Solid waste-based high-volume ultrafine fly ash frost-resistant concrete and preparation method thereof

Abstract

The present invention discloses a solid waste-based, high-volume ultrafine fly ash frost-resistant concrete and a preparation method thereof, which realizes high-value utilization of solid waste resources through a three-stage fly ash synergistic efficiency enhancement technology. The concrete comprises, by weight, 50-55 parts of ultrafine fly ash, 5-10 parts of primary fly ash, 5-10 parts of secondary fly ash, 30-37 parts of cement, 130 parts of river sand, 0.33-0.9 parts of water reducer, and 195 parts of crushed stone. The concrete has low production cost and simple process, provides technical support for the high-value utilization of industrial solid waste, and is suitable for the field of green and low-carbon construction.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and in particular to a solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash and a preparation method thereof. Background Art

[0002] As a pozzolanic material, fly ash, when properly used in concrete, can not only achieve efficient resource utilization and reduce production costs, but also improve concrete properties to a certain extent. Therefore, how to handle and utilize fly ash has become a research hotspot.

[0003] At present, fly ash concrete generally has problems such as low admixture utilization efficiency and insufficient solid waste disposal capacity. On the one hand, due to the design defects of the traditional cementitious system, the fly ash content in the existing fly ash concrete is generally small, and most of them are single-type fly ash. The utilization rate of fly ash is low, the first-level ash content is generally less than 30%, and the activity of ultrafine fly ash and the synergistic effect of graded ash are not fully utilized, resulting in a large amount of second-level and below fly ash still being mainly stockpiled, and the comprehensive utilization rate of solid waste is low. On the other hand, blindly increasing the fly ash content can easily cause problems such as fly ash particles floating up and exudation, weakening of aggregate interface, and a significant decrease in the early strength of concrete. In order to improve the mechanical properties of fly ash, activators are also added to increase the preparation cost. This "low content-low value" application model seriously restricts the large-scale disposal of solid waste and hinders the efficient resource utilization of fly ash.

[0004] Patent application CN118619625A discloses frost-resistant concrete and its preparation method. Although this invention uses solid waste materials as raw materials to prepare concrete, the amount of solid waste used is relatively small, making it impossible to recycle solid waste resources. Patent application CN105731919B discloses ultra-high fly ash content concrete. Although the fly ash content of the concrete in this invention can reach 80% of the cementitious material, the additional addition of water reducers and air entraining agents increases the preparation cost. Therefore, the present invention provides a solid waste-based, high-content, ultra-fine fly ash-resistant concrete and its preparation method. Summary of the Invention

[0005] In view of the defects of the prior art, the purpose of the present invention is to provide a solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0006] The present invention solves the technical problem by adopting the following technical solutions:

[0007] The present invention provides a solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash, comprising the following raw materials in parts by weight:

[0008] The content of ultrafine fly ash is 50-60 parts by weight, the content of first-level fly ash is 5-15 parts by weight, the content of second-level fly ash is 5-10 parts by weight, the content of cement is 20-37 parts by weight, the content of river sand is 130 parts by weight, the content of water reducer is 0.33-0.9 parts by weight, and the content of crushed stone is 195 parts by weight.

[0009] Preferably, the cement type is PO42.5 ordinary Portland cement; the water reducer is polycarboxylate high-efficiency water reducer; and the water is ordinary domestic water.

[0010] Preferably, the fly ash is ultrafine fly ash, first-level fly ash, and second-level fly ash; the water requirement ratio of the three fly ashes is 95%-97%, and the loss on ignition is 1.5%-2%; the fineness of ultrafine fly ash is 1.5%-3% of the 45μm square hole sieve residue, and the strength activity index is 85%-90%; the fineness of first-level fly ash is 10%-12% of the 45μm square hole sieve residue, and the strength activity index is 75%-80%; the fineness of second-level fly ash is 14%-16% of the 45μm square hole sieve residue, and the strength activity index is 75%-80%.

[0011] Preferably, 4-8 parts of additives are further added to the antifreeze concrete; wherein the additives are prepared by:

[0012] S1: Prepare a 5-8% by mass fraction sodium dodecylbenzenesulfonate solution, then fully blend 5-8 parts of silicon micropowder, 2-3 parts of basalt fiber, 4-7 parts of sodium dodecylbenzenesulfonate solution and 1-2 parts of silane coupling agent KH550 to obtain silicon micropowder;

[0013] S2: sintering the carbon nanotubes, boron nitride, and silicon carbide in a weight ratio of 5:2:2 to obtain a carbon nanotube agent.

[0014] S3: ball milling the silicon micropowder and carbon nanotubes in a weight ratio of 7:5 to obtain the first ball milling solution.

[0015] The first ball milling liquid and the modified shell powder are subjected to secondary ball milling treatment in a weight ratio of 5:4. After the ball milling is completed, the additive is filtered and dried to obtain the additive.

[0016] Preferably, the sintering temperature of the blending sintering treatment is 300-350° C., and the sintering is performed for 1 hour; the ball milling speed of the primary ball milling treatment is 1250-1350 r / min, and the ball milling is performed for 2 hours; and the ball milling speed of the secondary ball milling treatment is 750-850 r / min, and the ball milling is performed for 5 hours.

[0017] The additive is blended with silicon micropowder, basalt fiber, sodium dodecylbenzenesulfonate solution and silane coupling agent, and is also improved by sintering with carbon nanotubes, boron nitride and silicon carbide, and ball milling with modified shell powder. The modified shell powder is improved by titanium dioxide through a modifying liquid, and then the shell powder liquid is blended. The additive is prepared by improving the coordination between the raw materials and enhancing the efficiency through the synergy between the raw materials, and further enhances the performance coordination and stability of the product in the system.

[0018] Preferably, the preparation method of the modified shell powder is:

[0019] S11: adding titanium dioxide to a modified liquid having a volume 3-5 times the total volume of titanium dioxide and stirring the solution until the stirring is complete to obtain a modified titanium dioxide liquid;

[0020] S12: Stir shell powder and sodium silicate solution in a weight ratio of 3:5 to obtain shell powder liquid, and blend the modified titanium dioxide liquid and shell powder liquid in a weight ratio of 7:5 and ball mill them for 1 hour at a ball mill speed of 1500r / min. After the ball milling is completed, filter and dry to obtain modified shell powder.

[0021] Preferably, the mass fraction of the sodium silicate solution is 5-8%;

[0022] The stirring speed of the stirring treatment is 350-400 r / min, and the stirring is for 1 hour; the modified liquid includes 2-4 parts by mass of 4% yttrium nitrate solution and 1-3 parts by mass of 5% sodium alginate solution.

[0023] The present invention also provides a method for preparing solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash, comprising the following steps:

[0024] Step (1) cement, ultrafine fly ash, primary fly ash, secondary fly ash, and river sand are sequentially placed in a mixer and stirred until uniform to obtain mixed dry material A;

[0025] Step (2) adding crushed stone and 50% of the total water, stirring until the surface of the aggregate is wetted, to obtain mixture B;

[0026] Step (3) adding polycarboxylate water reducer and remaining water to obtain mixture C;

[0027] Step (4) evenly apply a release agent to the inner surface of the mold, then evenly pour the mixture C into the mold, let it stand, demould it, and place it in a standard curing room for curing. After the curing is completed, a large amount of ultrafine fly ash concrete can be obtained.

[0028] Preferably, the stirring rate in step (1) is 62.5 r / min, and the stirring time is 2-3 min; the stirring rate in step (2) is 62.5 r / min, and the stirring time is 2 min; and the stirring rate in step (3) is 62.5 r / min, and the stirring time is 4-6 min.

[0029] Preferably, in step (4), the mixture C is poured into the mold in two times, and is vibrated after each pouring, with the total vibration time being not less than 1 minute; the curing conditions in the standard curing room are: the temperature is controlled at 20±2°C, and the humidity is greater than or equal to 95%.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention achieves high-value utilization of solid waste: the total utilization rate of fly ash reaches 70%-80%; multi-grade fly ash synergistic efficiency: ultrafine fly ash (50%-55%), primary fly ash (5%-10%), and secondary fly ash (5%-10%) are adopted in a three-grade ratio, wherein ultrafine ash provides volcanic ash activity, and primary and secondary ashes fill pores; low-carbon and low-cost preparation process: low cost, no chemical activator is required, and by controlling the water-binder ratio and the amount of polycarboxylate water-reducing agent, a 7-day compressive strength of ≥15MPa and a 28-day strength of ≥30MPa are achieved, meeting the requirements of mechanical properties and frost resistance. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] The solid waste-based frost-resistant concrete of this embodiment, which contains a large amount of ultrafine fly ash, includes the following raw materials in parts by weight:

[0034] The content of ultrafine fly ash is 50-60 parts by weight, the content of first-level fly ash is 5-15 parts by weight, the content of second-level fly ash is 5-10 parts by weight, the content of cement is 20-37 parts by weight, the content of river sand is 130 parts by weight, the content of water reducer is 0.33-0.9 parts by weight, and the content of crushed stone is 195 parts by weight.

[0035] The cement type in this embodiment is PO42.5 ordinary Portland cement; the water reducer is polycarboxylate high-efficiency water reducer; and the water is ordinary domestic water.

[0036] The fly ash in this embodiment is ultrafine fly ash, first-level fly ash, and second-level fly ash; the water requirement ratio of the three types of fly ashes is 95%-97%, and the loss on ignition is 1.5%-2%; the fineness of the ultrafine fly ash is 1.5%-3% of the 45μm square hole sieve residue, and the strength activity index is 85%-90%; the fineness of the first-level fly ash is 10%-12% of the 45μm square hole sieve residue, and the strength activity index is 75%-80%; the fineness of the second-level fly ash is 14%-16% of the 45μm square hole sieve residue, and the strength activity index is 75%-80%.

[0037] The antifreeze concrete of this embodiment is further added with 4-8 parts of an additive; wherein the additive is prepared by:

[0038] S1: Prepare a 5-8% by mass fraction sodium dodecylbenzenesulfonate solution, then fully blend 5-8 parts of silicon micropowder, 2-3 parts of basalt fiber, 4-7 parts of sodium dodecylbenzenesulfonate solution and 1-2 parts of silane coupling agent KH550 to obtain silicon micropowder;

[0039] S2: sintering the carbon nanotubes, boron nitride, and silicon carbide in a weight ratio of 5:2:2 to obtain a carbon nanotube agent.

[0040] S3: ball milling the silicon micropowder and carbon nanotubes in a weight ratio of 7:5 to obtain the first ball milling solution.

[0041] The first ball milling liquid and the modified shell powder are subjected to secondary ball milling treatment in a weight ratio of 5:4. After the ball milling is completed, the additive is filtered and dried to obtain the additive.

[0042] The sintering temperature of the blending sintering treatment in this embodiment is 300-350° C., and the sintering is performed for 1 hour. The ball milling speed of the primary ball milling treatment is 1250-1350 r / min, and the ball milling is performed for 2 hours. The ball milling speed of the secondary ball milling treatment is 750-850 r / min, and the ball milling is performed for 5 hours.

[0043] The preparation method of the modified shell powder of this embodiment is:

[0044] S11: adding titanium dioxide to a modified liquid having a volume 3-5 times the total volume of titanium dioxide and stirring the solution until the stirring is complete to obtain a modified titanium dioxide liquid;

[0045] S12: Stir shell powder and sodium silicate solution in a weight ratio of 3:5 to obtain shell powder liquid, and blend the modified titanium dioxide liquid and shell powder liquid in a weight ratio of 7:5 and ball mill them for 1 hour at a ball mill speed of 1500r / min. After the ball milling is completed, filter and dry to obtain modified shell powder.

[0046] The mass fraction of the sodium silicate solution in this embodiment is 5-8%;

[0047] The stirring speed of the stirring treatment is 350-400 r / min, and the stirring is for 1 hour; the modified liquid includes 2-4 parts by mass of 4% yttrium nitrate solution and 1-3 parts by mass of 5% sodium alginate solution.

[0048] The method for preparing a solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash in this embodiment includes the following steps:

[0049] Step (1) cement, ultrafine fly ash, primary fly ash, secondary fly ash, and river sand are sequentially placed in a mixer and stirred until uniform to obtain mixed dry material A;

[0050] Step (2) adding crushed stone and 50% of the total water, stirring until the surface of the aggregate is wetted, to obtain mixture B;

[0051] Step (3) adding polycarboxylate water reducer and remaining water to obtain mixture C;

[0052] Step (4) evenly apply a release agent to the inner surface of the mold, then evenly pour the mixture C into the mold, let it stand, demould it, and place it in a standard curing room for curing. After the curing is completed, a large amount of ultrafine fly ash concrete can be obtained.

[0053] In step (1) of this embodiment, the stirring rate is 62.5 r / min, and the stirring time is 2-3 min; the stirring rate in step (2) is 62.5 r / min, and the stirring time is 2 min; and the stirring rate in step (3) is 62.5 r / min, and the stirring time is 4-6 min.

[0054] In step (4) of this embodiment, the mixture C is poured into the mold twice, and is vibrated after each pouring, with the total vibration time being no less than 1 minute; the curing conditions in the standard curing room are: the temperature is controlled at 20±2°C, and the humidity is greater than or equal to 95%.

[0055] Example 1. The solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash in this example is composed of the following components in parts by weight: 55 parts of ultrafine fly ash, 10 parts of first-level fly ash, 5 parts of second-level fly ash, 30 parts of cement, 130 parts of river sand, 195 parts of crushed stone, 35 parts of mixing water, and 0.9 part of water reducer; among them, the water requirement ratio of ultrafine fly ash, first-level fly ash, and second-level fly ash is 95%-97%, and the loss on ignition is 1.5%-2%. The fineness of ultrafine fly ash is 1.5%-3% of the 45μm square hole sieve residue, and the strength activity index is 85%-90%; the fineness of first-level fly ash is 10%-12% of the 45μm square hole sieve residue, and the strength activity index is 75%-80%; the fineness of second-level fly ash is 14%-16% of the 45μm square hole sieve residue, and the strength activity index is 75%-80%; the cement is PO42.5 ordinary Portland cement; the river sand is standard river sand with a particle size of less than 4.7mm; the gravel is 5-20mm continuously graded gravel; the water is ordinary domestic water; the water reducer is a pure water-reducing type water reducer produced by Shanxi Feike New Materials Technology Co., Ltd.; 6 parts of additives are also added to the antifreeze concrete.

[0056] The method for preparing solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash in this embodiment includes the following steps:

[0057] Step (1): 30 parts of cement, 55 parts of ultrafine fly ash, 10 parts of first-grade fly ash, 5 parts of second-grade fly ash, 130 parts and 6 parts of additive river sand are sequentially put into a mixer, and stirred at a rate of 62.5 r / min for 2-3 minutes until uniform, to obtain mixture A.

[0058] Step (2): add 195 parts of crushed stone and 17.5 parts of water into a mixer and stir at a rate of 62.5 r / min for 2 min to obtain mixture B.

[0059] Step (3), add 0.9 parts of water reducer and 17.5 parts of water to obtain mixture C.

[0060] Step (4): evenly apply a release agent to the inner surface of the mold, and then pour the mixture C into the mold twice. After each pouring, vibrate it for a total vibration time of not less than 1 minute, let it stand, demould it, and put it into a standard curing room for curing. The curing conditions of the standard curing room are: temperature controlled at 20±2℃, humidity greater than or equal to 95%. After curing to the specified age, take it out to obtain solid waste-based high-volume ultrafine fly ash antifreeze concrete.

[0061] The preparation method of the additive is:

[0062] S1: Prepare a 6.5% mass fraction of sodium dodecylbenzenesulfonate solution, then fully blend 6.5 parts of silicon micropowder, 2.5 parts of basalt fiber, 5.5 parts of sodium dodecylbenzenesulfonate solution and 1.5 parts of silane coupling agent KH550 to obtain silicon micropowder;

[0063] S2: sintering the carbon nanotubes, boron nitride, and silicon carbide in a weight ratio of 5:2:2 to obtain a carbon nanotube agent.

[0064] S3: ball milling the silicon micropowder and carbon nanotubes in a weight ratio of 7:5 to obtain the first ball milling solution.

[0065] The first ball milling liquid and the modified shell powder are subjected to secondary ball milling treatment in a weight ratio of 5:4. After the ball milling is completed, the additive is filtered and dried to obtain the additive.

[0066] The sintering temperature of the blending sintering treatment in this embodiment is 325° C., and the sintering is performed for 1 hour. The ball milling speed of the primary ball milling treatment is 1300 r / min, and the ball milling is performed for 2 hours. The ball milling speed of the secondary ball milling treatment is 800 r / min, and the ball milling is performed for 5 hours.

[0067] The preparation method of the modified shell powder of this embodiment is:

[0068] S11: adding titanium dioxide to a modified liquid having a volume 4 times the total volume of titanium dioxide and stirring the mixture until the stirring is complete to obtain a modified titanium dioxide liquid;

[0069] S12: Stir shell powder and sodium silicate solution in a weight ratio of 3:5 to obtain shell powder liquid, and blend the modified titanium dioxide liquid and shell powder liquid in a weight ratio of 7:5 and ball mill them for 1 hour at a ball mill speed of 1500r / min. After the ball milling is completed, filter and dry to obtain modified shell powder.

[0070] The mass fraction of the sodium silicate solution in this embodiment is 6.5%;

[0071] The stirring speed of the stirring treatment is 370 r / min, and the stirring is performed for 1 hour; the modified liquid includes 3 parts of 4% by mass yttrium nitrate solution and 2 parts of 5% by mass sodium alginate solution.

[0072] To test the mechanical and frost resistance properties of the solid waste-based, high-volume ultrafine fly ash frost-resistant concrete prepared in this example, a casting mold measuring 100 mm × 100 mm × 100 mm was used. The strength of a 150 mm standard specimen in actual construction was correlated using a conversion factor (0.95). Compressive strength tests were conducted according to the test methods specified in the "GB / T 50081-2019 Standard for Testing Methods for Physical and Mechanical Properties of Concrete." Compressive strength tests were conducted on compressive specimens cured for 7 and 28 days. Frost resistance tests were conducted on frost-resistant specimens cured for 28 days.

[0073] Example 2. The solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash in this example is composed of the following components in parts by weight: 53 parts of ultrafine fly ash, 5 parts of first-class fly ash, 5 parts of second-class fly ash, 37 parts of cement, 130 parts of river sand, 195 parts of crushed stone, 44 parts of mixing water, 0.4 parts of water reducer and 5 parts of additives.

[0074] The preparation method of the solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash and the preparation method of the additive in this embodiment are the same as those in Example 1.

[0075] The mold size, compressive strength test, and frost resistance performance test methods for the solid waste-based, high-volume ultrafine fly ash frost-resistant concrete in this embodiment are the same as those in Example 1.

[0076] Example 3. The solid waste-based antifreeze concrete with a large amount of ultrafine fly ash in this example is composed of the following components in parts by weight: 60 parts of ultrafine fly ash, 5 parts of first-class fly ash, 10 parts of second-class fly ash, 25 parts of cement, 130 parts of river sand, 195 parts of gravel, 38 parts of mixing water, 0.5 parts of water reducer and 8 parts of additives.

[0077] The preparation method of the solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash and the preparation method of the additive in this embodiment are the same as those in Example 1.

[0078] The mold size and compressive strength testing method for casting the solid waste-based high-content ultrafine fly ash frost-resistant concrete in this embodiment are the same as those in Example 1.

[0079] Example 4. The solid waste-based antifreeze concrete with a large amount of ultrafine fly ash in this example is composed of the following components in parts by weight: 60 parts of ultrafine fly ash, 15 parts of first-class fly ash, 5 parts of second-class fly ash, 20 parts of cement, 130 parts of river sand, 195 parts of gravel, 35 parts of mixing water, 0.33 parts of water reducer and 8 parts of additives.

[0080] The preparation method of the solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash and the preparation method of the additive in this embodiment are the same as those in Example 1.

[0081] The mold size, compressive strength test, and frost resistance performance test methods for the solid waste-based, high-volume ultrafine fly ash frost-resistant concrete in this embodiment are the same as those in Example 1.

[0082] After testing, the compressive strength of the solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash of Examples 1 to 4 is shown in Table 1.

[0083]

[0084] It can be seen from Table 1 that the 7-day compressive strength of the concrete of the present invention is 16.2-24MPa, and the 28-day strength is ≥30MPa. The solid waste-based, high-content, ultrafine fly ash frost-resistant concrete of the present invention has good strength development characteristics. At the age of 7 days, the strength range covers 16.3-24MPa, which can meet some engineering scenarios with certain requirements for early strength; the 28-day strength is stable at ≥30MPa, reflecting a significant increase in strength in the later period and stable performance, which can effectively ensure the long-term bearing capacity of the structure. This strength development law, thanks to the unique proportion and process of raw materials such as solid waste-based, high-content, and ultrafine fly ash, provides reliable performance support for the application of concrete in various anti-freeze projects. Compared with traditional concrete, it has outstanding advantages in resource utilization and performance.

[0085] After testing, the frost resistance data of the solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash added according to Examples 1 to 4 are shown in Table 2.

[0086]

[0087] As shown in Table 2, after 150 freeze-thaw cycles, the mass loss rate of the specimen in Example 4 was greater than 5%, and the relative dynamic elastic modulus was less than 60%. After 200 freeze-thaw cycles, the mass loss rate of the specimen in Example 3 was greater than 5%, and the relative dynamic elastic modulus was less than 60%. According to the "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" and the "Specifications for Durability Design of Concrete Structures in Highway Engineering," Example 4, with freeze-thaw cycles exceeding 100, is classified as environmental exposure class D3 (normal freeze-thaw), meeting the F100 standard and suitable for ordinary building structures with certain durability requirements (such as civil building foundations and general industrial plant floors). Example 3, with freeze-thaw cycles exceeding 150, is classified as environmental exposure class D4 (severe freeze-thaw), meeting the F150 standard and suitable for important structures in cold regions. Examples 1 and 2, with freeze-thaw cycles exceeding 200, are classified as environmental exposure class D4 (severe freeze-thaw), meeting the F200 standard and suitable for structures in extremely cold regions or with high durability requirements (such as dams and bridges). Therefore, on the whole, the solid waste-based, high-content ultrafine fly ash frost-resistant concrete of the present invention shows high durability and reliability in freeze-thaw cycles, and can meet the antifreeze requirements in actual engineering applications. Although some embodiments show performance degradation at lower cycle times, overall, their antifreeze performance is still relatively excellent. The fly ash content of the concrete of the present invention reaches more than 70% of the cementitious material, which can greatly reduce the material cost and is more in line with the environmental protection concept of solid waste resource recycling. At the same time, the three-level ratio of ultrafine fly ash, first-level fly ash, and second-level fly ash is used to reinforce the solid waste-based, high-content ultrafine fly ash frost-resistant concrete, which not only reduces the concrete manufacturing cost, but also ensures the corresponding construction performance and use performance. The preparation process is simple, easy to operate and does not require expensive equipment, achieving low cost and low energy consumption, and is suitable for large-scale promotion and application in actual engineering.

[0088] The above is a detailed introduction to a solid waste-based, high-volume ultrafine fly ash antifreeze concrete and its preparation method provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for those skilled in the art, based on the ideas of the present application, other different forms of changes can be made on the basis of the above description. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash, characterized in that: It includes the following raw materials in parts by weight: The content of ultrafine fly ash is 50-60 parts by weight, the content of first-grade fly ash is 5-15 parts by weight, the content of second-grade fly ash is 5-10 parts by weight, the content of cement is 20-37 parts by weight, the content of river sand is 130 parts by weight, the content of water reducer is 0.33-0.9 parts by weight, and the content of crushed stone is 195 parts by weight; 4-8 parts of additives are also added to the antifreeze concrete; wherein the additives are prepared by: S1: Prepare a 5-8% by mass fraction sodium dodecylbenzenesulfonate solution, then fully blend 5-8 parts of silicon micropowder, 2-3 parts of basalt fiber, 4-7 parts of sodium dodecylbenzenesulfonate solution and 1-2 parts of silane coupling agent KH550 to obtain silicon micropowder; S2: sintering the carbon nanotubes, boron nitride, and silicon carbide in a weight ratio of 5:2:2 to obtain a carbon nanotube agent. S3: ball milling the silicon micropowder and carbon nanotubes in a weight ratio of 7:5 to obtain the first ball milling solution. The first ball milling liquid and the modified shell powder are subjected to secondary ball milling treatment in a weight ratio of 5:

4. After the ball milling is completed, the additive is filtered and dried to obtain the additive.

2. The solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash according to claim 1, characterized in that: The cement model is PO42.5 ordinary Portland cement; the water reducer is polycarboxylic acid high-efficiency water reducer; and the water is ordinary domestic water.

3. The solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash according to claim 1, characterized in that: The fly ash includes ultrafine fly ash, first-grade fly ash and second-grade fly ash; the water requirement ratio of the three fly ashes is 95%-97%, and the loss on ignition is 1.5%-2%; the fineness of ultrafine fly ash is 1.5%-3% of the 45μm square hole sieve residue, and the strength activity index is 85%-90%; the fineness of first-grade fly ash is 10%-12% of the 45μm square hole sieve residue, and the strength activity index is 75%-80%; the fineness of second-grade fly ash is 14%-16% of the 45μm square hole sieve residue, and the strength activity index is 75%-80%.

4. The solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash according to claim 1, characterized in that: The sintering temperature of the blending sintering treatment is 300-350° C., and the sintering is performed for 1 hour. The ball milling speed of the first-stage ball milling treatment is 1250-1350 r / min, and the ball milling is performed for 2 hours. The ball milling speed of the second-stage ball milling treatment is 750-850 r / min, and the ball milling is performed for 5 hours.

5. The solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash according to claim 1, characterized in that: The preparation method of the modified shell powder is: S11: adding titanium dioxide to a modified liquid having a volume 3-5 times the total volume of titanium dioxide and stirring the solution until the stirring is complete to obtain a modified titanium dioxide liquid; S12: Stir shell powder and sodium silicate solution in a weight ratio of 3:5 to obtain shell powder liquid, and blend the modified titanium dioxide liquid and shell powder liquid in a weight ratio of 7:5 and ball mill them for 1 hour at a ball mill speed of 1500r / min. After the ball milling is completed, filter and dry to obtain modified shell powder.

6. The solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash according to claim 5, characterized in that: The mass fraction of the sodium silicate solution is 5-8%; The stirring speed of the stirring treatment is 350-400 r / min, and the stirring is for 1 hour; the modified liquid includes 2-4 parts by mass of 4% yttrium nitrate solution and 1-3 parts by mass of 5% sodium alginate solution.

7. The method for preparing a solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: Step (1) cement, ultrafine fly ash, primary and secondary fly ash, river sand and additives are sequentially placed in a mixer and stirred until uniform to obtain mixed dry material A; Step (2) adding crushed stone and 50% of the total water, stirring until the surface of the aggregate is wetted, to obtain mixture B; Step (3) adding polycarboxylate water reducer and remaining water to obtain mixture C; Step (4) evenly apply a release agent to the inner surface of the mold, then evenly pour the mixture C into the mold, let it stand, demould it, and place it in a standard curing room for curing. After the curing is completed, a large amount of ultrafine fly ash concrete can be obtained.

8. The method for preparing solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash according to claim 7, characterized in that: The stirring rate in step (1) is 62.5 r / min, and the stirring time is 2-3 min; the stirring rate in step (2) is 62.5 r / min, and the stirring time is 2 min; the stirring rate in step (3) is 62.5 r / min, and the stirring time is 4-6 min.

9. The method for preparing solid waste-based frost-resistant concrete with a large amount of ultrafine fly ash according to claim 8, characterized in that: Step (4) Mixture C is poured into the mold in two batches, and is vibrated after each pouring, with the total vibration time being no less than 1 minute; the curing conditions in the standard curing room are: the temperature is controlled at 20±2°C, and the humidity is greater than or equal to 95%.

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