali content of the nanofiber solution is adjusted to obtain a better excitation effect. Again, add the mixture of cementitious material precursor powder and fine sand to the alkali-activated solution of nanofibers in turn, and then add micron fibers, so that the nanofibers are evenly distributed on the alkali-excited gelled material with the solution, and are effectively distributed on the micron fibers . Finally, the product is cured under appropriate temperature conditions to ensure that the cross-linking reaction of nanofibers and the polymerization reaction of alkali-activated gelling materials proceed simultaneously. Nanofibers can not only self-assemble nanofiber weaving networks, but also attach to micron fibers and fine sand. , forming a "mace"-like multi-scale fiber structure. With the help of the above structure, the drying shrinkage rate and flexural performance of the product can be controlled, and then a gelled material with high shrinkage resistance and high flexural performance can be produced.

In the present invention, the nanofibers are selected from filter paper fibers, and the cellulose content in the filter paper fibers is more than 90%, which can obtain a purer nanofiber solution; in addition, with respect to other cellulose fibers (such as cotton linters, etc.), the filter paper The fiber has high crystallinity (1000-1500), it is easier to form longer nanofibers, and the resulting cellulose solution has a higher viscosity, so it has better water retention performance and can play an internal maintenance role on the alkali-activated gelling material matrix , Release the stored water when the alkali stimulates the early reaction of the gelling material, prevent drying shrinkage and cracking caused by excessive water loss, promote the reaction, and improve the compactness of the matrix.

Furthermore, filter paper fibers and other raw materials cannot be directly dissolved, and must be frozen and thawed at a specific temperature to form a cellulose molecular solution, which is further polymerized into nanofibers. The conventional freeze-thaw technique used with NaOH/urea solution is usually pre-cooled to -5~-10°C. However, under the above-mentioned temperature conditions, the filter paper fiber is completely insoluble, even if the dissolution time is prolonged, it is only slightly dissolved. The present invention finds through extensive exploration that the optimal freezing temperature of the filter paper fibers is -35-45° C., and the freezing time is 6-12 hours. Under this temperature and time condition, the filter paper fiber can be completely dissolved, and the cellulose exists in the solution in the form of extremely small nanofibers; if the temperature is further lowered, gel will be produced while completely dissolving, and the nanofibers have been cross-linked. It is not conducive to the uniform distribution of nanofibers in the alkali excitation solution, and at the same time reduces the free water content in the solution, affecting the uniform distribution of nanofibers in the gelled material and the fluidity of the slurry during the mixing process.

In addition, in the preparation method, it is necessary to control the order of adding raw materials: first dry mix the fine sand and matrix powder, and then add the dry mixture to the fiber alkali excitation solution to obtain a fluid slurry; if directly adding fiber alkali When the excitation solution is added to the dry mix, the solution will react locally and rapidly with the matrix powder in contact with it at the moment of addition, resulting in insufficient matrix reaction, resulting in uneven strength distribution and increased structural weakness. However, the microfibers need to be added to the flowing slurry in the last step. If the microfibers are added to the solution first, a large number of cellulose molecules will be gathered due to the hydrophilic groups and high surface energy on the surface of the microfibers, and the nanofibers obtained in the matrix will It will be very small, which will affect the water retention effect of nanofibers on the matrix.

In the present invention, the curing temperature is set at 55-65° C., and the curing time is set at 6-8 days. Under the temperature and time conditions, the polymerization reaction speed of the alkali-activated gelling material can be kept consistent with the nanofiber crosslinking reaction speed, so that the two proceed simultaneously. Nanofibers exist not only in the voids of the matrix, but also inside the matrix of the gelled material. The nanofibers are regenerated from the inside of the matrix gel, embedded deeply into the matrix gel at the other end, and finally covered and wrapped by the matrix gel generated by further reaction. On the one hand, nanofibers form a woven network and exist in the cementitious material matrix, which plays a role in connecting the micro-cracks and pores of the matrix; on the other hand, nanofibers exist on the surface of micron fibers and fine sand, forming a mace multi-scale structure, improving the The interfacial bonding strength between the fiber and the matrix increases the energy required to pull out the micron fibers under load, and then comprehensively realizes the control of the drying shrinkage of the product and improves its toughness.

Further, in the multi-scale fiber-reinforced alkali-activated gelling material, the content of nanofibers is 0.25-1 wt%, and the volume ratio of micron fibers is 0.5-2%. Under the conditions of the above content range, nanofibers can be evenly distributed on the matrix and microfibers, and the slurry has a certain fluidity. By controlling the amount of microfibers added, it is possible to obtain fluidity-controllable and different flexural properties. Material.

Preferably, in the multi-scale fiber-reinforced alkali-activated gelling material, the content of nanofibers is 0.5 wt%, and the volume ratio of micron fibers is 2%. It is found through research that under the above conditions, the flexural properties of the product reach a peak value, and beyond this range, the flexural properties will have a certain downward trend.

Further, in the step S1, the mass ratio of sodium hydroxide, urea, and deionized water is (6-8):(8-14):(76-88). Preferably, in the step S1, the mass ratio of sodium hydroxide, urea, and deionized water is 7:12:81.

Further, in the nanofiber solution, the nanofibers have a diameter of 20-100 nm and a length of 180-2000 nm.

Further, in the step S2, the amount of sodium hydroxide added is determined by the type and amount of the gelling material precursor powder in the step S3.

Further, the geopolymer precursor powder is selected from one or a combination of metakaolin, fly ash, and slag.

Further, the micron fibers are selected from polyvinyl alcohol fibers, polyethylene fibers, polypropylene fibers or combinations thereof. Preferably, the micron fiber has a diameter of 30-60 μm and a length of 6-12 mm.

Further, in the step S4, the time for stirring and mixing after adding the micron fiber should not be too long, it is advisable to control it at about 5 minutes. When the stirring time is too short, the micron fiber is unevenly distributed and easily exists on the surface of the slurry. Fiber agglomeration will occur when it is too long. Preferably, the mixing time for obtaining the second product is 4-6 minutes.

The technical solution adopted by the present invention to achieve the second objective is to provide a multi-scale fiber reinforced alkali-activated gelling material prepared based on the preparation method described in the first objective of the present invention.

In the multi-scale fiber-reinforced alkali-activated cementitious material, the nanofibers are evenly dispersed in the matrix of the cementitious material and self-assembled to form a fiber weaving network, and at the same time, the nanofibers are reductively aggregated on the surface of the micron fibers and fine sand to form a mace-shaped multi- scale structure.

Compared with prior art, the beneficial effect of the present invention is:

(1) The preparation method of a multi-scale fiber-reinforced alkali-activated gelling material provided by the present invention, the nanofibers are uniformly dispersed in the alkali-activated gelling material with the solution, and the water loss rate of the alkali-activated gelling material matrix is improved by water retention , to provide bridging and filling of gel pores, promote compact microstructure, reduce the risk of cracking, and combine internal maintenance and fiber bridging into one.

(2) The preparation method of a multi-scale fiber reinforced alkali-activated gelling material provided by the present invention uses multi-scale fibers to strengthen the alkali-activated gelling material, and the hydrophilic groups on the surface of the nanofibers improve the relationship between the micron fiber and the alkali-activated gel. The interfacial bonding between the matrix of the gelling material improves the mechanical properties of the alkali-activated gelling material, and a multi-scale fiber-reinforced alkali-activated gelling material with high flexural and shrinkage resistance is obtained.

(3) In the multi-scale fiber-reinforced alkali-activated gelling material prepared by the present invention, the crosslinking reaction of the nanofibers and the polymerization reaction of the alkali-activated gelling material proceed simultaneously. On the one hand, the in-situ polymerization of the nanofibers is uniformly dispersed in the matrix to form a Assemble the nanofiber weaving network, on the other hand, the nanofiber is also attached to the micron fiber and fine sand, forming a "mace"-like multi-scale fiber structure. The existence of the above structure can effectively control the drying shrinkage of the product and improve the toughness.

Description of drawings

Figure 1 is a schematic flow diagram of a method for preparing a multi-scale fiber-reinforced alkali-activated gelling material provided by an embodiment of the present invention;

Fig. 2 is a 2000× scanning electron micrograph at a resolution of 2 μm of the multiscale fiber-reinforced alkali-excited gelled material prepared in Example 1 of the present invention;

Fig. 3 is a graph of the 7-day flexural strength of the multi-scale fiber-reinforced alkali-activated gelled material prepared in Example 1 of the present invention.

Fig. 4 is the 5000 × scanning electron micrograph at the resolution of 1 μm of the alkali-excited gelling material without fibers in Comparative Example 1;

Fig. 5 is the 7-day flexural strength curve graph of the alkali-excited gelling material without fiber of comparative example 1;

Fig. 6 is a 2000× scanning electron microscope image of a 2 μm fiber-reinforced alkali-excited gelled material in a comparative example at a resolution of 2 μm;

Fig. 7 is a graph of the 7-day flexural strength of the 2-micron fiber-reinforced alkali-activated gelled material of the comparative example.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

The present invention will be further described below in conjunction with specific examples, but not as a limitation of the present invention.

Example 1

A method for preparing a multi-scale fiber-reinforced alkali-activated gelling material, comprising the following steps:

Step 1: Dissolve 70g NaOH in 810g deionized water, cool to room temperature, add 120g urea, and let it stand for 24 hours to obtain a pre-solution with a total weight of 1000g for dissolving filter paper fibers. See Figure 1 for the dissolution steps. Break the filter paper fibers with a wall breaker, weigh 0.5% of the solution mass filter paper fiber fragments into the solution, and distribute the fragments evenly by ultrasonic waves. The product was frozen in a -40°C refrigerator for 8 hours, and then thawed at room temperature at 25°C to obtain a nanofiber solution.

Step 2: Slowly add 23g of sodium hydroxide to the nanofiber solution in step 1 in 5 times to adjust the alkali concentration of the solution, and let it stand for 24 hours for later use.

Step 3: Pour 800g of metakaolin and 160g of fine sand into a blender and stir evenly, then add 1000g of nanofiber solution and mix evenly.

Step 4: Add polyvinyl alcohol fibers with a volume fraction of 2% to the product obtained in step 3, stir for 5 minutes, then install a mold and vibrate for 2 minutes. Control the temperature at 60°C in a constant temperature and humidity curing box, cure for 12 hours to remove the mold, and then continue curing for 7 days to finally obtain a multi-scale fiber-reinforced alkali-activated gelled material.

FIG. 2 is a scanning electron micrograph of the multiscale fiber-reinforced alkali-excited gelled material prepared in Example 1. FIG. It can be seen from Figure 2 that the nanofibers are polymerized on the surface of the polyvinyl alcohol fiber in situ, forming a unique "mace" multi-scale structure. The existence of the nanofibers improves the interface bonding between the microfibers and the matrix, and improves the extraction of the microfibers. energy required.

Fig. 3 is the 7-day flexural strength curve of the multiscale fiber-reinforced alkali-activated gelling material prepared in Example 1. It can be seen from Fig. 3 that the multi-scale fiber-reinforced alkali-activated gelling material exhibits a multi-stage cracking mode. The scale promotes matrix reaction to increase the first cracking strength, and the microfibers provide fiber bridging at the micron scale to increase the final cracking strength.

Example 2

A method for preparing a multi-scale fiber-reinforced alkali-activated gelling material, comprising the following steps:

Step 1: Dissolve 70g NaOH in 810g deionized water, cool to room temperature, add 120g urea, and let it stand for 24 hours to obtain a pre-solution with a total weight of 1000g for dissolving filter paper fibers. See Figure 1 for the dissolution steps. Break the filter paper fibers with a wall breaker, weigh 1% of the solution mass filter paper fiber fragments into the solution, and distribute the fragments evenly by ultrasonic waves. The product was frozen in a refrigerator at -35°C for 12 hours, and then thawed at room temperature at 25°C to obtain a nanofiber solution.

Step 2: Slowly add 23g of sodium hydroxide to the nanofiber solution in step 1 in 5 times to adjust the alkali concentration of the solution, and let it stand for 24 hours for later use.

Step 3: Pour 800g of metakaolin and 160g of fine sand into a blender and stir evenly, then add 1000g of nanofiber solution and mix evenly.

Step 4: Add polyvinyl alcohol fibers with a volume fraction of 1% to the product obtained in step 3, stir for 5 minutes, then install a mold and vibrate for 2 minutes. Control the temperature at 60°C in a constant temperature and humidity curing box, cure for 12 hours to remove the mold, and then continue curing for 7 days to finally obtain a multi-scale fiber-reinforced alkali-activated gelled material.

Example 3

A method for preparing a multi-scale fiber-reinforced alkali-activated gelling material, comprising the following steps:

Step 1: Dissolve 70g NaOH in 810g deionized water, cool to room temperature, add 120g urea, and let it stand for 24 hours to obtain a pre-solution with a total weight of 1000g for dissolving filter paper fibers. See Figure 1 for the dissolution steps. Break the filter paper fibers with a wall breaker, weigh 0.5% of the solution mass filter paper fiber fragments into the solution, and distribute the fragments evenly by ultrasonic waves. The product was frozen in a refrigerator at -45°C for 6 hours, and then thawed at room temperature at 25°C to obtain a nanofiber solution.

Step 2: Slowly add 23g of sodium hydroxide to the nanofiber solution in step 1 in 5 times to adjust the alkali concentration of the solution, and let it stand for 24 hours for later use.

Step 3: Pour 800g of metakaolin and 160g of fine sand into a blender and stir evenly, then add 1000g of nanofiber solution and mix evenly.

Step 4: Add polyvinyl alcohol fibers with a volume fraction of 1.5% to the product obtained in step 3, stir for 5 minutes, then install a mold and vibrate for 2 minutes. Control the temperature at 60°C in a constant temperature and humidity curing box, cure for 12 hours to remove the mold, and then continue curing for 7 days to finally obtain a multi-scale fiber-reinforced alkali-activated gelled material.

Example 4

A method for preparing a multi-scale fiber-reinforced alkali-activated gelling material, comprising the following steps:

Step 1: Dissolve 70g NaOH in 810g deionized water, cool to room temperature, add 120g urea, and let it stand for 24 hours to obtain a pre-solution with a total weight of 1000g for dissolving filter paper fibers. See Figure 1 for the dissolution steps. Break the filter paper fibers with a wall breaker, weigh 1% of the solution mass filter paper fiber fragments into the solution, and distribute the fragments evenly by ultrasonic waves. The product was frozen in a -40°C refrigerator for 8 hours, and then thawed at room temperature at 25°C to obtain a nanofiber solution.

Step 2: Slowly add 23g of sodium hydroxide to the nanofiber solution in step 1 in 5 times to adjust the alkali concentration of the solution, and let it stand for 24 hours for later use.

Step 3: Pour 800g of metakaolin and 160g of fine sand into a blender and stir evenly, then add 1000g of nanofiber solution and mix evenly.

Step 4: Add polyvinyl alcohol fibers with a volume fraction of 0.5% to the product obtained in step 3, stir for 5 minutes, then install a mold and vibrate for 2 minutes. Control the temperature at 55°C in a constant temperature and humidity curing box, cure for 12 hours to remove the mold, and then continue curing for 8 days to finally obtain a multi-scale fiber-reinforced alkali-activated gelled material.

Example 5

A method for preparing a multi-scale fiber-reinforced alkali-activated gelling material, comprising the following steps:

Step 1: Dissolve 70g NaOH in 810g deionized water, cool to room temperature, add 120g urea, and let it stand for 24 hours to obtain a pre-solution with a total weight of 1000g for dissolving filter paper fibers. See Figure 1 for the dissolution steps. Break the filter paper fibers with a wall breaker, weigh 0.5% of the solution mass filter paper fiber fragments into the solution, and distribute the fragments evenly by ultrasonic waves. The product was frozen in a -40°C refrigerator for 8 hours, and then thawed at room temperature at 25°C to obtain a nanofiber solution.

Step 2: Slowly add 23g of sodium hydroxide to the nanofiber solution in step 1 in 5 times to adjust the alkali concentration of the solution, and let it stand for 24 hours for later use.

Step 3: Pour 800g of fly ash and 160g of fine sand into a blender and stir evenly, then add 400g of nanofiber solution and mix evenly.

Step 4: Add polyvinyl alcohol fibers with a volume fraction of 2% to the product obtained in step 3, stir for 5 minutes, then install a mold and vibrate for 2 minutes. Control the temperature at 65°C in a constant temperature and humidity curing box, cure for 12 hours to remove the mold, and then continue curing for 6 days to finally obtain a multi-scale fiber-reinforced alkali-activated gelled material.

Comparative example 1

Adjustment is made on the basis of Example 1, the difference is that no filter paper fiber is added in step 1, no polyvinyl alcohol fiber is added in step 4, and other conditions and steps remain unchanged to obtain a conventional alkali-activated glue without fiber reinforcement condensate material.

The scanning electron micrograph of the alkali-excited gelled material prepared in Comparative Example 1 is shown in FIG. 4 . It can be seen from FIG. 4 that there is no fiber inside the matrix of the product prepared in Comparative Example 1. The 7-day flexural strength curve is shown in Figure 5, which is a typical brittle crack. It can be seen from the comparison that the first cracking strength of the product obtained by adopting the technical solution of multi-scale fiber reinforcement modification in Example 1 is 129% higher than that of the cementitious material without fiber reinforcement in Comparative Example 1, and the final cracking strength is 280% higher.

Comparative example 2

Adjustment is made on the basis of Example 1, the difference is that no filter paper fiber is added in step 1, polyvinyl alcohol fiber with a content of 2% is added in step 4, and other conditions and steps remain unchanged to obtain a micron fiber-reinforced conventional Alkali activates the gelling material.

The scanning electron microscope image of the alkali-activated gelling material prepared in Comparative Example 2 is shown in Figure 6. The surface of the polyvinyl alcohol fiber is smooth, and the interface fracture with the alkali-activated gelling material matrix is neat. The 7-day flexural strength curve of the micron-fiber-reinforced alkali-excited gelling material is shown in Figure 7. Due to the existence of micron-fibers, it also presents a multi-segment cracking mode, but due to the lack of nano-fiber reinforcement and the joint action of multi-scale fibers, its product is the first The cracking strength and final cracking strength are not high. Compared with Comparative Example 2, the first cracking strength of Example 1 is increased by 106%, and the final cracking strength is increased by 65%.

The alkali-activated gelling materials obtained in Example 1 and Comparative Examples 1 and 2 were placed under the same curing conditions (60° C.), and the mass loss ratios after 3 days and 7 days of curing were measured. The results are shown in Table 1 below.

Table 1

group 3d mass loss rate/% 7d Mass loss rate/% Example 1 13.06 16.78 Comparative example 1 24.7 24.70 Comparative example 2 21.2 22.65

It can be seen from the above table,

The mass loss rate in Example 1 of the present invention is far less than that of Comparative Examples 1 and 2, and the mass loss after curing for 3 days and 7 days in Comparative Example 1 is the same, indicating that it has reached the maximum in 3 days. Losses are somewhat mitigated, but not as well as in Example 1 where the multiscale fibers work together. This shows that the multi-scale fiber-reinforced alkali-activated gelling material prepared by the present invention can give full play to the water retention of nanofibers, greatly reduce the water quality loss in the early stage of the alkali-activated gelling material reaction, control the water loss rate, and then reduce the early cracking of the material risk.

The above are only preferred embodiments of the present invention, and are not intended to limit the implementation and protection scope of the present invention. For those skilled in the art, they should be able to realize equivalent replacements and obvious changes made by using the contents of the description of the present invention. The obtained schemes should all be included in the protection scope of the present invention.

Claims (10)

1. A preparation method for multi-scale fiber-reinforced alkali-activated gelling material, comprising the following steps: S1. Put the filter paper fibers in a mixed solvent composed of sodium hydroxide, urea and deionized water, freeze at -45 to -35°C for 6 to 12 hours and then thaw to obtain a nanofiber solution; S2, adding sodium hydroxide to the nanofiber solution to adjust the concentration to obtain a nanofiber alkali excitation solution; S3. Dry mixing the cementitious material precursor powder and fine sand to obtain a mixture, adding the nanofiber alkali excitation solution to the mixture, and mixing to obtain the first product; S4. Add micron fibers to the first product, and mix to obtain the second product. After the second product is molded and vibrated, it is maintained at 55-65°C for 6-8 days to obtain a multi-scale fiber-reinforced alkali Excite the gelling material. 2. The preparation method according to claim 1, characterized in that, in the multi-scale fiber-reinforced alkali-activated gelling material, the content of nanofibers is 0.25-1 wt%, and the volume ratio of micron fibers is 0.5-2%. 3. The preparation method according to claim 1, characterized in that, in the step S1, the mass ratio of sodium hydroxide, urea, and deionized water is (6～8):(8～14):(76～ 88). 4. The preparation method according to claim 3, characterized in that, in the nanofiber solution, the nanofibers have a diameter of 20-100 nm and a length of 180-2000 nm. 5. The preparation method according to claim 1, characterized in that, in the step S2, the amount of sodium hydroxide added is determined by the type and amount of the gelling material precursor powder in the step S3. 6. The preparation method according to claim 1, characterized in that, the cementitious material precursor powder is selected from one or more combinations of metakaolin, fly ash, and slag. 7. The preparation method according to claim 1, characterized in that, the micron fibers are selected from one or more combinations of polyvinyl alcohol fibers, polyethylene fibers, and polypropylene fibers. 8 . The preparation method according to claim 7 , characterized in that, the diameter of the micron fiber is 30-60 μm, and the length is 6-12 mm. 9. The preparation method according to claim 1, characterized in that, in the step S4, the stirring time for the mixing to obtain the second product is 4-6 minutes. 10. A multi-scale fiber-reinforced alkali-activated gelling material prepared by the preparation method according to any one of claims 1-9, characterized in that, In the multi-scale fiber-reinforced alkali-activated cementitious material, the nanofibers are evenly dispersed in the matrix of the cementitious material and self-assembled to form a fiber weaving network, and at the same time, the nanofibers are reductively aggregated on the surface of the micron fibers and fine sand to form a mace-shaped multi- scale structure.

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