CN116750987A - Special antifreezing agent for high-performance concrete in severe cold region and cold-resistant high-performance concrete - Google Patents
Special antifreezing agent for high-performance concrete in severe cold region and cold-resistant high-performance concrete Download PDFInfo
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- 239000004574 high-performance concrete Substances 0.000 title claims abstract description 48
- 239000012782 phase change material Substances 0.000 claims abstract description 47
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 34
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000002131 composite material Substances 0.000 claims abstract description 21
- 239000011858 nanopowder Substances 0.000 claims abstract description 15
- 239000002893 slag Substances 0.000 claims abstract description 15
- VGTPCRGMBIAPIM-UHFFFAOYSA-M sodium thiocyanate Chemical compound [Na+].[S-]C#N VGTPCRGMBIAPIM-UHFFFAOYSA-M 0.000 claims abstract description 13
- 239000001509 sodium citrate Substances 0.000 claims abstract description 12
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 claims abstract description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000010881 fly ash Substances 0.000 claims abstract description 6
- 239000011398 Portland cement Substances 0.000 claims abstract description 5
- 229920005646 polycarboxylate Polymers 0.000 claims abstract description 5
- 239000003638 chemical reducing agent Substances 0.000 claims abstract 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 36
- 239000000377 silicon dioxide Substances 0.000 claims description 16
- BGHCVCJVXZWKCC-UHFFFAOYSA-N tetradecane Chemical compound CCCCCCCCCCCCCC BGHCVCJVXZWKCC-UHFFFAOYSA-N 0.000 claims description 16
- 239000004005 microsphere Substances 0.000 claims description 15
- 230000002528 anti-freeze Effects 0.000 claims description 12
- YCOZIPAWZNQLMR-UHFFFAOYSA-N heptane - octane Natural products CCCCCCCCCCCCCCC YCOZIPAWZNQLMR-UHFFFAOYSA-N 0.000 claims description 12
- 239000002994 raw material Substances 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 9
- 238000002360 preparation method Methods 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 2
- 239000004567 concrete Substances 0.000 abstract description 21
- 238000010257 thawing Methods 0.000 abstract description 12
- 230000000052 comparative effect Effects 0.000 description 16
- 238000012360 testing method Methods 0.000 description 15
- 238000007710 freezing Methods 0.000 description 6
- 238000010276 construction Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 230000008014 freezing Effects 0.000 description 5
- 238000006703 hydration reaction Methods 0.000 description 5
- 206010003549 asthenia Diseases 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 239000011325 microbead Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 239000008030 superplasticizer Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000007605 air drying Methods 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 238000009435 building construction Methods 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000003469 silicate cement Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
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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
- 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
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
-
- 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
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/60—Agents for protection against chemical, physical or biological attack
- C04B2103/601—Agents for increasing frost resistance
-
- 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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/76—Use at unusual temperatures, e.g. sub-zero
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Materials Applied To Surfaces To Minimize Adherence Of Mist Or Water (AREA)
Abstract
The invention discloses a special antifreezing agent for high-performance concrete in severe cold areas and cold-resistant high-performance concrete, wherein the antifreezing agent comprises, by mass, 6-10 parts of sodium thiocyanate, 5-8 parts of calcium nitrate, 7-10 parts of a composite phase-change material, 3-5 parts of carbide slag nano powder and 3 parts of sodium citrate. The high-performance concrete comprises, by mass, 330-360 parts of ordinary Portland cement, 60-90 parts of fly ash, 630-660 parts of fine aggregate, 1150-1200 parts of coarse aggregate and 8-10 parts of high-performance polycarboxylate water reducer; the special antifreezing agent for the high-performance concrete in severe cold areas is also included, and the dosage is 7.5-9 parts. The antifreezing agent provided by the invention is specially applied to severe cold areas (the temperature fluctuation reaches-15 ℃ to-5 ℃ and even reaches-20 ℃ in extreme areas), and besides the antifreezing, the early strength is promoted, the working performance of the concrete is ensured, and the compressive strength of the concrete added with the antifreezing agent reaches 58.2MPa; the compressive strength loss for 200 freeze thawing cycles is only 1.2-1.4%.
Description
Technical Field
The invention relates to the technical field of concrete antifreezing agents, in particular to a special antifreezing agent for high-performance concrete in severe cold areas and cold-resistant high-performance concrete.
Background
In the three North regions and the Qinghai-Tibet plateau regions of China, the duration time in winter is long, the temperature is mostly-15 ℃ to-5 ℃, and the extreme minimum temperature in part of regions can even reach-40 ℃. With the development of engineering construction, the long cold air temperature brings a plurality of problems to the winter construction of concrete. For many years, under the common efforts of domestic and foreign experts and construction technicians, the winter construction technology of China has been greatly developed. At present, the antifreeze performance of concrete for low temperature/negative temperature environment is mainly realized by the way of adding antifreeze. The antifreezing agent is mainly used for realizing antifreezing, and is mainly used for reducing the freezing point, eliminating internal frost heaving stress (expansion stress), improving early strength performance, improving working performance and the like.
The average air temperature in the plateau alpine region of China is very low, freeze thawing is frequent, air drying is carried out, and if the conventional high-performance concrete is directly used as a road and bridge building material in the plateau alpine region, the expected high durability and mechanical property can not be achieved, and even obvious strength loss can be generated. Therefore, how to use proper antifreezing agent and high-performance concrete to cope with the building construction needs in these alpine regions is a difficult problem currently posed to construction engineering specialists and technicians.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a special antifreezing agent for high-performance concrete in severe cold areas and cold-resistant high-performance concrete, which are realized by the following technology.
The high-performance concrete special antifreezing agent for severe cold areas comprises, by mass, 6-10 parts of sodium thiocyanate, 5-8 parts of calcium nitrate, 7-10 parts of composite phase-change material, 3-5 parts of carbide slag nano powder and 3 parts of sodium citrate;
the preparation method of the composite phase change material comprises the following steps: taking a liquid phase-change material with the phase-change temperature of 0-10 ℃, adding the hollow silica microspheres into the liquid phase-change material, stirring the mixture for 30-60min in vacuum, and stirring the mixture for 10-20min at normal pressure under the environment lower than the phase-change temperature to obtain a composite phase-change material; the mass ratio of the phase change material to the silica hollow microsphere is (0.3-0.5): 1.
Preferably, in the preparation method of the composite phase change material, the mass ratio of the phase change material to the silica hollow microspheres is 0.45:1.
Preferably, the phase change material is n-tetradecane and/or n-pentadecane.
More preferably, the raw materials comprise 9 parts by mass of sodium thiocyanate, 7 parts by mass of calcium nitrate, 9 parts by mass of composite phase-change material, 4 parts by mass of carbide slag nano powder and 3 parts by mass of sodium citrate.
The invention also provides a preparation method of the special antifreezing agent for high-performance concrete, which is prepared by directly stirring and uniformly mixing sodium thiocyanate, calcium nitrate, composite phase-change material, carbide slag nano powder and sodium citrate in an environment lower than the phase-change temperature.
The invention also provides cold-resistant high-performance concrete, which comprises, by mass, 330-360 parts of ordinary Portland cement, 60-90 parts of fly ash, 630-660 parts of fine aggregate, 1150-1200 parts of coarse aggregate and 8-10 parts of high-performance polycarboxylate superplasticizer; the antifreeze for high-performance concrete for severe cold areas according to any one of claims 1 to 3 is further included in an amount of 7.5 to 9 parts.
Preferably, the raw materials of the cold-resistant high-performance concrete comprise 350 parts of ordinary Portland cement, 70 parts of fly ash, 650 parts of fine aggregate, 1180 parts of coarse aggregate and 9 parts of high-performance polycarboxylate superplasticizer according to mass fraction; 8 parts of any one of the special antifreezing agents for high-performance concrete.
The high-performance concrete needs to be additionally made of materials such as fly ash microbeads and the like because the high-performance concrete needs to achieve ultra-high mechanical strength and also needs to ensure good working performance and self-compaction performance; the common silicate cement is marked as P.O42.5, and other raw materials can be directly purchased in the market. When the conventional high-performance concrete is used in high and cold areas, the hydration heat reaction among raw materials is seriously affected due to very low ambient temperature, so that the early strength of the concrete is obviously insufficient, the requirement on maintenance is high, and standard maintenance is required to be performed first, and then constant low-temperature maintenance is required.
The special antifreezing agent provided by the invention is designed specifically for high-performance concrete used in severe cold areas, and the raw materials of the antifreezing agent comprise sodium thiocyanate, calcium nitrate and carbide slag nano powder, so that Ca (OH) in a low-temperature environment can be obviously improved 2 Increased solubility, and a slow hydration reaction; the nucleation effect of the carbide slag nano powder can induce the calcium hydroxide crystals to attach and generate, and finally the hydration reaction is promoted to be carried out rapidly through the multi-party synergistic effect.
When the composite phase change material is prepared, one part of the phase change material is embedded in the silica hollow microsphere and the other part is attached to the surface of the silica hollow microsphere by controlling the dosage proportion of the phase change material to the silica hollow microsphere and a special vacuum stirring preparation process, so that the inside of the silica hollow microsphere is in a semi-filling state with different degrees. The hollow structure of the silica hollow microsphere has good heat preservation effect, and can reduce the influence of the environment low temperature/negative temperature environment on the inside of the concrete. The steel fiber used in the high-performance concrete has certain heat conducting property. Therefore, through the balance of the functions of the two, the internal temperature distribution of the high-performance concrete is basically consistent, and the hydration reaction temperature environment in the concrete is effectively improved. In the composite phase change material, the silica hollow microsphere has volcanic ash characteristics, can enhance the interface cementation performance, avoid the migration of moisture, chloride ions and sulfate ions, and ensure the durability of concrete to a certain extent. Because the environmental temperature greatly fluctuates in a low-temperature/negative-temperature environment, the fluctuation range often reaches-15 ℃ to 5 ℃, and the freezing and thawing frequency is very high, if the concrete is not aligned to be restrained, the cracking of the inside of the concrete due to frost heaving stress is inevitably caused. The phase change material positioned inside and outside the hollow silica microspheres can buffer and neutralize the frost heaving stress through liquid and solid state transformation in the hydration reaction process and the normal use process of concrete, thereby reducing the loss influence on the mechanical property of the concrete caused by temperature fluctuation to the greatest extent. A part of the phase change material is embedded in the silica hollow microsphere, so that the amount of free phase change material in the concrete is reduced on the premise of ensuring the phase change effect of the phase change material, and the performance loss of the high-performance concrete due to the repeated phase change process of the phase change material is avoided.
Compared with the prior art, the invention has the following advantages: the antifreezing agent provided by the invention is specially applied to severe cold areas (the temperature fluctuation reaches-15 ℃ to-5 ℃ and even reaches-20 ℃) and is specially developed and obtained aiming at high-performance concrete, and not only can play a very good role in antifreezing, promoting early strength and guaranteeing the working performance of the concrete, but also can effectively avoid the mechanical property loss caused by repeated freezing and thawing when the high-performance concrete is applied for a long time and a month. The compressive strength of the high-performance concrete prepared by adding the antifreezing agent can reach 58.2MPa at the highest; the compressive strength loss of the concrete after 200 times of freeze thawing cycles is only 1.2-1.4%.
Detailed Description
The following description of the present invention will be made clearly and fully, and it is apparent that the embodiments described are only some, but not all, of the embodiments of the present invention. All other embodiments, which can be made by one of ordinary skill in the art without undue burden on the person of ordinary skill in the art based on embodiments of the present invention, are within the scope of the present invention.
The carbide slag nano powder used in the following examples and comparative examples is prepared by grinding, and the gradation is 0.20-0.32 μm; the phase-change material is n-tetradecane, and the phase-change temperature is 5.8 ℃; 200-250 meshes of silica hollow microspheres; other raw materials are available for direct purchase at the store.
The composite phase change materials used in the following examples and comparative examples were prepared by the following methods, unless otherwise specified: taking n-tetradecane which is a liquid phase-change material, adding the hollow silica microspheres into the n-tetradecane, stirring the mixture for 45min at 100rpm under the vacuum degree of 2000Pa, and stirring the mixture for 20min at 100rpm under the normal pressure (0.1 MPa) under the environment of 0 ℃ to obtain a composite phase-change material; the mass ratio of the phase change material to the silica hollow microsphere is 0.45:1.
Example 1
The antifreezing agent provided by the embodiment comprises, by mass, 9 parts of sodium thiocyanate, 7 parts of calcium nitrate, 9 parts of composite phase-change material, 4 parts of carbide slag nano powder and 3 parts of sodium citrate.
Example 2
The antifreezing agent provided by the embodiment comprises, by mass, 6 parts of sodium thiocyanate, 8 parts of calcium nitrate, 7 parts of composite phase-change material, 5 parts of carbide slag nano powder and 3 parts of sodium citrate.
Example 3
The antifreezing agent provided by the embodiment comprises, by mass, 10 parts of sodium thiocyanate, 5 parts of calcium nitrate, 10 parts of composite phase-change material, 3 parts of carbide slag nano powder and 3 parts of sodium citrate.
Example 4
The antifreeze provided by the embodiment has the same raw materials as those of the embodiment 1, and is characterized in that the mass ratio of the n-tetradecane of the phase-change material to the silica hollow microspheres used in the preparation of the composite phase-change material is 0.3:1.
Comparative example 1
The antifreezing agent provided by the comparative example comprises 9 parts of sodium thiocyanate, 7 parts of calcium nitrate, 4 parts of carbide slag nano powder and 3 parts of sodium citrate in parts by mass; no phase change material is added.
Comparative example 2
The antifreezing agent provided by the comparative example comprises, by mass, 9 parts of sodium thiocyanate, 7 parts of calcium nitrate, 9 parts of phase change material, 4 parts of carbide slag nano powder and 3 parts of sodium citrate; the phase change material is normal n-tetradecane, and the n-tetradecane is not treated by using silica hollow micro beads or any other hollow micro bead material. Test example: performance test of high performance concrete
The antifreeze shown in the above examples and comparative examples was used in the preparation of high-performance concrete, respectively, and the formulation of the high-performance concrete was as follows in Table 1.
Table 1 formulation of high performance concrete
The concrete slurries prepared in the examples and the comparative examples are cast and hardened by a conventional method to prepare compressive strength test pieces of 100mm multiplied by 100 mm; according to an antifreezer product detection method of JC475 concrete antifreezer, carrying out negative temperature curing for 7d at minus 15 ℃ firstly, then turning to standard curing for 28d, and carrying out mechanical property test according to common concrete mechanical property test method standard (GB/T50081-2019). Forming high-performance concrete without adding any antifreezing agent in a normal temperature environment, and performing conventional standard curing to form a blank group; the high-performance concrete without any antifreezing agent is molded in normal temperature environment, and is subjected to negative temperature curing for 7d at minus 15 ℃ and then standard curing for 28d, and the two groups are used as blank. The compressive strength ratio of each example and comparative example was calculated based on the test data of the control group.
The mechanical strength loss condition of 200 times of freeze thawing cycles of each test piece is tested, and the specific method is as follows: placing the cured concrete test piece in the water for soaking for 4 days, wherein the water level is about 20mm higher than the upper surface of the test piece; after the soaking is finished, taking out the water on the surface of the test piece, wiping the water, and putting the test piece into a constant temperature environment of-15 ℃ for freezing for 4 hours; after freezing, putting the mixture into warm water to be melted for 4 hours, wherein the water level is about 20mm higher than the upper surface of the test piece; and after the melting is finished, the once freeze-thawing cycle is finished. And taking out the test piece, and sending the test piece into a freezer for the next circulation test, wherein the total circulation is 200 times. The test results are shown in table 2 below.
Table 2 results of concrete performance test
| 28d compressive strength, MPa | Compressive strength ratio, percent | Loss of compressive Strength% | |
| Blank group | 64.3 | —— | 7.7 |
| Blank two groups | 24.5 | 73.8 | 9.3 |
| Example 1 | 58.2 | 95.7 | 1.2 |
| Example 2 | 56.1 | 94.2 | 1.3 |
| Example 3 | 57.6 | 95.2 | 1.4 |
| Example 4 | 56.7 | 94.6 | 1.4 |
| Comparative example 1 | 38.4 | 83.1 | 5.8 |
| Comparative example 2 | 43.6 | 87.6 | 2.9 |
From the test results of the above table, it can be seen that, in comparison with a group of high-performance concrete which is not used with an antifreezing agent and is subjected to standard curing, the antifreezing agent is not used, but the conventional standard curing is adopted, so that the mechanical properties are not affected; however, due to the lack of the anti-freezing agent, the compressive strength loss is obvious after the freeze thawing cycle. When the second group is compared with the high-performance concrete which is cured at the negative temperature and is cured at the standard temperature, the mechanical property is worst and the compression strength loss of the freeze thawing cycle is very large due to the lack of the function of the antifreezing agent.
By comparing examples 1-3, it can be found that the variation of the amount of each raw material of the antifreeze has a certain influence on the performance of the high-performance concrete after the antifreeze is added, but the difference between the raw materials is not large, for example, the compressive strength can reach more than 56MPa, and the compressive strength loss of freeze thawing cycle is low.
As can be seen from comparative example 1, comparative examples 1, 2, blank one and blank two, when no phase change material is added to the antifreeze of comparative example 1, significant compressive strength loss occurs after freeze thawing cycle, but the loss amount is relatively small due to the effect of the antifreeze; the mode of carrying out negative temperature curing and then standard curing has obvious adverse effect on the mechanical strength. When the silicon dioxide hollow microspheres are not added into the antifreezing agent of the comparative example 2, obvious compressive strength loss is caused after freeze thawing cycle, and the mechanical strength is obviously reduced; however, the loss of compressive strength and the decrease of mechanical properties are somewhat less than those of comparative example 1 due to the phase change material.
The above detailed description describes in detail the practice of the invention, but the invention is not limited to the specific details of the above embodiments. Many simple modifications and variations of the technical solution of the present invention are possible within the scope of the claims and technical idea of the present invention, which simple modifications are all within the scope of the present invention.
Claims (7)
1. The special antifreezing agent for high-performance concrete in severe cold areas is characterized by comprising, by mass, 6-10 parts of sodium thiocyanate, 5-8 parts of calcium nitrate, 7-10 parts of composite phase-change material, 3-5 parts of carbide slag nano powder and 3 parts of sodium citrate;
the preparation method of the composite phase change material comprises the following steps: taking a liquid phase-change material with the phase-change temperature of 0-10 ℃, adding the hollow silica microspheres into the liquid phase-change material, stirring the mixture for 30-60min in vacuum, and stirring the mixture for 10-20min at normal pressure under the environment lower than the phase-change temperature to obtain a composite phase-change material; the mass ratio of the phase change material to the silica hollow microsphere is (0.3-0.5): 1.
2. The antifreeze special for high-performance concrete in severe cold areas of claim 1, wherein the composite phase change material is prepared by a method in which the mass ratio of the phase change material to the silica hollow microspheres is 0.45:1.
3. The antifreeze for high-performance concrete for severe cold regions according to claim 1, wherein the phase change material is n-tetradecane and/or n-pentadecane.
4. The special antifreezing agent for high-performance concrete in severe cold areas according to any one of claims 1-3, wherein the raw materials comprise, by mass, 9 parts of sodium thiocyanate, 7 parts of calcium nitrate, 9 parts of composite phase-change material, 4 parts of carbide slag nano powder and 3 parts of sodium citrate.
5. A preparation method of the special antifreezing agent for high-performance concrete in severe cold areas is characterized in that the antifreezing agent is prepared by directly stirring and uniformly mixing sodium thiocyanate, calcium nitrate, composite phase-change material, carbide slag nano powder and sodium citrate in an environment lower than a phase-change temperature.
6. The cold-resistant high-performance concrete is characterized by comprising, by mass, 330-360 parts of ordinary Portland cement, 60-90 parts of fly ash, 630-660 parts of fine aggregate, 1150-1200 parts of coarse aggregate and 8-10 parts of high-performance polycarboxylate water reducer; the antifreeze for high-performance concrete for severe cold areas according to any one of claims 1 to 3 is further included in an amount of 7.5 to 9 parts.
7. The cold-resistant high-performance concrete according to claim 6, wherein the raw materials comprise, by mass, 350 parts of ordinary Portland cement, 70 parts of fly ash, 650 parts of fine aggregate, 1180 parts of coarse aggregate and 9 parts of high-performance polycarboxylate water reducer; 8 parts of the special antifreezer for high-performance concrete for severe cold areas according to any one of claims 1 to 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310648524.0A CN116750987A (en) | 2023-06-02 | 2023-06-02 | Special antifreezing agent for high-performance concrete in severe cold region and cold-resistant high-performance concrete |
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