Low-carbon tailings concrete and preparation method thereof

Abstract

The application discloses a kind of low-carbon tailings concrete and preparation method thereof, it is related to environmental protection tailings concrete technical field.A kind of low-carbon tailings concrete, by including the following mass parts of raw materials: cement 100 parts, tailings micro powder 45-75 parts, composite aggregate 150-300 parts, water 30-50 parts, additive 1-5 parts, anti-aging agent 0.5-2 parts.The application utilizes tailings micro powder to replace part of cement, reduces the cement consumption from production source, significantly reduces carbon emission in the process of cement production.At the same time, industrial waste slag tailings and construction waste rock are converted into composite aggregate, realize resource efficient recycling, have the advantages of environment-friendly and cost control, alleviate the pressure of natural aggregate exploitation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environment-friendly tailings concrete, and particularly relates to a low-carbon tailings concrete and a preparation method thereof. BACKGROUND

[0002] In the current booming construction industry, concrete is widely used as a core building material. Traditional concrete is mainly composed of cement and natural sandstone, but with the increasing awareness of environmental protection and the highlighting of resource shortage, its limitations gradually emerge in the aging angle.

[0003] The durability of traditional concrete is limited. Under the long-term natural environmental erosion, such as acid rain and seawater erosion, calcium hydroxide in cement stone will react, causing damage to the internal structure of concrete and reducing the strength. At the same time, the mining of natural aggregates not only destroys the ecology, but also causes aging phenomenon in the environment, such as the increase of surface roughness of machine-made sandstone under long-term friction and weathering, which affects the bonding force with the cement paste and further reduces the overall performance of the concrete.

[0004] From the perspective of crack resistance, once cracks appear in traditional concrete, rainwater and harmful substances will enter, accelerating the corrosion of internal steel bars, forming a vicious cycle and further shortening the service life of the building structure.

[0005] The emergence of low-carbon tailings concrete aims to solve these aging-related problems. It uses tailings micro-powder to replace part of the cement, not only reducing carbon emissions in the cement production process, but also effectively filling the pores of the cement paste due to the high specific surface area and activity of the tailings micro-powder, improving the compactness of the concrete and enhancing the erosion resistance. At the same time, with specific composite aggregates and admixtures, the cohesion and crack resistance of the concrete can be improved, the aging process can be delayed, the durability and service life of the building structure can be improved, and the current sustainable development of the building demand can be met. SUMMARY

[0006] The present application aims to provide a low-carbon tailings concrete, which improves the durability and crack resistance of the concrete by adding tailings micro-powder and anti-aging agent, effectively delays aging, and prolongs the service life of the building structure.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: a low-carbon tailings concrete is made from raw materials containing the following mass fractions: cement 100 parts, tailings micro-powder 45-75 parts, composite aggregate 150-300 parts, water 30-50 parts, admixture 1-5 parts, and anti-aging agent 0.5-2 parts.

[0008] The anti-aging agent is a structure represented by Chemical Formula 1:

[0009] Chemical Formula 1: ;

[0010] R1 in the chemical formula 1 is methyl, amino, nitro or methoxy.

[0011] Further, the cement is P.O 42.5 Portland cement or PⅡ 52.5 Portland cement.

[0012] Further, the tailing fines are iron tailing fines, and the specific surface area of the fines is ≥400 m 2 / kg.

[0013] Further, the composite aggregate is composed of 70-100 parts of machine-made sand and 80-130 parts of recycled coarse aggregate.

[0014] Further, the recycled coarse aggregate has a particle size of 5-25 mm and a water absorption rate ≤8%.

[0015] Further, the recycled coarse aggregate is building rubble.

[0016] Further, the admixture is a mixture of polycarboxylic acid water reducer, defoaming agent and retarder in a mass ratio of 1:1:1.

[0017] Further, the water reducer is polycarboxylic acid water reducer.

[0018] Further, the defoaming agent is polyether-modified silicone oil.

[0019] Further, the retarder is one or more of sodium gluconate, citrate or pyrophosphate.

[0020] Further, the antioxidant is any one of the compounds shown in the following structures:

[0021] ;

[0022] .

[0023] A preparation method of low-carbon tailing concrete, comprising the following steps:

[0024] S1. The cement, tailing fines and 50% of the composite aggregate are put into a mixer and dry-mixed for 1-3 min until uniform;

[0025] S2. 70% of the water and all of the admixture are added, and wet-mixed for 2-6 min to form a uniform slurry;

[0026] S3. 50% of the composite aggregate, the antioxidant and 30% of the water are added, and the stirring is continued for 1-5 min to obtain a low-carbon tailing concrete.

[0027] Further, the low-carbon tailing concrete needs to be subjected to standard curing after being poured.

[0028] Further, the standard curing adopts the environment curing of temperature 20±2 DEG C, relative humidity >=95% for 28 days, and covering the evaporation-proof film after initial setting.

[0029] A building structural member is characterized by being cast using a low-carbon tailings concrete or a preparation method of a low-carbon tailings concrete.

[0030] Further, the building structural member can be used as a lightweight building material.

[0031] Further, the building structural member can be used to prepare an outer protective shell of an energy-saving boiler and auxiliary equipment.

[0032] The anti-aging agent is a novel phosphite anti-aging agent, which has strong electrophilicity, antioxidant capacity and anti-ultraviolet activity. The anti-aging agent can effectively capture free radicals generated in environmental erosion (such as acid rain or ultraviolet light), neutralize free radicals, inhibit oxidative chain reaction, thereby reducing the degradation of the internal structure of the concrete. The molecular structure of the anti-aging agent helps to reduce the internal stress of the concrete. The anti-aging agent absorbs or disperses stress through its flexible organic chain segment, while promoting more uniform hydration reaction.

[0033] The mass fraction formula system of the low-carbon tailings concrete solves key technical problems through a multi-level synergistic mechanism: in terms of low-carbon synergy, tailings micro powder partially replaces cement to reduce carbon emissions, the active components thereof react with cement hydration products to enhance the strength of the interface transition zone, and physically fill the cement paste pores to improve the density, thereby jointly inhibiting aggregate-paste peeling cracks and improving erosion resistance; in terms of workability and crack resistance, the gradient grading of mechanism sand and recycled coarse aggregate complements each other to reduce the demand for paste and plastic shrinkage stress, the water reducing agent in the compounded admixture reduces the water-cement ratio to improve the strength, the retarder delays the hydration heat peak to inhibit temperature cracks, the defoaming agent eliminates air bubbles to reduce porosity to enhance frost resistance / anti-permeability, and the three synergistically ensure paste uniformity to solve the strength unevenness caused by aggregate settlement segregation; in terms of durability synergy, a specific anti-aging agent captures H + ions generated by acid rain erosion through a strong electrophilic group to inhibit chemical corrosion, the antioxidant segment terminates the free radical chain reaction to delay ultraviolet oxidative aging, and the flexible organic chain absorbs internal stress to reduce microcrack expansion; the dynamic synergy of the preparation process avoids premature decomposition of the anti-aging agent to ensure long-term anti-aging efficiency, and through gradient feeding, the bulk density is optimized to improve the final strength.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] 1. Low carbon emission reduction and resource recycling: The present application uses tailings powder to replace part of the cement, reduces the cement consumption from the production source, and significantly reduces the carbon emissions in the cement production process. At the same time, industrial waste residues and construction waste rocks are converted into composite aggregates, realizing efficient recycling of resources, with the advantages of environmental friendliness and cost control, and relieving the pressure of natural aggregate mining.

[0036] 2. Significantly improve the comprehensive performance of concrete: The present application fills the pores of cement paste by the high specific surface area and activity of tailings powder, improves the compactness and erosion resistance; the strong electrophilic group of the anti-aging agent captures free radicals, inhibits oxidation and chemical corrosion, improves the compressive strength to 50-58MPa, reduces the freeze-thaw mass loss rate to 1.5%-3%, reduces the ultraviolet aging strength loss to 5%-8%, and significantly enhances the durability and crack resistance.

[0037] 3. Optimize the preparation process synergistically: The present application adopts gradient feeding dynamic synergistic process, dry mixing first and then adding water in batches, optimizes the stirring sequence and time, avoids premature decomposition of the anti-aging agent, and ensures long-term anti-aging effect. At the same time, the grading of composite aggregate reduces the demand for paste, the compounding of admixture reduces the water-cement ratio, delays the hydration heat peak, eliminates bubbles, solves the problem of aggregate settlement and segregation, and ensures the uniformity and strength uniformity of concrete. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The nuclear magnetic resonance of the anti-aging agent 1 of the present application. DETAILED DESCRIPTION

[0039] The technical solutions of the present application will be described in detail below in combination with the drawings in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0040] Example 1-1

[0041] Synthesis of anti-aging agent 1:

[0042] ;

[0043] Under nitrogen atmosphere, 20 g of raw material 1, 10.19 g of raw material 2, 45.59 g of cesium carbonate and 300 ml of toluene were added into the reaction system, and the air in the reaction system was replaced with nitrogen for 3 times. Under nitrogen protection, 1.93 g of Pd(DBA)2 and 0.9 g of triphenylphosphine were added, the temperature was raised to 100°C, and the reaction was carried out under nitrogen protection for 6 hours. After the reaction was completed, it was cooled to room temperature, 150 mL of water was added, extracted with ethyl acetate for 3 times, washed with saturated brine once, then dried with anhydrous sodium sulfate, and the solvent was rotary evaporated. Finally, 20.91 g of intermediate 1 was obtained by column chromatography (ethyl acetate and petroleum ether as eluent). The liquid phase detection purity was 99.8%, and the mass spectrum M / Z+1 was 337.

[0044] Under nitrogen atmosphere, 20.91 g of intermediate 1, 3.28 g of NaH and 300 ml of anhydrous tetrahydrofuran were added into the reaction system, stirred at 20°C for 2h, then 4.27 g of phosphorus trichloride was added, and the reaction was carried out at 60°C for 24h. After filtration, the tetrahydrofuran was evaporated, and 51.97 g of antioxidant 1 was obtained by column chromatography (ethyl acetate and n-heptane as eluent). The liquid phase detection purity was 99.9%, and the mass spectrum M / Z+1 was 1038.

[0045] Antioxidant 1 1 H NMR, Chloroform-d, Figure 1 : δ 8.49 (s, 3H), 7.74 (s, 2H), 7.65 (dd, 3H), 7.55 (m, 1H), 7.50-7.43 (m, 4H), 7.32-7.21 (m, 4H), 7.14 (m, 1H), 2.43 (m, 9H), 1.62 (s, 3H), 1.59 (s, 3H), 1.56 (d, 6H), 1.51 (dd, 12H), 1.44 (s, 3H), 1.42-1.37 (m, 12H), 1.37-1.32 (m, 9H), 1.30 (d, 6H).

[0046] Example 1-2 to Example 1-4

[0047] Antioxidants 2-4 were synthesized in Example 1-2 to Example 1-4 in turn, referring to the preparation method of Example 1-1, replacing the raw material 2 therein, and the rest being the same as Example 1-1. The specific structure of raw material 2, the structure of antioxidants 2-4, and the mass spectrum M / Z+1 data are shown in Table 1.

[0048] Table 1.

[0049]

[0050] Example 2

[0051] Preparation of a low-carbon tailings concrete

[0052] 1. Raw material ratio:

[0053] Cement: 100 parts, selected from: P.O42.5 Portland cement, purchased from Tangshan Tianlu Cement Co., Ltd.;

[0054] Tailings micro-powder: 60 parts, selected from: iron tailings micro-powder, specific surface area ≥ 400 m 2 / kg, purchased from Fujian Makeng Mining Co., Ltd.;

[0055] Composite aggregate: 225 parts (of which machine-made sand 75 parts, recycled coarse aggregate 150 parts; recycled coarse aggregate particle size 5-25 mm, water absorption rate ≤ 8%, from construction rubble), machine-made sand purchased from Ningbo Haishu Senhua Machine-made Sand Manufacturing Co., Ltd.; construction rubble purchased from Guangxi Guota Rubble Building Material Co., Ltd.;

[0056] Water: 40 parts;

[0057] Admixture: 3 parts (mixed by polycarboxylic acid water reducer, defoaming agent and retarder in a mass ratio of 1:1:1; wherein the water reducer is polycarboxylic acid water reducer, the defoaming agent is polyether modified silicone oil, and the retarder is sodium gluconate), polycarboxylic acid water reducer purchased from Shandong Jinluye New Material Co., Ltd. (JLY-01 series polycarboxylic acid high-performance water reducer), polyether modified silicone oil purchased from Qingdao Meiside Silicone Co., Ltd., and sodium gluconate purchased from Xinxiang Zhongxin Chemical Co., Ltd.;

[0058] Antioxidant: 1 part (antioxidant 1 synthesized in Example 1-1);

[0059] 2. Preparation method:

[0060] S1. Put cement (100 parts), tailings micro-powder (60 parts) and 50% of composite aggregate (i.e. 112.5 parts, of which machine-made sand 37.5 parts, recycled coarse aggregate 75 parts) into a mixer, dry mix for 2 minutes at room temperature (25°C), until the mixture is uniform and free of lumps;

[0061] S2. Add 70% of water (28 parts) and all of the admixture (3 parts), wet mix at medium speed (stirring speed 100 rpm) for 4 minutes, to form a uniform and well-flowing slurry;

[0062] S3. Add the remaining 50% of composite aggregate (112.5 parts, of which machine-made sand 37.5 parts, recycled coarse aggregate 75 parts), antioxidant (1 part) and the remaining 30% of water (12 parts), continue to stir for 3 minutes, until the mixture is uniform and there is no obvious aggregate sedimentation, to obtain a low-carbon tailings concrete product;

[0063] The obtained concrete is poured into a standard mold (size 150 mm x 150 mm x 150 mm) and standard curing is performed: after initial setting (about 1 hour), an evaporation-proof film is covered to prevent water loss; placed in a constant temperature and humidity curing box, the temperature is controlled at 20±2℃, the relative humidity is ≥95%; the curing is continued for 28 days.

[0064] Examples 3 to 5

[0065] A low-carbon tailings concrete is prepared according to the preparation method of Example 2, wherein the antioxidant is replaced by the antioxidants 2-4 prepared in Examples 1-2 to 1-4, and the rest is the same as Example 2.

[0066] Comparative Example 1

[0067] A low-carbon tailings concrete is prepared according to the preparation method of Example 2, wherein the antioxidant is replaced by (antioxidant 168), and the rest is the same as Example 2.

[0068] Comparative Example 2

[0069] A low-carbon tailings concrete is prepared according to the preparation method of Example 2, wherein the antioxidant is replaced by , and the rest is the same as Example 2.

[0070] Comparative Example 3

[0071] A low-carbon tailings concrete is prepared according to the preparation method of Example 2, wherein the antioxidant is replaced by , and the rest is the same as Example 2.

[0072] Comparative Example 4

[0073] A low-carbon tailings concrete is prepared according to the preparation method of Example 2, wherein the antioxidant is not added, and the rest is the same as Example 2.

[0074] Comparative Example 5

[0075] A low-carbon tailings concrete is prepared according to the preparation method of Example 2, wherein the water reducing agent is not added, and the rest is the same as Example 2.

[0076] Comparative Example 6

[0077] A low-carbon tailings concrete is prepared according to the preparation method of Example 2, wherein the retarder is not added, and the rest is the same as Example 2.

[0078] Performance test:

[0079] A low-carbon tailings concrete prepared in Example 2-Example 5, Comparative Example 1-Comparative Example 6 was subjected to performance tests:

[0080] 1. Compressive strength: The compressive strength of the test blocks at 28 days of curing was tested according to GB / T50081-2002 “Standard for testing methods of mechanical properties of ordinary concrete”, and the data is shown in Table 2;

[0081] 2. Durability: The test was performed according to the relevant detection method of GB / T 50082-2024 “Standard for testing methods of long-term performance and durability of ordinary concrete”. The freezing temperature and thawing temperature of the test sample were -20°C to -15°C and 6°C to 8°C, respectively. The time for one cycle of freeze-thaw was 4h, and the freeze-thaw was performed for 200 times. The mass loss rate of the test block before and after the test was calculated, and the data is shown in Table 2;

[0082] 3. Weather resistance experiment: the concrete test sample cured for 28 days was placed in a UV aging test box, the ultraviolet wavelength was UVA-340, the irradiation intensity was 0.76 W / m 2 , and the aging period was 1000h. Every 8 hours UV irradiation + 4 hours condensation was performed to simulate the real environment. The compressive strength after aging was measured (based on GB / T50081-2002 method), and the compressive strength loss rate (%) was calculated, and the data is shown in Table 2.

[0083] Table 2.

[0084]

[0085] The anti-aging agent significantly improves the anti-aging performance of the concrete through strong electrophilicity and antioxidant capacity. The anti-aging agent captures the free radicals generated by H + and ultraviolet rays. The molecular structure of the anti-aging agent promotes uniform hydration and reduces internal stress. The tailings micro-powder and composite aggregate optimize the packing density, and the admixtures (water reducing agent, defoaming agent, and retarder) reduce the water-cement ratio and eliminate pores. Comparative Examples 1-3 use alternative anti-aging agents, which cannot efficiently inhibit oxidation reactions. Comparative Example 4 (without anti-aging agent) has the weakest anti-aging ability; Comparative Example 5 (without water reducing agent) has many pores; and Comparative Example 6 (without retarder) has uneven hydration heat and produces micro-cracks. The low-carbon tailings concrete of the present application significantly improves the compressive strength, durability, and weather resistance through the synergy of the anti-aging agent and multiple components.

[0086] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements, and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A low carbon tailings concrete, characterized in that, The low-carbon tailing concrete is prepared from raw materials including cement 100 parts, tailing powder 45-75 parts, composite aggregate 150-300 parts, water 30-50 parts, additive 1-5 parts, and anti-aging agent 0.5-2 parts. The anti-aging agent is a structure shown in Chemical Formula 1: Chemical Formula 1: ; R1 in the Chemical Formula 1 is methyl, amino, nitro, or methoxy. The additive is a mixture of polycarboxylic acid water reducing agent, defoaming agent, and retarder in a mass ratio of 1:1:

1.

2. A low carbon tailings concrete according to claim 1, characterized in that, The cement is P.O 42.5 Portland cement or PⅡ 52.5 Portland cement.

3. A low carbon tailings concrete as claimed in claim 1, characterized in that, The tailings powder is iron tailings powder, and the specific surface area of the powder is ≥400 m 2 / kg.

4. A low carbon tailings concrete as claimed in claim 1, characterized in that, The composite aggregate is composed of machine-made sand 70-100 parts and recycled coarse aggregate 80-130 parts. The recycled coarse aggregate has a particle size of 5-25 mm and a water absorption rate of ≤8%. The recycled coarse aggregate is building rubble.

5. A low carbon tailings concrete as claimed in claim 1, wherein, The defoaming agent is polyether-modified silicone oil. The retarder is one or more of sodium gluconate, citrate, or pyrophosphate.

6. A method of producing a low carbon tailings concrete according to any one of claims 1 to 5, characterised in that, The method comprises the following steps: S1. The cement, tailing powder, and 50% of the composite aggregate are put into a mixer and dry-mixed for 1-3 min until uniform; S2. 70% of the water and all of the additive are added, and wet-mixed for 2-6 min to form a uniform slurry; S3. 50% of the composite aggregate, the anti-aging agent, and 30% of the water are added, and the stirring is continued for 1-5 min to obtain the low-carbon tailing concrete.

7. A method of producing low carbon tailings concrete according to claim 6, characterised in that, The low-carbon tailing concrete needs to be cured and then subjected to standard curing.

8. A method of producing low carbon tailings concrete according to claim 7, characterised in that, The standard curing is performed in an environment with a temperature of 20±2℃ and a relative humidity of ≥95% for 28 days, and an anti-evaporation film is covered after initial setting.

9. A building structural member, characterised in that: The low-carbon tailing concrete is prepared by pouring the low-carbon tailing concrete prepared by the method of any one of claims 1-5 or any one of claims 6-8.

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