A kind of ash-based anti-cracking road concrete and a preparation method thereof

Abstract

The application discloses a kind of based on ash anti-cracking road concrete and preparation method thereof, belong to cement concrete preparation technical field, the road concrete is by weight fraction, including the following component composition: cement 100-130 parts, fine aggregate 300-400 parts, coarse aggregate 400-460 parts, ash 60-90 parts, admixture 30-50 parts, additive 5-12 parts, water 80-100 parts, the fine aggregate is river sand or machine-made sand, and the coarse aggregate is limestone, granite or basalt;The application is based on the basic composition of existing concrete, and the surface of the ash is treated by using the modified agent to improve the mechanical strength of the ash concrete.

Description

Technical Field

[0001] This invention relates to the field of cement concrete preparation technology, specifically to a crack-resistant road concrete based on ash and slag and its preparation method. Background Technology

[0002] Residue refers to the solid residues such as slag, fly ash, and ash produced during the combustion of fuel in thermal power generation. my country's thermal power plants produce about 580 million tons of fly ash annually, of which 180 million tons are discarded, resulting in a waste rate of 31%. Residue contains harmful substances and poses potential risks to the environment and human health. Therefore, these ash residues generally need to be treated and comprehensively utilized to reduce environmental pollution. Currently, the main treatment of ash residue is storage in ash residue yards. However, ash residues will diffuse during long-term storage, especially in southern regions. After leaching and rainwater washing, the heavy metals in the ash residue diffuse into the surrounding environment, seriously affecting the ecological security of the region. Other ways to comprehensively utilize ash residues include: (1) Cement production: Some chemical components and minerals in power plant ash residues can be used in cement production. For example, silicates and iron oxides can be used as additives in cement to improve the performance and quality of cement; (2) coal ash brick making: sintering power plant ash can produce coal ash bricks for use in construction and road infrastructure; (3) mine backfilling: some ash with high content of heavy metals and minerals can be recycled and reused for mine backfilling or other uses; (4) landfilling: some unusable ash can be landfilled to reduce environmental pollution; (5) power generation: using high-efficiency condensation reactors, fluidized beds and other technologies, the heat energy in ash can be utilized to generate electricity. This method can turn waste into treasure while reducing environmental pollution; (6) agricultural use: using ash as a soil conditioner can improve soil quality and increase soil fertility, thereby increasing crop yield. Among them, the cement industry uses a large amount of ash, which is expected to be a way to utilize a large amount of ash resources. However, the current addition of ash to concrete mainly has the problems of low early strength, easy cracking and low durability, which limits the large-scale application of ash in concrete. Summary of the Invention

[0003] To address the above problems, this invention provides a crack-resistant road concrete based on ash and slag and its preparation method.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A type of crack-resistant road concrete based on ash residue, comprising the following components by weight:

[0006] The mixture contains 100-130 parts cement, 300-400 parts fine aggregate, 400-460 parts coarse aggregate, 60-90 parts ash, 30-50 parts admixture, 5-12 parts additives, and 80-100 parts water. The fine aggregate is river sand or manufactured sand, and the coarse aggregate is limestone, granite, or basalt.

[0007] In some preferred embodiments, the ash is ash from a thermal power plant.

[0008] In some preferred embodiments, the ash from the thermal power plant comprises the following components by mass percentage: 20-40% SiO2, 30-50% CaO, 3-10% MgO, 2-10% Al2O3, 1-8% Fe2O3, and the balance being unavoidable impurities.

[0009] In some preferred embodiments, the ash is pretreated thermal power plant ash, and the pretreatment includes the following steps:

[0010] (1) Take the ash residue from the thermal power plant and disperse it in water, adjust the pH to alkaline, add an ethanol solution of silane coupling agent, stir the reaction thoroughly at room temperature overnight, filter it out and wash it until neutral, and dry it for later use.

[0011] (2) Weigh tributylethylphosphine bromide and dissolve it in deionized water to obtain a tributylethylphosphine bromide solution. The tributylethylphosphine bromide solution is subjected to ion exchange through an ion exchange resin. The alkaline solution is collected, and aminotriacetic acid is added. The mixture is stirred at room temperature for 6-18 hours. After the reaction is completed, the mixture is concentrated under reduced pressure to a solid content of 4-10 g / 100 mL to obtain a modified solution.

[0012] The concentration of the tributylethylphosphine bromide solution is 3-4 g / 100 mL; the mass ratio of the tributylethylphosphine bromide to the aminotriacetic acid is (2.5-3.5):10.

[0013] (3) Immerse the dried ash obtained in step (1) in the modified solution at room temperature, stir and react overnight, filter out, wash and dry to obtain the product.

[0014] In some preferred embodiments, the admixture is one or more of fly ash, blast furnace slag, silica fume, volcanic ash, steel slag, and silica fume.

[0015] In some preferred embodiments, the admixture includes one or more of the following: water-reducing agent, air-entraining agent, defoamer, slump retainer, wetting agent, and reinforcing agent.

[0016] In some preferred embodiments, the water-reducing agent is sodium gluconate, naphthalene-based water-reducing agent, or polycarboxylate water-reducing agent; the slump-retaining agent is a slump-retaining mother liquor.

[0017] In some preferred embodiments, the reinforcing agent is modified cellulose, and its preparation method includes the following steps:

[0018] Weigh polyvinyl alcohol and dissolve it in deionized water. Heat and stir until completely dissolved. Add boron nitride nanotubes and ultrasonically disperse for 1-60 minutes to form a uniform boron nitride nanotube-polyvinyl alcohol suspension. Add cellulose nanofibers and stir again to react overnight. Then, vacuum filter through a cellulose acetate membrane to peel the obtained product off the filter membrane. After vacuum drying, the modified cellulose is obtained.

[0019] The concentration of polyvinyl alcohol in the solution is 6-12 wt%.

[0020] In some preferred embodiments, the mass ratio of the polyvinyl alcohol to the boron nitride nanotubes and the cellulose nanofibers is (3-3.4):1:(8-8.6).

[0021] Another aspect of the present invention is to provide a method for preparing the aforementioned ash-based crack-resistant road concrete, the method specifically comprising the following steps:

[0022] (1) Weigh each raw material according to the preset weight ratio and set aside for use;

[0023] (2) First, the cement, the admixture and the ash are mixed together at a mixing speed of 30-50 r / min;

[0024] (3) Add the coarse aggregate, the fine aggregate, the additive and water, and continue to stir and mix at 30-50 r / min for 30-120 s. After stirring evenly, the mixture is obtained.

[0025] The beneficial effects of this invention are as follows:

[0026] To address the problems of low early strength, easy cracking, and poor durability associated with conventional addition of thermal power plant ash to concrete, this invention, through component modification and adjustment, produces a crack-resistant and durable concrete based on conventional concrete and modified thermal power plant ash, applicable to road construction. Specifically, this invention uses thermal power plant ash as raw material on the basis of existing concrete, and performs surface treatment on the ash with a modifier to improve the mechanical strength of the ash concrete. Using tributylethylphosphine bromide as raw material, after alkalization treatment with alkaline ion exchange resin, electron-withdrawing acetic acid substituent groups are introduced through aminotriacetic acid, reducing the negative inductive effect of amine groups in the anion and significantly improving its interaction with carbon dioxide. This achieves multi-site absorption of carbon dioxide by the modified ash, effectively promoting concrete hydration and early strength growth. Furthermore, this invention uses modified cellulose nanofibers as a reinforcing agent, which on the one hand further improves the splitting strength of the concrete, and on the other hand, the invention improves the thermal conductivity of the nanofibers through boron nitride nanotube modification, avoiding hydration cracking caused by uneven release of hydration heat, and improving the durability of road concrete. Detailed Implementation

[0027] The present invention will be further described in conjunction with the following embodiments.

[0028] Example 1

[0029] A type of crack-resistant road concrete based on ash residue, comprising the following components by weight:

[0030] 122 parts P.O42.5 cement, 340 parts river sand, 426 parts granite coarse aggregate, 72 parts thermal power plant ash, and P800 type silica fume (specific surface area ≥800m²). 2 12 parts ( / kg), 26 parts volcanic ash, 1.5 parts polycarboxylate superplasticizer, 1.8 parts slump-retaining mother liquor, and 100 parts water;

[0031] The fineness modulus of the river sand is 2.6; the coarse aggregate of the granite has a particle size of no more than 20 mm, and the weight of the 10-20 mm portion is no more than 43%.

[0032] The ash residue from the thermal power plant comprises the following components by mass percentage: SiO2 37.2%, CaO 46.9%, MgO 6.2%, Al2O3 5.8%, Fe2O3 2.7%, and the balance being unavoidable impurities;

[0033] The ash and slag from the thermal power plant also includes pretreatment, which includes the following steps:

[0034] (1) Take the ash residue from the thermal power plant and disperse it in water, adjust the pH to 8-9, add an ethanol solution of KH550, stir the reaction thoroughly at room temperature overnight, filter it out and wash it until neutral, and dry it for later use.

[0035] (2) Weigh out tributylethylphosphine bromide and dissolve it in deionized water to obtain a tributylethylphosphine bromide solution. The tributylethylphosphine bromide solution is subjected to ion exchange through an ion exchange resin. The alkaline solution is collected, aminotriacetic acid is added, and the reaction is stirred at room temperature for 12 hours. After the reaction is completed, the solution is concentrated under reduced pressure to a solid content of 4.8 g / 100 mL to obtain a modified solution.

[0036] The concentration of the tributylethylphosphine bromide solution is 4 g / 100 mL; the mass ratio of the tributylethylphosphine bromide to the aminotriacetic acid is 3:10.

[0037] (3) Immerse the dried ash obtained in step (1) in the modified solution at room temperature, stir and react overnight, filter out, wash and dry to obtain the product;

[0038] The volcanic ash has an average particle size of 18.5 μm and an activity index of 0.75.

[0039] The method for preparing crack-resistant road concrete based on ash slag includes the following steps:

[0040] (1) Weigh each raw material according to the preset weight ratio and set aside for use;

[0041] (2) First, the cement, silica fume, pozzolanic and ash residue are mixed at a mixing speed of 30-50 r / min;

[0042] (3) Add the granite coarse aggregate, the river sand, the water-reducing agent, the slump-preserving mother liquor and water, and continue to stir and mix at 30-50 r / min for 100 s. After stirring evenly, the mixture is obtained.

[0043] Example 2

[0044] A type of crack-resistant road concrete based on ash residue, comprising the following components by weight:

[0045] 122 parts P.O42.5 cement, 340 parts river sand, 426 parts granite coarse aggregate, 72 parts thermal power plant ash, and P800 type silica fume (specific surface area ≥800m²). 2 12 parts ( / kg), 26 parts volcanic ash, 1.5 parts polycarboxylate superplasticizer, 1.8 parts slump-retaining mother liquor, 8.6 parts reinforcing agent, and 100 parts water;

[0046] The fineness modulus of the river sand is 2.6; the coarse aggregate of the granite has a particle size of no more than 20 mm, and the weight of the 10-20 mm portion is no more than 43%.

[0047] The ash residue from the thermal power plant comprises the following components by mass percentage: SiO2 37.2%, CaO 46.9%, MgO 6.2%, Al2O3 5.8%, Fe2O3 2.7%, and the balance being unavoidable impurities;

[0048] The ash and slag from the thermal power plant also includes pretreatment, which includes the following steps:

[0049] (1) Take the ash residue from the thermal power plant and disperse it in water, adjust the pH to 8-9, add an ethanol solution of KH550, stir the reaction thoroughly at room temperature overnight, filter it out and wash it until neutral, and dry it for later use.

[0050] (2) Weigh out tributylethylphosphine bromide and dissolve it in deionized water to obtain a tributylethylphosphine bromide solution. The tributylethylphosphine bromide solution is subjected to ion exchange through an ion exchange resin. The alkaline solution is collected, aminotriacetic acid is added, and the reaction is stirred at room temperature for 12 hours. After the reaction is completed, the solution is concentrated under reduced pressure to a solid content of 4.8 g / 100 mL to obtain a modified solution.

[0051] The concentration of the tributylethylphosphine bromide solution is 4 g / 100 mL; the mass ratio of the tributylethylphosphine bromide to the aminotriacetic acid is 3:10.

[0052] (3) Immerse the dried ash obtained in step (1) in the modified solution at room temperature, stir and react overnight, filter out, wash and dry to obtain the product;

[0053] The volcanic ash has an average particle size of 18.5 μm and an activity index of 0.75.

[0054] The reinforcing agent is modified cellulose, and its preparation method includes the following steps:

[0055] Polyvinyl alcohol was weighed and dissolved in deionized water. The mixture was heated and stirred until completely dissolved. Boron nitride nanotubes were added and ultrasonically dispersed for 10 minutes to form a uniform boron nitride nanotube-polyvinyl alcohol suspension. Cellulose nanofibers were added, and the mixture was stirred and reacted overnight. The mixture was then vacuum filtered through a cellulose acetate membrane (pore size 0.22 μm). The obtained product was peeled off the filter membrane and vacuum dried to obtain the modified cellulose. The concentration of polyvinyl alcohol was 10 wt%. The mass ratio of polyvinyl alcohol to boron nitride nanotubes and cellulose nanofibers was 3.2:1:8.3.

[0056] The method for preparing crack-resistant road concrete based on ash slag includes the following steps:

[0057] (1) Weigh each raw material according to the preset weight ratio and set aside for use;

[0058] (2) First, the cement, silica fume, pozzolanic and ash residue are mixed at a mixing speed of 30-50 r / min;

[0059] (3) Add the granite coarse aggregate, the river sand, the water-reducing agent, the slump-preserving mother liquor, the reinforcing agent and water, and continue to stir and mix at 30-50 r / min for 100 s. After stirring evenly, the mixture is obtained.

[0060] Example 3

[0061] A type of crack-resistant road concrete based on ash residue, comprising the following components by weight:

[0062] 122 parts P.O42.5 cement, 340 parts river sand, 426 parts granite coarse aggregate, 72 parts thermal power plant ash, and P800 type silica fume (specific surface area ≥800m²). 2 12 parts ( / kg), 26 parts volcanic ash, 1.5 parts polycarboxylate superplasticizer, 1.8 parts slump-retaining mother liquor, 8.6 parts reinforcing agent, and 100 parts water;

[0063] The fineness modulus of the river sand is 2.6; the coarse aggregate of the granite has a particle size of no more than 20 mm, and the weight of the 10-20 mm portion is no more than 43%.

[0064] The ash residue from the thermal power plant comprises the following components by mass percentage: SiO2 37.2%, CaO 46.9%, MgO 6.2%, Al2O3 5.8%, Fe2O3 2.7%, and the balance being unavoidable impurities;

[0065] The ash and slag from the thermal power plant also includes pretreatment, which includes the following steps:

[0066] The ash residue from thermal power plants is collected, dispersed in water, and the pH is adjusted to above 10. After soaking overnight, it is rinsed and dried to obtain the final product.

[0067] The volcanic ash has an average particle size of 18.5 μm and an activity index of 0.75.

[0068] The method for preparing crack-resistant road concrete based on ash slag includes the following steps:

[0069] (1) Weigh each raw material according to the preset weight ratio and set aside for use;

[0070] (2) First, the cement, silica fume, pozzolanic and ash residue are mixed at a mixing speed of 30-50 r / min;

[0071] (3) Add the granite coarse aggregate, the river sand, the water-reducing agent, the slump-preserving mother liquor and water, and continue to stir and mix at 30-50 r / min for 100 s. After stirring evenly, the mixture is obtained.

[0072] Example 4

[0073] A type of crack-resistant road concrete based on ash residue, comprising the following components by weight:

[0074] 122 parts P.O42.5 cement, 340 parts river sand, 426 parts granite coarse aggregate, 72 parts thermal power plant ash, and P800 type silica fume (specific surface area ≥800m²). 2 12 parts ( / kg), 26 parts volcanic ash, 1.5 parts polycarboxylate superplasticizer, 1.8 parts slump-retaining mother liquor, 8.6 parts reinforcing agent, and 100 parts water;

[0075] The fineness modulus of the river sand is 2.6; the coarse aggregate of the granite has a particle size of no more than 20 mm, and the weight of the 10-20 mm portion is no more than 43%.

[0076] The ash residue from the thermal power plant comprises the following components by mass percentage: SiO2 37.2%, CaO 46.9%, MgO 6.2%, Al2O3 5.8%, Fe2O3 2.7%, and the balance being unavoidable impurities;

[0077] The ash and slag from the thermal power plant also includes pretreatment, which includes the following steps:

[0078] (1) Take the ash residue from the thermal power plant and disperse it in water, adjust the pH to 8-9, add an ethanol solution of KH550, stir the reaction thoroughly at room temperature overnight, filter it out and wash it until neutral, and dry it for later use.

[0079] (2) Weigh out tributylethylphosphine bromide and dissolve it in deionized water to obtain a tributylethylphosphine bromide solution. The tributylethylphosphine bromide solution is subjected to ion exchange through an ion exchange resin. The alkaline solution is collected, aminotriacetic acid is added, and the reaction is stirred at room temperature for 12 hours. After the reaction is completed, the solution is concentrated under reduced pressure to a solid content of 4.8 g / 100 mL to obtain a modified solution.

[0080] The concentration of the tributylethylphosphine bromide solution is 4 g / 100 mL; the mass ratio of the tributylethylphosphine bromide to the aminotriacetic acid is 3:10.

[0081] (3) Immerse the dried ash obtained in step (1) in the modified solution at room temperature, stir and react overnight, filter out, wash and dry to obtain the product;

[0082] The volcanic ash has an average particle size of 18.5 μm and an activity index of 0.75.

[0083] The reinforcing agent is the cellulose nanofiber described in Example 2;

[0084] The method for preparing crack-resistant road concrete based on ash slag includes the following steps:

[0085] (1) Weigh each raw material according to the preset weight ratio and set aside for use;

[0086] (2) First, the cement, silica fume, pozzolanic and ash residue are mixed at a mixing speed of 30-50 r / min;

[0087] (3) Add the granite coarse aggregate, the river sand, the water-reducing agent, the slump-preserving mother liquor, the reinforcing agent and water, and continue to stir and mix at 30-50 r / min for 100 s. After stirring evenly, the mixture is obtained.

[0088] Example 5

[0089] A type of crack-resistant road concrete based on ash residue, comprising the following components by weight:

[0090] 122 parts P.O42.5 cement, 340 parts river sand, 426 parts granite coarse aggregate, 72 parts thermal power plant ash, and P800 type silica fume (specific surface area ≥800m²). 2 12 parts ( / kg), 26 parts volcanic ash, 1.5 parts polycarboxylate superplasticizer, 1.8 parts slump-retaining mother liquor, and 100 parts water;

[0091] The fineness modulus of the river sand is 2.6; the coarse aggregate of the granite has a particle size of no more than 20 mm, and the weight of the 10-20 mm portion is no more than 43%.

[0092] The ash residue from the thermal power plant comprises the following components by mass percentage: SiO2 37.2%, CaO 46.9%, MgO 6.2%, Al2O3 5.8%, Fe2O3 2.7%, and the balance being unavoidable impurities;

[0093] The volcanic ash has an average particle size of 18.5 μm and an activity index of 0.75.

[0094] The method for preparing crack-resistant road concrete based on ash slag includes the following steps:

[0095] (1) Weigh each raw material according to the preset weight ratio and set aside for use;

[0096] (2) First, the cement, silica fume, pozzolanic and ash residue are mixed at a mixing speed of 30-50 r / min;

[0097] (3) Add the granite coarse aggregate, the river sand, the water-reducing agent, the slump-preserving mother liquor and water, and continue to stir and mix at 30-50 r / min for 100 s. After stirring evenly, the mixture is obtained.

[0098] Experimental Example

[0099] Referring to the methods in GB / T 50081-2002, GBJ 81-1985, and SL 352-2006, the mechanical properties of the concrete samples described in Examples 1-5 were tested, and the results are as follows:

[0100]

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A type of crack-resistant road concrete based on ash and slag, characterized in that, By weight, it comprises the following components: 100-130 parts cement, 300-400 parts fine aggregate, 400-460 parts coarse aggregate, 60-90 parts ash, 30-50 parts admixture, 5-12 parts additives, and 80-100 parts water. The fine aggregate is river sand or manufactured sand, and the coarse aggregate is limestone, granite, or basalt. The ash residue is pretreated thermal power plant ash residue, and the pretreatment includes the following steps: (1) Take the ash residue from the thermal power plant and disperse it in water, adjust the pH to alkaline, add an ethanol solution of silane coupling agent, stir the reaction thoroughly at room temperature overnight, filter it out and wash it until neutral, and dry it for later use. (2) Weigh tributylethylphosphine bromide and dissolve it in deionized water to obtain a tributylethylphosphine bromide solution. The tributylethylphosphine bromide solution is subjected to ion exchange through an ion exchange resin. The alkaline solution is collected, and aminotriacetic acid is added. The reaction is stirred at room temperature for 6-18 hours. After the reaction is completed, the solution is concentrated under reduced pressure to a solid content of 4-10 g / 100 mL to obtain a modified solution. The concentration of the tributylethylphosphine bromide solution is 3-4 g / 100 mL; the mass ratio of the tributylethylphosphine bromide to the aminotriacetic acid is (2.5-3.5):

10. (3) Immerse the dried ash obtained in step (1) in the modified solution at room temperature, stir and react overnight, filter out, wash and dry to obtain the product.

2. The ash-based crack-resistant road concrete according to claim 1, characterized in that, The ash from the thermal power plant comprises the following components by mass percentage: SiO2 20-40%, CaO 30-50%, MgO 3-10%, Al2O3 2-10%, Fe2O3 1-8%, and the balance being unavoidable impurities.

3. The crack-resistant road concrete based on ash and slag according to claim 1, characterized in that, The admixture is one or more of the following: fly ash, blast furnace slag, silica fume, volcanic ash, steel slag, and silica fume.

4. The crack-resistant road concrete based on ash and slag according to claim 1, characterized in that, The admixtures include one or more of the following: water-reducing agents, air-entraining agents, defoamers, slump-retaining agents, wetting agents, and reinforcing agents.

5. The crack-resistant road concrete based on ash and slag according to claim 4, characterized in that, The water-reducing agent is a naphthalene-based water-reducing agent or a polycarboxylate water-reducing agent; the slump-retaining agent is a slump-retaining mother liquor.

6. The crack-resistant road concrete based on ash and slag according to claim 4, characterized in that, The reinforcing agent is modified cellulose, and its preparation method includes the following steps: Weigh polyvinyl alcohol and dissolve it in deionized water. Heat and stir until completely dissolved. Add boron nitride nanotubes and ultrasonically disperse for 1-60 minutes to form a uniform boron nitride nanotube-polyvinyl alcohol suspension. Add cellulose nanofibers and stir again to react overnight. Then, vacuum filter through a cellulose acetate membrane to peel the obtained product off the filter membrane. After vacuum drying, the modified cellulose is obtained. The concentration of polyvinyl alcohol in the solution is 6-12 wt%.

7. The crack-resistant road concrete based on ash and slag according to claim 6, characterized in that, The mass ratio of the polyvinyl alcohol to the boron nitride nanotubes and the cellulose nanofibers is (3-3.4):1:(8-8.6).

8. A method for preparing crack-resistant road concrete based on ash slag according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Weigh each raw material according to the preset weight ratio and set aside for use; (2) First, mix the cement, the admixture and the ash at a mixing speed of 30-50 r / min; (3) Add the coarse aggregate, the fine aggregate, the additive and water, and continue to stir and mix at 30-50 r / min for 30-120 s. After stirring evenly, the mixture is obtained.

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