Low-carbon concrete prepared based on brick slag and metal tailings and preparation method thereof

Abstract

The application relates to the field of building materials, and particularly discloses low-carbon concrete prepared based on brick slag and metal tailings and a preparation method thereof. The low-carbon concrete comprises the following raw materials: cement, water, coarse aggregate, fine aggregate, mineral admixture, rice husk ash, additive and anti-cracking fiber. The coarse aggregate comprises waste brick slag particles and gravel, and the fine aggregate comprises waste brick slag powder and sand. The waste brick slag powder and the waste brick slag particles are obtained by crushing waste brick slag, then performing enhancement modification treatment, and then performing hydrophobic modification treatment, crushing and grading. The preparation method comprises the following steps: mixing the cement, the coarse aggregate, the fine aggregate, the mineral admixture, the rice husk ash and the anti-cracking fiber to prepare an initial mixture; mixing the additive and the water to prepare a mixed solution, then adding the prepared initial mixture, and stirring and mixing to prepare the low-carbon concrete. The application has the characteristics of relieving the problems of the reduction of the compressive strength and the crack resistance of the concrete in which the waste brick slag is used as the aggregate.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building materials, more particularly, it relates to a low-carbon concrete prepared based on brick slag combined with metal tailings and a preparation method thereof. BACKGROUND

[0002] With the rapid development of social economy and the acceleration of urbanization, a large number of building construction brings huge demand for building materials. Traditional concrete consumes a large amount of natural resources such as sand, stone, cement, etc. during the production process and emits a large amount of carbon dioxide, at the same time, in recent years, a large amount of construction waste is generated every year, especially the demolished buildings are mostly brick-concrete structure buildings, among the construction waste generated by the demolition of these buildings, a considerable proportion is building waste bricks, how to realize the recycling of these building waste bricks has been widely studied.

[0003] In recent years, in order to reduce the carbon footprint of the construction industry, the use of industrial waste as a substitute material to prepare new type of concrete has been explored, the industrial waste includes but is not limited to fly ash, slag, brick slag, slag, etc. Especially, the recycling of a large amount of brick slag has important significance for resource recycling and solving the problem of construction waste disposal.

[0004] However, compared with natural aggregate, waste brick slag has high porosity and high water absorption rate, and its compressive strength is lower than that of natural aggregate, so when it is directly added to concrete as aggregate, the compressive strength of the concrete is reduced, and due to its water absorption and porosity, stress is generated inside the concrete, and its strong water absorption leads to uneven water distribution, and during the subsequent drying process, shrinkage stress is generated due to water evaporation, which reduces the crack resistance of the concrete and reduces its durability. SUMMARY

[0005] In order to alleviate the problem of reduced compressive strength and crack resistance of concrete using waste brick slag as aggregate, the present application provides a low-carbon concrete prepared based on brick slag combined with metal tailings and a preparation method thereof.

[0006] In a first aspect, the present application provides a low-carbon concrete prepared based on brick slag combined with metal tailings, which adopts the following technical scheme:

[0007] A low-carbon concrete prepared based on brick slag combined with metal tailings, comprising the following raw materials by weight: 350-400 parts of cement, 145-180 parts of water, 620-760 parts of coarse aggregate, 260-350 parts of fine aggregate, 80-120 parts of mineral admixture, 40-60 parts of rice husk ash, 5-10 parts of additive and 15-20 parts of anti-cracking fiber;

[0008] The coarse aggregate includes waste brick slag particles and gravel, the fine aggregate includes waste brick slag powder and sand, and the mineral admixture at least includes metal tailings.

[0009] The waste brick slag powder and the waste brick slag particles are obtained by crushing the waste brick slag, then performing the reinforcing modification treatment and the hydrophobic modification treatment on the waste brick slag.

[0010] The reinforcing modification treatment specifically comprises the following steps: immersing the crushed waste brick slag in a modified mixed solvent containing a silane coupling agent, a binder, water and a crack filling filler, and then performing high-temperature treatment.

[0011] By adopting the technical scheme, the mineral admixture and rice husk ash are used to partially replace the cement in the application, so that the carbon emission is reduced. The rice husk ash is a low-carbon material, has excellent pore structure and active ingredients, and can significantly improve the strength and durability of the concrete when mixed into the concrete, while reducing the amount of cement and carbon emission. In addition, the waste brick slag and the metal tailings are used to replace part of the cement in the application, so that the amount of cement is reduced, the carbon emission of the concrete is reduced, the problem of waste garbage stacking is solved, resource recycling is realized, the dependence on natural resources is reduced, industrial waste is effectively utilized, and sustainable development is promoted.

[0012] The high water absorption of the waste brick slag is caused by the high porosity of the waste brick slag itself and a large number of microcracks generated in the crushing process, which reduces the compressive strength of the concrete and the crack resistance. Therefore, the waste brick slag is subjected to the reinforcing modification treatment and the hydrophobic modification treatment in the application, which improves the mechanical properties of the waste brick slag itself, thereby improving the compressive strength of the concrete, and reduces the water absorption of the waste brick slag, thereby reducing the crack resistance caused by the high water absorption. In particular, the waste brick slag is immersed in a modified mixed solvent containing a silane coupling agent, a binder, water and a crack filling filler, and then subjected to high-temperature treatment. The crack filling filler fills the microcracks of the waste brick slag, and is combined with the waste brick slag at the cracks under the action of the binder, and is fixed and sintered with the microspheres and the crack filling filler during high-temperature treatment. In addition, the intermediate phase pitch and the binder form a continuous network structure during high-temperature curing and fill the cracks, thereby improving the strength and toughness of the waste brick slag, providing a stress buffer interval for the subsequent concrete volume shrinkage, improving the crack resistance, and finally realizing the crack filling of the microcracks in the waste slag powder and the loading of the crack filling filler in the pore structure of the waste slag powder, thereby reducing the porosity, improving the mechanical properties and crack resistance, and further reducing the problems of the high water absorption, the mechanical properties and the crack resistance caused by the high water absorption.

[0013] Optionally, the crack filling filler comprises fly ash, silica fume and alkaline substance in a mass ratio of 1:(0.8-1.2):(0.5-0.8), and the alkaline substance is selected from magnesium acetate and sodium metaaluminate in a mass ratio of 1:(1.2-1.5).

[0014] By adopting the technical scheme, when the crack filling filler in the application contains silica fume and fly ash, the silica fume and fly ash have small particle size and good filling performance, can effectively fill the microcracks in the waste brick slag, and the addition of magnesium acetate and sodium metaaluminate forms a soluble salt solution in the aqueous solution, so that the soluble salt solution fully penetrates into the microcracks of the waste brick slag, helps to introduce the sodium metaaluminate and magnesium acetate into the microcrack structure of the waste brick slag, and then high-temperature calcination is performed, the sodium metaaluminate reacts with silicate in the waste brick slag to generate a new compound, which can effectively fill the cracks, and the magnesium acetate solution penetrates into the cracks and forms nano magnesium oxide deposited in the cracks of the waste brick slag under the action of high-temperature calcination. In this way, the selection of the crack filling filler in the application not only realizes the filling of microcracks by using silica fume and fly ash, but also realizes the filling of microcracks by using the nano magnesium oxide formed by the penetration of magnesium acetate solution and sodium metaaluminate solution and subsequent calcination and the composite precipitate formed between the waste brick slag, which not only realizes the filling of microcracks, but also forms a good transition compatible interface between the waste brick slag, improves the mechanical properties of the waste brick slag, and further realizes the fixation and further filling effect of the filler by adding the binder, thereby significantly improving the performance of the waste brick slag.

[0015] Optionally, the modified mixed solvent comprises the following raw materials in parts by weight:

[0016] 5-10 parts of silane coupling agent, 3-8 parts of binder, 20-30 parts of water, 15-20 parts of crack filling filler, and 8-15 parts of aluminum sludge.

[0017] By adopting the technical scheme, the aluminum sludge is a waste in water treatment and has certain viscosity and plasticity. The addition of the aluminum sludge in the application enables the fine and colloidal substances in the aluminum sludge to penetrate into the microcracks of the waste brick slag, gradually deposit in the cracks, and fill the microcracks of the waste brick slag. In addition, the aluminum oxide and other components in the aluminum sludge may react with the silicate components in the waste brick slag to generate more complex silicate or aluminate compounds, fill the microcracks, and form a certain skeletal structure after subsequent calcination, thereby filling and supporting the large pores in the waste brick slag to some extent and improving the mechanical strength of the waste brick slag. The addition of the silane coupling agent can improve the compatibility of the system and further facilitate the dispersion in the system and the filling in the waste brick slag.

[0018] Optionally, the binder is selected from one or more of polyethylene glycol, hydroxyethyl cellulose, polyvinyl alcohol, and carboxymethyl cellulose.

[0019] By using the above technical solution, the use of the above binder enables the modified mixed solvent to have certain bonding properties, which helps to bond and fix the crack filling filler and other raw materials in the pores of the waste brick slag, and at the same time enables the modified mixed solvent to have better fluidity, which helps the sodium metaaluminate and magnesium acetate solution in the crack filling filler to penetrate and solidify the waste brick slag, thereby improving the comprehensive performance of the concrete.

[0020] Optionally, the high-temperature treatment specifically comprises first treating at 80-90°C for 40-60 min, and then treating at 300-340°C for 1-2 h.

[0021] Optionally, the hydrophobic modification treatment specifically comprises impregnating the waste brick slag after the enhancement modification treatment in a hydrophobic modification solution and then drying, and the hydrophobic modification solution comprises the following raw materials in parts by weight: 12-18 parts of vinyl versatate, 8-15 parts of mesophase pitch microspheres, 5-10 parts of a silane coupling agent, 1-3 parts of an initiator, 5-12 parts of acrylamide, 5-10 parts of propylene alcohol, and 20-30 parts of water.

[0022] By using the above technical solution, when the waste brick slag is impregnated in the hydrophobic modification solution, the hydrophobic modification solution is added with vinyl versatate, mesophase pitch microspheres, and acrylamide and propylene alcohol. The mesophase pitch microspheres contain rich aromatic groups and unsaturated double bond groups. Therefore, in the present application, under the action of the initiator, the vinyl versatate reacts with the unsaturated bonds of the mesophase pitch microspheres and the acrylamide to form a hydrophobic polymer, and then forms a chemical bond with the waste brick slag after the enhancement modification treatment under the action of the silane coupling agent. In this way, the enhancement modification and the hydrophobic modification of the waste brick slag can be realized, the problem of uneven stress distribution and reduced crack resistance caused by the large water absorption of the waste brick slag can be reduced, and the addition of the acrylamide and the propylene alcohol in the present application introduces amino and hydroxyl functional groups, which can improve the compatibility of the modified waste brick slag in the concrete system. In this way, the balance between the water absorption and the hydrophilicity of the waste brick slag is achieved, the hydrophobicity of the waste brick slag itself is improved, the water absorption rate is reduced, and the compatibility in the concrete is improved due to the introduction of the hydroxyl and amino groups, thereby improving the compressive strength and crack resistance of the concrete.

[0023] Optionally, the coarse aggregate comprises waste brick slag particles and gravel at a mass ratio of 1:(0.6-0.8), and the fine aggregate comprises waste brick slag powder and sand at a mass ratio of 1:(0.4-0.6).

[0024] The particle size of the waste brick slag particles is 5-10 mm, and the particle size of the waste brick slag powder is 0.2-0.35 mm.

[0025] By adopting the technical scheme, the application significantly improves the adding proportion of the waste brick slag particles in the concrete and improves the mechanical properties and durability of the concrete.

[0026] Optionally, the mineral admixture is selected from slag, fly ash and gold tailings in a mass ratio of 1:(1.2-1.5):(2-3).

[0027] Optionally, the additive agent is selected from polycarboxylate superplasticizer, and the anti-cracking fiber is selected from one or more of glass fiber and polypropylene fiber.

[0028] By adopting the technical scheme, when the mineral admixture is selected, the cement consumption is reduced while the quality of the concrete is ensured, and the industrial waste is recycled.

[0029] In a second aspect, the application provides a preparation method of low-carbon concrete prepared based on brick slag and metal tailings, which adopts the following technical scheme:

[0030] A preparation method of low-carbon concrete prepared based on brick slag and metal tailings, comprising the following steps:

[0031] Mixing cement, coarse aggregate, fine aggregate, mineral admixture, rice husk ash and anti-cracking fiber to prepare a primary mixture;

[0032] Mixing an additive agent with water to prepare a mixed solution, then adding the prepared primary mixture, and stirring and mixing to prepare low-carbon concrete.

[0033] By adopting the technical scheme, the application provides a simple and convenient method, which is easy to realize industrialization, and the application realizes recycling of industrial waste, reduces cement consumption and carbon emissions, and reduces dependence on natural resources.

[0034] In summary, the application has the following beneficial effects:

[0035] 1. In this application, waste brick slag undergoes reinforcement modification followed by hydrophobic modification. This improves the mechanical properties of the waste brick slag, thereby increasing the compressive strength of the concrete. Furthermore, the hydrophobic modification reduces the water absorption rate of the waste brick slag, mitigating the subsequent reduction in crack resistance caused by high water absorption. Specifically, in this application, the waste brick slag is impregnated in a modified mixed solvent containing silane coupling agent, binder, water, and crack filler, followed by high-temperature treatment. The crack filler fills the micro-cracks in the waste brick slag, and then, under the action of the binder, it bonds with the waste brick slag at the cracks. During high-temperature curing, the microspheres and crack filler are fixed and sintered. Moreover, the mesophase asphalt and binder form a continuous network during high-temperature curing. The structure fills the cracks, improving not only the strength but also the toughness of the waste brick slag. 2. The addition of aluminum sludge in this application allows the fine and colloidal substances in the aluminum sludge to penetrate into the micro-cracks of the waste brick slag, gradually depositing inside the cracks to fill them. Moreover, the aluminum oxide and other components in the aluminum sludge may react with the silicate components in the waste brick slag to form more complex silicate or aluminate complexes, thus filling the micro-cracks. After subsequent calcination, a certain skeleton structure is formed, which fills and supports the large pores inside the waste brick slag to a certain extent, improving the mechanical strength of the waste brick slag. The addition of silane coupling agent can improve the compatibility of the system and further facilitate dispersion and filling in the waste brick slag.

[0036] 3. Impregnation modification in a hydrophobic modification solution achieves reinforcement and hydrophobic modification of waste brick slag, reducing the problems of uneven stress distribution and reduced crack resistance caused by high water absorption. In addition, the addition of acrylamide and allyl alcohol in this application introduces amino and hydroxyl functional groups, which can improve the compatibility of modified waste brick slag in the concrete system. This achieves a balance between the water absorption and hydrophilicity of waste brick slag, making the waste brick slag itself more hydrophobic and reducing its water absorption rate. At the same time, the introduction of hydroxyl and amino groups improves its compatibility in concrete, thereby improving the compressive strength and crack resistance of concrete. Detailed Implementation

[0037] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.

[0038] In the following examples, the cement used is PO42.5 grade ordinary Portland cement; the water-reducing agent is a polycarboxylate type water-reducing agent; the metal tailings are gold tailings slag, obtained by crushing, shaping, and screening gold tailings to a particle size of 1-5mm; and the fly ash is Class F, Grade I fly ash.

[0039] The waste brick slag particles and waste brick slag powder in the following examples are prepared from the modified waste brick slag broken, classified and screened in the following preparation examples, and the particle size of the waste brick slag particles is 5-10 mm, and the particle size of the waste brick slag powder is 0.2-0.35 mm.

[0040] The silica ash in the following preparation example is selected from the micro-silica powder of Sichuan Langtian Resource Comprehensive Utilization Co., Ltd., and the particle size is 1000-1200 mesh;

[0041] The fly ash is selected from F-class I-grade fly ash.

[0042] The mesophase pitch microspheres in the following preparation example are micron-sized spherical carbon materials formed by separating and washing the mesophase small spheres from the pitch matrix when the pitch compound is heated to generate thermal polycondensation reaction to form anisotropic mesophase small spheres, and the mesophase pitch in the following preparation example is specifically selected, and the parameters are as follows: specific surface area: ≤5.0 cm 2 / g, ash content: ≤0.3%, tap density: ≥1.3 g / cm 3 , D50: ≤30.0 μm, specific capacity: ≥350 mAh / g.

[0043] The modified waste brick slag in the following preparation example is obtained by enhancing and modifying the waste brick slag.

[0044] Preparation Example 1

[0045] A preparation method of modified waste brick slag, comprising the following steps:

[0046] S1, the waste brick slag is first subjected to preliminary crushing, and then subjected to impregnation treatment in a modified mixed solvent, the impregnation temperature is 40°C, the impregnation treatment is 35 min, and then the waste brick slag is filtered and subjected to high-temperature treatment, the high-temperature treatment is specifically as follows: first treated at 85°C for 50 min, and then treated at 320°C for 1.5 h;

[0047] S2, the waste brick slag treated in step S1 is impregnated in a hydrophobic modification solution, the impregnation temperature is 65°C, and the impregnation treatment is 1.5 h, and then the waste brick slag is filtered and dried to obtain the modified waste brick slag.

[0048] The modified mixed solvent in step S1 is prepared by mixing the following raw materials:

[0049] 8 kg of silane coupling agent KH-550, 5 kg of adhesive, 25 kg of water, and 18 kg of crack filling filler, wherein the adhesive is polyvinyl alcohol, the crack filling filler includes silica ash, fly ash and alkaline substance in a mass ratio of 1:1:0.6, and the alkaline substance is selected from magnesium acetate and sodium metaaluminate in a mass ratio of 1:1.3;

[0050] The hydrophobic modification solution in step S2 is prepared by mixing the following raw materials:

[0051] 15 kg vinyl versatate, 10 kg mesophase pitch microspheres, 8 kg silane coupling agent KH-550, 2 kg initiator dibenzoyl peroxide, 8 kg acrylamide, 8 kg acryl alcohol and 25 kg water.

[0052] Preparation Example 2

[0053] A preparation method of modified waste brick slag, comprising the following steps:

[0054] S1, the waste brick slag is first crushed, then immersed in a modified mixed solvent, the immersion temperature is 35℃, the immersion treatment is 40min, then filtered and treated at high temperature, the high temperature treatment is specifically: first treated at 80℃ for 60min, then treated at 300℃ for 2h;

[0055] S2, the waste brick slag treated in step S1 is immersed in a hydrophobic modification solution, the immersion temperature is 60℃, treated for 2h, then filtered and dried to obtain the modified waste brick slag.

[0056] The modified mixed solvent in step S1 is prepared by mixing the following raw materials:

[0057] 5kg silane coupling agent KH-550, 3kg binder, 20kg water, 15kg crack filling filler, wherein the binder is polyethylene glycol, the crack filling filler includes silica fume, fly ash and alkaline substance in a mass ratio of 1:0.8:0.5, and the alkaline substance is selected from magnesium acetate and sodium metaaluminate in a mass ratio of 1:1.2;

[0058] The hydrophobic modification solution in step S2 is prepared by mixing the following raw materials:

[0059] 12kg vinyl versatate, 8kg mesophase pitch microspheres, 5kg silane coupling agent KH-550, 1kg initiator dibenzoyl peroxide, 5kg acrylamide, 5kg acryl alcohol and 20kg water.

[0060] Preparation Example 3

[0061] A preparation method of modified waste brick slag, comprising the following steps:

[0062] S1, the waste brick slag is first crushed, then immersed in a modified mixed solvent, the immersion temperature is 45℃, the immersion treatment is 30min, then filtered and treated at high temperature, the high temperature treatment is specifically: first treated at 90℃ for 40min, then treated at 340℃ for 1h;

[0063] S2, the waste brick slag treated in step S1 is immersed in a hydrophobic modification solution, the immersion temperature is 0℃, treated for 1h, then filtered and dried to obtain the modified waste brick slag.

[0064] The modified mixed solvent in step S1 is prepared by mixing the following raw materials:

[0065] 10 kg of silane coupling agent KH-550, 8 kg of a binder, 30 kg of water, and 20 kg of a crack filling filler, wherein the binder is selected from hydroxyethyl cellulose, the crack filling filler comprises silica fume, fly ash, and an alkaline substance in a mass ratio of 1:1.2:0.8, and the alkaline substance is selected from magnesium acetate and sodium metaaluminate in a mass ratio of 1:1.5;

[0066] The hydrophobic modified solution in step S2 is prepared by mixing the following raw materials:

[0067] 18 kg of vinyl versatate, 15 kg of mesophase pitch microspheres, 10 kg of silane coupling agent KH-550, 3 kg of initiator dibenzoyl peroxide, 12 kg of acrylamide, 10 kg of propylene glycol, and 30 kg of water.

[0068] Preparation Example 4

[0069] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that 12 kg of aluminum sludge is further added to the modified mixed solvent in step S1.

[0070] Preparation Example 5

[0071] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that 8 kg of aluminum sludge is further added to the modified mixed solvent in step S1.

[0072] Preparation Example 6

[0073] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that 15 kg of aluminum sludge is further added to the modified mixed solvent in step S1.

[0074] Preparation Example 7

[0075] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that magnesium acetate is selected as the alkaline substance in the crack filling filler in step S1.

[0076] Preparation Example 8

[0077] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that magnesium hydroxide is selected as the alkaline substance in the crack filling filler in step S1.

[0078] Preparation Example 9

[0079] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that calcium hydroxide is selected as the alkaline substance in the crack filling filler in step S1.

[0080] Preparation Example 10

[0081] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that the alkali substance in the crack filling filler in step S1 is selected as sodium metaaluminate.

[0082] Preparation Example 11

[0083] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that the high-temperature treatment in step S1 is specifically operated as follows: treatment at 85℃ for 140 min.

[0084] Preparation Example 12

[0085] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that acrylamide and propylene alcohol are not added in the hydrophobic modification solution in step S2.

[0086] Preparation Example 13

[0087] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that the mesophase pitch microspheres are not added in the hydrophobic modification solution in step S2.

[0088] Preparation Example 14

[0089] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that the mesophase pitch microspheres are replaced by coal tar pitch in step S2.

[0090] Comparative Preparation Example 1

[0091] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that only the hydrophobic modification treatment in step S2 is performed on the waste brick slag after preliminary crushing, and the enhancement modification treatment in step S1 is not performed.

[0092] Comparative Preparation Example 2

[0093] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that only the enhancement modification treatment in step S1 is performed on the waste brick slag after preliminary crushing, and the hydrophobic modification treatment in step S2 is not performed.

[0094] Comparative Preparation Example 3

[0095] A preparation method of modified waste brick slag is performed according to the method in Preparation Example 1, except that the crack filling filler is not added in the modified mixed solvent in step S1.

[0096] Comparative Preparation Example 4

[0097] A method for preparing modified waste brick slag, according to the method in Preparation Example 1, the difference is that no alkali is added to the crack filling filler in step S1.

[0098] Example 1

[0099] A method for preparing low-carbon concrete based on brick slag combined with metal tailings, comprising the following steps:

[0100] Mixing 380 kg of cement, 680 kg of coarse aggregate, 300 kg of fine aggregate, 100 kg of mineral admixture, 50 kg of rice husk ash and 18 kg of anti-cracking fiber to prepare a preliminary mixture;

[0101] Mixing 8 kg of admixture with 165 kg of water to prepare a mixed solution, then adding the prepared preliminary mixture, and stirring and mixing to prepare low-carbon concrete.

[0102] The coarse aggregate includes waste brick slag particles and gravel at a mass ratio of 1:0.7, and the fine aggregate includes waste brick slag powder and sand at a mass ratio of 1:0.5; the waste brick slag particles are obtained by crushing and screening the modified waste brick slag prepared in Preparation Example 1 to obtain waste brick slag particles with a particle size of 5-10 mm, the waste brick slag powder is obtained by crushing and screening the modified waste brick slag prepared in Preparation Example 1 to obtain waste brick slag powder with a particle size of 0.2-0.35 mm, the gravel is gravel with a continuous particle size of 5-15 mm, and the sand has a particle size of 0.2-0.3 mm;

[0103] The mineral admixture is selected from slag, fly ash and gold tailings at a mass ratio of 1:1.3:2.5; the admixture is selected from polycarboxylic acid water reducer, and the anti-cracking fiber is selected from glass fiber with a length of 10-15 mm and a diameter of 0.02-0.03 mm.

[0104] Example 2

[0105] A method for preparing low-carbon concrete based on brick slag combined with metal tailings, comprising the following steps:

[0106] Mixing 350 kg of cement, 620 kg of coarse aggregate, 260 kg of fine aggregate, 80 kg of mineral admixture, 40 kg of rice husk ash and 15 kg of anti-cracking fiber to prepare a preliminary mixture;

[0107] Mixing 5 kg of admixture with 145 kg of water to prepare a mixed solution, then adding the prepared preliminary mixture, and stirring and mixing to prepare low-carbon concrete.

[0108] The coarse aggregate comprises waste brick slag particles and gravel at a mass ratio of 1:0.6, and the fine aggregate comprises waste brick slag powder and sand at a mass ratio of 1:0.4; the waste brick slag particles are waste brick slag particles with a particle size of 5-10 mm obtained by crushing and screening the modified waste brick slag prepared in Preparation Example 2, the waste brick slag powder is waste brick slag powder with a particle size of 0.2-0.35 mm obtained by crushing and screening the modified waste brick slag prepared in Preparation Example 1, the gravel is gravel with a continuous particle size of 5-15 mm, and the sand has a particle size of 0.2-0.3 mm;

[0109] The mineral admixture is selected from slag, fly ash and gold tailings at a mass ratio of 1:1.2:2; the admixture is selected from polycarboxylic acid water reducing agent, and the anti-cracking fiber is selected from glass fiber with a length of 10-15 mm and a diameter of 0.02-0.03 mm.

[0110] Example 3

[0111] A preparation method of low-carbon concrete based on brick slag combined with metal tailings, comprising the following steps:

[0112] 400 kg of cement, 760 kg of coarse aggregate, 350 kg of fine aggregate, 120 kg of mineral admixture, 60 kg of rice husk ash and 20 kg of anti-cracking fiber are mixed to prepare a primary mixture;

[0113] 10 kg of admixture is mixed with 180 kg of water to prepare a mixed solution, which is then added to the prepared primary mixture, and the low-carbon concrete is prepared after stirring and mixing.

[0114] The coarse aggregate comprises waste brick slag particles and gravel at a mass ratio of 1:0.8, and the fine aggregate comprises waste brick slag powder and sand at a mass ratio of 1:0.6; the waste brick slag particles are waste brick slag particles with a particle size of 5-10 mm obtained by crushing and screening the modified waste brick slag prepared in Preparation Example 1, the waste brick slag powder is waste brick slag powder with a particle size of 0.2-0.35 mm obtained by crushing and screening the modified waste brick slag prepared in Preparation Example 1, the gravel is gravel with a continuous particle size of 5-15 mm, and the sand has a particle size of 0.2-0.3 mm;

[0115] The mineral admixture is selected from slag, fly ash and gold tailings at a mass ratio of 1:1.5:3; the admixture is selected from polycarboxylic acid water reducing agent, and the anti-cracking fiber is selected from glass fiber with a length of 10-15 mm and a diameter of 0.02-0.03 mm.

[0116] Examples 4-14

[0117] A preparation method of low-carbon concrete based on brick slag combined with metal tailings, which is prepared according to the method in Example 1, except that the coarse aggregate and the fine aggregate are the coarse aggregate and the fine aggregate with a target particle size obtained by crushing and screening the modified waste brick slag prepared in Preparation Examples 4-14.

[0118] Comparative Examples 1-4

[0119] A method for preparing low-carbon concrete based on brick slag and metal tailings, which is prepared according to the method in Example 1, except that the coarse aggregate and fine aggregate are respectively the coarse aggregate and fine aggregate with a target particle size obtained after modification of the waste brick slag in Comparative Preparation Examples 1-4.

[0120] Performance detection

[0121] The concrete prepared in the examples and comparative examples of the present application was subjected to 28d compressive strength detection according to GB / T50081-2016 "Standard for Testing Methods of Mechanical Properties of Ordinary Concrete", and in addition, the cracking area per unit volume per square meter of the concrete was detected according to GB / T50081-2019 "Standard for Testing Methods of Long-term Performance and Durability of Ordinary Concrete", and the detection results are shown in Table 1 below.

[0122] Table 1:

[0123]

[0124] Referring to the detection results in Table 1 above, the low-carbon concrete prepared in the examples of the present application has excellent compressive strength and durability, and in combination with the detection results of Example 1 and Examples 4-6, it can be seen that when the waste brick slag is modified and aluminum sludge is added to the modified mixed solvent during the modification process, the mechanical properties and crack resistance of the concrete can be further improved. In combination with the detection results of Example 7 and Example 10, when the alkaline substance in the crack filling filler is selected as a single sodium metaaluminate or magnesium acetate, the crack resistance is reduced, and at the same time, the compressive strength is also reduced. In combination with the detection results of Example 8 and Example 9, when the magnesium acetate is replaced by an equal amount of magnesium hydroxide or calcium hydroxide, it can be seen that the crack resistance and compressive strength are significantly reduced, which may be due to the fact that the magnesium acetate solution is more easily permeable, and then after high-temperature calcination, nano-magnesium oxide can better fill and repair the micro-cracks of the waste brick slag.

[0125] In combination with the test results of Example 1 and Example 11, the lower temperature after the impregnation treatment in the modified mixed solvent can only play a role of drying, while in Example 1, the high-temperature calcination treatment is also performed, on the one hand, the magnesium acetate can form nano-magnesium oxide, and on the other hand, it is also helpful to form an action with the waste brick slag to improve the performance of the concrete. In combination with the test results of Example 12 and Example 13, in Example 12, when the acrylamide and propylene alcohol are not added, it can be seen that the compressive strength and crack resistance are reduced, and the uniform dispersion of the waste brick slag in the concrete is affected after the hydrophobic modification. In combination with the test results of Example 13 and 14, when the intermediate phase pitch microspheres are not added or ordinary pitch is added in the hydrophobic modification solution, it can be seen that the crack resistance and compressive strength are reduced. The more unsaturated groups in the intermediate phase pitch microspheres form chemical bonds with the hydrophobic agent, and more importantly, the addition of the microspheres can further fill the pore structure of the waste brick slag to some extent, and improve the mechanical properties.

[0126] In combination with the test results of Example 1 and Comparative Example 1 and Comparative Example 2, it can be seen that when the waste brick slag is only subjected to the enhancement modification treatment or the hydrophobic modification treatment, the comprehensive performance is reduced, especially when the waste brick slag is only subjected to the enhancement modification treatment without the hydrophobic modification treatment, the performance is still weaker than the performance of the concrete in Example 1. In combination with the test results of Comparative Example 3 and Comparative Example 4, when the crack filling filler is not added, the crack resistance is significantly reduced, and the compressive strength is also reduced. When the alkaline substance is not added in the crack filling filler, the crack resistance and the compressive strength are improved compared with Comparative Example 3, but still far weaker than the test results of Example 1. The filling of the micro-cracks in the waste brick slag is obviously related to the crack resistance and the compressive strength.

[0127] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contributions after reading the present specification, and the modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A low-carbon concrete based on brick slag and metal tailings, characterized in that, Including the following parts by weight of raw materials: 350-400 parts cement, 145-180 parts water, 620-760 parts coarse aggregate, 260-350 parts fine aggregate, 80-120 parts mineral admixture, 40-60 parts rice husk ash, 5-10 parts additives and 15-20 parts crack-resistant fiber; Among them, coarse aggregate includes waste brick slag particles and crushed stone, fine aggregate includes waste brick slag powder and sand, and mineral admixtures include at least metal tailings; Waste brick slag powder and waste brick slag particles are obtained by crushing waste brick slag, performing reinforcement and modification treatment, then performing hydrophobic modification treatment, and finally crushing and classifying the waste brick slag to obtain waste brick slag particles and waste brick slag powder respectively. The enhancement and modification treatment specifically involves impregnating the crushed waste brick slag in a modified mixed solvent containing silane coupling agent, binder, water and crack filler, followed by high-temperature treatment. The crack filling material comprises silica fume, fly ash and alkaline substances in a mass ratio of 1:(0.8-1.2):(0.5-0.8), wherein the alkaline substances are selected from magnesium acetate and sodium aluminate in a mass ratio of 1:(1.2-1.5). The modified mixed solvent comprises the following raw materials in parts by weight: 5-10 parts silane coupling agent, 3-8 parts binder, 20-30 parts water, 15-20 parts crack filler, 8-15 parts aluminum sludge; The specific operation of hydrophobic modification treatment is as follows: the waste brick slag after reinforcement modification treatment is impregnated in a hydrophobic modification solution and then dried. The hydrophobic modification solution includes the following raw materials in parts by weight: 12-18 parts ethylene tert-carbonate, 8-15 parts mesophase pitch microspheres, 5-10 parts silane coupling agent, 1-3 parts initiator, 5-12 parts acrylamide, 5-10 parts allyl alcohol and 20-30 parts water.

2. The low-carbon concrete based on brick slag and metal tailings as described in claim 1, characterized in that: The adhesive is selected from one or more of polyethylene glycol, hydroxyethyl cellulose, polyvinyl alcohol, and carboxymethyl cellulose.

3. The low-carbon concrete based on brick slag and metal tailings as described in claim 1, characterized in that: The specific operation of high-temperature treatment is to first treat at 80-90℃ for 40-60 minutes, and then treat at 300-340℃ for 1-2 hours.

4. The low-carbon concrete based on brick slag and metal tailings as described in claim 1, characterized in that: The coarse aggregate comprises waste brick slag particles and crushed stone in a mass ratio of 1:(0.6-0.8), and the fine aggregate comprises waste brick slag powder and sand in a mass ratio of 1:(0.4-0.6). The particle size of the waste brick slag particles is 5-10 mm, and the particle size of the waste brick slag powder is 0.2-0.35 mm.

5. The low-carbon concrete based on brick slag and metal tailings as described in claim 1, characterized in that: The mineral admixture is selected from slag, fly ash and gold tailings in a mass ratio of 1:(1.2-1.5):(2-3).

6. The low-carbon concrete based on brick slag and metal tailings as described in claim 1, characterized in that: The additive is selected from polycarboxylate superplasticizer, and the crack-resistant fiber is selected from one or more of glass fiber and polypropylene fiber.

7. A method for preparing low-carbon concrete based on brick slag and metal tailings as described in any one of claims 1-6, characterized in that: Includes the following steps: A preliminary mixture is prepared by mixing cement, coarse aggregate, fine aggregate, mineral admixtures, rice husk ash, and crack-resistant fibers. The admixture is mixed with water to prepare a mixed solution, and then the prepared initial mixture is added. After stirring and mixing, low-carbon concrete is obtained.

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