An lc3-basalt fiber recycled block concrete and a preparation method thereof

Abstract

The application relates to the technical field of concrete preparation, in particular to LC3-basalt fiber recycled block concrete and a preparation method thereof, which comprises the following preparation steps: S1. LC3 cement, recycled blocks, natural sand and gravel are poured into a mixer and uniformly dry-mixed to obtain dry mixed materials; S2. water, modified water reducing agent and performance modifier are added to the dry mixed materials for wet mixing, and modified basalt fibers are uniformly scattered during the wet mixing process; the wet mixed materials are uniformly stirred to obtain wet mixed materials; S3. the wet mixed materials are poured into a test mold, demolded after standing at room temperature, and cured for 26-28 days to obtain the LC3-basalt fiber recycled block concrete. Through the synergistic effect of the modified basalt fibers, the modified water reducing agent and the performance modifier, the compressive strength, the high-temperature strength retention rate and the tensile strength of the concrete are remarkably improved, and the chemical activation and densification after the recycled blocks are added are realized.

Description

Technical Field

[0001] This invention relates to the field of concrete preparation technology, specifically to an LC3-basalt fiber recycled block concrete and its preparation method. Background Technology

[0002] Recycled block concrete technology breaks down waste concrete into large-scale recycled blocks (characteristic size approximately 50-100mm), which are then mixed with fresh concrete for pouring. This reduces the amount of new concrete used, significantly lowers the consumption of cement and natural sand and gravel, and enables the large-scale utilization of construction solid waste, resulting in significant energy conservation, emission reduction, and environmental protection benefits. Currently, recycled block concrete has been successfully applied in some pilot projects, and relevant industry standards have been promulgated, demonstrating promising prospects for widespread application.

[0003] However, recycled block concrete still faces significant challenges in practical applications. Building structures are frequently threatened by fire during their service life, and because the outer layer of virgin concrete in recycled block concrete typically uses high-strength grade material to balance the performance of the recycled blocks, it is prone to surface cracking at high temperatures, and its mechanical properties degrade rapidly after exposure to high temperatures. These problems severely affect the safety and reliability of structures under fire conditions, limiting the application of recycled block concrete in large-area load-bearing structures.

[0004] To improve the high-temperature performance of recycled block concrete, existing research mainly focuses on optimizing the cementitious system and adding fibers. Limestone-calcined clay cement (LC3) has attracted attention due to its low-carbon characteristics and good retention of mechanical properties after high temperatures; basalt fiber, due to its excellent thermal stability and anti-cracking ability, has been used to improve the high-temperature resistance of concrete. However, current research on the application of LC3 cement and basalt fiber composites in recycled block concrete is still insufficient, especially regarding the synergistic mechanism of the two under high-temperature conditions, the deformation compatibility of the interface between new and old materials under thermal loads, and the influence of these composites on the evolution of high-temperature damage and residual mechanical properties of concrete.

[0005] Therefore, there is an urgent need to develop a recycled block concrete material that combines good room temperature performance with excellent high-temperature resistance, and to elucidate its high-temperature damage mechanism and performance evolution law, so as to promote the safe application of such materials in high-temperature sensitive environments. This invention is proposed against this background. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide LC3-basalt fiber recycled block concrete and its preparation method.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing LC3-basalt fiber recycled block concrete includes the following preparation steps:

[0009] S1. By weight, pour 350-450 parts of LC3 cement, 200-400 parts of recycled blocks, 500-650 parts of natural sand, and 800-1000 parts of crushed stone (5-20mm) into a mixer and dry mix for 1-2 minutes until uniform to obtain a dry mix.

[0010] S2. Add 140-180 parts of water, 3.5-4.5 parts of modified water-reducing agent and 8-10 parts of performance modifier to the dry mixture obtained in step S1, wet mix for 5-8 minutes, and evenly sprinkle 5-7 parts of modified basalt fiber during wet mixing, and stir evenly to obtain wet mixture.

[0011] S3. Pour the wet mixture into the mold, let it stand at room temperature for 22-24 hours, then demold it and place it in a standard curing room for 26-28 days to obtain LC3-basalt fiber recycled block concrete.

[0012] The preparation of modified basalt fibers includes the following steps:

[0013] S11. By mass, add 1.5-3 parts of organosilane coupling agent KH-560 to 85-92 parts of deionized water, add 0.1-0.3 parts of glacial acetic acid while stirring at 300-400 r / min, adjust the pH to 4-5, and hydrolyze and activate for 30-45 min to obtain silane hydrolysate;

[0014] S12. Add 0.7-1.5 parts of nano-silica to the silane hydrolysate and disperse it by ultrasonication at 40kHz for 10-15 minutes. Then add 3-6 parts of waterborne epoxy emulsion (non-ionic self-emulsifying waterborne epoxy emulsion, solid content 45-55%) and stir at 300-400r / min for 15-20 minutes. Let it stand to defoam and obtain the surface-modified impregnation solution.

[0015] S13. Immerse 80-100 parts of basalt fiber in the surface modification impregnation solution for 20-30 minutes, remove the fiber, centrifuge to dehydrate for 3-5 minutes, and dry at 80℃ for 40-50 minutes to obtain modified basalt fiber.

[0016] Preferably, the preparation of the modified water-reducing agent includes the following steps:

[0017] S21. By mass, 8-10 parts of nano-titanium dioxide are dispersed in 80-100 parts of anhydrous ethanol. After ultrasonic dispersion for 18-20 min, 2.2-2.5 parts of itaconic acid are added. The mixture is stirred and reacted in a water bath at 60℃ for 3-4 h. After centrifugation, the mixture is washed 3-4 times with ethanol and dried under vacuum at 50℃ for 24 h to obtain modified nano-titanium dioxide.

[0018] S22. Mix 300-350 parts of ethylene glycol monovinyl polyethylene glycol ether and 550-600 parts of deionized water in a reactor, stir and heat to 35-40℃, purge with nitrogen to remove oxygen for 18-20 min, then slowly add the modified nano titanium dioxide obtained in step S21, 28-32 parts of acrylic acid, 80-100 parts of deionized water, and 1.2-1.8 parts of ammonium persulfate, and stir at 120-150 r / min for 4-5 h.

[0019] S23. Let the reaction solution obtained in step S22 mature for 40-50 minutes, and adjust the pH to 6-7 with sodium hydroxide at 25-30℃ to obtain the modified water-reducing agent.

[0020] Preferably, the preparation of the performance modifier includes the following steps:

[0021] S31. By weight, add 8-12 parts of polyvinyl alcohol to 45-55 parts of deionized water at 80℃, keep warm and stir for 45-60 minutes until completely dissolved, then cool to 30℃ to obtain PVA aqueous solution.

[0022] S32. Slowly add 40-60 parts of sodium silicate and 15-25 parts of polyaluminum sulfate at a speed of 300-400 r / min, and continue stirring for 20-30 min to obtain an emulsion;

[0023] S33. Add 1.8-3 parts of nano silica and 0.3-0.6 parts of polyether defoamer to the emulsion obtained in step S32, stir for 15-20 minutes, let stand for 30 minutes to defoam, and obtain the performance modifier.

[0024] Preferably, the recycled blocks are selected from waste concrete with a particle size of 50-100mm.

[0025] Preferably, the temperature of the standard curing room in step S3 is 18-22℃ and the relative humidity is ≥95%.

[0026] Preferably, the centrifugal dehydration speed in step S13 is 800-1000 rpm.

[0027] Preferably, the frequency of ultrasonic dispersion in step S21 is 40 kHz.

[0028] Preferably, the stirring speed in step S21 is 300-400 r / min.

[0029] Preferably, the stirring speed in step S33 is 400-500 r / min.

[0030] An LC3-basalt fiber recycled block concrete is prepared by the above preparation method.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] 1. The modified basalt fiber of this invention significantly enhances the interfacial bonding strength between the fiber and the hydration products of LC3 cement through chemical bonding, while maintaining maximum integrity of the fiber structure during the stirring process.

[0033] 2. This invention significantly improves the compressive strength, high-temperature strength retention, and tensile strength of concrete through the synergistic effect of modified basalt fiber, modified water-reducing agent, and performance modifier, achieving chemical activation and densification after the addition of recycled blocks. Without sacrificing carbon reduction benefits, this invention solves the application bottleneck of poor high-temperature performance of recycled block concrete, providing key technical support for the large-scale promotion of building solid waste resource utilization and low-carbon structural systems. Attached Figure Description

[0034] Figure 1 This is a process flow diagram for preparing LC3-basalt fiber recycled block concrete of the present invention;

[0035] Figure 2 This is a flow chart of the preparation process of the modified basalt fiber of the present invention;

[0036] Figure 3 This is a process flow diagram for preparing the modified water-reducing agent of the present invention;

[0037] Figure 4 This is a flow chart of the preparation process of the performance modifier of the present invention. Detailed Implementation

[0038] The present invention will now be clearly and completely described in conjunction with embodiments thereof. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] Please see Figures 1-4 The present invention provides a technical solution:

[0040] Example 1

[0041] A method for preparing LC3-basalt fiber recycled block concrete:

[0042] Before preparing LC3-basalt fiber recycled block concrete, modified basalt fibers, modified water-reducing agents, and performance modifiers are first prepared:

[0043] The preparation of modified basalt fibers includes the following steps:

[0044] S11. Add 1.5g of organosilane coupling agent KH-560 to 85g of deionized water, add 0.1g of glacial acetic acid while stirring at 300r / min, adjust the pH to 4, and hydrolyze and activate for 30min to obtain silane hydrolysate;

[0045] S12. Add 0.7g of nano-silica to the silane hydrolysate and disperse it by ultrasonication at 40kHz for 10min. Then add 3g of waterborne epoxy emulsion and stir at 300r / min for 15min. Let it stand to defoam and obtain the surface-modified impregnation solution.

[0046] S13. Immerse 80g of basalt fiber in the surface modification impregnation solution for 20min and then remove it. Centrifuge at 800rpm for 3min to dehydrate and dry at 80℃ for 40min to obtain modified basalt fiber.

[0047] The preparation of modified water-reducing agents includes the following steps:

[0048] S21. Disperse 8g of nano-titanium dioxide in 80g of anhydrous ethanol, ultrasonically disperse at 40kHz for 18min, add 2.2g of itaconic acid, stir at 300r / min for 3h in a 60℃ water bath, centrifuge, wash 3 times with ethanol, and vacuum dry at 50℃ for 24h to obtain modified nano-titanium dioxide.

[0049] S22. Mix 300g of ethylene glycol monovinyl polyethylene glycol ether and 550g of deionized water in a reactor, stir and heat to 35°C, purge with nitrogen for 18 min and then slowly add the modified nano titanium dioxide obtained in step S21, 28g of acrylic acid, 80g of deionized water and 1.2g of ammonium persulfate, and stir at 120r / min for 4h.

[0050] S23. The reaction solution obtained in step S22 is aged for 40 minutes, and the pH is adjusted to 6 with sodium hydroxide at 25°C to obtain the modified water-reducing agent.

[0051] The preparation of performance modifiers includes the following steps:

[0052] S31. Add 8g of polyvinyl alcohol to 45g of deionized water at 80℃, keep warm and stir for 45min until completely dissolved, then cool to 30℃ to obtain PVA aqueous solution;

[0053] S32. Slowly add 40g sodium silicate and 15g polyaluminum sulfate at a speed of 300r / min, and continue stirring for 20min to obtain an emulsion;

[0054] S33. Add 1.8g of nano silica and 0.3g of polyether defoamer to the emulsion obtained in step S32, stir at 400r / min for 15min, let stand for defoaming for 30min, and obtain the performance modifier.

[0055] S1. Pour 350g LC3 cement, 200g recycled blocks, 500g natural sand, and 800g crushed stone into a mixer and dry mix for 1 minute until uniform to obtain a dry mix.

[0056] S2. Add 140g of water, 3.5g of modified water-reducing agent and 8g of performance modifier to the dry mixture obtained in step S1, wet mix for 5 minutes, and evenly sprinkle 5g of modified basalt fiber during the wet mixing process, and stir evenly to obtain the wet mixture.

[0057] S3. Pour the wet mixture into the mold, let it stand at room temperature for 22 hours, then demold it and place it in a standard curing room (temperature 18℃, relative humidity 95%) for 26 days to obtain LC3-basalt fiber recycled block concrete.

[0058] Example 2

[0059] A method for preparing LC3-basalt fiber recycled block concrete:

[0060] Before preparing LC3-basalt fiber recycled block concrete, modified basalt fibers, modified water-reducing agents, and performance modifiers are first prepared:

[0061] The preparation of modified basalt fibers includes the following steps:

[0062] S11. Add 3g of organosilane coupling agent KH-560 to 92g of deionized water, add 0.3g of glacial acetic acid while stirring at 400r / min, adjust the pH to 5, and hydrolyze and activate for 45min to obtain silane hydrolysate;

[0063] S12. Add 1.5g of nano-silica to the silane hydrolysate and disperse it by ultrasonication at 40kHz for 15min. Then add 6g of waterborne epoxy emulsion and stir at 400r / min for 20min. Let it stand to defoam and obtain the surface-modified impregnation solution.

[0064] S13. Immerse 100g of basalt fiber in the surface modification impregnation solution for 30min and then remove it. Centrifuge at 1000rpm for 5min to dehydrate and dry at 80℃ for 50min to obtain modified basalt fiber.

[0065] The preparation of modified water-reducing agents includes the following steps:

[0066] S21. 10g of nano-titanium dioxide was dispersed in 100g of anhydrous ethanol, ultrasonically dispersed at 40kHz for 20min, and then 2.5g of itaconic acid was added. The mixture was stirred at 400r / min for 4h under a water bath at 60℃. After centrifugation, the mixture was washed 4 times with ethanol and vacuum dried at 50℃ for 24h to obtain modified nano-titanium dioxide.

[0067] S22. Mix 350g of ethylene glycol monovinyl polyethylene glycol ether and 600g of deionized water in a reactor, stir and heat to 40°C, purge with nitrogen for 20 min to remove oxygen, and then slowly add the modified nano titanium dioxide obtained in step S21, 32g of acrylic acid, 100g of deionized water and 1.8g of ammonium persulfate. Stir at 150r / min for 5 h.

[0068] S23. The reaction solution obtained in step S22 is aged for 50 minutes, and the pH is adjusted to 7 with sodium hydroxide at 30°C to obtain the modified water-reducing agent.

[0069] The preparation of performance modifiers includes the following steps:

[0070] S31. Add 12g of polyvinyl alcohol to 55g of deionized water at 80℃, keep warm and stir for 60min until completely dissolved, then cool to 30℃ to obtain PVA aqueous solution;

[0071] S32. Slowly add 60g sodium silicate and 25g polyaluminum sulfate at a speed of 400r / min, and continue stirring for 30min to obtain an emulsion;

[0072] S33. Add 3g of nano silica and 0.6g of polyether defoamer to the emulsion obtained in step S32, stir at 500r / min for 20min, let stand to defoam for 30min, and obtain the performance modifier.

[0073] S1. Pour 450g LC3 cement, 400g recycled blocks, 650g natural sand, and 1000g crushed stone into a mixer and dry mix for 2 minutes until uniform to obtain a dry mix.

[0074] S2. Add 180g of water, 4.5g of modified water-reducing agent and 10g of performance modifier to the dry mixture obtained in step S1, wet mix for 8 minutes, and evenly sprinkle 7g of modified basalt fiber during the wet mixing process, and stir evenly to obtain the wet mixture.

[0075] S3. Pour the wet mixture into the mold, let it stand at room temperature for 24 hours, then demold it and place it in a standard curing room (temperature 22℃, relative humidity 98%) for 28 days to obtain LC3-basalt fiber recycled block concrete.

[0076] Example 3

[0077] A method for preparing LC3-basalt fiber recycled block concrete:

[0078] Before preparing LC3-basalt fiber recycled block concrete, modified basalt fibers, modified water-reducing agents, and performance modifiers are first prepared:

[0079] The preparation of modified basalt fibers includes the following steps:

[0080] S11. Add 2g of organosilane coupling agent KH-560 to 90g of deionized water, add 0.2g of glacial acetic acid while stirring at 350r / min, adjust the pH to 4.5, and hydrolyze and activate for 38min to obtain silane hydrolysate;

[0081] S12. Add 1.2g of nano-silica to the silane hydrolysate and disperse it by ultrasonication at 40kHz for 12min. Then add 5g of waterborne epoxy emulsion and stir at 350r / min for 17min. Let it stand to defoam and obtain the surface modified impregnation solution.

[0082] S13. Immerse 90g of basalt fiber in a surface-modified impregnation solution for 25min and remove it. Centrifuge at 900rpm for 4min to dehydrate and dry at 80℃ for 45min to obtain modified basalt fiber.

[0083] The preparation of modified water-reducing agents includes the following steps:

[0084] S21. 9g of nano-titanium dioxide was dispersed in 90g of anhydrous ethanol and ultrasonically dispersed at 40kHz for 19min. Then, 2.3g of itaconic acid was added and the mixture was stirred at 350r / min for 3.5h in a 60℃ water bath. After centrifugation, the mixture was washed three times with ethanol and vacuum dried at 50℃ for 24h to obtain modified nano-titanium dioxide.

[0085] S22. Mix 340g of ethylene glycol monovinyl polyethylene glycol ether and 580g of deionized water in a reactor, stir and heat to 38°C, purge with nitrogen for 19 min to remove oxygen, and then slowly add the modified nano titanium dioxide obtained in step S21, 30g of acrylic acid, 90g of deionized water and 1.5g of ammonium persulfate. Stir at 140r / min for 4.5h.

[0086] S23. The reaction solution obtained in step S22 is aged for 45 minutes, and the pH is adjusted to 6.5 with sodium hydroxide at 28°C to obtain the modified water-reducing agent.

[0087] The preparation of performance modifiers includes the following steps:

[0088] S31. Add 10g of polyvinyl alcohol to 50g of deionized water at 80℃, keep warm and stir for 50min until completely dissolved, then cool to 30℃ to obtain PVA aqueous solution;

[0089] S32. Slowly add 50g sodium silicate and 20g polyaluminum sulfate at a speed of 350r / min, and continue stirring for 25min to obtain an emulsion;

[0090] S33. Add 2.2g of nano silica and 0.5g of polyether defoamer to the emulsion obtained in step S32, stir at 450r / min for 18min, let stand for defoaming for 30min, and obtain the performance modifier.

[0091] S1. Pour 400g LC3 cement, 300g recycled blocks, 550g natural sand, and 900g crushed stone into a mixer and dry mix for 1.5 minutes until uniform to obtain a dry mix.

[0092] S2. Add 160g of water, 4g of modified water-reducing agent and 9g of performance modifier to the dry mixture obtained in step S1, wet mix for 7 minutes, and evenly sprinkle 6g of modified basalt fiber during the wet mixing process, and stir evenly to obtain the wet mixture.

[0093] S3. Pour the wet mixture into the mold, let it stand at room temperature for 23 hours, then demold it and place it in a standard curing room (temperature 20℃, relative humidity 97%) for 27 days to obtain LC3-basalt fiber recycled block concrete.

[0094] Comparative Example 1

[0095] The only difference between Comparative Example 1 and Example 1 is that the modified basalt fiber is replaced with conventional basalt fiber in this comparative example. The other steps are exactly the same in Comparative Example 1 and Example 1.

[0096] Comparative Example 2

[0097] The only difference between Comparative Example 2 and Example 1 is that the modified water-reducing agent is replaced with a polycarboxylate water-reducing agent in this comparative example. The remaining steps are exactly the same in Comparative Example 2 and Example 1.

[0098] Comparative Example 3

[0099] The only difference between Comparative Example 3 and Example 1 is that no performance modifier was added in this comparative example; the other steps are exactly the same in Comparative Example 3 and Example 1.

[0100] Performance testing:

[0101] According to GB / T 50081-2019, the compressive strength of LC3-basalt fiber recycled block concrete obtained in Examples 1-3 and Comparative Examples 1-3 with dimensions of 100mm×100mm×100mm was tested using a pressure testing machine at a loading rate of 0.8MPa / s until failure. The splitting tensile strength was tested using the strip splitting method at a loading rate of 0.08MPa / s. The data obtained are shown in Table 1 below:

[0102] Table 1 Mechanical property test data

[0103]

[0104] According to GB / T 50081-2019, the LC3-basalt fiber recycled block concrete obtained in Examples 1-3 and Comparative Examples 1-3 with dimensions of 100mm×100mm×100mm was heated to 200℃, 400℃, and 600℃ respectively, held at that temperature for 2 hours, and then naturally cooled before measuring the compressive strength and the ratio to the room temperature strength. The data obtained are shown in Table 2 below:

[0105] Table 2 Data on compressive strength retention rate after high temperature

[0106]

[0107] The data in Tables 1 and 2 show that the LC3-basalt fiber recycled block concrete obtained in Examples 1-3 of this invention outperforms the comparative examples in terms of compressive strength, splitting tensile strength, and retention rate of compressive strength after high temperature. This indicates that the synergistic effect of modified basalt fiber, modified water-reducing agent, and performance modifier can stimulate the surface activity of LC3-basalt fiber recycled block concrete, promote secondary hydration, fill pores, and achieve chemical activation and densification. While maintaining the low-carbon advantages of LC3 cement, this invention achieves high performance in large-volume recycled blocks, providing key technical support for the resource utilization of building solid waste and low-carbon structural systems, and possessing significant economic and social benefits.

[0108] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing LC3-basalt fiber recycled block concrete, characterized in that, The preparation steps include the following: S1. By weight, add 350-450 parts of LC3 cement, 200-400 parts of recycled blocks, 500-650 parts of natural sand, and 800-1000 parts of crushed stone into a mixer and dry mix for 1-2 minutes until uniform to obtain a dry mix. S2. Add 140-180 parts of water, 3.5-4.5 parts of modified water-reducing agent and 8-10 parts of performance modifier to the dry mixture obtained in step S1, wet mix for 5-8 minutes, and evenly sprinkle 5-7 parts of modified basalt fiber during wet mixing, and stir evenly to obtain wet mixture. S3. Pour the wet mixture into the mold, let it stand at room temperature for 22-24 hours, then demold it and place it in a standard curing room for 26-28 days to obtain LC3-basalt fiber recycled block concrete. The preparation of the modified basalt fiber includes the following steps: S11. By mass, add 1.5-3 parts of organosilane coupling agent KH-560 to 85-92 parts of deionized water, add 0.1-0.3 parts of glacial acetic acid while stirring at 300-400 r / min, adjust the pH to 4-5, and hydrolyze and activate for 30-45 min to obtain silane hydrolysate; S12. Add 0.7-1.5 parts of nano-silica to the silane hydrolysate and disperse it by ultrasonication at 40kHz for 10-15min. Then add 3-6 parts of waterborne epoxy emulsion and stir at 300-400r / min for 15-20min. Let it stand to defoam and obtain the surface-modified impregnation solution. S13. Immerse 80-100 parts of basalt fiber in the surface modification impregnation solution for 20-30 minutes, remove the fiber, centrifuge to dehydrate for 3-5 minutes, and dry at 80℃ for 40-50 minutes to obtain modified basalt fiber. The preparation of the modified water-reducing agent includes the following steps: S21. By mass, 8-10 parts of nano-titanium dioxide are dispersed in 80-100 parts of anhydrous ethanol. After ultrasonic dispersion for 18-20 min, 2.2-2.5 parts of itaconic acid are added. The mixture is stirred and reacted in a water bath at 60℃ for 3-4 h. After centrifugation, the mixture is washed 3-4 times with ethanol and dried under vacuum at 50℃ for 24 h to obtain modified nano-titanium dioxide. S22. Mix 300-350 parts of ethylene glycol monovinyl polyethylene glycol ether and 550-600 parts of deionized water in a reactor, stir and heat to 35-40℃, purge with nitrogen to remove oxygen for 18-20 min, then slowly add the modified nano titanium dioxide obtained in step S21, 28-32 parts of acrylic acid, 80-100 parts of deionized water, and 1.2-1.8 parts of ammonium persulfate, and stir at 120-150 r / min for 4-5 h. S23. The solution obtained in step S22 is aged for 40-50 minutes, and the pH is adjusted to 6-7 with sodium hydroxide at 25-30℃ to obtain the modified water-reducing agent; The preparation of the performance modifier includes the following steps: S31. By mass, add 8-12 parts of polyvinyl alcohol to 45-55 parts of deionized water at 80℃, keep warm and stir for 45-60 minutes until completely dissolved, then cool to 30℃ to obtain PVA aqueous solution. S32. Slowly add 40-60 parts of sodium silicate and 15-25 parts of polyaluminum sulfate at a speed of 300-400 r / min, and continue stirring for 20-30 min to obtain an emulsion; S33. Add 1.8-3 parts of nano-silica and 0.3-0.6 parts of polyether defoamer to the emulsion obtained in step S32, stir for 15-20 minutes, let stand for 30 minutes to defoam, and obtain the performance modifier. The recycled blocks are selected from waste concrete with a particle size of 50-100mm.

2. The method for preparing LC3-basalt fiber recycled block concrete according to claim 1, characterized in that, In step S3, the temperature of the standard curing room is 18-22℃ and the relative humidity is ≥95%.

3. The method for preparing LC3-basalt fiber recycled block concrete according to claim 1, characterized in that, In step S13, the centrifugal dehydration speed is 800-1000 rpm.

4. The method for preparing LC3-basalt fiber recycled block concrete according to claim 1, characterized in that, In step S21, the frequency of ultrasonic dispersion is 40 kHz.

5. The method for preparing LC3-basalt fiber recycled block concrete according to claim 1, characterized in that, The stirring speed in step S21 is 300-400 r / min.

6. The method for preparing LC3-basalt fiber recycled block concrete according to claim 1, characterized in that, The stirring speed in step S33 is 400-500 r / min.

7. An LC3-basalt fiber recycled block concrete, characterized in that, It is prepared by the preparation method described in any one of claims 1-6.

Images