阅读说明：本技术 超高分子量聚乙烯纤维增强超高延性混凝土及其制备方法 (Ultrahigh molecular weight polyethylene fiber reinforced ultrahigh-ductility concrete and preparation method thereof ) 是由 余江滔 周新基 于 2019-11-18 设计创作，主要内容包括：本发明公开了一种异形超高分子量聚乙烯纤维增强超高延性混凝土,主要成分包括水泥、硅灰、粉煤灰、石英砂、减水剂、异形截面PE纤维和水；各组分的重量份：水泥500-800份、硅灰0-250份、粉煤灰500-800份、砂500-800份、减水剂5-40份、水180-350份、PE纤维10-20份；纤维的掺量为纤维混凝土总体积的1%~2%。本发明通过纤维实际应用,提供一种解决现有技术中的混凝土高抗拉强度,高抗压强度与高延性难以共存的技术难题,同时保证生产的高性能混凝土塌落度大于180mm且可泵送现浇。(The invention discloses special-shaped ultrahigh molecular weight polyethylene fiber reinforced ultrahigh-ductility concrete, which mainly comprises cement, silica fume, fly ash, quartz sand, a water reducing agent, special-shaped section PE fibers and water; the weight parts of each component are as follows: 800 parts of cement, 0-250 parts of silica fume, 800 parts of fly ash, 500 parts of sand, 5-40 parts of water reducing agent, 350 parts of water and 180 parts of PE fiber; the mixing amount of the fibers is 1% -2% of the total volume of the fiber concrete. According to the invention, through the practical application of the fiber, the technical problem that the high tensile strength, the high compressive strength and the high ductility of the concrete in the prior art are difficult to coexist is solved, and the slump of the produced high-performance concrete is ensured to be larger than 180mm and can be pumped for cast-in-place.)

1. The ultra-high molecular weight polyethylene fiber reinforced ultra-high ductility concrete is characterized in that: the main components comprise cement, silica fume, fly ash, quartz sand, a water reducing agent, PE fibers with special-shaped cross sections and water; the weight parts of each component are as follows: 800 parts of cement, 0-250 parts of silica fume, 800 parts of fly ash, 500 parts of quartz sand, 5-40 parts of water reducing agent, 350 parts of water and 180 parts of profiled cross section PE fiber; the mixing amount of the fibers is 1% -2% of the total volume of the fiber concrete.

2. The ultra-high molecular weight PE fiber reinforced ultra-high ductility concrete according to claim 1, characterized in that: the profiled cross section PE fiber is a fiber with a non-circular cross section, can be a PE fiber with a rough surface in a deformed steel bar shape or a shape close to the deformed steel bar shape and a hollow fiber with a longitudinal pore channel, and can also be one or more non-circular cross sections such as a triangle, a pentagon, a dumbbell, an ellipse, a cross and the like, and the area/volume specific surface area is limited to 150000-300000 m ²/m ³(ii) a The fiber length is 2 mm-75 mm, the preferable fiber length is 12 mm-24 mm, the diameter is 5 μm-150 μm, the preferable fiber diameter is 20 μm-28 μm, the tensile strength is 1500-3900 MPa, the elastic modulus is 40-150 GPa, the ultimate elongation is 1% -5%, and the length-diameter ratio is more than 200, preferably more than 400.

3. The ultra-high molecular weight PE fiber reinforced ultra-high ductility concrete according to claim 1, characterized in that: the cement is composite portland cement or ordinary portland cement; the fly ash is primary or secondary fly ash, and the specific surface area is more than or equal to 500m ²Kg, density 2.6g/cm ³(ii) a The particle size of the quartz sand is 0.1-1.0 mm, and the SiO of the quartz sand ₂The mass content of the compound is more than or equal to 80 percent; the water reducing agent is a non-retarding polycarboxylate water reducing agent, the solid content of the water reducing agent is 40-50%, and the water reducing rate is more than or equal to 40%.

4. A preparation method of ultra-high molecular weight PE fiber reinforced ultra-high ductility concrete is characterized by comprising the following steps: the method comprises the following steps:

1) preparing raw materials according to a formula;

2) adding the cement, the silica fume, the fly ash, the quartz sand, the water reducing agent, the water and the PE fiber with the special-shaped cross section into a stirring device according to the formula ratio for stirring;

3) and after stirring, transferring the mixture into a mold, vibrating for 1-2min for molding, curing, and demolding to obtain the ultrahigh-ductility concrete.

5. The method for preparing ultra-high-molecular-weight PE fiber-reinforced ultra-high-ductility concrete according to claim 4, wherein the method comprises the following steps: step 2) comprises three steps of dry stirring, wet stirring and fiber adding and stirring; firstly, cement, silica fume, fly ash, quartz sand and a water reducing agent are dry-stirred for 2-3min and fully and uniformly mixed; then adding water with the formula amount for wet stirring, and fully and uniformly mixing; finally adding the special-shaped PE fiber, controlling the stirring speed at 20-48r/min, stirring for 4-8min, and fully and uniformly mixing.

Technical Field

The invention belongs to the technical field of building materials, and relates to ultra-high molecular weight PE fiber reinforced ultra-high ductility concrete and a preparation method thereof.

Background

The ultra-high molecular weight PE fiber is a fiber spun from PE powder with the molecular weight of 100-900 ten thousand, the crystallinity is 65-85%, the density is 0.92-0.96 g/cm3, the fiber is the fiber with the highest specific strength and specific modulus in the world at present, and the fiber, Carbon Fiber (CF) and aramid fiber (Kevlar) are called as 'three high-tech fiber in the world'. The ultra-high molecular weight PE fiber is prepared by stretching ultra-high molecular weight polyethylene which is polymerized by ethylene and butadiene monomers under the action of a catalyst, has the strength of 25cN/dtex or more and can be up to 40cN/dtex at most, has good wear resistance, impact resistance, corrosion resistance, pressure resistance, freezing resistance, self-lubrication, no toxicity, no pollution, recyclability, stress cracking resistance and other excellent performances, and is widely applied to the fields of machinery, chemistry, medical sanitation and the like. The characteristic of good stress cracking resistance is most important in the application of the ultra-high molecular weight PE fiber, the stress cracking resistance of the fiber is 200 times that of the common high-density PE fiber, and 4 times that of the cross-linked PE fiber, so that the toughness requirement of high-strength and high-ductility concrete can be met.

As the most widely used building materials in the world, the concrete has the defects of low bending strength and high brittleness, so that the concrete is easy to crack or even break in use, and the overall safety and the service life of a building or a structure are seriously influenced. Some of the building structures and parts existing in large numbers in modern buildings, such as bridge decks of high-speed rail viaducts, large-span sea-crossing and river-crossing bridges, expansion joints and key nodes of super high-rise buildings, have to adopt high-strength high-ductility concrete materials with bending resistance, tensile strength and ductility as high as possible due to the complex and harsh stress environment.

The Ultra-high performance concrete (Ultra-high performance concrete UHPC) has the compression strength of over 120MPa and the ultimate tensile strength of 5-10 MPa. The patent ZL201510026894.6 adopts steel fiber with the diameter of 0.12-0.22 mm, the length of 6-14 mm and the tensile strength of more than 2000MPa as a toughening material to prepare the ultra-high toughness concrete, and the concrete has the bending strength of 20-40 MPa in 28 days and the compressive strength of 120-180 MPa. The patent ZL201210566338.4 adopts polyacrylonitrile fibers and steel fibers as toughening materials to prepare the high-toughness concrete, and the optimal bending strength of the high-toughness concrete in 28 days is 8.6 MPa. The invention patent 201110323697.2 discloses a concrete and a preparation method thereof. The concrete comprises a cementing material, river sand, a superplasticizer, water, steel fibers and polypropylene fibers. The 28-day flexural strength of the steel is 17.1-18.6 MPa, and the compressive strength of the steel is 132-143 MPa. The above patent only focuses on the strength (compressive strength, bending strength) index, adopts ordinary round section fiber reinforced concrete, does not have the relevant parameters directly reflecting ductility index (tensile deformability), and still belongs to the quasi-brittle concrete in the traditional field.

Disclosure of Invention

The invention aims to provide ultra-high molecular weight PE fiber reinforced high-ductility concrete, which solves the technical problems of low tensile strength, high brittleness and poor crack control capability of the concrete in the prior art.

The purpose of the invention can be realized by the following technical scheme:

the ultra-high molecular weight polyethylene fiber reinforced ultra-high ductility concrete is characterized in that: the main components comprise cement, silica fume, fly ash, quartz sand, a water reducing agent, PE fibers with special-shaped cross sections and water; the weight parts of each component are as follows: 800 parts of cement, 0-250 parts of silica fume, 800 parts of fly ash, 500 parts of sand, 5-40 parts of a water reducing agent, 350 parts of water and 180 parts of special-shaped section PE fibers; the mixing amount of the fibers is 1% -2% of the total volume of the fiber concrete.

The profiled fibers are non-cylindrical fibers, can be PE fibers with rough surfaces in the deformed steel bar shape or the deformed steel bar shape close to the deformed steel bar shape and hollow fibers with longitudinal ducts, and can also be one or more of the shapes of a triangle, a pentagon, a dumbbell, an ellipse, a cross and a longitudinal duct, and the area/volume specific surface area is limited to 150000-300000 m ²/m ³(ii) a The fiber has the length of 2 mm-75 mm, the diameter of 5 μm-150 μm, the tensile strength of 1500-3900 MPa, the elastic modulus of 40-150 GPa, the ultimate elongation of 1% -5%, and the length-diameter ratio of more than 200.

The cement is composite portland cement or ordinary portland cement; the fly ash is primary or secondary fly ash, and the specific surface area is more than or equal to 500m ²Kg, density 2.6g/cm ³(ii) a The grain diameter of the sand is 0.1-1.0 mm, and the SiO of the sand ₂The mass content of the compound is more than or equal to 80 percent; the water reducing agent is a non-retarding polycarboxylate water reducing agent, the solid content of the non-retarding polycarboxylate water reducing agent is 40-50%, and the water reducing rate is more than or equal to 40%.

The preparation method of the special-shaped ultrahigh molecular weight PE fiber reinforced ultrahigh ductility concrete is characterized by comprising the following steps of: the method comprises the following steps:

1) preparing raw materials according to a formula;

2) firstly, respectively adding cement, silica fume, fly ash, sand, a water reducing agent, water and fibers in a formula ratio into a stirring device for stirring;

3) and after stirring, transferring the mixture into a mold, vibrating for 1-2min for molding, curing, and demolding to obtain the ultrahigh-ductility concrete.

Step 2) comprises three steps of dry stirring, wet stirring and fiber adding and stirring; firstly, cement, silica fume, fly ash, sand and a water reducing agent are dry-stirred for 2-3min and fully and uniformly mixed; then adding water with the formula amount for wet stirring, and fully and uniformly mixing; adding special-shaped PE fiber, stirring at 20-48r/min for 4-8min, and mixing.

The maintenance is normal temperature standard maintenance or high temperature water bath maintenance; wherein, the normal temperature standard curing conditions are as follows: maintaining at 20-25 deg.C and humidity of 90% +/-5% for 28 days; the high-temperature water bath maintenance conditions are as follows: controlling the temperature to be 85-95 ℃, and maintaining in water bath for 48 hours.

The ultra-high ductility concrete has the tensile deformation capacity of more than 12 percent and the tensile strength of more than 20 MPa; the bending strength is 20-50 MPa; the compressive strength is 100MPa to 200 MPa; has good fluidity, can be pumped and cast in situ.

The ultra-high molecular weight PE fiber with the special-shaped section has ultra-high tensile strength, and can ensure that the fiber is not easily broken in the process of pulling out. If traditional low-activity mineral admixtures such as fly ash and the like are added, the material has similar tensile deformation capacity, but the tensile strength is difficult to exceed 10 MPa. Compared with the existing regular cross-section fiber or other types of fibers such as polypropylene fiber and the like, the fiber with the same specification has larger specific surface area, thereby increasing the contact area between the fiber and the matrix and improving the fiber bridging capacity.

According to the invention, through the practical application of the fiber, the technical problem that the high tensile strength, the high compressive strength and the high ductility of the concrete in the prior art are difficult to coexist is solved, and the slump of the produced high-performance concrete is ensured to be larger than 180mm and can be pumped for cast-in-place.

Drawings

FIGS. 1 (a) to (f) are schematic structural diagrams of the ultra-high molecular weight PE fiber with a special-shaped cross section along the length direction;

FIGS. 2 (a) - (f) are schematic cross-sectional structures of the ultra-high molecular weight PE fiber with a special-shaped cross section according to the invention;

FIG. 3 is a schematic diagram showing the relationship between stress-strain and age of the ultrahigh-strength ultrahigh-ductility cement-based material toughened by the ultrahigh-molecular-weight PE fibers with the profiled cross section.

FIG. 4, FIG. 5, and FIG. 6 are schematic diagrams comparing stress-strain and age of ultra-high strength and ultra-high ductility cement-based materials toughened by ultra-high molecular weight PE fibers in examples 1, 2, and 3, respectively.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is described in detail with the specific embodiments. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

Based on the characteristics of the profiled section ultra-high molecular weight PE fiber, the ultra-high ductility concrete can be prepared by using the fiber, and the following description is combined with the examples for details.