A concrete material for elevated tunnels, its preparation method and application

Abstract

The present invention discloses a concrete material for elevated tunnels, its preparation method and application, belonging to the technical field of high-performance concrete and its production. The raw materials for preparing the concrete material of the present invention include: silt ceramsite, manufactured sand, silty clay, cement, fly ash, polyphenylene sulfide microfibers, composite modified emulsion, water reducer, foaming agent, water; wherein the composite modified emulsion is prepared by compounding and blending EVA emulsion, polyvinyl acetate emulsion and fluorosilicone emulsion. The concrete prepared by the process of the present invention has high compressive and flexural strength, high slump, excellent impermeability and wear resistance, can meet the high-performance requirements of concrete for viaducts and subway tunnels, and has good practicability.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-performance concrete and its manufacturing technology, and particularly relates to a concrete material for elevated tunnels, its preparation method and application. Background Art

[0002] With the economic development, the urban population in China is increasing day by day, and traffic congestion has become a common problem faced by major cities at present. Building elevated roads and developing subways are practical ways to alleviate and improve traffic congestion: elevated roads are built overhead, avoiding intersections with ground roads in a three-dimensional intersection manner. A reasonable layout of elevated roads can optimize the use of space, making it possible to achieve large-capacity and rapid traffic on existing roads with limited width; while subways are generally located in underground tunnels, with exclusive rights of way and no plane intersections, which is an independent transportation system and is not affected by the ground road conditions, having the advantages of high efficiency, no pollution and large capacity.

[0003] Urban elevated roads are restricted by many factors: firstly, to reduce the bridge length and ramp length, it is necessary to choose the smallest possible height and obtain a larger span under a certain pier height. In addition, it also requires a larger width-span ratio to increase the traffic flow, and the increase in new structures such as curved bridges, sloping bridges, and skew bridges makes the stress on the bridge deck complex and the performance requirements increase significantly. Most subway tunnels are located underground and mainly use integral concrete sleepers, which have the characteristics of neatness, beauty and convenient maintenance. However, due to various factors, uneven settlement of the roadbed is likely to occur, resulting in significant differences in the loads and stresses transmitted to the sleeper surface, and thus having a greater impact on its durability and service life.

[0004] In view of this, in order to adapt to the rapid development of urban transportation, it is of great significance to study a high-performance concrete material suitable for elevated roads and subway tunnels. Summary of the Invention

[0005] In response to the problems mentioned in the background art, the present invention provides a concrete material for elevated tunnels, its preparation method and application. The aggregate of the concrete of the present invention is selected from silt ceramsite, manufactured sand, silty clay, etc., and at the same time, polyphenylene sulfide microfibers and a modified emulsion prepared by coordinating EVA emulsion, polyvinyl acetate emulsion and fluorosilicon emulsion are incorporated, greatly improving the strength and stability of the concrete material and meeting the high-performance requirements of the concrete for elevated roads and subway tunnels.

[0006] To achieve the above object, the present invention specifically adopts the following technical solutions:

[0007] The present invention provides a concrete material for elevated tunnels, and its preparation raw materials include the following components in parts by weight:

[0008] 290 - 420 parts of silt ceramsite,

[0009] 160 - 240 parts of manufactured sand,

[0010] 70 - 85 parts of silty clay,

[0011] 95 - 150 parts of cement,

[0012] 50 - 70 parts of fly ash,

[0013] 40 - 65 parts of polyphenylene sulfide microfiber,

[0014] 15 - 32 parts of composite modified emulsion,

[0015] 5 - 7 parts of water - reducing agent,

[0016] 3 - 6 parts of foaming agent,

[0017] 60 - 90 parts of water;

[0018] Among them, the composite modified emulsion is prepared by compounding and blending EVA emulsion, polyvinyl acetate emulsion and fluorosilicone emulsion.

[0019] Preferably, the raw materials for preparing the concrete material include, by weight:

[0020] 360 parts of sludge ceramsite,

[0021] 200 parts of manufactured sand,

[0022] 80 parts of silty clay,

[0023] 115 parts of cement,

[0024] 60 parts of fly ash,

[0025] 52 parts of polyphenylene sulfide microfiber,

[0026] 26 parts of composite modified emulsion,

[0027] 6 parts of water - reducing agent,

[0028] 4 parts of foaming agent,

[0029] 72 parts of water.

[0030] Preferably, the sludge ceramsite is a bio - porous ceramsite made from sludge, with a particle size range of 10 - 25 mm, a bulk density of 360 - 400 kg / m 3 , and a compressive strength of not less than 1.8 MPa.

[0031] The main raw materials used in the concrete of the present invention include silt ceramsite, manufactured sand, silty clay, cement and fly ash. First, the present invention selects high-strength silt ceramsite as the aggregate of the concrete, which can coordinate the matching relationship between the unit weight and strength of the concrete, effectively overcome the defect of large self-weight of conventional concrete, and can meet the requirements of large bridge deck span and large width-span ratio; Secondly, the present invention mixes and dopes silt ceramsite, manufactured sand and silty clay, and the combination of the three can effectively improve the compactness of the concrete, and the penetration and reaction between them can also offset the defect of large later shrinkage of the concrete.

[0032] Preferably, the fineness modulus of the manufactured sand is 2.5 - 3.0; the plastic index of the silty clay is 15 - 17, and the clay particle content is 45%.

[0033] Preferably, the polyphenylene sulfide microfiber is 6 - 9 mm in length and 20 - 40 μm in diameter.

[0034] Preferably, the preparation method of the composite modified emulsion is: take EVA emulsion, polyvinyl acetate emulsion, fluorosilicone emulsion, mix and stir evenly, add cationic hydroxyethyl cellulose and aminopropyltrimethoxysilane, heat to 70 °C and perform ultrasonic treatment for 15 min, and continue to stir evenly to obtain the composite modified emulsion.

[0035] Preferably, the raw materials for preparing the composite modified emulsion are calculated by weight as follows: 50 parts of EVA emulsion, 14 - 25 parts of polyvinyl acetate emulsion, 5 - 12 parts of fluorosilicone emulsion, 3 - 7 parts of cationic hydroxyethyl cellulose, and 2 - 4 parts of aminopropyltrimethoxysilane.

[0036] Preferably, the water reducer is a high-performance polycarboxylate water reducer with a solid content of 20% and a water reduction rate of 30%; the cement is ordinary 42.5-grade Portland cement.

[0037] The present invention adopts a raw material system of composite aggregate synergistically with polyphenylene sulfide microfiber. Polyphenylene sulfide fiber is a high-performance fiber with excellent mechanical properties, chemical resistance and thermal properties. Incorporating polyphenylene sulfide microfiber into the aforementioned composite aggregate of the present invention can play a role in homogenizing the load of the concrete, thereby greatly improving the compressive, flexural and load-bearing properties of the concrete material; The present invention also adopts a composite modified emulsion, which is mainly composed of EVA emulsion, polyvinyl acetate emulsion and fluorosilicone emulsion by compounding and blending. On the one hand, it can further improve the water resistance, acid and alkali resistance of the concrete, and on the other hand, it can promote the construction of a multi-dimensional composite structure by the selected composite aggregate and polyphenylene sulfide microfiber of the present invention, greatly improving the dense compressive property of the concrete, and the structure is stable and the strength is high after the concrete is formed.

[0038] The present invention also provides a preparation method of the above-mentioned concrete material for elevated tunnels, including the following steps:

[0039] 1) Weigh each raw material according to the formula dosage for standby, mix the silt ceramsite, manufactured sand, silty clay, cement, and fly ash, and stir well.

[0040] 2) Add a water reducer and 1 / 2 of the water to the mixed material obtained in step 1) and stir evenly. Then, slowly pour the composite modified emulsion and the remaining amount of water into it, and continuously stir to obtain a mixed slurry.

[0041] 3) Add polyphenylene sulfide microfibers to the mixed slurry obtained in step 2), continuously stir slowly, then add a foaming agent, and finally stir well.

[0042] The concrete material prepared by the present invention can be applied to viaducts and subway tunnels.

[0043] Compared with the prior art, the beneficial effects of the present invention include:

[0044] The present invention rationally selects silt ceramsite, manufactured sand, silty clay, etc. as aggregate for viaducts and subway tunnels with complex stress, and at the same time incorporates polyphenylene sulfide microfibers and a modified emulsion coordinated with the compound of EVA emulsion, polyvinyl acetate emulsion, and fluorosilicon emulsion to prepare a high-strength and high-stability concrete material. The prepared concrete has a stable structure, high strength, and good compactness after forming, can homogenize the load, and meet the high-performance requirements of concrete for viaducts and subway tunnels. Specific Embodiments

[0045] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with embodiments. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified in the manufacturer are all conventional products that can be obtained through commercial purchase.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0047] In the experiments of the present invention: the silt ceramsite used is commercially available, with a particle size range of 10 - 25 mm, a bulk density of 385 kg / m 3 , and a compressive strength of 2.2 MPa; the manufactured sand used is commercially available, with a fineness modulus of 2.7; the silty clay used is commercially available, with a plasticity index of 17 and a clay particle content of 45%; the cement used is ordinary 42.5-grade Portland cement; the specific surface area of the fly ash used is about 380 m 2 / kg, and the density is 2.3 g / m3 , the loss on ignition is 3.43%; the polyphenylene sulfide microfibers used are 6 - 9 mm in length and 20 - 40 μm in diameter; the solid content of the EVA emulsion (commercially available BJ - 707) is 54.5%, the solid content of the polyvinyl acetate emulsion (commercially available JYS15445) is 50%, and the solid content of the fluorosilicone emulsion (commercially available SD - 5681) is 48%; the water - reducing agent is a commercially available high - performance polycarboxylate water - reducing agent with a solid content of 20% and a water - reducing rate of 30%; the foaming agent is a composite foam foaming agent; the water is tap water.

[0048] Example 1

[0049] A preparation method for concrete materials used in elevated tunnels, comprising:

[0050] 1. Take 50 parts by weight of EVA emulsion, 16 parts of polyvinyl acetate emulsion, 10 parts of fluorosilicone emulsion, 5 parts of cationic hydroxyethyl cellulose, and 3 parts of aminopropyltrimethoxysilane for standby. Mix and stir the EVA emulsion, polyvinyl acetate emulsion, and fluorosilicone emulsion evenly, add cationic hydroxyethyl cellulose and aminopropyltrimethoxysilane, heat to 70 °C, and perform ultrasonic treatment for 15 min, then continue to stir evenly to obtain a composite modified emulsion.

[0051] 2. Take 360 parts by weight of silt ceramsite, 200 parts of manufactured sand, 80 parts of silty clay, 115 parts of cement, 60 parts of fly ash, 52 parts of polyphenylene sulfide microfibers, 26 parts of the above - prepared composite modified emulsion, 6 parts of water - reducing agent, 4 parts of foaming agent, and 72 parts of water for standby. Mix silt ceramsite, manufactured sand, silty clay, cement, and fly ash, and stir evenly; add the water - reducing agent and 1 / 2 of the water to the obtained mixed material and stir evenly, then slowly pour the composite modified emulsion and the remaining amount of water into it, and continue to stir to obtain a mixed slurry; add the polyphenylene sulfide microfibers to the mixed slurry, continuously stir slowly, then add the foaming agent, and finally stir evenly to obtain.

[0052] Example 2

[0053] A preparation method for concrete materials used in elevated tunnels, comprising:

[0054] 1. Take 50 parts by weight of EVA emulsion, 25 parts of polyvinyl acetate emulsion, 5 parts of fluorosilicone emulsion, 3 parts of cationic hydroxyethyl cellulose, and 3 parts of aminopropyltrimethoxysilane for standby. Mix and stir the EVA emulsion, polyvinyl acetate emulsion, and fluorosilicone emulsion evenly, add cationic hydroxyethyl cellulose and aminopropyltrimethoxysilane, heat to 70 °C, and perform ultrasonic treatment for 15 min, then continue to stir evenly to obtain a composite modified emulsion.

[0055] 2. Take 290 parts of silt ceramsite, 240 parts of manufactured sand, 70 parts of silty clay, 115 parts of cement, 70 parts of fly ash, 65 parts of polyphenylene sulfide microfiber, 15 parts of the above-prepared composite modified emulsion, 6 parts of water reducing agent, 4 parts of foaming agent, and 72 parts of water for standby. Mix the silt ceramsite, manufactured sand, silty clay, cement, and fly ash and stir well. Add the water reducing agent and 1 / 2 of the water to the obtained mixture and stir evenly. Then, slowly pour the composite modified emulsion and the remaining amount of water into it and continuously stir to obtain a mixed slurry. Add the polyphenylene sulfide microfiber to the mixed slurry, continuously stir slowly, and then add the foaming agent and finally stir well to obtain the product.

[0056] Example 3

[0057] A preparation method for concrete materials for elevated tunnels, comprising:

[0058] 1. Take 50 parts of EVA emulsion, 14 parts of polyvinyl acetate emulsion, 12 parts of fluorosilicone emulsion, 6 parts of cationic hydroxyethyl cellulose, and 2 parts of aminopropyltrimethoxysilane for standby. Mix the EVA emulsion, polyvinyl acetate emulsion, and fluorosilicone emulsion and stir evenly. Add the cationic hydroxyethyl cellulose and aminopropyltrimethoxysilane, heat up to 70 °C, and perform ultrasonic treatment for 15 min, and then continue to stir evenly to obtain a composite modified emulsion.

[0059] 2. Take 420 parts of silt ceramsite, 160 parts of manufactured sand, 85 parts of silty clay, 115 parts of cement, 50 parts of fly ash, 40 parts of polyphenylene sulfide microfiber, 32 parts of the above-prepared composite modified emulsion, 6 parts of water reducing agent, 4 parts of foaming agent, and 72 parts of water for standby. Mix the silt ceramsite, manufactured sand, silty clay, cement, and fly ash and stir well. Add the water reducing agent and 1 / 2 of the water to the obtained mixture and stir evenly. Then, slowly pour the composite modified emulsion and the remaining amount of water into it and continuously stir to obtain a mixed slurry. Add the polyphenylene sulfide microfiber to the mixed slurry, continuously stir slowly, and then add the foaming agent and finally stir well to obtain the product.

[0060] Comparative Example 1

[0061] This comparative example refers to the step parameters of Example 1, and the difference lies in changing the preparation raw material system of the composite modified emulsion. The specific change steps are as follows:

[0062] Take 50 parts of EVA emulsion, 16 parts of polyvinyl acetate emulsion, and 3 parts of aminopropyltrimethoxysilane for standby. Mix the EVA emulsion and polyvinyl acetate emulsion and stir evenly. Add aminopropyltrimethoxysilane, heat up to 70 °C, and perform ultrasonic treatment for 15 min, and then continue to stir evenly to obtain a composite modified emulsion; replace the composite modified emulsion prepared in this comparative example with an equal amount in Step 2.

[0063] Comparative Example 2

[0064] This comparative example refers to the step parameters of Example 1, the difference being that steel fibers with a length of 6 - 9 mm, a diameter of 20 - 40 μm, and a tensile strength exceeding 2000 MPa are used instead of the polyphenylene sulfide microfibers used in Step 2.

[0065] Comparative Example 3

[0066] This comparative example refers to the step parameters of Example 1, the difference being that the composite aggregate system of the concrete material is adjusted. Specifically, 440 parts by weight of shale ceramsite (particle size range of 10 - 30 mm, bulk density 336 kg / m 3 , compressive strength 2.2 MPa), 200 parts of manufactured sand, 115 parts of cement, and 60 parts of fly ash are taken; other raw materials remain unchanged.

[0067] According to the relevant standards of GB / T 50080, GB / T 50081, GB / T 50082, and JTG E30, the concrete material samples prepared in Examples 1 - 3 and Comparative Examples 1 - 3 of the present invention are tested, and the results are shown in the following table.

[0068] Table 1

[0069]

[0070] It can be seen from the test results in Table 1 that the concrete material prepared by the process of the present invention not only has high compressive and flexural strengths and high slump, but also has good impermeability and abrasion resistance. The internal viscosity of the concrete is strong, the interior is uniform after molding, and the structure is more stable, greatly improving the strength and stability of the bridge deck and ballast bed surface, and effectively extending its service life.

[0071] The embodiments described above only represent several preferred embodiments of the present invention. The description is relatively specific and detailed, but it does not limit the present invention. It should be noted that for those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the concept and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A concrete material for elevated tunnels, characterized in that, The raw materials for its preparation include the following components by weight parts: 290 - 420 parts of silt ceramsite, 160 - 240 parts of manufactured sand, 70 - 85 parts of silty clay, 95 - 150 parts of cement, 50 - 70 parts of fly ash, 40 - 65 parts of polyphenylene sulfide microfiber, 15 - 32 parts of composite modified emulsion, 5 - 7 parts of water reducing agent, 3 - 6 parts of foaming agent, 60 - 90 parts of water; Among them, the polyphenylene sulfide microfiber is 6 - 9 mm in length and 20 - 40 μm in diameter; the composite modified emulsion is obtained by mixing and stirring evenly EVA emulsion, polyvinyl acetate emulsion, and fluorosilicon emulsion, adding cationic hydroxyethyl cellulose and aminopropyltrimethoxysilane, heating to 70°C and ultrasonically treating for 15 min, and then continuing to stir evenly. Its raw materials include the following components by weight parts: 50 parts of EVA emulsion, 14 - 25 parts of polyvinyl acetate emulsion, 5 - 12 parts of fluorosilicon emulsion, 3 - 7 parts of cationic hydroxyethyl cellulose, and 2 - 4 parts of aminopropyltrimethoxysilane.

2. The concrete material for elevated tunnels according to claim 1, characterized in that, The raw materials for the preparation of the concrete material include the following by weight parts: 360 parts of silt ceramsite, 200 parts of manufactured sand, 80 parts of silty clay, 115 parts of cement, 60 parts of fly ash, 52 parts of polyphenylene sulfide microfiber, 26 parts of composite modified emulsion, 6 parts of water reducing agent, 4 parts of foaming agent, 72 parts of water.

3. The concrete material for elevated tunnels according to claim 1, wherein, The sludge ceramsite is a bio-porous ceramsite made from sludge, with a particle size range of 10 - 25 mm, a bulk density of 360 - 400 kg / m 3 , and a compressive strength of not less than 1.8 MPa.

4. The concrete material for elevated tunnels according to claim 1, characterized in that, The fineness modulus of the manufactured sand is 2.5 - 3.0; the plasticity index of the silty clay is 15 - 17, and the clay particle content is 45%.

5. The concrete material for elevated tunnels according to claim 1, characterized in that, The water reducing agent is a high - performance polycarboxylate water reducing agent with a solid content of 20% and a water reduction rate of 30%; the cement is ordinary 42.5 - grade Portland cement.

6. The preparation method of the concrete material for elevated tunnels according to any one of claims 1-5, characterized in that, It includes the following steps: 1) Weigh each raw material according to the formula dosage for standby, and mix the silt ceramsite, manufactured sand, silty clay, cement, and fly ash, and stir evenly. 2) Add the water reducing agent and 1 / 2 of the water to the mixed material obtained in step 1) and stir evenly. Then, slowly pour the composite modified emulsion and the remaining amount of water into it, and continuously stir to obtain a mixed slurry. 3) Add the polyphenylene sulfide microfiber to the mixed slurry obtained in step 2), continuously stir slowly, then add the foaming agent, and finally stir evenly.

7. Application of the concrete material obtained by the preparation method according to claim 6 in viaducts and subway tunnels.

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