CN113248211A - Concrete and preparation method and application thereof - Google Patents

Concrete and preparation method and application thereof Download PDF

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Publication number
CN113248211A
CN113248211A CN202110653334.9A CN202110653334A CN113248211A CN 113248211 A CN113248211 A CN 113248211A CN 202110653334 A CN202110653334 A CN 202110653334A CN 113248211 A CN113248211 A CN 113248211A
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concrete
water
cement
parts
mixture
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李烨
刘铁军
周傲
王浩东
郭恒珲
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Shenzhen Graduate School Harbin Institute of Technology
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Shenzhen Graduate School Harbin Institute of Technology
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/04—Portland cements
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/02—Granular materials, e.g. microballoons
    • C04B14/04—Silica-rich materials; Silicates
    • C04B14/06—Quartz; Sand
    • C04B14/068—Specific natural sands, e.g. sea -, beach -, dune - or desert sand
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B16/00—Use of organic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of organic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B16/04—Macromolecular compounds
    • C04B16/06—Macromolecular compounds fibrous
    • C04B16/0616—Macromolecular compounds fibrous from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • C04B16/0625—Polyalkenes, e.g. polyethylene
    • C04B16/0633—Polypropylene
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B18/04—Waste materials; Refuse
    • C04B18/14—Waste materials; Refuse from metallurgical processes
    • C04B18/146—Silica fume
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/02—Selection of the hardening environment
    • C04B40/0263—Hardening promoted by a rise in temperature
    • C04B40/0268—Heating up to sintering temperatures
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Structural Engineering (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Civil Engineering (AREA)
  • Toxicology (AREA)
  • Health & Medical Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

The invention belongs to the technical field of building materials, and particularly relates to concrete and a preparation method and application thereof. The concrete provided by the invention comprises the following components in parts by weight: 1 part of cement; 0.9-1.1 parts of fine aggregate; 0.2-0.4 part of quartz powder; 0.1-0.3 part of silica fume; 0.03-0.04 part of a water reducing agent; 0.003-0.0075 parts of polypropylene fiber; 0.18-0.26 part of water; the water-glue ratio is (0.13-0.24): 1. the normal-temperature compressive strength of the concrete provided by the invention is more than 120MPa, and the concrete has excellent mechanical properties; and the residual mechanical property after high temperature is excellent. In addition, after re-curing, the concrete provided by the invention has higher recovery capability.

Description

Concrete and preparation method and application thereof
Technical Field
The invention belongs to the technical field of building materials in civil engineering, and particularly relates to concrete and a preparation method and application thereof.
Background
Among various fires, the fire with the highest occurrence frequency and the most serious loss belongs to the building fire. As the building material with the largest use amount in civil engineering at present, the traditional concrete has relatively low mechanical property and poor durability, and the high temperature caused by fire causes the deterioration of the mechanical property of the concrete, thereby causing the reduction and even the failure of the safety performance of the structure and causing great loss of life and property.
In the prior art, member repair and performance recovery improvement are mainly realized by a concrete spraying method, a sectional area increasing method, a steel reinforcing method and the like after a fire disaster. The mechanical property recovery phenomenon of the concrete after fire is rarely researched, and the concrete capable of recovering the mechanical property is not provided. The research on the mechanical property of the concrete after the fire disaster is restored has important significance for effectively repairing the building structure and reducing the economic loss. Therefore, there is a need for a concrete having high residual compressive strength at high temperatures and a certain ability to recover after high temperatures.
Disclosure of Invention
The invention aims to provide concrete with high residual compressive strength at high temperature and high recovery capability after high temperature.
In order to achieve the above purpose, the invention provides the following technical scheme:
the invention provides concrete which comprises the following preparation raw materials in parts by weight: 1 part of cement; 0.9-1.1 parts of fine aggregate; 0.2-0.4 part of quartz powder; 0.1-0.3 part of silica fume; 0.03-0.04 part of a water reducing agent; 0.003-0.0075 parts of polypropylene fiber; 0.18 to 0.26 portion of water, and the water-to-glue ratio is (0.13 to 0.24): 1.
Preferably, the cement comprises portland cement.
Preferably, the fine aggregate comprises river sand; the grain diameter of the fine aggregate is less than or equal to 1.20 mm.
Preferably, the particle size of the quartz powder is 100-150 meshes.
Preferably, the average particle size of the silica fume is 0.10-0.30 μm; s in the silica fumeiO2The content of (A) is more than or equal to 90 percent.
Preferably, the water reducing agent comprises a polycarboxylic acid water reducing agent; the solid content of the water reducing agent is 20-40%.
Preferably, the diameter of the polypropylene fiber is 20-40 μm, the length of the polypropylene fiber is 9-20 mm, and the tensile strength of the polypropylene fiber is 400-500 MPa.
The invention also provides a preparation method of the concrete, which comprises the following steps:
carrying out first mixing on cement, silica fume, fine aggregate and quartz powder to obtain a mortar mixture;
carrying out second mixing on water, a water reducing agent and the mortar mixture to obtain a mortar mixture;
thirdly mixing the polypropylene fiber and the mortar mixture to obtain a mixture;
and pouring, molding and maintaining the mixture to obtain the concrete.
The invention also provides the application of the concrete or the concrete prepared by the method in building engineering.
Preferably, when in use, after the concrete is subjected to high temperature, the method further comprises a restoration curing process, and specifically comprises the following steps:
performing 3-5 times of circulating curing on the high-temperature concrete;
and the circulating re-maintenance comprises the steps of re-maintenance of the carbonization box and re-maintenance of the saturated calcium hydroxide aqueous solution in sequence.
The concrete provided by the invention comprises the following preparation raw materials in parts by weight: 1 part of cement; 0.9-1.1 parts of fine aggregate; 0.2-0.4 part of quartz powder; 0.1-0.3 part of silica fume; 0.03-0.04 part of a water reducing agent; 0.003-0.0075 parts of polypropylene fiber; 0.18-0.26 part of water. The water-glue ratio is (0.13-0.24): 1. According to the invention, the concrete contains more unhydrated cement particles by adopting a smaller water-cement ratio (the ratio of water to the mass of cement to the mass of silica fume), the unhydrated cement particles are not decomposed at high temperature, and the strong hydration activity is kept, and the unhydrated cement particles are rehydrated at the early high temperature (200-400 ℃) to generate the cement paste containing C-S-H gel and silica fumeCa(OH)2The hydration product of the crystal is used for filling concrete cracks caused by high temperature and enhancing the strength of the concrete; in addition, the mineral admixture (silica fume) doped in the invention can perform a pozzolanic reaction with calcium hydroxide crystals in hydration products, consume a part of calcium hydroxide crystals, avoid volume change caused by calcium hydroxide decomposition to a certain extent, further reduce high-temperature damage, enable high-temperature residual strength to be higher and be easier to repair; and on the other hand, the volcanic ash reaction product enables the microstructure to be denser. In addition, the microstructure of the concrete is more compact after the concrete is subjected to early high temperature (200-400 ℃); therefore, when the temperature continues to rise, the microstructure in the concrete is not easy to change, so that the concrete still has good residual compressive strength when subjected to the high temperature of 600-1000 ℃. In addition, the polypropylene fibers are melted at high temperature to form a communication network, so that the steam pressure in the concrete can be discharged to reduce high-temperature damage, the high-temperature residual strength is higher, and the repair is easier.
Furthermore, the invention can only generate fine cracks after the concrete is heated by limiting the particle size distribution of the aggregate (fine aggregate and quartz powder), and the crack density is small, thereby being beneficial to repairing the cracks by rehydration products.
The data of the examples show that: the concrete provided by the invention has the normal-temperature compressive strength of more than 120MPa, the tensile strength of more than 6MPa and the flexural strength of more than 18 MPa. After heat treatment at 200-400 ℃, the compressive strength of the obtained concrete is at least 1.2 times higher than that of the normal temperature, and after heat treatment at 600 ℃, the compressive strength of the obtained concrete is not lower than 75% of the initial strength; after curing again, the compressive strength is restored to over 80 percent of the initial strength. After the heat treatment at 800 ℃, the compressive strength of the obtained concrete is not lower than 40% of the initial strength; after curing again, the compressive strength is restored to over 75 percent of the initial strength. After heat treatment at 1000 ℃, the compressive strength of the obtained concrete is not lower than 20% of the initial strength; after curing again, the compressive strength is restored to over 70 percent of the initial strength.
The invention also provides a preparation method of the concrete, which comprises the following steps: carrying out first mixing on cement, silica fume, fine aggregate and quartz powder to obtain a mortar mixture; carrying out second mixing on water, a water reducing agent and the mortar mixture to obtain a mortar mixture; thirdly mixing the polypropylene fiber and the mortar mixture to obtain a mixture; and pouring, molding and maintaining the mixture to obtain the concrete. The preparation method provided by the invention is simple to operate, wide in raw material source and easy for industrial production.
The invention also provides a curing method of the concrete after high temperature, which comprises the following steps: performing 3-5 times of circulating curing on the high-temperature concrete; and the circulating re-curing comprises sequentially carrying out carbonization re-curing and saturated calcium hydroxide aqueous solution re-curing. In the invention, unhydrated cement particles in the concrete after high-temperature treatment are rehydrated to generate C-S-H gel and Ca (OH)2The crystals, dehydrated hydration product (e.g. CaO) are rehydrated and carbonized to form CaCO3、Ca(OH)2Carbonisation to form CaCO3Mineral admixtures and Ca (OH)2The volcanic ash reaction is carried out to obtain a volcanic ash reaction product, and the generated C-S-H gel, Ca (OH)2Crystals, CaCO3And the volcanic ash reaction product can fill cracks and gaps in the concrete caused by high temperature, so that the strength of the concrete is recovered.
Drawings
FIG. 1 is a flow chart of the concrete preparation process of the present invention.
Detailed Description
The concrete provided by the invention comprises the following preparation raw materials in parts by weight: 1 part of cement; 0.9-1.1 parts of fine aggregate; 0.2-0.4 part of quartz powder; 0.1-0.3 part of silica fume; 0.03-0.04 part of a water reducing agent; 0.003-0.0075 parts of polypropylene fiber; 0.18 to 0.26 portion of water, and the water-to-glue ratio (0.13 to 0.24) is 1.
In the present invention, unless otherwise specified, all the starting materials required for the preparation are commercially available products well known to those skilled in the art.
The preparation raw materials of the concrete comprise 1 part of cement in parts by mass. In the present invention, the cement preferably comprises portland cement; the strength of the portland cement is preferably 52.5. In the embodiment of the invention, the portland cement is specifically PII52.5R provided by Jiangxi Yao cement Co.
The preparation raw materials of the concrete comprise 0.9-1.1 parts of fine aggregate by mass, and preferably 0.94-1.0 part of cement. In the embodiment of the present invention, the amount of the fine aggregate is preferably 0.94 parts or 1.0 part. In the present invention, the fine aggregate preferably includes river sand. In the present invention, the particle size of the fine aggregate is preferably not more than 1.20 mm; more preferably 1.18mm or less. In the invention, the particle size of the fine aggregate is set within the range, which is beneficial to rationalizing the aggregate grading of the concrete and having good workability, and is further beneficial to improving the mechanical property and the durability of the concrete.
The preparation raw materials of the concrete comprise, by mass, 0.2-0.4 part of quartz powder, and more preferably 0.25-0.35 part of cement. In the embodiment of the invention, the amount of the quartz powder is preferably 0.25 parts or 0.31 parts. In the present invention, the average particle size of the quartz powder is preferably 100 to 150 mesh, and more preferably 120 mesh. In the invention, the particle size of the quartz powder is set within the range, which is beneficial to rationalizing the concrete aggregate gradation and having good workability, and is further beneficial to improving the mechanical property and the durability of the concrete.
The preparation raw materials for preparing the concrete comprise, by mass, 0.1-0.3 part of silica fume, and more preferably 0.1-0.2 part of cement. In the present embodiment, the amount of the surfactant is preferably 0.1 part or 0.2 part. In the present invention, the average particle size of the silica fume is preferably 0.10 to 0.30 μm, and more preferably 0.22 to 0.25 μm. In the invention, SiO in the silica fume2The content of (B) is preferably not less than 90%. In the invention, the arrangement of the grain size and the dosage of the silica fume is beneficial to rationalizing the concrete aggregate gradation, having good workability and generating volcanic ash reaction, and further being beneficial to improving the mechanical property and the durability of the concrete.
Based on the mass parts of cement, the preparation raw materials of the concrete comprise 0.03-0.04 part of water reducing agent, and preferably 0.033-0.04 part. In the present embodiment, 0.036 parts and 0.033 parts are particularly preferable. In the present invention, the water reducing agent preferably comprises a polycarboxylic acid water reducing agent. In the present invention, the solid content of the polycarboxylic acid water reducing agent is preferably 20 to 40%, and more preferably 25 to 40%. The water reducing rate of the polycarboxylate superplasticizer is preferably 25-50%, and more preferably 30-40%.
The preparation raw materials of the concrete comprise, by mass, 0.003-0.0075 parts of polypropylene fibers, and preferably 0.003-0.005 parts of cement. Specifically, 0.003 part is preferable in examples of the present invention. In the present invention, the diameter of the polypropylene fiber is preferably 20 to 40 μm, and more preferably 30 to 40 μm. In the present invention, the length of the polypropylene fiber is preferably 9 to 20mm, and more preferably 9 to 15 mm. In the present invention, the tensile strength of the polypropylene fiber is preferably 400 to 600MPa, and more preferably 400 to 500 MPa. In the invention, the polypropylene fiber is added, which is beneficial to ensuring that the concrete does not burst at high temperature on the premise of ensuring excellent workability.
The preparation raw material of the concrete comprises 0.18-0.26 part of water, and preferably 0.19-0.24 part of cement by mass. In the examples of the present invention, 0.20 parts, 0.22 parts and 0.24 parts are particularly preferable. In the invention, the addition of the water with the above dosage is beneficial to improving the compactness of the matrix of the concrete on the premise of ensuring the excellent workability of the concrete, thereby improving the mechanical property and the durability of the concrete.
In the invention, the water-to-glue ratio is 0.13-0.24: 1; more preferably 0.15 to 0.22: 1.
the invention also provides a preparation method of the concrete, which comprises the following steps:
carrying out first mixing on cement, silica fume, fine aggregate and quartz powder to obtain a mortar mixture;
carrying out second mixing on water, a water reducing agent and the mortar mixture to obtain a mortar mixture;
thirdly mixing the polypropylene fiber and the mortar mixture to obtain a mixture;
and pouring, molding and maintaining the concrete mixture to obtain the concrete.
The cement, the silica fume, the fine aggregate and the quartz powder are mixed for the first time to obtain the mortar mixture.
In the present invention, the first mixing is preferably performed by stirring; the rotation speed of the stirring is preferably 130-150 rpm/min, and more preferably 140 rpm/min; the stirring time is preferably 3-5 min, and more preferably 3 min. In the present invention, the stirring device is preferably a mortar mixer.
According to the invention, water, a water reducing agent and the mortar mixture are subjected to second mixing to obtain a mortar mixture.
In the present invention, the order of the second mixing is preferably: uniformly mixing water and a water reducing agent to obtain a mixed solution; the mixed solution is preferably added to the mortar mixture in 2 portions. In the present invention, the mixed solution is preferably added to the mortar mixture at the end of the first mixing. In the present invention, the second mixing mode is preferably stirring, and the rotation speed of the stirring is preferably the same as the rotation speed of the first mixing. In the present invention, the time for the second mixing is preferably 3 to 5min, and more preferably 3 min.
The polypropylene fiber and the mortar mixture are subjected to third mixing to obtain a mixture.
In the present invention, the polypropylene fibers are preferably added to the mortar mix at the end of the second mixing. In the present invention, the third mixing mode is preferably stirring, and the rotation speed of the stirring is preferably 270 to 290rpm/min, and more preferably 280 to 290 rpm/min. In the present invention, the time for the third mixing is preferably 5 to 8min, and more preferably 6 min.
The concrete is obtained by pouring, molding and maintaining the mixture.
In the invention, the pouring molding is preferably to add the mixture to the mold. In the present invention, the shape or material of the mold is not particularly limited, and a mold known to those skilled in the art may be used. In the embodiment of the invention, the die is preferably a cubic die with a side length of 50 mm.
After the casting molding, the invention preferably further comprises: and compacting the cast mixture to obtain the concrete sample. In the invention, the frequency of the tap is preferably 2860 times/min, and the time is preferably 40-50 s. In the present invention, the tapping is preferably performed on a vibrating table.
After the compaction, the invention preferably further comprises the steps of covering a plastic film after the concrete sample is initially set, and standing and removing the mold to obtain the concrete. In the present invention, the temperature of the standing is preferably room temperature; the standing time is preferably 20-24 h, and more preferably 24 h. The operation of removing the mold is not particularly limited in the present invention, and the operation means known to those skilled in the art may be adopted.
In the present invention, the curing is preferably performed in water. In the present invention, the curing temperature is preferably 20 ± 3 ℃; the time is preferably 27 to 28 d.
The invention also provides the application of the concrete or the concrete prepared by the technical scheme in building engineering.
The invention also provides a restoring and curing process after the concrete is subjected to high temperature during application, which specifically comprises the following steps:
performing 3-5 times of circulating curing on the high-temperature concrete;
and the circulating re-maintenance comprises the steps of re-maintenance of the carbonization box and re-maintenance of the saturated calcium hydroxide aqueous solution in sequence.
In an embodiment of the present invention, the concrete after the high temperature treatment is obtained by preferably performing a heat treatment on the prepared concrete.
In the present invention, the heat treatment temperature is preferably 200 to 1000 ℃, and in the embodiment of the present invention, it is more preferably 200 ℃, 400 ℃, 600 ℃, 800 ℃, 1000 ℃. In the invention, the heating rate of the heat treatment is preferably 1-2 ℃/min, particularly preferably 1 ℃/min, and the heat preservation time for the heat treatment to reach the target temperature is preferably 1-2 h, particularly preferably 1 h. In the present invention, the temperature reduction mechanism of the heat treatment is preferably furnace temperature reduction. In the present invention, the heat treatment apparatus is preferably a muffle furnace.
In the present invention, the temperature for re-curing the carbonization chamber is preferably 25 to 35 ℃, and more preferably 30 ℃. In the present invention, the humidity for re-curing the carbonization chamber is preferably 35 to 45%, and more preferably 40%. In the present invention, the CO of the carbonization chamber is maintained again2The concentration is preferably 15 to 25%, and more preferably 20%. In the present invention, the time for re-curing the carbonization chamber is preferably 3 days.
In the present invention, the saturated Ca (OH)2The ambient temperature for the re-curing of the aqueous solution is preferably 20. + -. 3 ℃. In the present invention, the time for further curing the saturated aqueous calcium hydroxide solution is preferably 3 days.
In the invention, the carbonization tank is maintained for 3 days, and then the saturated calcium hydroxide aqueous solution is maintained for 3 days as 1 cycle; the specific process of 5 times of circulating and maintaining comprises the following steps: curing the mixture in the carbonization tank for 3d, and then curing the mixture in the saturated Ca (OH)2The aqueous solution was maintained for 3 days, and 1 cycle was repeated, and 5 cycles were performed in sequence, and the aqueous solution was maintained for 30 days.
Fig. 1 is a flow chart of the preparation of the concrete of the present invention, and as can be seen from fig. 1, the preparation process of the concrete of the present invention is as follows: carrying out first mixing on cement, silica fume, fine aggregate and quartz powder to obtain a mortar mixture; carrying out second mixing on water, a water reducing agent and the mortar mixture to obtain a mortar mixture; thirdly mixing the polypropylene fiber and the mortar mixture to obtain a mixture; and pouring, molding and maintaining the mixture to obtain the concrete.
In order to further illustrate the present invention, the concrete provided by the present invention, the preparation method and the application thereof are described in detail below with reference to the examples, but they should not be construed as limiting the scope of the present invention.
The reagents used in the following examples are all commercially available.
Examples 1 to 4
TABLE 1 Mass of preparation raw materials used in examples 1 to 4 (unit: kg)
Examples Cement Silica fume River sand Quartz powder Water (W) Water reducing agent Polypropylene fiber
Example 1 888.23 177.65 834.94 275.35 191.84 31.98 3.00
Example 2 929.87 92.99 874.08 288.26 184.11 30.69 3.00
Example 3 887.08 177.42 887.08 221.77 191.61 31.93 3.00
Example 4 879.28 175.86 826.53 272.58 211.03 31.65 3.00
The concrete preparation materials described in examples 1 to 4 were added as shown in Table 1.
And stirring the cement, the silica fume, the fine aggregate and the quartz powder in a mortar stirrer at a slow speed (140rpm) for 3min to obtain a mortar mixture.
And in the process of slow stirring (140rpm), uniformly mixing water and a water reducing agent, adding the mixture into the mortar mixture twice, and continuously stirring at 140rpm for 3min to obtain a mortar mixture.
Polypropylene fibers were added to the mortar mix under slow stirring (140rpm) and then stirred at 285rpm for 6min to give a blend.
And putting the mixture into a mold (the mold is a cubic mold with the side length of 50 mm), vibrating for 40-50 s by using a vibrating table (the frequency is 2860 times/min) to obtain a concrete sample, covering a plastic film after the concrete sample is initially set, standing at room temperature for 24h, and then removing the mold. And curing the demolded concrete sample in water at the temperature of 20 +/-3 ℃ for 27 days to obtain the concrete.
Wherein the cement is portland cement PII52.5R provided by Jiangxi Yadong cement Co.Ltd as a cementing material; the fine aggregate is river sand with the particle size of less than 1.18 mm; the average grain diameter of the quartz powder is 120 meshes; the silica fume has an average particle diameter of 0.24 μm, wherein SiO2The content is 92.74 percent; the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent, the solid content is 24%, and the water reducing rate is 35%; the polypropylene fiber has a diameter of 31 μm, a length of 2mm, and a tensile strength of 400 to 500 MPa.
TABLE 2 Mass of raw materials for preparation (unit: kg) used in comparative examples 1 to 2
Comparative example Cement Silica fume River sand Quartz powder Water (W) Water reducing agent Polypropylene fiber
Comparative example 1 831.72 166.34 781.81 257.83 359.30 2.99 3
Comparative example 2 917.78 0 862.72 284.51 330.40 4.59 3
The preparation raw materials of the concrete described in comparative examples 1-2 were added according to table 2, and the preparation method, the types of the raw materials, and the operation steps were completely the same as those of examples 1-4, and are not described herein again.
The concrete obtained in examples 1 to 4 and comparative examples 1 to 2 was subjected to a compressive strength test.
The test method comprises the following steps: the surface of the concrete was wiped dry with a towel to remove free water from the surface. Then, the temperature of the concrete is raised to 200 ℃, 400 ℃, 600 ℃, 800 ℃ and 1000 ℃ by a muffle furnace at the temperature raising speed of 1 ℃/min, and the constant temperature is kept for 1h, so that the internal temperature of the concrete is ensured to be uniform. Then, the concrete samples were cooled to room temperature in a furnace, and some of them were tested for their compressive strength at a loading rate of 2400N/s using a universal testing machine, and the results are shown in Table 3.
TABLE 3 variation of compressive strength of concrete with temperature in examples 1 to 4 and comparative examples 1 to 2
Figure BDA0003112701860000091
And (3) performing circulating curing on the other part of the concrete test piece subjected to high temperature in the examples 1-4 and the comparative examples 1-2, wherein the circulating curing method comprises the following steps:
carrying out 5 times of circulating re-curing on the concrete test pieces treated at high temperature in the examples 1-4 and the comparative examples 1-2;
and the circulating re-maintenance comprises the steps of re-maintenance of the carbonization box and re-maintenance of the saturated calcium hydroxide aqueous solution in sequence. Curing the carbonization chamber for 3d and saturated Ca (OH)2And water is maintained for 3d for one cycle. The concrete conditions of the re-maintenance of the carbonization box are as follows: temperature 30 deg.C, humidity 40%, CO2The concentration is 20%; saturated Ca (OH)2The environmental temperature for water re-curing is 20 +/-3 ℃. And after the curing is finished, drying the test piece at room temperature for 24 hours, and removing the influence of free water on the compressive strength. And testing the compressive strength of the re-cured concrete test piece by using a universal testing machine at a loading speed of 2400N/s.
The concrete samples after the cyclic re-curing in examples 1 to 4 and comparative examples 1 to 2 were subjected to the compressive strength recovery performance test, and the test results are shown in table 4.
Compressive strength before and after re-curing at 4600 deg.C, 800 deg.C and 1000 deg.C
Figure BDA0003112701860000092
Figure BDA0003112701860000101
From tables 3 and 4, it can be found that: after heat treatment at 200-400 ℃, the compressive strength of the obtained concrete is at least 1.2 times higher than that of the normal temperature, and after heat treatment at 600 ℃, the compressive strength of the obtained concrete is not lower than 75% of the initial strength; after curing again, the compressive strength is restored to over 80 percent of the initial strength. After the heat treatment at 800 ℃, the compressive strength of the obtained concrete is not lower than 40% of the initial strength; after curing again, the compressive strength is restored to over 75 percent of the initial strength. After heat treatment at 1000 ℃, the compressive strength of the obtained concrete is not lower than 20% of the initial strength; after curing again, the compressive strength is restored to over 70 percent of the initial strength.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. The concrete comprises the following preparation raw materials in parts by weight: 1 part of cement; 0.9-1.1 parts of fine aggregate; 0.2-0.4 part of quartz powder; 0.1-0.3 part of silica fume; 0.03-0.04 part of a water reducing agent; 0.003-0.0075 parts of polypropylene fiber; 0.18-0.26 parts of water, wherein the water-to-glue ratio is (0.13-0.24): 1.
2. the concrete of claim 1, wherein the cement comprises portland cement.
3. The concrete of claim 1, wherein the fine aggregate comprises river sand; the grain diameter of the fine aggregate is less than or equal to 1.20 mm.
4. The concrete according to claim 1, wherein the quartz powder has a particle size of 100 to 150 mesh.
5. The concrete according to claim 1, wherein the silica fume has an average particle diameter of 0.10 to 0.30 μm; SiO in the silica fume2The content of (A) is more than or equal to 90 percent.
6. The concrete of claim 1, wherein the water reducer comprises a polycarboxylic acid water reducer; the solid content of the water reducing agent is 20-40%.
7. The concrete according to claim 1, wherein the polypropylene fibers have a diameter of 20 to 40 μm, a length of 9 to 20mm, and a tensile strength of 400 to 500 MPa.
8. A method of producing a concrete according to any one of claims 1 to 7 comprising the steps of:
carrying out first mixing on cement, silica fume, fine aggregate and quartz powder to obtain a mortar mixture;
carrying out second mixing on water, a water reducing agent and the mortar mixture to obtain a mortar mixture;
thirdly mixing the polypropylene fiber and the mortar mixture to obtain a mixture;
and pouring, molding and maintaining the mixture to obtain the concrete.
9. Use of a concrete according to any one of claims 1 to 7 or a concrete prepared by the method according to claim 8 in construction work.
10. The use according to claim 9, wherein, in the application, after the concrete is subjected to high temperature, the method further comprises a restoration curing process, and specifically comprises the following steps:
performing 3-5 times of circulating curing on the high-temperature concrete;
and the circulating re-maintenance comprises the steps of re-maintenance of the carbonization box and re-maintenance of the saturated calcium hydroxide aqueous solution in sequence.
CN202110653334.9A 2021-06-11 2021-06-11 Concrete and preparation method and application thereof Pending CN113248211A (en)

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Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
任国宏等: "发泡混凝土碱浸试块碳酸化增强固碳特性研究", 《材料导报》 *
杨婷等: "超高性能混凝土高温后性能试验研究", 《土木与环境工程学报(中英文)》 *
汪澜: "《水泥混凝土——组成·性能·应用》", 31 January 2005, 中国建材工业出版社 *

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