Rock gelling agent for red mud concrete as well as preparation method and application of rock gelling agent

Abstract

The invention belongs to the technical field of additives for concrete, and relates to a rock solidifying agent for red mud concrete as well as a preparation method and application of the rock solidifying agent for the red mud concrete, the rock solidifying agent for the red mud concrete comprises the following components in parts by weight: 40-50 parts of silica sol, 8-14 parts of calcium carbonate, 20-30 parts of organic silicon resin emulsion, 10-16 parts of silane coupling agent and 5-10 parts of modified interface enhancer; the particle size of the silica sol is 10-100 nanometers, and the particle size of the calcium carbonate is 20-100 nanometers; the modified interface reinforcing agent is prepared from the following components in parts by weight: 8 to 15 parts of calcium stearate and 85 to 95 parts of single-component silicone glass cement. Through multi-mechanism cooperation of nanometer enhancement, interface optimization and hydrophobic protection, unification of performance, environmental protection and economical efficiency of the red mud concrete is realized, and a key technical support is provided for large-scale recycling of the red mud.

Description

Technical Field

[0001] The present invention belongs to the technical field of additives for concrete, and relates to a rock hardening agent for red mud concrete, a preparation method thereof, and an application thereof. Background Art

[0002] Red mud is an industrial waste residue generated after extracting alumina from bauxite by the Bayer process. It has strong alkalinity (pH value up to 12 - 13) and contains a large amount of oxides such as iron, aluminum, and silicon. The output of red mud is huge, with hundreds of millions of tons generated globally every year. The traditional treatment method mainly focuses on stacking, occupying a large amount of land resources and posing environmental pollution risks (such as soil alkalization, groundwater pollution, etc.). The chemical composition and mineral composition of red mud endow it with certain potential utilization value. However, due to its strong alkalinity and low activity, when directly used as a concrete admixture, it is difficult to undergo an effective hydration reaction with cement, resulting in insufficient concrete strength. Summary of the Invention

[0003] Aiming at the deficiencies of the above-mentioned existing technologies, the present invention provides a rock hardening agent for red mud concrete, a preparation method thereof, and an application thereof, so as to provide a curing agent for red mud concrete, solidify red mud, and improve the comprehensive performance of red mud concrete. The specific technical solutions are as follows:

[0004] The first object of the present invention is to provide a rock hardening agent for red mud concrete, which comprises the following components in parts by weight:

[0005] 40 - 50 parts of silica sol, 8 - 14 parts of calcium carbonate, 20 - 30 parts of silicone resin emulsion, 10 - 16 parts of silane coupling agent, 5 - 10 parts of modified interface enhancer;

[0006] The particle size of the silica sol is 10 - 100 nanometers, and the particle size of the calcium carbonate is 20 - 100 nanometers;

[0007] The modified interface enhancer comprises the following components in parts by weight: 8 - 15 parts of calcium stearate and 85 - 95 parts of one - component silicone glass glue.

[0008] The present invention adds silica sol and calcium carbonate with nanoscale dimensions. Through the filling effect and pozzolanic reaction, the silica sol and calcium carbonate synergistically enhance the density, form a dense structure, accelerate the early hydration reaction of red mud concrete, greatly improve the early and late strengths of red mud concrete, and then enhance the durability of red mud concrete. Among them, the silica sol has high activity and gelling properties, can react with the active components of cement and red mud in the red mud concrete to generate stable silicate gels, and its nanoscale particles fill the pores of the concrete, improve the density, and enhance the compressive and flexural strengths; nanometer calcium carbonate, as a crystal nucleus, can accelerate the hydration reaction of cement particles and improve the early strength of the concrete; nanometer calcium carbonate, as a filler, can refine the microstructure of the concrete, reduce the porosity, improve the density and mechanical properties, and its active surface reacts with calcium aluminate C3A and Ca(OH)2 to generate hydrated calcium aluminate and composite calcium carbonate. These products all have gelling properties, reduce the formation of ettringite, lower the risk of early shrinkage and cracking, and further enhance the strength and toughness of the concrete.

[0009] The active end groups (such as -OH) of the silicone resin emulsion added in the present invention react with Al-OH and Si-OH on the surface of red mud to form chemical bonds, and the interfacial bonding strength is increased by 30%-40%. After the -Si(OR)3 of the silane coupling agent (such as KH-550 containing amino group) is hydrolyzed, Si-OH is generated, which condenses with the surface hydroxyl groups of red mud and cement hydration products to form Si-O-Si or Si-O-Al bonds; the other end organic group (such as -NH2) reacts with the active groups of the silicone resin to achieve molecular-level bonding between the organic phase and the inorganic phase, prevent the separation of the silicone resin and the inorganic matrix, and improve the uniformity of the composite system. Secondly, the silicone resin emulsion and the silane coupling agent form a hydrophobic film, inhibit the penetration of moisture and erosion media, significantly reduce the water absorption rate of the concrete, resist freeze-thaw cycles, chloride ion erosion and sulfate corrosion, and extend the service life.

[0010] In addition, the silica sol and the silicone emulsion can adjust the rheology of the slurry, alleviate the problem of high viscosity of red mud concrete, improve the pumpability and casting density, and facilitate casting; in addition, by adjusting the ratio of silica sol to calcium carbonate and adding a slump-retaining water reducer to the red mud concrete, the setting time of the red mud concrete can be flexibly controlled, which is convenient for manual operation.

[0011] The modified interfacial enhancer in the present invention mainly plays the role of physical lubrication of calcium stearate + chemical bonding of silicone rubber in red mud concrete, achieving "rigidity and flexibility combined" in the interfacial zone (the compressive strength is increased by 20% and the toughness is increased by 30%). The hydrophobic layer of calcium stearate and the silicone rubber film are superimposed, the contact angle reaches 120°, the water absorption rate is further reduced, and the freeze-thaw resistance is improved. The surface of red mud particles is smooth and contains alkaline substances, with poor adhesion to the cement matrix, and it is easy to form a weak transition zone. Calcium stearate in the modified interfacial enhancer can not only reduce the surface energy of red mud particles, but also inhibit alkaline aggregation. First, the hydrophobic long chains of calcium stearate wrap the red mud particles, reducing their friction with the cement matrix, improving the dispersibility of red mud in concrete, and preventing uneven strength caused by agglomeration; second, the free Na + / K + in red mud is easily adsorbed with water to form an alkaline liquid film. The calcium ions (Ca 2+ ) of calcium stearate can partially replace the alkaline ions, reduce the local pH fluctuation, relieve the risk of alkali-aggregate reaction, and reduce the initiation of microcracks; third, calcium stearate forms a monolayer on the inner wall of the pores, the contact angle > 90°, and is superimposed with the silicone rubber film, and the contact angle is further increased to 120°, significantly reducing the water absorption rate of concrete and improving the freeze-thaw resistance (the relative dynamic elastic modulus ≥ 85% after 300 freeze-thaw cycles).

[0012] The -Si-O- bond in the silicone rubber of the modified interfacial enhancer forms a covalent bond with the aluminosilicate on the surface of red mud and the cement hydration product (C-S-H gel), and the interfacial bonding strength is increased by more than 50%; secondly, the elastic modulus (0.5 - 1.0 GPa) of the silicone rubber is relatively large after curing, which can absorb the micro-stress caused by the difference in thermal expansion coefficients between red mud and the cement matrix and reduce cracking. In addition, the Si-O bond energy of the silicone rubber is high, which can resist the erosion of ultraviolet rays and acid rain, and continuously improve the durability of red mud concrete.

[0013] The present invention provides key technical support for the large-scale resource utilization of red mud. In addition to obvious economic benefits, the environmental and social benefits are very prominent.

[0014] Furthermore, the preparation method of the modified interfacial enhancer: Put calcium stearate and one-component silicone glass glue into a container at the same time for mixing, the rotation speed is not less than 2000 r / min, and continuously stir for at least 5 min until evenly mixed to obtain a mixed phase, which is the modified interfacial enhancer; then store the mixed phase in a sealed container, and cover the mixed phase with silicone oil with a thickness of 1 - 2 mm for preservation.

[0015] In the modified interface enhancer of the present invention, calcium stearate, as a hydrophobic lubricant, can reduce the cohesive force between silicone rubber molecules, help the silicone rubber disperse more evenly, and reduce agglomeration. In addition, the carboxyl group (-COOH) of calcium stearate can have a weak interaction with the silanol group (-SiOH) in the silicone rubber, improving the interfacial adhesion between the silicone rubber and non-polar substrates (such as plastics and metals). Moreover, the hydrophobic long chain of calcium stearate covers the surface of the silicone rubber, reducing the interference of the water film on the substrate surface and enhancing the wet-state bonding strength.

[0016] The modified interface enhancer of the present invention is stored with a 1-2 mm thick silicone oil covering it. Since one-component silicone glass glue is prone to hardening in the air, adding silicone oil has two functions: one is to isolate the air, and the other is that adding silicone oil to concrete can also play a role in waterproofing and crack prevention. That is, the high hydrophobicity of silicone oil forms a water-repellent film in the capillary pores of concrete, slowing down the water evaporation rate, extending the internal hydration reaction time, and reducing early plastic shrinkage cracks.

[0017] Furthermore, the tuff agent for red mud concrete comprises the following components in parts by weight:

[0018] 45 parts of silica sol, 10 parts of calcium carbonate, 25 parts of organosilicon resin emulsion, 13 parts of silane coupling agent, and 7 parts of modified interface enhancer.

[0019] Furthermore, the silica sol has an SiO2 content of 20-40%, a pH value of 9-11, a viscosity at 25°C ≤ 15 mPa·s, and a density of 1.15-1.25 g / cm 3 , such as the silica sol produced by Shandong Lubi Chemical Industry Co., Ltd.

[0020] Furthermore, the specific surface area of the calcium carbonate is 15-30 m 2 / g, the CaCO3 content ≥ 98%, the oil absorption value is 20-30 g / 100 g, the pH value is 8.0-10.0, and the water content is ≤ 0.5%; such as the calcium carbonate produced by Shandong Lubi Chemical Industry Co., Ltd.

[0021] Furthermore, the solid content of the organosilicon resin emulsion is 40-60%, the pH value is 6-8, the viscosity at 25°C is 100-1000 mPa·s, the particle size is 200-800 nm, and the heat resistance is -40°C to 180°C; such as the organosilicon resin emulsion produced by Shandong Xinglu Chemical Industry Co., Ltd.

[0022] Furthermore, the silane coupling agent is one or more of γ-aminopropyltriethoxysilane (KH-550), γ-glycidoxypropyltrimethoxysilane, or vinyltrimethoxysilane.

[0023] Furthermore, the silane coupling agent is γ-aminopropyltriethoxysilane.

[0024] Further, the purity of the γ-aminopropyltriethoxysilane is ≥98%, and the density at 25°C is 0.94 - 0.96 g / cm 3 , boiling point: 217°C; such as the γ-aminopropyltriethoxysilane produced by Shandong Dongyue Organic Silicon Materials Co., Ltd.

[0025] Further, the modified interface enhancer comprises the following components in parts by weight: 10 parts of calcium stearate and 90 parts of one-component silicone glass glue.

[0026] Further, the calcium content of the calcium stearate is 6.5% - 7.5%, the moisture content is ≤2.0%, the melting point is 150 - 155°C, and the particle size is such that the passing rate of 200 mesh is ≥99%; such as the calcium stearate produced by Shandong Zibo Hailan Chemical Co., Ltd.

[0027] Further, the solid content of the one-component silicone glass glue is ≥99%, the surface drying time at 25°C and 50% RH is 10 - 30 min, the curing time at 25°C and 50% RH is 24 h, the tensile strength is ≥1.5 MPa, the elongation at break is ≥300%, and the service temperature is -50°C to 150°C; such as the one-component silicone glass glue produced by Shandong Dongyue Organic Silicon Materials Co., Ltd.

[0028] The second object of the present invention is to provide a preparation method of the above-mentioned coagulant for red mud concrete, comprising the following steps:

[0029] S1: Add silica sol into the container of the ultrasonic nano-homogenizer, then add calcium carbonate, and homogenize at a working frequency of 50 - 70 kHz for 10 - 20 min at room temperature until uniformly dispersed to obtain a nano-mixed solution;

[0030] S2: Add the organosilicon resin emulsion and the silane coupling agent into the nano-mixed solution, and homogenize at a working frequency of 30 - 50 kHz for 5 - 10 min until uniformly dispersed to obtain a mixed latex solution;

[0031] S3: After standing the mixed latex solution at room temperature for 1 - 3 h, add the modified interface enhancer, and homogenize at a working frequency of 10 - 30 kHz for 5 - 10 min at room temperature to form a uniform and stable latex. After standing at room temperature for 1 - 3 h, the coagulant for red mud concrete is obtained.

[0032] The present invention uses silica sol and calcium carbonate, two nano-materials, and adopts ultrasonic technology, with a relatively simple preparation process, low cost, and good comprehensive benefits.

[0033] The third object of the present invention is to provide a red mud concrete comprising the above-mentioned coagulant for red mud concrete.

[0034] Further, the red mud concrete comprises the following components in parts by weight:

[0035] 15-25 parts of red mud, 10-20 parts of P.O 42.5 grade cement, 6-10 parts of blast furnace slag powder, 25-30 parts of natural gravel, 10-20 parts of natural sand, 3-7 parts of rock setting agent for red mud concrete, 1-3 parts of water reducing agent, 0.3-0.7 parts of dispersant, 6-7 parts of water.

[0036] Furthermore, the red mud is one or more of as-received Bayer process red mud, sintering process red mud, and combined process red mud.

[0037] The beneficial effects of the present invention are as follows:

[0038] Through the multi-mechanism synergy of nano-enhancement + interface optimization + hydrophobic protection, the present invention realizes the unity of the performance, environmental friendliness, and economy of red mud concrete, providing key technical support for the large-scale resource utilization of red mud. As a cheap raw material, red mud replaces part of the cement. The amount of rock setting agent is small but the effect is remarkable, and the comprehensive cost is lower than that of traditional reinforcing agents. The rock setting agent for red mud concrete does not contain strong alkalis or heavy metals, avoiding secondary pollution. Using red mud reduces the pollution of solid waste storage in the aluminum industry, conforming to the concept of "treating waste with waste". It can be resourcefully utilized in place at the red mud yard and used for road surfaces, slope protection projects, etc., as well as durable structures in high-salinity and humid areas such as coastal breakwaters and building foundations in saline-alkali lands. Therefore, the present invention has achieved breakthroughs in terms of performance, environmental protection, and cost, providing a feasible path for the large-scale resource utilization of red mud. Description of the Drawings

[0039] Figure 1 It is a photo of the rock setting agent for red mud concrete prepared in Example 1 of the present invention. Detailed Embodiments

[0040] The principles and features of the present invention are described below in conjunction with examples. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0041] For those not specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. For reagents or instruments not indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0042] Silica sol: Produced by Shandong Lubei Chemical Industry Co., Ltd., with a SiO2 content of 20-40%, a particle size of 10-100 nm, a pH value of 9-11, a viscosity of ≤15 mPa·s (25 °C), and a density of 1.15-1.25 g / cm 3 ;

[0043] Calcium carbonate: Produced by Shandong Lubei Chemical Industry Co., Ltd., with a particle size of 20-100 nm and a specific surface area of 15-30 m 2 / g, CaCO3 content: ≥98%, oil absorption value: 20 - 30 g / 100 g, pH value: 8.0 - 10.0, moisture: ≤0.5%;

[0044] Silicone resin emulsion: Produced by Shandong Xinglu Chemical Industry Co., Ltd., with a solid content of 40 - 60%, pH value of 7 - 9, viscosity: 100 - 1000 mPa·s (25°C), particle size: 200 - 800 nm, heat resistance: -40°C to 180°C;

[0045] Silane coupling agent: γ-aminopropyltriethoxysilane (KH-550) produced by Shandong Dongyue Organic Silicon Materials Co., Ltd., purity: ≥98%, density: 0.94 - 0.96 g / cm 3 (25°C), boiling point: 217°C;

[0046] Calcium stearate: Produced by Shandong Zibo Hailan Chemical Industry Co., Ltd., calcium content: 6.5% - 7.5%, moisture: ≤2.0%, melting point: 150 - 155°C, particle size: passing rate of 200 mesh ≥99%;

[0047] One-component silicone sealant: Produced by Shandong Dongyue Organic Silicon Materials Co., Ltd., solid content: ≥99%, surface drying time: 10 - 30 minutes (25°C, 50% RH), curing time: 24 hours (25°C, 50% RH), tensile strength: ≥1.5 MPa, elongation at break: ≥300%, service temperature: -50°C to 150°C;

[0048] Red mud: As-received Bayer red mud; powdery, specific surface area between 300 m 2 / kg - 350 m 2 / kg; pH value between 13 - 14;

[0049] P·O 42.5 grade cement: Produced by Pingyin Shanshui Cement Co., Ltd., specific surface area between 350 m 2 / kg ~ 380 m 2 / kg, compressive strength: 3-day strength: ≥17.0 MPa; 28-day strength: ≥42.5 MPa; flexural strength: 3-day strength: ≥3.5 MPa, 28-day strength: ≥6.5 MPa;

[0050] Ground granulated blast furnace slag: Specific surface area between 350 m 2 / kg - 400 m 2 / kg;

[0051] Natural gravel: Limestone gravel, where the ratio of 10 - 20 mm gravel to 5 - 10 mm gravel is 7:3;

[0052] Natural sand: River sand, fineness modulus between 2.7 - 3.1;

[0053] Water reducing agent: Polycarboxylate superplasticizer (HD-PCE series) produced by Shandong Huadi Building Technology Co., Ltd., with a solid content of 35%, and a water reduction rate as high as 35%-40%;

[0054] Dispersant: TH-612 industrial grade sodium hexametaphosphate produced by Shandong Taihe Water Treatment Technology Co., Ltd., white powder, P2O5 content ≥ 68%, pH value 5.8 - 7, total phosphate (calculated as PO4 3- by weight) ≥ 68.5%.

[0055] The above substances are used in the following examples or comparative examples.

[0056] Example 1:

[0057] A setting rock agent for red mud concrete, comprising the following components in parts by weight:

[0058] 45 parts of silica sol, 10 parts of calcium carbonate, 25 parts of silicone resin emulsion, 13 parts of silane coupling agent, 7 parts of modified interface enhancer;

[0059] The preparation method of the modified interface enhancer comprises the following steps:

[0060] By weight, 10 parts of calcium stearate and 90 parts of one-component silicone glass glue are simultaneously put into a small high-speed shearing machine container for mixing, with a rotation speed of 2500 r / min, and continuously stirred for 5 min until evenly mixed to obtain a mixed phase, that is, the modified interface enhancer. The mixed phase is stored in a sealed container, and a 1-mm-thick silicone oil is covered on the mixed phase for storage.

[0061] The preparation method of the setting rock agent for red mud concrete comprises the following steps:

[0062] S1: Add silica sol to the ultrasonic nano-homogenizer container, and then add calcium carbonate. Start the machine at a working frequency of 60 kHz at room temperature for 15 min until evenly dispersed to obtain a nano-mixed solution;

[0063] S2: Add the silicone resin emulsion and the silane coupling agent to the nano-mixed solution, start the machine at a working frequency of 40 kHz for 10 min until evenly dispersed to obtain a mixed latex solution;

[0064] S3: After the mixed latex solution is left standing at room temperature for 2 h, add the modified interface enhancer, start the machine at a working frequency of 20 kHz at room temperature for 10 min until a uniform and stable latex is formed. After standing at room temperature for 2 h, pour it into a volumetric flask, mark it, and obtain the setting rock agent for red mud concrete. After testing, its density is 1.08 g / cm 3 , pH 9.5, solid content 28%, see attached Figure 1 .

[0065] In this embodiment, a red mud concrete includes the following components by weight:

[0066] 20 parts of original state Bayer red mud, 15 parts of P.O 42.5 grade cement, 8 parts of blast furnace slag powder, 28 parts of natural crushed stone, 15 parts of natural sand, 5 parts of tuff agent for red mud concrete, 2.0 parts of water reducing agent, 0.5 parts of dispersant, and 6.5 parts of water.

[0067] The preparation method of the red mud concrete test specimens includes the following steps:

[0068] 1. Randomly sample from the discharge port of the mixer to ensure representativeness; load into 150mm×150mm×150mm and 150mm×150mm×550mm molds in two layers, with each layer having approximately the same thickness; for the tests of compressive strength, flexural tensile strength, and freeze-thaw resistance, 3 pieces are taken as a group, and at least two groups are prepared; for the impermeability test, 6 pieces are taken as a group, and at least 2 groups are prepared;

[0069] 2. Fix the test mold on the vibrating table with a frequency of 50Hz±3Hz and an amplitude of 0.5mm±0.1mm, and vibrate until the surface shows bleeding, usually for 15 - 30 seconds;

[0070] 3. Scrape off the excess concrete and level the surface with a trowel;

[0071] 4. Let it stand at room temperature (20±5℃) for 24 - 48 hours, avoiding vibration;

[0072] 5. When removing the mold, gently tap the test mold to avoid damaging the edges and corners of the specimen;

[0073] 6. Standard curing: Place it in a curing room with a temperature of 20±2℃ and a relative humidity of ≥95%; conduct corresponding performance tests at the specified age.

[0074] The red mud concrete test specimens prepared above are tested. The 28-day compressive strength of the red mud concrete reaches 75.8MPa, the freeze-thaw resistance grade (quick freeze method) reaches F300, and the impermeability grade is P12. All indicators meet the corresponding requirements of the "Technical Specification for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and the "Technical Specification for the Application of High Performance Concrete" (CECS 207:2006).

[0075] In this embodiment, silica sol and calcium carbonate fill the micropores to improve the density; the silicone resin emulsion enhances the hydrophobicity and improves the freeze-thaw resistance; the coupling agent and the interface enhancer optimize the interfacial bonding force between red mud and cement, achieving a balance between strength and durability; the synergistic effect of each component is significant, and the overall performance of the red mud concrete with the addition of the tuff agent for red mud concrete is superior to that without admixture (comparative example 7).

[0076] Example 2:

[0077] A coagulant for red mud concrete, comprising the following components in parts by weight:

[0078] 50 parts of silica sol, 12 parts of calcium carbonate, 20 parts of silicone resin emulsion, 10 parts of silane coupling agent, 8 parts of modified interface enhancer.

[0079] The preparation method of the modified interface enhancer in this example, the preparation method of the coagulant for red mud concrete, the components and preparation method of red mud concrete are the same as those in Example 1, and will not be elaborated here.

[0080] The coagulant for red mud concrete prepared in this example was tested, and its density was 1.06 g / cm 3 , pH 9.7, solid content 29%; the red mud concrete specimens were tested, and the 28-day compressive strength of the red mud concrete reached 78.2 MPa, the frost resistance grade (rapid freezing method) reached F250, and the impermeability grade was P10. All indicators met the corresponding requirements of the "Technical Specification for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and the "Technical Specification for the Application of High-Performance Concrete" (CECS207:2006).

[0081] In this example, the increase in the proportion of silica sol improves the gelling activity and slightly increases the strength, but the decrease in the organic components leads to a slight decrease in frost resistance / impermeability.

[0082] Example 3:

[0083] A coagulant for red mud concrete, comprising the following components in parts by weight:

[0084] 45 parts of silica sol, 10 parts of calcium carbonate, 25 parts of silicone resin emulsion, 13 parts of silane coupling agent, 7 parts of modified interface enhancer.

[0085] The preparation method of the modified interface enhancer includes the following steps:

[0086] By weight, 8 parts of calcium stearate and 92 parts of one-component silicone glass glue are simultaneously put into a small high-speed shear machine container for mixing, the rotation speed is 3000 r / min, and stirring is continued for 5 min until evenly mixed to obtain a mixed phase, that is, the modified interface enhancer. The mixed phase is stored in a sealed container, and a silicone oil with a thickness of 1 mm is covered on the mixed phase for storage.

[0087] In this example, the preparation method of the coagulant for red mud concrete, the components and preparation method of red mud concrete are the same as those in Example 1, and will not be elaborated here.

[0088] The coagulant for red mud concrete prepared in this example was tested, and its density was 1.06 g / cm 3, pH 9.5, solid content 27%; After testing the red mud concrete specimens, the 28-day compressive strength of the red mud concrete reached 76.9 MPa, the frost resistance grade (rapid freezing method) reached F300, and the impermeability grade was P12. All indicators met the corresponding requirements of the "Technical Specifications for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and the "Technical Specification for the Application of High-Performance Concrete" (CECS207:2006).

[0089] In this Example 3, different from Example 1, the components and preparation method of the modified interface enhancer are different. The amount of calcium stearate is reduced to 8 parts and the one-component silicone sealant is increased to 92 parts. The compressive strength has increased slightly, while the durability performance has not changed significantly. This is because calcium stearate mainly plays a role in hydrophobicity.

[0090] Example 4:

[0091] A setting rock agent for red mud concrete, comprising the following components in parts by weight:

[0092] 40 parts of silica sol, 14 parts of calcium carbonate, 30 parts of organosilicon resin emulsion, 16 parts of silane coupling agent, 10 parts of modified interface enhancer;

[0093] The preparation method of the modified interface enhancer includes the following steps:

[0094] By weight, 10 parts of calcium stearate and 90 parts of one-component silicone sealant are simultaneously put into a small high-speed shearing machine container for mixing at a speed of 3000 r / min and continuously stirred for 5 min until evenly mixed to obtain a mixed phase, which is the modified interface enhancer. The mixed phase is stored in a sealed container, and a silicone oil with a thickness of 1 mm is covered on the mixed phase for storage.

[0095] In this example, the preparation method of the setting rock agent for red mud concrete, the components and preparation method of the red mud concrete are the same as those in Example 1, which will not be elaborated here.

[0096] The setting rock agent for red mud concrete prepared in this example was tested, and its density was 1.04 g / cm 3 , pH 9.2, solid content 26%; After testing the red mud concrete specimens, the 28-day compressive strength of the red mud concrete reached 72.4 MPa, the frost resistance grade (rapid freezing method) reached F320, and the impermeability grade was P12. All indicators met the corresponding requirements of the "Technical Specifications for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and the "Technical Specification for the Application of High-Performance Concrete" (CECS207:2006).

[0097] In Example 4, different from Example 1, the proportions of the components of the coagulant for red mud concrete are different, the preparation method of the modified interface enhancer is different, the compressive strength is slightly reduced, while the durability performance is improved. This is because the proportion of silicone resin and coupling agent increases, significantly enhancing the frost resistance, but the reduction of the inorganic cementitious component leads to a slight decrease in strength.

[0098] Example 5:

[0099] A coagulant for red mud concrete, comprising the following components in parts by weight:

[0100] 42 parts of silica sol, 8 parts of calcium carbonate, 30 parts of silicone resin emulsion, 10 parts of silane coupling agent, 10 parts of modified interface enhancer.

[0101] The preparation method of the modified interface enhancer in this example is the same as that in Example 4, and will not be elaborated here.

[0102] In this example, the preparation method of the coagulant for red mud concrete, the components of red mud concrete and the preparation method are the same as those in Example 1, and will not be elaborated here.

[0103] The coagulant for red mud concrete prepared in this example was tested, and its density was 1.04 g / cm 3 , pH 9.3, solid content 27%; the red mud concrete specimens were tested, and the 28-day compressive strength of the red mud concrete reached 70.1 MPa, the frost resistance grade (rapid freezing method) reached F250, and the impermeability grade was P10. All indexes met the corresponding requirements of "Technical Specification for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and "Technical Specification for Application of High Performance Concrete" (CECS207:2006).

[0104] In Example 5, different from Example 1, the proportions of the components of the coagulant for red mud concrete are different, the preparation method of the modified interface enhancer is different, the compressive strength is slightly reduced, while the durability performance is improved. This is because the reduction of calcium carbonate leads to insufficient compactness of the microstructure, and both the compressive strength and durability decrease.

[0105] Comparative Example 1:

[0106] A coagulant for red mud concrete, comprising the following components in parts by weight:

[0107] 0 parts of silica sol, 10 parts of calcium carbonate, 25 parts of silicone resin emulsion, 13 parts of silane coupling agent, 7 parts of modified interface enhancer.

[0108] The preparation method of the modified interface enhancer in this example, the preparation method of the coagulant for red mud concrete, and the components and preparation method of red mud concrete are the same as those in Example 1, and will not be elaborated here.

[0109] In this comparative example, compared with Example 1, without adding silica sol, the density of the tuff agent for red mud concrete prepared is 1.03 g / cm 3 , pH is 9.0, and the solid content is 20%; after testing the specimens, the 28-day compressive strength of the red mud concrete reaches 52.3 MPa, the frost resistance grade (rapid freezing method) reaches F150, and the impermeability grade is P6. All indicators do not meet the corresponding requirements of the "Technical Specification for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and the "Technical Specification for the Application of High Performance Concrete" (CECS207:2006) C70.

[0110] In this comparative example, 0 parts of silica sol results in insufficient slurry density and a significant decrease in strength; the porosity increases, and the frost resistance / impermeability performance deteriorates. It can be seen that silica sol plays a decisive role in mechanical properties and durability.

[0111] Comparative Example 2:

[0112] A tuff agent for red mud concrete, comprising the following components in parts by weight:

[0113] 45 parts of silica sol, 10 parts of calcium carbonate, 0 parts of silicone resin emulsion, 13 parts of silane coupling agent, 7 parts of modified interface enhancer.

[0114] In this example, the preparation method of the modified interface enhancer, the preparation method of the tuff agent for red mud concrete, the components of the red mud concrete and the preparation method are the same as those in Example 1, and will not be elaborated here.

[0115] In this comparative example, compared with Example 1, without adding silicone resin emulsion, the density of the tuff agent for red mud concrete prepared is 1.07 g / cm 3 , pH is 9.6, and the solid content is 26%; after testing the specimens, the 28-day compressive strength of the red mud concrete reaches 68.5 MPa, the frost resistance grade (rapid freezing method) reaches F150, and the impermeability grade is P6. All indicators do not meet the corresponding requirements of the "Technical Specification for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and the "Technical Specification for the Application of High Performance Concrete" (CECS207:2006) C70.

[0116] In this comparative example, 0 parts of silicone resin emulsion results in a decrease in hydrophobicity and elasticity, an accelerated expansion of microcracks during freeze-thaw cycles, a weakened interfacial bonding force, and a significant reduction in impermeability.

[0117] Comparative Example 3:

[0118] A tuff agent for red mud concrete, comprising the following components in parts by weight:

[0119] 45 parts of silica sol, 10 parts of calcium carbonate, 25 parts of silicone resin emulsion, 0 part of silane coupling agent, 7 parts of modified interface enhancer.

[0120] In this example, the preparation method of the modified interface enhancer, the preparation method of the coagulant for red mud concrete, the components and preparation method of red mud concrete are the same as those in Example 1, and will not be elaborated here.

[0121] In this comparative example, compared with Example 1, without adding silane coupling agent, the coagulant for red mud concrete prepared above was tested, and its density was 1.10 g / cm 3 , pH 9.7, solid content 29%; after testing the specimens, the 28-day compressive strength of red mud concrete reached 60.7 MPa, the frost resistance grade (rapid freezing method) reached F150, and the impermeability grade was P6. All indexes did not meet the corresponding requirements of "Technical Specifications for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and "Technical Specification for Application of High Performance Concrete" (CECS207:2006) C70.

[0122] In this comparative example, 0 part of silane coupling agent led to the weakening of the interface bonding force between red mud and cement, resulting in a decrease in strength; the water penetration path increased, and the impermeability decreased significantly.

[0123] Comparative Example 4:

[0124] A coagulant for red mud concrete, comprising the following components in parts by weight:

[0125] 30 parts of silica sol, 6 parts of calcium carbonate, 12 parts of silicone resin emulsion, 8 parts of silane coupling agent, 4 parts of modified interface enhancer.

[0126] In this example, the preparation method of the modified interface enhancer, the preparation method of the coagulant for red mud concrete, the components and preparation method of red mud concrete are the same as those in Example 1, and will not be elaborated here.

[0127] In this comparative example, compared with Example 1, each component decreased the corresponding weight parts. The coagulant for red mud concrete prepared above was tested, and its density was 1.02 g / cm 3 , pH 9.3, solid content 15%; after testing the specimens, the 28-day compressive strength of red mud concrete reached 48.6 MPa, the frost resistance grade (rapid freezing method) reached F100, and the impermeability grade was less than P6. All indexes did not meet the corresponding requirements of "Technical Specifications for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and "Technical Specification for Application of High Performance Concrete" (CECS207:2006) C70.

[0128] In this comparative example, compared with Example 1, the effective active components of the tuff agent for red mud concrete are reduced, resulting in insufficient filling and cementation, and the overall performance deteriorates comprehensively, failing to meet the requirements of C70 concrete. Therefore, the solid content should be reasonably controlled within the range of 25-30%.

[0129] Comparative Example 5:

[0130] A tuff agent for red mud concrete, comprising the following components in parts by weight:

[0131] 45 parts of silica sol, 6 parts of calcium carbonate, 25 parts of silicone resin emulsion, 13 parts of silane coupling agent, 7 parts of modified interface enhancer.

[0132] In this example, the preparation method of the modified interface enhancer, the preparation method of the tuff agent for red mud concrete, the components and preparation method of red mud concrete are the same as those in Example 1, and will not be elaborated here.

[0133] In this comparative example, compared with Example 1, when the calcium carbonate is reduced to 6 parts, the density of the prepared tuff agent for red mud concrete is measured to be 1.05 g / cm 3 , pH 9.3, and the solid content is 19%; after the test piece is tested, the 28-day compressive strength of the red mud concrete reaches 66.7 MPa, the frost resistance grade (rapid freezing method) reaches F250, and the impermeability grade is P10. All indicators do not meet the corresponding requirements of "Technical Specifications for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and "Technical Specification for Application of High Performance Concrete" (CECS207:2006) for C70.

[0134] Comparative Example 6:

[0135] A tuff agent for red mud concrete, comprising the following components in parts by weight:

[0136] 45 parts of silica sol, 10 parts of calcium carbonate, 25 parts of silicone resin emulsion, 13 parts of silane coupling agent, 0 part of modified interface enhancer.

[0137] In this example, the preparation method of the tuff agent for red mud concrete, the components and preparation method of red mud concrete are the same as those in Example 1, and will not be elaborated here.

[0138] In this comparative example, compared with Example 1, when the dosage of the modified interface enhancer is 0, the density of the prepared tuff agent for red mud concrete is measured to be 1.07 g / cm 3, pH 9.7, solid content 31%; After testing the manufactured parts, the 28-day compressive strength of the red mud concrete reached 47.3 MPa, the frost resistance grade (rapid freezing method) only reached F150, and the impermeability grade was P8. All indicators did not meet the corresponding requirements of the "Technical Specification for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and the "Technical Specification for the Application of High-Performance Concrete" (CECS207:2006) C70.

[0139] Comparative Example 7:

[0140] A kind of red mud concrete, comprising the following components in parts by weight:

[0141] 20 parts of as-received Bayer red mud, 15 parts of P.O 42.5 grade cement, 8 parts of blast furnace slag powder, 28 parts of natural gravel, 15 parts of natural sand, 0 part of red mud concrete coagulant, 2.0 parts of high-performance water reducer, 0.5 part of dispersant, 6.5 parts of water.

[0142] The preparation method of the red mud concrete in this example is the same as that in Example 1 and will not be elaborated here.

[0143] In this comparative example, compared with Example 1, without adding the red mud concrete coagulant, after testing the manufactured parts, the 28-day compressive strength of the red mud concrete reached 17.2 MPa, the frost resistance grade (rapid freezing method) reached F50, and the impermeability grade was below P6. All indicators did not meet the corresponding requirements of the "Technical Specification for Highway Bridge and Culvert Construction" (JTG / T 3650-2020) and the "Technical Specification for the Application of High-Performance Concrete" (CECS207:2006) C70.

[0144] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A coagulant for red mud concrete, characterized in that, Comprising the following components in parts by weight: 40 - 50 parts of silica sol, 8 - 14 parts of calcium carbonate, 20 - 30 parts of silicone resin emulsion, 10 - 16 parts of silane coupling agent, 5 - 10 parts of modified interface enhancer; The particle size of the silica sol is 10 - 100 nm, and the particle size of the calcium carbonate is 20 - 100 nm; The modified interface enhancer comprises the following components in parts by weight: 8 - 15 parts of calcium stearate and 85 - 95 parts of one - component silicone sealant.

2. The tuff agent for red mud concrete according to claim 1, wherein, The SiO2 content of the silica sol is 20-40%, the pH value is 9-11, the viscosity at 25°C is ≤15 mPa·s, and the density is 1.15-1.25 g / cm 3 ; the specific surface area of the calcium carbonate is 15-30 m 2 / g, the CaCO3 content is ≥98%, the oil absorption value is 20-30 g / 100 g, the pH value is 8.0-10.0, and the water content is ≤0.5%.

3. The tuff agent for red mud concrete according to claim 1, characterized in that, The solid content of the silicone resin emulsion is 40 - 60%, the pH value is 6 - 8, the viscosity at 25°C is 100 - 1000 mPa·s, the particle size is 200 - 800 nm, and the heat resistance is - 40°C to 180°C.

4. The tuff agent for red mud concrete according to claim 1, characterized in that, The silane coupling agent is one or more of γ - aminopropyltriethoxysilane (KH - 550), γ - glycidoxypropyltrimethoxysilane, or vinyltrimethoxysilane.

5. The tuff agent for red mud concrete according to claim 1, characterized in that, The calcium content of the calcium stearate is 6.5% - 7.5%, the moisture content is ≤2.0%, the melting point is 150 - 155°C, and the passing rate of 200 - mesh is ≥99%.

6. The tuff agent for red mud concrete according to claim 3, wherein, The solid content of the one - component silicone sealant is ≥99%, the surface - drying time at 25°C and 50% RH is 10 - 30 min, the curing time at 25°C and 50% RH is 24 h, the tensile strength is ≥1.5 MPa, the elongation at break is ≥300%, and the service temperature is - 50°C to 150°C.

7. A preparation method of a coagulant for red mud concrete according to any one of claims 1 to 6, characterized in that, Comprising the following steps: S1: Add the silica sol into the container of an ultrasonic nano - homogenizer, and then add calcium carbonate. At room temperature, homogenize for 10 - 20 min at a working frequency of 50 - 70 kHz until uniformly dispersed to obtain a nano - mixed solution; S2: Add the silicone resin emulsion and the silane coupling agent into the nano - mixed solution, and homogenize for 5 - 10 min at a working frequency of 30 - 50 kHz until uniformly dispersed to obtain a mixed latex solution; S3: Let the mixed latex solution stand at room temperature for 1 - 3 h, then add the modified interface enhancer, and homogenize at a working frequency of 10 - 30 kHz for 5 - 10 min at room temperature to form a uniform and stable latex. After standing at room temperature for 1 - 3 h, a coagulant for red - mud concrete is obtained.

8. A red - mud concrete comprising the above - mentioned coagulant for red - mud concrete.

9. The red mud concrete according to claim 8, wherein, Comprising the following components in parts by weight: 15 - 25 parts of red mud, 10 - 20 parts of P.O42.5 grade cement, 6 - 10 parts of blast - furnace slag powder, 25 - 30 parts of natural gravel, 10 - 20 parts of natural sand, 3 - 7 parts of coagulant for red - mud concrete, 1 - 3 parts of water - reducing agent, 0.3 - 0.7 part of dispersant, 6 - 7 parts of water.

10. The red mud concrete according to claim 9, characterized in that, The red mud is one or more of as - received Bayer - process red mud, sinter - process red mud, and combined - process red mud.

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