An economical green low-carbon ultra-high performance concrete

Abstract

The present invention relates to an economical green and low-carbon ultra-high performance concrete. The components of the concrete are in a mass ratio of (kg / m 3 ): cement 450 - 550, metakaolin 150 - 200, granulated blast furnace slag powder 300 - 400, manufactured sand 350 - 450, powdered coal gangue 400 - 500, servo fiber 78 - 156, functional agent 13.5 - 20, composite admixture 40 - 58.5, and water 160 - 180. The preparation method is as follows: First, add cement, granulated blast furnace slag powder, and powdered coal gangue into a mixer and stir; Second, premix and stir the manufactured sand with 30% of the composite admixture and 30% of the water; Third, premix and stir the metakaolin with the functional agent and 30% of the composite admixture; Fourth, mix 40% of the composite admixture and 70% of the water evenly, and then stir slowly; Fifth, add the servo fiber and stir slowly until evenly mixed.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete, and particularly relates to an economical green and low-carbon ultra-high performance concrete. Background Art

[0002] As the urbanization process enters a new stage, people have higher and higher requirements for the quality of concrete structure buildings closely related to their lives. Ultra-high performance concrete (UHPC) has characteristics such as ultra-high strength, high toughness, high workability and high durability, and has become a research hotspot in the field of concrete structure construction at home and abroad, and has been more and more widely used in the fields of municipal engineering, architecture, urban renewal, etc.

[0003] At present, ultra-high performance concrete mainly takes raw materials such as Portland cement, river sand or quartz sand, steel fiber, etc. as the core components to achieve the denseness of its system, and then meet the performance requirements such as high strength, high toughness and high durability; however, there are some problems that cannot be ignored in this type of mix design: (1) As a cementitious material, if the dosage of Portland cement is too large, it will greatly increase the carbon dioxide emissions; (2) As a natural resource, due to over-exploitation, the quality control of river sand in the current market is difficult and the price rises rapidly, and the environmental protection situation is becoming increasingly severe; (3) Although quartz sand has excellent quality, its price is expensive, which will greatly increase the production cost of concrete and is not conducive to the market competition of concrete; (4) As the main toughening material, steel fiber has an important impact on the durability of concrete, but there are problems such as high price, difficult to disperse, easy to be exposed and rust, and heavy weight.

[0004] Therefore, how to provide an economical green and low-carbon ultra-high performance concrete is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] Aiming at the problem of the dependence of traditional ultra-high performance concrete on materials such as Portland cement, river sand or quartz sand, steel fiber, etc., the present invention proposes an economical green and low-carbon ultra-high performance concrete, which uses metakaolin and slag powder to partially replace Portland cement, uses manufactured sand and pulverized coal gangue to replace natural river sand or quartz sand, uses servo fiber based on bamboo fiber and PVA fiber to replace steel fiber, and uses functional agents to activate the activity of the powder system, providing low-carbon and green cementitious materials, fine aggregates and fiber materials, effectively overcoming the dependence of traditional ultra-high performance concrete on materials such as Portland cement, river sand or quartz sand, steel fiber, etc., reducing the production cost of concrete, and promoting the large-scale application process of ultra-high performance concrete.

[0006] To solve the above technical problems, the present invention includes the following technical solutions:

[0007] An economical green and low-carbon ultra-high performance concrete, and the components of the concrete are in a mass ratio of (kg / m 3 ):

[0008] Cement 450 - 550, metakaolin 150 - 200, granulated blast furnace slag powder 300 - 400, manufactured sand 350 - 450, pulverized coal gangue 400 - 500, servo fiber 78 - 156, functional agent 13.5 - 20, composite admixture 40 - 58.5, and water 160 - 180.

[0009] Furthermore, the servo fiber is made from bamboo fiber and PVA fiber by a paired cementing process.

[0010] Furthermore, the manufacturing process of the servo fiber includes the following steps:

[0011] The first step: The preparation process of surface modification and enhancement of bamboo fiber based on nano-calcium carbonate: Place fresh bamboo in a pressure tank, introduce high-temperature saturated steam into the tank, pressurize to make the temperature in the tank reach 160 - 180 °C, and keep warm for 40 - 60 min; Drain the steam in the tank and take out the bamboo tube, cut the bamboo tube into bamboo slices; Use a bamboo slice hammer to beat the bamboo slices to obtain long filament bamboo fiber; Based on the wet chemical deposition technology, adopt the in-situ modification process of nano-calcium carbonate to precisely construct a nano-level calcium carbonate enhancement layer on the surface of the long filament bamboo fiber; Cut the long filament bamboo fiber into short filament bamboo fibers with a length range of 15 - 25 mm;

[0012] The second step: Paste it on the surface of the short filament bamboo fiber to obtain the servo fiber.

[0013] Furthermore, the length of the PVA fiber is 5 - 15 mm, the diameter is 18 - 22 μm, and the density is 1.0 - 1.5 g / cm 3 .

[0014] Furthermore, the functional agent is a mixed solution formed by mixing sodium hydroxide and kiln dust in a mass ratio of 2:1, and the total admixture ratio is 9% - 10% of the mass of metakaolin.

[0015] Furthermore, the composite admixture is compounded from a polycarboxylate superplasticizer and a calcium sulfoaluminate type expansive agent, and the total admixture ratio is 3.5% - 6.5% of the total amount of cementitious materials.

[0016] Furthermore, the cement is P.Ⅱ52.5 Portland cement, the metakaolin is an ultra-fine powder with a specific surface area of 26500 m 2 / Kg, and the granulated blast furnace slag powder is S95 slag powder.

[0017] Furthermore, the manufactured sand has a stone powder content ≤ 5% and a quartz content ≥ 60%, and the pulverized coal gangue is a high-strength lightweight aggregate of coal gangue.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0019] The present invention provides an economical, green, low-carbon and ultra-high performance concrete. The components of the concrete are in a mass ratio of (kg / m 3 ) : cement 450 - 550, metakaolin 150 - 200, granulated blast furnace slag powder 300 - 400, manufactured sand 350 - 450, powdered coal gangue 400 - 500, servo fiber 78 - 156, functional agent 13.5 - 20, composite admixture 40 - 58.5, and water 160 - 180. The preparation method of the economical, green, low-carbon and ultra-high performance concrete includes: First, add 100% cement, granulated blast furnace slag powder and powdered coal gangue into a mixer, and stir slowly for 10 - 25 s until uniform; Second, premix 100% manufactured sand with 30% composite admixture and 30% water until uniform to obtain premixed manufactured sand, put the premixed manufactured sand into the mixer, first stir slowly for 10 - 25 s, and then stir quickly for 8 - 10 s until uniform; Third, premix 100% metakaolin with 100% functional agent and 30% composite admixture until uniform to obtain premixed metakaolin, put the premixed metakaolin into the mixer, first stir slowly at 9 - 12 r / min for 10 - 25 s, and then stir quickly at 12 - 24 r / min for 8 - 10 s until uniform; Fourth, after standing for 10 - 15 s, start slow stirring; Fifth, mix 40% composite admixture with 70% water evenly, and then slowly and evenly put it into the mixer, and stir slowly for 45 - 60 s until uniform; Sixth, put 100% servo fiber slowly and evenly into the mixer, and stir slowly for 60 - 120 s until uniform to obtain the economical, green, low-carbon and ultra-high performance concrete.

[0020] Compared with the prior art, the beneficial effects of the present invention are mainly as follows:

[0021] (1) For the economical, green, low-carbon and ultra-high performance concrete provided by the present invention, solid wastes - metakaolin and slag powder are used to replace about 50% of the amount of Portland cement, which can significantly reduce the heat of hydration of cement, reduce the risk of concrete shrinkage and cracking, improve the durability of concrete, and at the same time can greatly reduce the production cost of concrete and reduce carbon dioxide emissions, having significant economic and low-carbon environmental protection significance.

[0022] (2) The economical green low-carbon ultra-high performance concrete provided by the present invention uses manufactured sand as fine aggregate to replace part of the traditional river sand or quartz sand, which can significantly reduce the extraction amount of river sand, save natural resources, protect the ecological environment, and reduce production costs; uses pulverized coal gangue to replace part of the traditional river sand or quartz sand, and utilizes its excellent filling effect, mechanical strength and certain pozzolanic activity, which can significantly improve the compactness of concrete, and then effectively improve the mechanical and durability properties of concrete. At the same time, it can also realize the resource utilization of solid waste and reduce the production cost of concrete, with significant social and economic benefits.

[0023] (3) The economical green low-carbon ultra-high performance concrete provided by the present invention uses servo fiber to replace traditional steel fiber. Through the surface modification enhancement preparation of bamboo fiber based on nano-calcium carbonate and its pairing cementation process with PVA fiber, the performance advantages of each can be fully exerted, and the interfacial bonding strength between the servo fiber and the concrete matrix can be significantly improved, effectively enhancing the toughness and crack resistance of the concrete. At the same time, it can also effectively reduce the density of the concrete to achieve a lightweight effect, and can also significantly reduce the production cost of the concrete, effectively promoting the sustainable development of the traditional concrete industry towards the direction of green and low-carbon.

[0024] (4) The economical green low-carbon ultra-high performance concrete provided by the present invention uses a functional agent composed of sodium hydroxide and kiln ash, which can effectively activate the activity of metakaolin and pulverized coal gangue, promote their hydration reaction process, and improve the compactness, mechanical and durability properties of the concrete. Specific embodiments

[0025] The following further details a kind of economical green low-carbon ultra-high performance concrete provided by the present invention in combination with specific embodiments. According to the following description, the advantages and features of the present invention will be clearer.

[0026] The following describes the economical green low-carbon ultra-high performance concrete of the present invention.

[0027] An economical green low-carbon ultra-high performance concrete, the components of the concrete are in a mass ratio of (kg / m 3 ):

[0028] Cement 450 - 550, metakaolin 150 - 200, granulated blast furnace slag powder 300 - 400, manufactured sand 350 - 450, pulverized coal gangue 400 - 500, servo fiber 78 - 156, functional agent 13.5 - 20, composite admixture 40 - 58.5, and water 160 - 180.

[0029] More preferably, the servo fiber is made by a pairing cementation process of bamboo fiber and PVA fiber.

[0030] More preferably, the manufacturing process of the servo fiber includes the following steps:

[0031] The first step is the preparation process for enhancing the surface modification of bamboo fibers based on nano-calcium carbonate: Place fresh bamboo in a pressure tank, introduce high-temperature saturated steam into the tank, pressurize to make the temperature in the tank reach 160 - 180 °C, and keep warm for 40 - 60 minutes; Drain the steam in the tank and take out the bamboo tube, cut the bamboo tube into bamboo slices; Use a bamboo slice hammer to beat the bamboo slices to obtain long filament bamboo fibers; Based on the wet chemical deposition technology, adopt the in-situ modification process of nano-calcium carbonate to precisely construct a nano-level calcium carbonate enhancement layer on the surface of the long filament bamboo fibers; Cut the long filament bamboo fibers into short filament bamboo fibers with a length range of 15 - 25 mm;

[0032] The second step is to paste it on the surface of the short filament bamboo fibers to obtain servo fibers.

[0033] More preferably, the length of the PVA fiber is 5 - 15 mm, the diameter is 18 - 22 μm, and the density is 1.0 - 1.5 g / cm 3 .

[0034] More preferably, the functional agent is a mixed solution formed by mixing sodium hydroxide and kiln ash in a mass ratio of 2:1, and the total admixture ratio is 9% - 10% of the mass of metakaolin.

[0035] More preferably, the composite admixture is compounded from a polycarboxylate-based superplasticizer and a calcium sulfoaluminate-based expansive agent, and the total admixture ratio is 3.5% - 6.5% of the total amount of cementitious materials.

[0036] More preferably, the cement is P.Ⅱ 52.5 Portland cement, the metakaolin is an ultra-fine powder with a specific surface area of 26500 m 2 / Kg, and the granulated blast furnace slag powder is S95 slag powder.

[0037] More preferably, the content of machine-made sand powder is ≤5%, the quartz content is ≥60%, and the pulverized coal gangue is a high-strength lightweight aggregate of coal gangue.

[0038] The following specifically describes the economical, green and low-carbon ultra-high performance concrete of the present invention with specific embodiments.

[0039] Example 1:

[0040] Table 1 and Table 2 show the mix proportion design and performance indexes of ordinary ultra-high performance concrete in Example 1; Table 3 and Table 4 show the mix proportion design and performance indexes of the economical, green and low-carbon ultra-high performance concrete in Example 1.

[0041] Table 1 Mix Proportion of Ordinary Ultra-High Performance Concrete (kg / m 3 )

[0042]

[0043] Table 2 Performance Indexes of Ordinary Ultra-High Performance Concrete

[0044]

[0045] Table 3 Mix Proportion of Economical Green Low-Carbon Ultra-High Performance Concrete (kg / m 3 )

[0046]

[0047] Table 4 Performance Indexes of Economical Green Low-Carbon Ultra-High Performance Concrete (kg / m 3 )

[0048]

[0049] Example 2:

[0050] Table 5 and Table 6 show the mix proportion design and its performance indexes of ordinary ultra-high performance concrete in Example 2; Table 7 and Table 8 show the mix proportion design and its performance indexes of economical green low-carbon ultra-high performance concrete in Example 2.

[0051] Table 5 Mix Proportion of Ordinary Ultra-High Performance Concrete (kg / m 3 )

[0052]

[0053] Table 6 Performance Indexes of Ordinary Ultra-High Performance Concrete

[0054]

[0055] Table 7 Mix Proportion of Economical Green Low-Carbon Ultra-High Performance Concrete (kg / m 3 )

[0056]

[0057] Table 8 Performance Indexes of Economical Green Low-Carbon Ultra-High Performance Concrete

[0058]

[0059] It can be seen that, compared with traditional ordinary ultra-high performance concrete, the economical green low-carbon ultra-high performance concrete of the present invention, while significantly reducing the cement consumption and using servo fibers to replace traditional steel fibers / PVA fibers, not only effectively guarantees the basic mechanical properties of concrete (compressive and flexural strengths), but also greatly improves the workability (slump flow and slump flow retention) and durability (shrinkage resistance) of concrete. At the same time, it also significantly reduces the production cost of concrete and carbon dioxide emissions, and has remarkable economic and social benefits. Therefore, the economical green low-carbon ultra-high performance concrete of the present invention has remarkable technical advancement and broad market prospects.

[0060] The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above examples. The above-described examples only represent several embodiments of the present invention, and their descriptions are relatively specific and detailed, but they cannot be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. An economical green low-carbon ultra-high performance concrete, characterized in that: The mass ratio of each component of the concrete is (kg / m 3 ): Cement 450~550, metakaolin 150~200, granulated blast furnace slag powder 300~400, machine-made sand 350~450, powdered coal gangue 400~500, servo fiber 78~156, functional agent 13.5~20, composite admixture 40~58.5 and water 160~180; The servo fiber is made of bamboo fiber and PVA fiber through a pairing bonding process, and the servo fiber manufacturing process includes: The first step is the surface modification and reinforcement preparation process of bamboo fiber based on nano calcium carbonate: based on wet chemical deposition technology, the nano calcium carbonate in-situ modification process is adopted to accurately construct a nano-scale calcium carbonate reinforcement layer on the surface of the long bamboo fiber; the long bamboo fiber is cut into short bamboo fibers with a length ranging from 15 to 25 mm; The second step is to use an epoxy resin-based bonding process to bond the PVA fibers to the surface of short bamboo fibers in a mass ratio of 1:3 to 1:8 to obtain servo fibers. The functional agent is a mixed solution of sodium hydroxide and kiln dust in a mass ratio of 2:1, and the total mixing ratio is 9% to 10% of the mass of the metakaolin.

2. The economical green low-carbon ultra-high performance concrete according to claim 1, characterized in that: The long-filament bamboo fiber production process comprises: Fresh bamboo is placed in a pressure tank, high-temperature saturated steam is introduced into the tank, and the pressure is increased to make the temperature inside the tank reach 160-180°C, and the temperature is kept for 40-60 minutes; the steam in the tank is discharged and the bamboo tube is taken out, and the bamboo tube is split into bamboo slices; the bamboo slices are beaten with a bamboo hammer to obtain long-filament bamboo fibers.

3. The economical green low-carbon ultra-high performance concrete according to claim 2, characterized in that: The PVA fiber has a length of 5-15 mm, a diameter of 18-22 μm, and a density of 1.0-1.5 g / cm 3 .

4. The economical green low-carbon ultra-high performance concrete according to claim 1, characterized in that: The composite admixture is prepared by compounding a polycarboxylic acid-based high-efficiency water reducing agent and a calcium sulphoaluminate-based expansion agent, and the total admixture ratio is 3.5% to 6.5% of the total amount of the cementitious material.

5. The economical green low-carbon ultra-high performance concrete according to claim 1, characterized in that: The cement is P.Ⅱ52.5 silicate cement, and the metakaolin is an ultrafine powder with a specific surface area of ​​26500m 2 / Kg, granulated blast furnace slag powder is S95 ore powder.

6. The economical green low-carbon ultra-high performance concrete according to claim 1, characterized in that: The machine-made sand and gravel powder has a content of ≤5% and a quartz content of ≥60%, and the powdery coal gangue is a high-strength lightweight aggregate of coal gangue.