CN114772996A - High-ductility cement-based composite material using coarse quartz sand as fine aggregate and preparation method thereof - Google Patents
High-ductility cement-based composite material using coarse quartz sand as fine aggregate and preparation method thereof Download PDFInfo
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- CN114772996A CN114772996A CN202210354544.2A CN202210354544A CN114772996A CN 114772996 A CN114772996 A CN 114772996A CN 202210354544 A CN202210354544 A CN 202210354544A CN 114772996 A CN114772996 A CN 114772996A
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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
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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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/20—Resistance against chemical, physical or biological attack
- C04B2111/2038—Resistance against physical degradation
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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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/50—Flexible or elastic materials
- C04B2111/506—Bendable material
Abstract
The application discloses a high-ductility cement-based composite material using coarse quartz sand as a fine aggregate and a preparation method thereof, wherein the cement is prepared from the following raw materials in parts by weight: 800-900 parts of fly ash: 3300 3500 parts of quartz sand: 844 and 846 parts of water: 1266 and 1268 parts, polycarboxylic acid high-efficiency water reducing agent: 33-36 parts of polyvinyl alcohol fiber, 71-73 parts of polyvinyl alcohol fiber and 1.9 parts of hydroxypropyl methyl cellulose ether; coarse quartz sand with the maximum particle size not more than 2.36mm is adopted and compared with traditional fine quartz sand, the fineness modulus of the traditional fine quartz sand is 0.77 and the fineness modulus of the coarse quartz sand is 3.96 respectively through a screening experiment, and the defects of high shrinkage, poor wear resistance and the like of the traditional fine quartz sand ECC are effectively overcome.
Description
Technical Field
The invention belongs to the technical field of cement composite materials, and particularly relates to a high-ductility cement-based composite material using coarse quartz sand as a fine aggregate and a preparation method thereof.
Background
Since the invention of cement in the 20's of the 19 th century, concrete has been continuously developed and applied as a building material to meet various demands. The price of the concrete material is lower than that of other building materials, and the concrete material has the advantages of available compressive strength, convenient material taking and the like, so that the concrete material is widely adopted in the fields of house building, infrastructure and the like in China, and the annual yield of the concrete in China is continuously over 20 billion cubic meters in recent years. The method provides higher requirements on safety, applicability and durability for building materials such as concrete materials widely used in various engineering construction. Although the traditional concrete material has a plurality of advantages, the traditional concrete material is easy to crack under the action of tensile load due to low tensile strength, and is a quasi-brittle material. The concrete member is usually the work of taking the crack, and in case the crack appears on member surface and crack width is greater than 100 mu m usually, harmful chemical such as water and chloride ion can accelerate the infiltration and get into inside the member, further aggravate the corrosion and the inflation of reinforcing bar to influence the functional of structure, had to invest capital in the later stage of engineering structure and repaired and maintain concrete structure, hindered the development of concrete material to a certain extent. Where fiber reinforcement is an important way to improve the performance of concrete.
With the further development of fiber reinforced concrete materials, Victor c.li, university of michigan, has proposed the concept of ecc (engineered concrete composites), also known as "bendable concrete", based on mesomechanics and fracture mechanics, among others, for more effective crack control. The ECC shows the characteristics of strain hardening and multi-crack cracking under the action of a bending load, the tensile ductility of the ECC can reach hundreds of times of that of the traditional concrete, and the width of the crack is less than 100 mu m.
The particle size of the fine quartz sand is about 200 μm at most, and the limited shrinkage effect of the aggregate in the matrix is smaller than the constraint effect of the sand in the concrete due to the small particle size of the aggregate, so that the drying shrinkage of the ECC is larger and is about 4-5 times of that of the concrete. Meanwhile, in pavement engineering, the ECC material prepared by using the traditional fine quartz sand has insufficient wear resistance and large mass loss in the wear process, so that the ECC is limited in application.
Chinese patent CN2019100370425 discloses a high-performance high-fly ash-doped fiber cement-based composite material and a preparation method thereof, belonging to the field of cement materials. The cement-based mortar consists of cement, fly ash, silica fume, quartz sand, water, a water reducing agent, a thickening agent and PVA fibers. The preparation method comprises the steps of mixing cement, fly ash, silica fume, quartz sand and a thickening agent, pouring into a stirrer, and dry-mixing for 2 minutes; pouring the water reducing agent into water, fully and uniformly mixing, and pouring into a stirrer for stirring; the PVA fiber was then added to the stirring pot, stirred at 60-70 rpm for 3 minutes, and then stirred at 170-180 rpm for 1 minute. The raw materials are easily available, the preparation method is simple, and the tensile and compressive mechanical properties are good. Meanwhile, the cement in the rubber material is replaced by the fly ash with large mixing amount, which is beneficial to reducing carbon emission and consuming industrial waste residues. However, the prior art is slightly insufficient considering that the drying shrinkage of ECC is increased by adding silica fume due to the over-small particle size of silica fume.
Disclosure of Invention
The technical problem to be solved is as follows: the invention provides a high-ductility cement-based composite material which uses coarse quartz sand as fine aggregate and has the characteristics of strain hardening and multi-joint cracking, aiming at the technical defects of overlarge drying shrinkage, insufficient wear resistance and the like caused by the undersize particle size of the traditional ECC aggregate. According to the invention, coarse quartz sand with the maximum particle size of about 2.36mm is used as fine aggregate for preparing ECC, so that the problems of large drying shrinkage, insufficient wear resistance and the like caused by the use of fine quartz sand in the traditional ECC are effectively solved.
In order to solve the technical problems, the invention adopts the technical scheme that:
the invention provides a high-ductility cement-based composite material using coarse quartz sand as fine aggregate, which is prepared from the following raw materials in parts by mass: cement: 800-900 parts of fly ash: 3300-3500 parts of quartz sand: 844 and 846 parts of water: 1266 and 1268 parts, polycarboxylic acid high-efficiency water reducing agent: 33-36 parts of polyvinyl alcohol fiber, 71-73 parts of hydroxypropyl methyl cellulose ether and 1.9 parts of hydroxypropyl methyl cellulose ether.
Preferably, the cement is P O42.5.5 ordinary portland cement.
Preferably, the polyvinyl alcohol fiber has a length of 12mm, a diameter of 40 μm, a tensile strength of 1200MPa, an elastic modulus of 39GPa, and an ultimate elongation of 6.5%.
Preferably, the quartz sand is coarse quartz sand with the maximum particle size not more than 2.36mm, and the sand-to-glue ratio is 0.2.
Preferably, the fly ash is a low calcium first grade fly ash.
Preferably, the high-ductility cement-based composite material is cured for 24 hours by adopting a water bath at 55 ℃.
Has the advantages that:
compared with the prior art, the method has the following advantages:
1. in the ECC matrix containing coarse sand, the internal constraint of the coarse sand in the matrix is larger than that of the fine sand, so that the drying shrinkage value of the ECC test piece is reduced to a certain extent; however, the existence of the grit causes the fiber to wrap the sand particles, so that the actual fiber content of the grit ECC is lower than a calculated value, and the existence of the grit also increases the fracture toughness of the matrix, which is not favorable for meeting the strength criterion and the energy criterion in the ECC design theory, so that the grit ECC loses part of ductility; however, in the embodiment, the ultimate tensile strain of the two types of coarse sand is more than 3%, and the performance basically meets the actual engineering requirement.
2. The existence of the coarse sand can reduce the 28-day dry shrinkage value of ECC by about 10% at most, and the shrinkage reducing effect is remarkable. And the ECC abrasion loss of the coarse quartz sand used as the fine aggregate is only 1.45kg/m2About 66.6% lower than the conventional ECC.
3. Compared with the CN2019100370425, namely a high-performance high-fly ash-content fiber cement-based composite material and a preparation method thereof, the invention does not adopt silica fume. The addition of silica fume increases the drying shrinkage of the ECC due to the too small silica fume particle size. On the contrary, the quartz sand with the maximum particle size of about 2.36mm is adopted, and compared with the traditional 80-100-mesh quartz sand, the constraint effect of the coarse quartz sand in the matrix is larger than that of the fine quartz sand, so that the drying shrinkage of the ECC can be reduced to a certain extent, the wear resistance of the ECC is improved, and the coarse sand ECC is better applied to practical engineering.
Drawings
FIG. 1 is a grading curve for two sands in an example of the present invention;
FIG. 2 is a tensile stress strain plot of a cementitious composite S1 in an example of the present invention.
FIG. 3 is a tensile stress-strain plot of a cementitious composite S2 in an example of the invention.
FIG. 4 is a 28d drying shrinkage trend graph for two cement-based composites in an example of the present invention.
FIG. 5 is a graph of wear test data for two cement-based composites in an example of the invention.
Detailed Description
The present invention will be described in further detail with reference to examples and comparative examples. It should be noted that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope or application of the invention.
Example 1:
a preparation method of a high-ductility cement-based composite material using quartz sand as a fine aggregate comprises the following steps:
the first step is as follows: weighing cement according to the mass part ratio: 844 parts of fly ash: 3377 parts of fine quartz sand: 844 parts of water: 1266 parts of polycarboxylic acid high-efficiency water reducing agent: 33 parts of polyvinyl alcohol fiber, 71 parts of polyvinyl alcohol fiber and 1.9 parts of hydroxypropyl methyl cellulose ether;
the second step is that: adding all the cementing materials and the fine quartz sand into a 15L stirring pot, stirring at low speed for 3min until the materials are uniformly mixed, and simultaneously adding three-fourths of water reducing agent into water for uniformly mixing;
the third step: after the dry powder is uniformly mixed by sand, slowly pouring a mixture of water and a water reducing agent, quickly stirring for 10min until a flowing state is uniform, starting to slowly stir, and slowly adding fibers;
the fourth step: after the fibers are completely added, rapidly stirring for 5min until the fibers have good dispersibility, then stopping stirring, pouring into a mold, covering films, maintaining for 24h at room temperature, and maintaining for 24h in a water bath kettle at 55 ℃.
The cement is P O42.5.5 ordinary portland cement; the length of the polyvinyl alcohol fiber is 12mm, the diameter is 40 mu m, the tensile strength is 1200MPa, the elastic modulus is 39GPa, and the ultimate elongation is 6.5%; the maximum grain size of the coarse quartz sand is not more than 2.36mm, and the sand-to-glue ratio is 0.2; the fly ash is low-calcium first-grade fly ash; and curing the high-ductility cement-based composite material in a water bath at 55 ℃ for 24 hours.
Example 2:
a method for preparing a high-ductility cement-based composite material using coarse quartz sand as a fine aggregate, comprising the steps of:
the first step is as follows: weighing cement according to the mass part ratio: 844 parts of fly ash: 3377 parts of coarse quartz sand with the maximum aggregate particle size of 2360 mu m: 844 parts of water: 1266 parts of polycarboxylic acid high-efficiency water reducing agent: 33 parts of polyvinyl alcohol fiber, 71 parts of polyvinyl alcohol fiber and 1.9 parts of hydroxypropyl methyl cellulose ether;
the second step is that: adding all the cementing materials and the coarse sand into a 15L stirring pot, stirring at a low speed for 3min until the materials are uniformly mixed, and simultaneously adding three quarters of the water reducing agent into water for uniformly mixing;
the third step: after the dry powder is uniformly mixed by sand, slowly pouring a mixture of water and a water reducing agent, quickly stirring for 10min until a flowing state is uniform, starting to slowly stir, and slowly adding fibers;
the fourth step: after the fibers are completely added, rapidly stirring for 5min until the fiber dispersibility is good, then stopping stirring, pouring into a mold, curing the film at room temperature for 24h, and curing in a water bath kettle at 55 ℃ for 24 h.
From FIG. 1, which is a gradation curve of two kinds of sands in the example of the present invention, it can be seen from FIG. 1 that the maximum particle size of the coarse sand in the example 2 (S2) is about 2.36mm, while the particle size of the conventional purified silica sand in the example 1 (S1) is about 100-.
Fig. 2 and 3 are a comparison of uniaxial tensile stress-strain curves of high ductility cement-based composites prepared from fine quartz sand and coarse sand, respectively, used in conventional ECC, and it can be seen from fig. 2 and 3 that strain levels above 3% can be maintained despite some loss in ductility due to the use of coarse sand as the fine aggregate for ECC.
Fig. 4 is a graph showing the change of drying shrinkage with age of two cement-based composites using conventional fine quartz sand and coarse sand as fine aggregate, and it can be seen that the presence of coarse sand can reduce the drying shrinkage value by about 10% at most, and the shrinkage reduction effect is significant.
Fig. 5 is a graph of wear resistance test data for two cement-based composites using fine quartz sand and coarse sand as the fine aggregate. It was found that the ECC wear amount using the coarse quartz sand as the fine aggregate was only 1.45kg/m2About 66.6% lower than the conventional ECC.
The disclosure and the proposed solutions have been described by way of example, but the scope of protection of this patent is not limited thereto. It should be noted that it will be obvious to a person skilled in the art that, without deviating from the patent content, several improvements and refinements can be made in the light of the patent solution and its patent idea, which are considered as the scope of protection of this patent.
Claims (6)
1. The high-ductility cement-based composite material using coarse quartz sand as fine aggregate is characterized by being prepared from the following raw materials in parts by mass: cement: 800 plus 900 parts of fly ash: 3300-3500 parts of quartz sand: 844 and 846 parts of water: 1266 and 1268 parts, polycarboxylic acid high-efficiency water reducing agent: 33-36 parts of polyvinyl alcohol fiber, 71-73 parts of hydroxypropyl methyl cellulose ether and 1.9 parts of hydroxypropyl methyl cellulose ether.
2. The high ductility cement-based composite material using coarse quartz sand as fine aggregate according to claim 1, characterized in that the cement is P O42.5.5 portland cement.
3. The high ductility cement-based composite material using coarse quartz sand as fine aggregate according to claim 1, characterized in that the polyvinyl alcohol fiber has a length of 12mm, a diameter of 40 μm, a tensile strength of 1200MPa, an elastic modulus of 39GPa, and an ultimate elongation of 6.5%.
4. The cement-based composite material with high ductility using coarse quartz sand as fine aggregate according to claim 1, wherein the quartz sand is coarse quartz sand having a maximum particle size of not more than 2.36mm and a sand-to-cement ratio of 0.2.
5. The high ductility cement-based composite material using coarse quartz sand as fine aggregate according to claim 1, wherein the fly ash is low calcium primary fly ash.
6. The high ductility cement-based composite material using coarse quartz sand as fine aggregate according to claim 1, wherein the high ductility cement-based composite material is cured with a water bath of 55 ℃ for 24 hours.
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| CN202210354544.2A CN114772996A (en) | 2022-04-06 | 2022-04-06 | High-ductility cement-based composite material using coarse quartz sand as fine aggregate and preparation method thereof |
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| CN202210354544.2A CN114772996A (en) | 2022-04-06 | 2022-04-06 | High-ductility cement-based composite material using coarse quartz sand as fine aggregate and preparation method thereof |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105906261A (en) * | 2016-04-15 | 2016-08-31 | 北京建筑大学 | PVA fiber reinforced cement-based composite material |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105906261A (en) * | 2016-04-15 | 2016-08-31 | 北京建筑大学 | PVA fiber reinforced cement-based composite material |
Non-Patent Citations (1)
| Title |
|---|
| 彭明强等: "国产PVA纤维用于高韧性纤维增强水泥基复合材料的试验研究", 《混凝土与水泥制品》 * |
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