Modified solid waste doped ultra-high air entraining concrete and preparation method thereof

Abstract

The invention relates to the technical field of building materials, in particular to ultra-high air-entraining concrete doped with modified solid waste and a preparation method of the ultra-high air-entraining concrete. The concrete comprises cement, a mineral admixture, modified solid waste slurry, fine aggregate, coarse aggregate, water and a polycarboxylic acid high-performance admixture. The modified solid waste slurry is prepared by physically mixing solid waste powder such as silica fume, stone powder, ultrafine powder and the like and then sequentially reacting with a modifier containing a specific dispersing agent, an active exciting agent, a suspending agent and a pH regulator, and the pH of the final slurry is controlled to be 4-5. The polycarboxylic acid high-performance admixture is a specific compound of a viscosity reduction type water reducing agent and a high-performance air entraining agent. Through the synergistic effect of the special modified solid waste slurry, the special admixture, the admixture, the aggregate and other components, the problem that the mechanical property and the impermeability of the ultra-high air-entraining concrete are greatly reduced due to excessive bubbles is effectively solved, the performance of a mixture is guaranteed, the concrete is light, and meanwhile, the concrete has the advantages of being high in practicability and the like. The strength and durability of the concrete are remarkably improved, various properties of the concrete are ensured to meet engineering requirements, and high-added-value utilization of solid waste resources is realized.

Description

Technical Field

[0001] This application relates to the field of building materials technology, and in particular to an ultra-high air-entraining concrete with modified solid waste added and its preparation method. Background Technology

[0002] Air-entrained concrete is a modified concrete formed by incorporating air-entraining agents to introduce uniformly distributed, closed micro-air bubbles with diameters ranging from 10μm to 1000μm into the concrete interior. Its core advantage stems from the optimization of the internal structure of the concrete by these air bubbles, thereby improving the concrete's workability and durability. It has become a key material in engineering construction under various complex environments. Ultra-high air-entrained concrete refers to concrete with even higher air content, which can reduce its density by more than 10%, enabling lightweight structures and facilitating energy conservation, emission reduction, and construction.

[0003] In addition, the application of industrial solid waste powder in concrete has shifted from "mainly for disposal" to "performance-driven + low-carbon leading". The maturity of the technology and the degree of engineering verification have continued to improve, and engineering applications are moving towards low-carbon, high-performance and solid waste treatment.

[0004] Currently, the commonly used solid waste powders in air-entrained concrete are mineral powder and fly ash. These two solid waste powder materials are relatively stable and are often used to replace cement and natural materials such as sand and gravel in concrete preparation, thereby reducing carbon emissions.

[0005] However, compared to materials like cement, sand, and gravel, solid waste powder is more prone to compositional changes and exhibits greater performance variations, easily leading to performance losses in concrete. The aforementioned solid waste powder materials can only meet the needs of existing ordinary air-entrained concrete. When applied to ultra-high air-entrained concrete, as the air content increases (exceeding 10%), various concrete properties undergo significant changes, such as a substantial decrease in compressive strength and a decline in chloride ion penetration resistance. The reasons for this are as follows: With a significant increase in air entrainment (exceeding 10%), the excessive number of air bubbles reduces the spacing between bubbles within the concrete, making them more prone to compression and coalescence. This leads to larger bubble sizes, with more closed pores becoming interconnected, increasing the likelihood of performance defects. This alters the load-bearing failure and chloride ion migration patterns, thereby weakening the concrete's mechanical properties (e.g., a significant decrease in compressive strength) and durability (e.g., reduced resistance to chloride ion penetration). Currently, although commonly used solid waste admixtures in air-entrained concrete (such as mineral powder and fly ash) have relatively stable properties, they only meet the requirements of ordinary air-entrained concrete. Under the harsh conditions of ultra-high air content, conventional solid waste materials are insufficient to compensate for the structural defects and performance losses caused by excessive air bubbles, failing to meet the performance requirements of ultra-high air-entrained concrete.

[0006] Therefore, how to prepare an ultra-high air-entraining concrete with added solid waste powder, so that it can achieve high air content and lightweight while maintaining excellent mechanical and durability properties, thereby realizing the reuse of solid waste resources, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] To address the problems of the prior art mentioned in the background section, this application provides an ultra-high air-entraining concrete with modified solid waste added, the technical solution of which is as follows: The ultra-high air-entraining concrete with modified solid waste provided in this application includes the following raw materials: cement, mineral admixtures, modified solid waste slurry, fine aggregate, coarse aggregate, water, and polycarboxylate high-performance admixture. The components of the polycarboxylate high-performance admixture include a viscosity-reducing high-performance water-reducing agent, a high-performance air-entraining agent, and water; The modified solid waste slurry is obtained by mixing solid waste powder with water to form a slurry, and then modifying the slurry with a modifier; the modifier includes a dispersant, an activator, a suspending agent, and a pH adjuster; The dispersant is a polycarboxylic acid type fast dispersant; the activity activator is one or more of nano-calcium carbonate and nano-hydrated calcium silicate; and the suspending agent is one or more of cellulose aqueous solution and sodium silicate aqueous solution.

[0008] In some embodiments, the mass ratio of solid waste powder, water and modifier in the modified solid waste slurry is (9-12):(8-10):(1-1.5); the mass ratio of dispersant, activator, suspending agent and pH adjuster in the modifier is (5-10):(80-90):(3-5):(12-18).

[0009] In some embodiments, the solid waste powder includes two or more combinations of silica fume, stone powder, and ultrafine powder.

[0010] In some embodiments, the dispersant is at least one of polycarboxylate rapid dispersant 08A, polycarboxylate rapid dispersant 07D, polycarboxylate rapid dispersant 04E, and polycarboxylate rapid dispersant 05B.

[0011] In some embodiments, the cellulose aqueous solution is an aqueous solution of hydroxypropyl methylcellulose with a concentration of 6% to 10%; In some embodiments, the pH adjuster is sodium hydroxide at a concentration of 5% to 10% or phosphoric acid at a concentration of 10% to 15%.

[0012] In some embodiments, the particle size distribution of the solid waste powder is within 20 μm.

[0013] In some embodiments, the modified solid waste slurry is obtained by first physically mixing various solid waste powders, then adding water and stirring evenly, and finally adding a modifier, stirring evenly, and then letting it stand. The modifier includes a dispersant, an activator, a suspending agent, and a pH adjuster, and the order of addition is as follows: first add the dispersant, then the activator, then the suspending agent, and finally the pH adjuster, so that the final pH value of the slurry is controlled at 4-5.

[0014] In some embodiments, the preparation process of the modified solid waste slurry is as follows: first, a variety of solid waste powders are physically mixed, and then water is added and stirred evenly to obtain a uniform solid waste slurry; while stirring, a modifier is added to the solid waste slurry, and the order of addition is: first, a dispersant is added, then an activator is added, then a suspending agent is added, and finally a pH adjuster is added. After each component is added, the mixture is stirred for 30s to 45s to mix evenly, and the final pH is controlled at 4 to 5.

[0015] In some embodiments, the polycarboxylate high-performance admixture is obtained by compounding a viscosity-reducing high-performance water-reducing agent, a high-performance air-entraining agent and water; in the polycarboxylate high-performance admixture, the mass ratio of the viscosity-reducing high-performance water-reducing agent, the high-performance air-entraining agent and water is (23-25):(3-5):(70-80).

[0016] In some embodiments, the raw material components, by weight, include: 280 to 330 parts cement, 130 to 180 parts mineral admixtures, 60 to 100 parts modified solid waste slurry, 700 to 800 parts fine aggregate, 760 to 840 parts coarse aggregate, 70 to 90 parts water, and 7 to 8 parts polycarboxylate high-performance admixture.

[0017] In some embodiments, the cement is one of P·O 42.5 cement, P·O 52.5 cement, and P·II 52.5 cement.

[0018] In some embodiments, the mineral admixture is one or a combination of fly ash and mineral powder.

[0019] In some embodiments, the fine aggregate is one or more combinations of manufactured sand, river sand, and mixed sand, which belongs to Zone II medium sand and has a stone powder content of 3% to 5%.

[0020] In some embodiments, the coarse aggregate is one or more combinations of 5mm-10mm crushed stone, 10mm-20mm crushed stone, and 5mm-20mm crushed stone, with a gradation satisfying a continuous gradation of 5mm-20mm. The apparent density of the coarse aggregate is 2650 kg / m³. 3 ~2700kg / m 3 The content of needle-shaped and flaky coarse aggregate is 3% to 5%, and the crushing value is 3% to 5%.

[0021] This application provides a method for preparing ultra-high air-entraining concrete with modified solid waste as described above, which includes the following steps: Weigh each raw material component; Fine aggregate, coarse aggregate, cement, and mineral admixtures are added to a mixer and stirred for 10 to 20 seconds to obtain solid mixture A. Water and polycarboxylate high-performance additives are mixed evenly to obtain liquid B; Pour liquid B into solid mixture A and stir for 60-80 seconds to obtain slurry C. The modified solid waste slurry is mixed evenly with slurry C and stirred for 50s to 90s to obtain an ultra-high air-entrained concrete mixture, wherein the fluidity of the mixture is controlled between 450mm and 550mm.

[0022] Compared with existing technologies, this application has the following technical advantages: This application effectively solves the problem of a significant decrease in mechanical and impermeability properties of ultra-high air-entrained concrete caused by excessive air bubbles through the synergistic effect of specially modified solid waste slurry with special admixtures, additives, aggregates, and other components. While ensuring the performance of the mixture and achieving lightweight concrete, the strength and durability of the concrete are significantly improved, ensuring that all properties of the concrete meet the engineering requirements and realizing the high-value-added utilization of solid waste resources. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] This application also provides the formulations (unit: parts by weight) of the embodiments and comparative examples shown in Table 1: Table 1

[0025] Specifically, the preparation processes of the embodiments and comparative examples provided in this application are as follows: Example 1 In this embodiment, the raw material components, by weight, include: 280 parts cement, 160 parts mineral admixture, 100 parts modified solid waste slurry, 800 parts fine aggregate, 760 parts coarse aggregate, 70 parts water, and 7 parts polycarboxylate high-performance admixture.

[0026] The specific steps of the preparation method of the modified solid waste slurry are as follows: (1) Mix the various solid waste powders physically first, then add water and mix evenly to obtain solid waste slurry.

[0027] The solid waste powders include silica fume and stone powder, with a mass ratio of 4:1. The particle size distribution of both silica fume and stone powder is mostly within 20 μm.

[0028] (2) Add modifiers to solid waste slurry while stirring. The order of addition is: dispersant, activator, suspending agent, pH adjuster. Stir for 30 seconds after each addition. Finally, control the pH at 4 and let stand for later use.

[0029] The mass ratio of solid waste powder, water, and modifier is 9:9:1.5. Within the modifier, the mass ratio of dispersant, activator, suspending agent, and pH adjuster is 7:80:3:15. The dispersant is a polycarboxylate-type rapid dispersant, model 05B; the activator is nano-calcium carbonate; and the pH adjuster is phosphoric acid with a concentration of 10%. The suspending agent is an aqueous solution of hydroxypropyl methylcellulose (also known as an aqueous solution of hydroxypropyl methylcellulose ether), with a concentration of 10%. The preparation process involves pre-dissolving hydroxypropyl methylcellulose in water.

[0030] The cement is P·O 52.5 cement, with a standard consistency of 26.8%, a fineness of 6.7%, and a 28-day compressive strength of 56.8 MPa; The mineral admixture consists of fly ash and mineral powder in a weight ratio of 1:3.

[0031] The fine aggregate is manufactured sand (dry sand) with a moisture content of less than 0.5%, belonging to Zone II medium sand, and an apparent density of 2600 kg / m³. 3 The stone powder content is 4.1%, and the crushing value is 15%.

[0032] The coarse aggregate is a combination of 5mm-10mm crushed stone and 10mm-20mm crushed stone, with a weight ratio of 1:4. The aggregate gradation meets the requirement of a continuous gradation of 5mm-20mm, and the apparent density is 2700 kg / m³. 3 The content of needle-like and flaky particles is 4%, and the crushing value is 4%.

[0033] The polycarboxylate high-performance admixture is obtained by compounding a viscosity-reducing high-performance water-reducing agent, a high-performance air-entraining agent, and water in a mass ratio of 23:4:80. It significantly reduces the viscosity of concrete, effectively controls the smooth formation of air bubbles in the concrete paste, and ensures their stable presence within the concrete. Furthermore, it significantly improves the later-stage strength of the paste. It has a solids content of 12%, a water reduction rate of 24%, and a 28-day compressive strength ratio of 137%.

[0034] Specifically, the viscosity-reducing high-performance water-reducing agent can be selected from Kezhijie's Point-VS08 product, and the high-performance air-entraining agent can be selected from Kezhijie's YQ5 product.

[0035] This application also provides a method for preparing ultra-high air-entraining concrete with modified solid waste as described above, which includes the following preparation steps: Weigh each raw material component: Weigh cement, mineral admixtures, modified solid waste slurry, fine aggregate, coarse aggregate, water, and polycarboxylate high-performance admixture according to a certain weight ratio; Fine aggregate, coarse aggregate, cement, and mineral admixtures are added to a mixer in sequence and mixed for 10 seconds to obtain solid mixture A. Water and polycarboxylate high-performance additives are mixed evenly to obtain liquid B; Pour liquid B into the solid mixture and stir for 60 seconds to obtain slurry C; The modified solid waste slurry and slurry C are mixed evenly for 50 seconds to obtain ultra-high air-entrained concrete mixture. At this time, the slurry is in the form of cotton and silk, and the fluidity of the mixture is controlled at 450 mm.

[0036] The obtained mixture was used for performance testing, and the remaining part was used for molding testing of mechanical and durability properties. Molding method: pour directly into a fixed mold, vibrate lightly for 5 seconds, and scrape the surface smooth. After standard curing, test its various properties.

[0037] Example 2 In this embodiment, the raw material components, by weight, include: 330 parts cement, 130 parts mineral admixture, 60 parts modified solid waste slurry, 770 parts fine aggregate, 780 parts coarse aggregate, 90 parts water, and 8 parts polycarboxylate high-performance admixture.

[0038] The specific steps of the preparation method of the modified solid waste slurry are as follows: (1) Mix the various solid waste powders physically first, then add water and mix evenly to obtain solid waste slurry.

[0039] The solid waste powders include silica fume and stone powder, with a mass ratio of 4:1. The particle size distribution of both silica fume and stone powder is mostly within 20 μm.

[0040] (2) Add modifiers to solid waste slurry while stirring. The order of addition is: dispersant, activator, suspending agent, pH adjuster. Stir for 45 seconds after each addition. Finally, control the pH at 5 and let it stand for later use.

[0041] The mass ratio of solid waste powder, water, and modifier is 9:10:1. Within the modifier, the mass ratio of dispersant, activator, suspending agent, and pH adjuster is 8:90:4:18. The dispersant is a polycarboxylate-type rapid dispersant, model 05B; the activator is nano-calcium carbonate; and the pH adjuster is phosphoric acid, with a concentration of 10%. The suspending agent is an aqueous solution of hydroxypropyl methylcellulose (also known as an aqueous solution of hydroxypropyl methylcellulose ether), with a concentration of 10%. The preparation process involves pre-dissolving hydroxypropyl methylcellulose in water.

[0042] The cement is P·O 52.5 cement, with a standard consistency of 26.8%, a fineness of 6.7%, and a 28-day compressive strength of 56.8 MPa; The mineral admixture consists of fly ash and mineral powder in a weight ratio of 1:3.

[0043] The fine aggregate is manufactured sand (dry sand) with a moisture content of less than 0.5%, belonging to Zone II medium sand, and an apparent density of 2600 kg / m³. 3 The stone powder content is 4.1%, and the crushing value is 15%.

[0044] The coarse aggregate consists of 5mm-10mm crushed stone and 10mm-20mm crushed stone, with a weight ratio of 1:4. The aggregate's gradation satisfies a continuous gradation of 5mm-20mm, and its apparent density is 2700 kg / m³. 3 The content of needle-like and flaky particles is 4%, and the crushing value is 4%.

[0045] The polycarboxylate high-performance admixture is obtained by compounding a viscosity-reducing high-performance water-reducing agent, a high-performance air-entraining agent, and water in a mass ratio of 23:3:80. It significantly reduces the viscosity of concrete, effectively controls the smooth formation of air bubbles in the concrete paste, and ensures their stable presence within the concrete. It also significantly improves the later-stage strength of the paste. Its solid content is 12%, its water reduction rate reaches 24%, and its 28-day compressive strength reaches 137%.

[0046] Specifically, the viscosity-reducing high-performance water-reducing agent can be selected from Kezhijie's Point-VS08 product, and the high-performance air-entraining agent can be selected from Kezhijie's YQ5 product.

[0047] This application also provides a method for preparing ultra-high air-entraining concrete with modified solid waste as described above, which includes the following preparation steps: Weigh each raw material component: Weigh cement, mineral admixtures, modified solid waste slurry, fine aggregate, coarse aggregate, water, and polycarboxylate high-performance admixture according to a certain weight ratio; Fine aggregate, coarse aggregate, cement, and mineral admixtures are added to a mixer in sequence and mixed for 20 seconds to obtain solid mixture A. Water and polycarboxylate high-performance additives are mixed evenly to obtain liquid B; Pour liquid B into the solid mixture and stir for 70 seconds to obtain slurry C; The modified solid waste slurry and slurry C are mixed evenly for 70 seconds to obtain ultra-high air-entrained concrete mixture. At this time, the slurry is in the form of cotton and silk, and the fluidity of the mixture is controlled at 550 mm.

[0048] The obtained mixture was used for performance testing, and the remaining part was used for molding testing of mechanical and durability properties. Molding method: pour directly into a fixed mold, vibrate lightly for 5 seconds, and scrape the surface smooth. After standard curing, test its various properties.

[0049] Example 3 In this embodiment, the raw material components, by weight, include: 300 parts cement, 150 parts mineral admixture, 80 parts modified solid waste slurry, 750 parts fine aggregate, 800 parts coarse aggregate, 80 parts water, and 7.8 parts polycarboxylate high-performance admixture.

[0050] The specific steps of the preparation method of the modified solid waste slurry are as follows: (1) Mix the various solid waste powders physically first, then add water and mix evenly to obtain solid waste slurry.

[0051] The solid waste powders include silica fume, stone powder, and ultrafine powder, with a weight ratio of 4:1:1. The particle size distribution of silica fume, stone powder, and ultrafine powder is mostly within 20μm.

[0052] (2) Add modifiers to solid waste slurry while stirring. The order of addition is: dispersant, activator, suspending agent, pH adjuster. Stir for 45 seconds after each addition. Finally, control the pH at 4.5 and let stand for later use.

[0053] The mass ratio of solid waste powder, water, and modifier is 10:10:1.5. Within the modifier, the mass ratio of dispersant, activator, suspending agent, and pH adjuster is 10:90:5:16. The dispersant is a polycarboxylate-type rapid dispersant, model 05B; the activator is nano-calcium carbonate; and the pH adjuster is phosphoric acid with a concentration of 10%. The suspending agent is an aqueous solution of hydroxypropyl methylcellulose (also known as an aqueous solution of hydroxypropyl methylcellulose ether), with a concentration of 10%. The preparation process involves pre-dissolving hydroxypropyl methylcellulose in water.

[0054] The cement is P·O 52.5 cement, with a standard consistency of 26.8%, a fineness of 6.7%, and a 28-day compressive strength of 56.8 MPa; The mineral admixture consists of fly ash and mineral powder in a weight ratio of 1:3.

[0055] The fine aggregate is manufactured sand (dry sand) with a moisture content of less than 0.5%, belonging to Zone II medium sand, and an apparent density of 2600 kg / m³. 3 The stone powder content is 4.1%, and the crushing value is 15%.

[0056] The coarse aggregate consists of 5mm-10mm crushed stone and 10mm-20mm crushed stone, with a weight ratio of 1:4. The aggregate's gradation satisfies a continuous gradation of 5mm-20mm, and its apparent density is 2700 kg / m³. 3 The content of needle-like and flaky particles is 4%, and the crushing value is 4%.

[0057] The polycarboxylate high-performance admixture is obtained by compounding a viscosity-reducing high-performance water-reducing agent, a high-performance air-entraining agent, and water in a mass ratio of 23:3:80. It significantly reduces the viscosity of concrete, effectively controls the smooth formation of air bubbles in the concrete paste, and ensures their stable presence within the concrete. It also significantly improves the later-stage strength of the paste. Its solid content is 12%, its water reduction rate reaches 24%, and its 28-day compressive strength reaches 137%.

[0058] Specifically, the viscosity-reducing high-performance water-reducing agent can be selected from Kezhijie's Point-VS08 product, and the high-performance air-entraining agent can be selected from Kezhijie's YQ5 product.

[0059] This application also provides a method for preparing ultra-high air-entraining concrete with modified solid waste as described above, which includes the following preparation steps: Weigh each raw material component: Weigh cement, mineral admixtures, modified solid waste slurry, fine aggregate, coarse aggregate, water, and polycarboxylate high-performance admixture according to a certain weight ratio; Fine aggregate, coarse aggregate, cement, and mineral admixtures are added to a mixer in sequence and mixed for 15 seconds to obtain solid mixture A. Water and polycarboxylate high-performance additives are mixed evenly to obtain liquid B; Pour liquid B into the solid mixture and stir for 80 seconds to obtain slurry C; The modified solid waste slurry and slurry C are mixed evenly for 90 seconds to obtain ultra-high air-entrained concrete mixture. At this time, the slurry is in the form of cotton and silk, and the fluidity of the mixture is controlled at 500 mm.

[0060] The obtained mixture was used for performance testing, and the remaining part was used for molding testing of mechanical and durability properties. Molding method: pour directly into a fixed mold, vibrate lightly for 5 seconds, and scrape the surface smooth. After standard curing, test its various properties.

[0061] Comparative Example 1 The only difference between Comparative Example 1 and Example 3 is that the modified solid waste slurry in Comparative Example 1 is replaced by conventional mineral admixtures and water. The conventional mineral admixtures are fly ash and mineral powder, two types of solid waste powders, in a weight ratio of 1:3. All other conditions remain unchanged.

[0062] Comparative Example 2 The only difference between Comparative Example 2 and Example 3 is that the modified solid waste slurry in Comparative Example 2 is replaced with solid waste powder, including silica fume, stone powder, and ultrafine powder, in a weight ratio of 4:1:1, while other conditions remain unchanged.

[0063] Comparative Example 3 The only difference between Comparative Example 3 and Example 3 is that the modified solid waste slurry of Example 3 is replaced with unmodified solid waste slurry of the same mass as that of Example 3, while other conditions remain unchanged. Comparative Example 4 The only difference between Comparative Example 4 and Example 3 is that the special polycarboxylate high-performance admixture in Comparative Example 4 is replaced with a common polycarboxylate water-reducing agent, while other conditions remain unchanged.

[0064] Comparative Example 5: The modifier was a carbon nanotube dispersion. The only difference between this comparative example and Example 3 is that the preparation process of the modified solid waste slurry in the comparative example is as follows: (1) Mix various solid waste powders physically first, then add water and mix evenly to obtain solid waste slurry. The various solid waste powders include silica fume, stone powder, and ultrafine powder, with a weight ratio of 4:1:1. The particle size distribution of silica fume, stone powder, and ultrafine powder is mostly within 20μm.

[0065] (2) Add carbon nanotube dispersion modifier to the solid waste slurry while stirring for 45 seconds, and let it stand for later use. The mass ratio of solid waste powder, water and modifier is 10:10:1.5.

[0066] All other conditions remain unchanged.

[0067] Comparative Example 6: The key component dispersant was omitted from the modifier. The only difference between this comparative example and Example 3 is that the modifier in the preparation of the modified solid waste slurry in the comparative example does not include a polycarboxylate-type rapid dispersant. The mass ratio of solid waste powder, water, and modifier is 10:10:1.5. The mass ratio of the activator and suspending agent in the modifier remains unchanged, and the amount of pH adjuster used ensures that the pH value of the slurry is consistent with that in Example 3.

[0068] The other steps and conditions remain unchanged.

[0069] Comparative Example 7: Nano-calcium carbonate, a key component and activity activator, omitted. The only difference between this comparative example and Example 3 is that the modifier in the preparation of the modified solid waste slurry in the comparative example does not include the activity activator nano-calcium carbonate. The mass ratio of solid waste powder, water, and modifier is 10:10:1.5. The mass ratio of dispersant and suspending agent in the modifier remains unchanged, and the amount of pH adjuster used ensures that the slurry pH value is consistent with that of Example 3.

[0070] The other steps and conditions remain unchanged.

[0071] Comparative Example 8: Cellulose aqueous solution (with key component omitted) The only difference between this comparative example and Example 3 is that, in the preparation process of the modified solid waste slurry in the comparative example, the modifier does not include the suspending agent cellulose aqueous solution. The mass ratio of solid waste powder, water, and modifier is 10:10:1.5. The mass ratio of dispersant and activator in the modifier remains unchanged, and the amount of pH adjuster used ensures that the slurry pH value is consistent with that of Example 3.

[0072] The other steps and conditions remain unchanged.

[0073] Comparative Example 9: Key component pH adjuster omitted The only difference between this comparative example and Example 3 is that the modifier in the preparation process of the modified solid waste slurry in the comparative example does not include a pH adjuster. The mass ratio of solid waste powder, water, and modifier is 10:10:1.5, and the mass ratios of dispersant, suspending agent, and activator in the modifier remain unchanged.

[0074] The other steps and conditions remain unchanged.

[0075] Comparative Example 10: Changing the key components The only difference between this comparative example and Example 3 is that, in the preparation process of the modified solid waste slurry in the comparative example, nano-silica and other materials replace the active activator nano-calcium carbonate, while other steps and conditions remain unchanged.

[0076] Comparative Example 11: Changing the key components The only difference between this comparative example and Example 3 is that, in the preparation process of the modified solid waste slurry in the comparative example, the polyacrylamide aqueous solution is used to replace the suspending agent cellulose aqueous solution by mass, while other steps and conditions remain unchanged.

[0077] Performance testing of products obtained in the examples and comparative examples: The concrete prepared in the above embodiments and comparative examples was tested for performance according to the standards GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", and GB / T 50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete". The results are shown in Table 2.

[0078] Table 2

[0079] In Table 2, the slump, spread, and apparent density are the properties of freshly mixed ultra-high air-entrained concrete mixture; the 28-day compressive strength and 28-day chloride ion migration coefficient represent the compressive strength and chloride ion migration coefficient of the concrete after 28 days of standard curing, respectively.

[0080] The apparent density of the reference sample is 2420 kg / m³. 3 The approximate value is used as the basis for calculating the density reduction rate. The apparent density test values ​​in this application are accurate to 10 decimal places according to the standard.

[0081] The test results in Table 2 show that: The test results of Examples 1-3 show that as the amount of modified solid waste slurry increases, the amount of cement decreases, and the amount of admixtures decreases, indicating that the modified solid waste slurry itself already has good dispersibility and no further admixtures are needed for dispersion. With the increase in the amount of modified solid waste slurry, the 28-day compressive strength and chloride ion migration coefficient show a trend of first increasing and then decreasing, indicating that there is an optimal effect on these two properties. This is because the average particle size of the particles in the modified solid waste slurry is nanometer-sized, which can fill the gaps in the original material system, enhance the density of concrete, and encapsulate micro-bubbles, achieving the effect of strengthening the bubble walls. However, with too many micro-particles, agglomeration is likely to occur. These agglomerates cannot be completely encapsulated by cement hydration products, forming stress concentration points inside the cement paste, leading to a decrease in performance.

[0082] Compared with Example 3, Comparative Example 1 showed no significant changes in concrete slump and spread under the same admixture dosage, indicating that the water requirements of the modified solid waste slurry and mineral admixtures were similar, suggesting that the modification method can improve the dispersibility of nanomaterials. The 28-day compressive strength decreased while the 28-day chloride ion migration coefficient increased, indicating that the modified solid waste slurry can significantly improve the concrete strength and chloride ion penetration resistance. This is because the modification method allows the nanoparticles to be evenly distributed in the concrete slurry, strengthening the concrete matrix and further improving its performance, thus compensating for the negative effects of the ultra-high air content.

[0083] Compared to Example 3, Comparative Example 2 used only the same solid waste powder as the modified solid waste slurry (directly replacing the modified solid waste slurry with unmodified solid waste powder), without any modification treatment. This resulted in reduced fluidity and a need for more additives for dispersion. The reason is that micro-nano-sized solid waste powder is prone to agglomeration, requiring more additives to adsorb onto its surface for dispersion. Furthermore, it requires a high water content, which will adsorb some of the concrete water, causing moisture loss from the bubble film, reducing bubble film stability, deteriorating the pore structure, and thus lowering performance. Modified solid waste slurry itself has a dispersing effect. When other raw materials are added, it can synergistically work with additives to achieve a better and more uniform distribution of cement, mineral admixtures, and solid waste powder. Moreover, the active activator can further increase the slurry density, improve strength, and hinder chloride ion penetration.

[0084] Compared with Comparative Example 1, Comparative Example 2 replaced the mineral admixture with solid waste powder and increased the amount of additives. However, the compressive strength and resistance to chloride ion penetration were significantly enhanced. This indicates that the introduced new solid waste powder can effectively fill the micropores in the system, improve the density of the slurry, and better optimize the bubble structure. The average particle size and spacing coefficient of the bubbles are reduced, and the performance is improved.

[0085] Compared with Example 3, Comparative Example 3 used unmodified solid waste slurry, which was simply solid waste slurry powder with water to become solid waste slurry. This also increased the amount of additives and reduced the compressive strength and chloride ion penetration resistance. This shows that simply adding water cannot change its nature, cannot achieve the dispersion and enhancement effect, and may even affect its original performance.

[0086] Compared to Example 3, Comparative Example 4 used a common water-reducing agent, which failed to achieve the core objectives of "ultra-high air entrainment" and "lightweighting" pursued in this application. The difference between this common water-reducing agent and the specialized admixture lies in the different types of water-reducing mother liquor and air-entraining agent used. Comparative Example 4 resulted in increased concrete fluidity, significantly increased viscosity, increased bulk density, and higher compressive strength, while maintaining comparable resistance to chloride ion penetration. This indicates that common water-reducing agents cannot introduce more high-quality air bubbles and cannot achieve an air content exceeding 10%. Specialized admixtures are needed to adjust the viscosity of the concrete, making it easier for air bubbles to form and remain stably within the concrete, reducing escape and aggregation.

[0087] Compared with Example 3, Comparative Example 5 replaced the modifier with carbon nanotube dispersion, which led to an increase in the amount of admixture and a decrease in compressive strength and chloride ion penetration resistance. Compared with Comparative Example 3, the addition of carbon nanotube dispersion in Comparative Example 5 can improve its compressive strength and chloride ion penetration resistance. This shows that carbon nanotube dispersion itself has the effect of improving concrete performance. However, the effect of using only carbon nanotube dispersion cannot be compared with the performance of the modifier in this application. This is because the suspending agent, pH adjuster and other synergistic compounding agents in this application can significantly affect the performance of solid waste slurry, including fluidity and uniformity.

[0088] Compared with Example 3, Comparative Example 6 removed the polycarboxylate rapid dispersant from the modifier, which resulted in a significant increase in the amount of special polycarboxylate high-performance additive required, and a slight decrease in compressive strength and chloride ion penetration resistance. This may be because the polycarboxylate rapid dispersant itself has the dual effects of water reduction and dispersion, and can be effectively adsorbed on the surface of each particle in the solid waste slurry, promoting the interaction between the solid waste slurry and other raw materials, and guiding uniform distribution.

[0089] It should be noted that the main difference between Comparative Example 6 and the present application is that the modifier does not include a polycarboxylate type fast dispersant. This difference is due to the poor effect caused by this variable, and is not due to the increased amount of special polycarboxylate high-performance additive.

[0090] When Comparative Example 6 is used directly with the same proportions of the special polycarboxylate high-performance admixture as Example 3 to compound modified solid waste slurry (the modifier does not include polycarboxylate-type rapid dispersant), the concrete mixture exhibits significantly reduced fluidity and poor air entrainment when tested. Therefore, to facilitate a horizontal comparison with the embodiments of this application, a substantial increase in the dosage of the special polycarboxylate high-performance admixture in Comparative Example 6 is necessary to control the lightweight level (i.e., apparent density) of its concrete to a level close to that of Example 3 for comparison. However, increasing the dosage of the special polycarboxylate high-performance admixture significantly increases costs, while its compressive strength and chloride ion penetration resistance slightly decrease, demonstrating a dual disadvantage in terms of cost and performance. Similarly, the adjustments to the special polycarboxylate high-performance admixture variables in Comparative Examples 7-9 and Comparative Example 10 are also for achieving a similar level of concrete lightweighting for concrete performance comparison as in the examples.

[0091] Compared with Example 3, Comparative Example 7 removed nano-calcium carbonate from the modifier. Although the amount of special polycarboxylate high-performance admixture required to obtain lightweight concrete with a similar level to Example 3 was slightly reduced, its compressive strength and chloride ion penetration resistance decreased significantly. The reason may be that the nano-calcium carbonate used in this application can adsorb hydrated calcium ions and hydroxide ions, provide nucleation sites for calcium hydroxide crystallization, reduce the nucleation barrier, and fill the micropores in the cement matrix, thereby improving the mechanical properties and durability of concrete.

[0092] Compared to Example 3, Comparative Example 8 removed the cellulose aqueous solution from the modifier. While achieving a similar level of lightweighting as Example 3, Comparative Example 8 required a significantly reduced amount of the specialized polycarboxylate high-performance additive, and its compressive strength and chloride ion penetration resistance decreased. This is because the cellulose aqueous solution used in this application effectively controls the consistency of the solid waste slurry, promoting uniform distribution of its components and preventing sedimentation and agglomeration due to gravity. Agglomeration of the solid waste slurry easily leads to clumping, preventing sufficient contact with the cement matrix and causing defects.

[0093] Furthermore, although the advantages of adding cellulose aqueous solution in compressive strength and chloride ion penetration resistance were not as significant in the comparative data, the presence or absence of cellulose significantly affects the application process. Especially in large-scale production and construction, without the synergistic use of cellulose aqueous solution, the modified solid waste slurry is prone to significant sedimentation, and even after standing for a period of time, it easily agglomerates, failing to fully contact the cement matrix, creating defects and causing significant deterioration of concrete performance. The reason why the deterioration in strength and other properties was not obvious in Comparative Example 8 is that it was a small-scale test, allowing for continuous stirring and making the sedimentation and agglomeration of the solid waste slurry less noticeable. However, in large-scale construction, the sedimentation and agglomeration of the solid waste slurry would be more pronounced, and its impact on the deterioration of concrete compressive strength and other properties would be more significant. Furthermore, without the addition of cellulose, large-scale construction will increase the difficulty of use and the labor intensity: without the addition of cellulose, the solid waste slurry is prone to settling, and even after the solid waste slurry has been left to stand for a period of time, it is easy to agglomerate and clump together. In order to reduce the impact of the solid waste slurry settling on the concrete performance, high-intensity stirring and agglomeration are required to restore it to a certain suspension state, which consumes manpower and reduces work efficiency.

[0094] Compared with Example 3, Comparative Example 9 removed the pH adjuster from the modifier. While achieving a similar level of lightweighting as Example 3, Comparative Example 9 required a slightly increased amount of the special polycarboxylate high-performance admixture, and its compressive strength and chloride ion penetration resistance slightly decreased. This is because the main function of the pH adjuster in this application is to adjust the pH value of the solid waste slurry, change the internal potential, reduce the electrostatic adsorption of nanoparticles in the solid waste slurry, promote the dispersion between particles, and enhance the overall performance of concrete.

[0095] Compared with Example 3, Comparative Example 10 replaced the nano-calcium carbonate in the modifier with nano-silica of equal mass. Its performance was similar, but its cost increased significantly and it did not meet the requirements for practicality.

[0096] Compared with Example 3, Comparative Example 11 replaced the cellulose aqueous solution in the modifier with an equal mass of polyacrylamide aqueous solution. The amount of special polycarboxylate high-performance admixture required increased significantly, and the density reduction rate could not reach 10%. The reason is that polyacrylamide promotes the formation of a dense flocculent network of fine particles in the concrete paste through the electro-neutralization adsorption bridging effect, consumes free water and increases the internal friction between particles, which increases the viscosity of the concrete, makes the bubble stability worse, and makes it difficult to form a uniform bubble distribution.

[0097] In summary, the modified solid waste slurry and the special polycarboxylate high-performance admixture of this application constitute a synergistic technical system for solving the performance bottleneck of ultra-high air-entrained concrete, with significant effects.

[0098] In summary, compared with the prior art, the ultra-high air-entraining concrete with modified solid waste provided in this application includes the following design concepts and beneficial effects: Design concept: To address the shortcomings of existing solutions mentioned in the background, this application balances the performance loss of concrete by introducing novel solid waste materials, modifying solid waste treatment, adjusting mix proportion parameters, and designing a high-performance air-entraining agent compound. By studying the particle size distribution curves of existing air-entrained concrete cementitious materials, particles within the missing gradation range are introduced to enhance its paste properties. Furthermore, through comprehensive design including mix proportion adjustment, solid waste modification treatment, and the use of high-performance admixtures, an ultra-high air-entraining concrete incorporating solid waste powder is prepared. This concrete achieves high air content and lightweighting while maintaining excellent mechanical and durability properties. 1. Modified solid waste slurry has super dispersibility, reduces the agglomeration of nano-sized particles, and the particle size can be optimized from micron to nano, which can significantly improve the density of concrete, enhance the performance of ultra-high air-entrained concrete, and make it easier to produce without the need for manual feeding, thus reducing costs.

[0099] 2. The special admixture for ultra-high air-entraining concrete can significantly adjust the viscosity of concrete, optimize the pore structure, and improve the performance of the paste, thereby further improving various indicators of concrete.

[0100] 3. The raw material ratio is determined according to the new mix design method. Based on the bubble size, spacing and volume ratio, the volume of slurry is calculated. Then, according to the principle of both mass and volume, parameters such as sand and gravel ratio are determined to achieve the best effect.

[0101] Beneficial effects 1. The modified solid waste slurry prepared in this application has excellent dispersibility and stability, which can effectively disperse solid waste particles to the nanoscale, fully fill the micropores of cement matrix and bubble walls, significantly improve the density and strength of concrete matrix under ultra-high air entrainment state, and effectively offset the performance loss caused by high air content.

[0102] 2. The polycarboxylate high-performance admixture specifically applied in this application can precisely control the rheological properties of ultra-high air-entrained concrete mixtures, significantly adjust the viscous state of concrete, facilitate the formation and stabilization of a large number of high-quality, fine air bubbles, optimize the pore structure of concrete, and thus synergistically improve various performance indicators of concrete.

[0103] 3. This application, through the synergistic innovation of modified solid waste slurry and special admixtures, successfully solved the industry problem of a sharp drop in the strength and durability of ultra-high air-entrained concrete. The resulting concrete has an apparent density of approximately 2170 kg / m³. 3 Under conditions of significant reduction in bulk density, the compressive strength can still be maintained above 52 MPa after 28 days, and the chloride ion migration coefficient is less than 2.5 × 10⁻⁶. -12 m² / s, achieving an ideal combination of lightweight, high strength, and high durability.

[0104] 4. This application reuses industrial solid waste, which is in line with the development direction of green and low-carbon building materials and has significant economic and environmental benefits.

[0105] This application provides an ultra-high air-entraining concrete with modified solid waste and its preparation method. The addition of modified solid waste powder to this ultra-high air-entraining concrete effectively solves the problem of a significant reduction in concrete performance. More significantly, the modified solid waste can be effectively and uniformly distributed in the concrete, improving the density of the concrete paste and enhancing the mechanical and durability properties of the concrete. Finally, by optimizing the concrete mix proportion parameters and using a special polycarboxylate high-performance admixture for solid waste-based ultra-high air-entraining concrete, the various properties of the concrete are ensured to meet engineering requirements.

[0106] It should be noted that: Unless otherwise specified, “~” is used in this article to represent a numerical range, and the range of this expression includes two endpoint values.

[0107] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments under the concept of this application, and are not intended to limit them; those skilled in the art can make adaptive adjustments within the concept and protection scope of this application.

[0108] In addition, unless otherwise specified, the raw materials used may be commercially available products in the field or prepared by conventional methods in the field; that is, the reagents and instruments used in this embodiment do not specify the manufacturer or other information, and are all conventional products that can be purchased from the market.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A type of ultra-high air-entraining concrete with modified solid waste, characterized in that, Including the following raw materials: Cement, mineral admixtures, modified solid waste slurry, fine aggregate, coarse aggregate, water, and polycarboxylate high-performance admixtures; The components of the polycarboxylate high-performance admixture include a viscosity-reducing high-performance water-reducing agent, a high-performance air-entraining agent, and water; The modified solid waste slurry is obtained by mixing solid waste powder with water to form a slurry, and then modifying the slurry with a modifier; the modifier includes a dispersant, an activator, a suspending agent, and a pH adjuster; The dispersant is a polycarboxylate-type fast dispersant; The active activator is one or more of nano-calcium carbonate and nano-hydrated calcium silicate; The suspending agent is one or a combination of cellulose aqueous solution and sodium silicate aqueous solution.

2. The ultra-high air-entraining concrete with modified solid waste as described in claim 1, characterized in that: The modified solid waste slurry has its pH value adjusted to 4-5 by a pH adjuster. In the modified solid waste slurry, the mass ratio of solid waste powder, water and modifier is (9-12):(8-10):(1-1.5). In the modified agent, the mass ratio of dispersant, activator, suspending agent and pH adjuster is (5-10):(80-90):(3-5):(12-18).

3. The ultra-high air-entraining concrete with modified solid waste as described in claim 1, characterized in that: The solid waste powder includes two or more of the following: silica fume, stone powder, and ultrafine powder. The dispersant is at least one of polycarboxylate rapid dispersant 08A, polycarboxylate rapid dispersant 07D, polycarboxylate rapid dispersant 04E, and polycarboxylate rapid dispersant 05B. The cellulose aqueous solution is an aqueous solution of hydroxypropyl methylcellulose with a concentration of 6% to 10%; The pH adjuster is sodium hydroxide at a concentration of 5% to 10% or phosphoric acid at a concentration of 10% to 15%.

4. The ultra-high air-entraining concrete with modified solid waste as described in claim 1, characterized in that: The particle size distribution of the solid waste powder is within 20 μm.

5. The ultra-high air-entraining concrete with modified solid waste as described in claim 1, characterized in that: The modified solid waste slurry is obtained by first physically mixing various solid waste powders, then adding water and stirring evenly, and finally adding a modifier, stirring evenly, and then letting it stand. The modifier includes a dispersant, an activator, a suspending agent, and a pH adjuster. The order of addition is as follows: first add the dispersant, then the activator, then the suspending agent, and finally the pH adjuster, so that the final pH value of the slurry is controlled at 4-5.

6. The ultra-high air-entraining concrete with modified solid waste as described in claim 1, characterized in that: The preparation process of the modified solid waste slurry is as follows: Multiple solid waste powders are first physically mixed, and then water is added and stirred evenly to obtain a uniform solid waste slurry. Add modifiers to the solid waste slurry while stirring. The order of addition is as follows: first add dispersant, then add activator, then add suspending agent, and finally add pH adjuster. Stir for 30 to 45 seconds after each component is added to mix evenly. Finally, control the pH at 4 to 5.

7. The ultra-high air-entraining concrete with modified solid waste as described in claim 1, characterized in that: The polycarboxylate high-performance admixture is obtained by compounding a viscosity-reducing high-performance water-reducing agent, a high-performance air-entraining agent, and water. In the polycarboxylic acid high-performance admixture, the mass ratio of viscosity-reducing high-performance water-reducing agent, high-performance air-entraining agent and water is (23-25):(3-5):(70-80).

8. The ultra-high air-entraining concrete with modified solid waste as described in claim 1, characterized in that: By weight, its raw material components include: 280-330 parts cement, 130-180 parts mineral admixtures, 60-100 parts modified solid waste slurry, 700-800 parts fine aggregate, 760-840 parts coarse aggregate, 70-90 parts water, and 7-8 parts polycarboxylate high-performance admixture.

9. The ultra-high air-entraining concrete with modified solid waste as described in claim 1, characterized in that: The cement is one of P·O 42.5 cement, P·O 52.5 cement, and P·II 52.5 cement; The mineral admixture is one or a combination of two of fly ash and mineral powder; The fine aggregate is one or more combinations of manufactured sand, river sand, and mixed sand, belonging to Zone II medium sand, with a stone powder content of 3% to 5%; The coarse aggregate is one or more combinations of 5mm-10mm crushed stone, 10mm-20mm crushed stone, and 5mm-20mm crushed stone, and its gradation meets the continuous gradation of 5mm-20mm.

10. A method for preparing ultra-high air-entrained concrete with modified solid waste as described in any one of claims 1-9, characterized in that, Includes the following steps: Weigh each raw material component; Fine aggregate, coarse aggregate, cement, and mineral admixtures are added to a mixer and stirred for 10 to 20 seconds to obtain solid mixture A. Water and polycarboxylate high-performance additives are mixed evenly to obtain liquid B; Pour liquid B into solid mixture A and stir for 60-80 seconds to obtain slurry C. The modified solid waste slurry is mixed evenly with slurry C and stirred for 50s to 90s to obtain an ultra-high air-entrained concrete mixture, wherein the fluidity of the mixture is controlled between 450mm and 550mm.

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