CN115477486B

CN115477486B - Milling type steel fiber and application thereof in ultra-high performance concrete and wear-resistant terrace

Info

Publication number: CN115477486B
Application number: CN202110598886.4A
Authority: CN
Inventors: 杨医博; 夏英淦; 刘少坤; 肖祺枫; 余之豪; 温礼静; 黄云龙; 郭文瑛; 王恒昌
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2021-05-31
Filing date: 2021-05-31
Publication date: 2024-12-27
Anticipated expiration: 2041-05-31
Also published as: CN115477486A; WO2022252465A1

Abstract

The invention discloses milled steel fibers and application thereof in ultra-high performance concrete and wear-resistant terraces. The steel fiber is obtained by milling a high-strength steel ingot or steel plate, the section of the steel fiber is arc-shaped or approximately rectangular, the upper surface and the lower surface or the whole surface of the steel fiber are rough, end hooks are arranged at two ends of the steel fiber, the length of the steel fiber is 12-22 mm, the width of the section is 2-3 mm, the thickness of the section is 0.2-0.4 mm, the length of an end hook is 1-2 mm, and the tensile strength of the steel fiber is 1500-2500 MPa. The body can be straight, arched and wavy, and the surface is provided with an anti-corrosion layer. Compared with the traditional microfilament steel fiber, the invention has the characteristics of high bonding strength, strong mechanical biting force and the like, can effectively improve the initial cracking strength of the ultra-high performance concrete, can further improve the structural durability, and is preferably applied to the fields of ultra-high performance concrete and ultra-high performance concrete wear-resistant terraces.

Description

Milling type steel fiber and application thereof in ultra-high performance concrete and wear-resistant terrace

Technical Field

The invention belongs to the field of building engineering materials, and particularly relates to milled steel fibers and application thereof in ultra-high-performance concrete and ultra-high-performance concrete wear-resistant terraces.

Background

Ultra-high performance concrete (UHPC) is a cement-based material based on close packing of aggregate and cementing material, low water-cement ratio, steel fiber reinforcement, ultra-high strength, high toughness and excellent durability, and engineering application is gradually developed in a plurality of engineering fields in recent years. The maximum aggregate particle size is less than 8mm, the aggregate particle size is generally less than 2.36mm, the water-gel ratio is less than 0.24, and the compressive strength is not less than 120MPa.

The fiber section of the microfilament steel fiber commonly adopted in the ultra-high performance concrete is circular, the diameter is 0.15-0.3 mm, the length is 10-20 mm, the tensile strength is equal to or more than 2000MPa, and the interfacial bonding strength is far lower than the tensile strength of the steel fiber, so that the synergistic effect of the microfilament steel fiber and the ultra-high performance concrete matrix is poor, and the anti-initiation performance of the ultra-high performance concrete is hardly influenced. After the ultra-high performance concrete reaches the initial cracking strength, the ultra-high performance concrete is cracked, and the internal microfilament steel fibers can be rapidly rusted in the natural environment, so that the structural durability is greatly reduced, the high durability of the ultra-high performance concrete is difficult to play a role, and a method for improving the initial cracking strength of the ultra-high performance concrete is urgently required to be developed.

The section of the common milled steel fiber in the current market is arc-shaped, the inner cambered surface is rough, the outer cambered surface is smooth, the length is 30-34 mm, the section width is 1.4-3.8 mm, the section thickness is 0.1-0.4 mm, and the tensile strength is 700-1000 MPa. The bonding strength of the milled steel fiber with common concrete is higher, but experiments in ultra-high performance concrete show that the common milled steel fiber has the defects of low tensile strength, overlong fiber and poor toughness, and the milled steel fiber breaks when the ultra-high performance concrete is damaged, so that the excellent bonding performance of the milled steel fiber is difficult to develop.

Disclosure of Invention

In order to solve the defects and the shortcomings of the prior art, the primary purpose of the invention is to provide a milling type steel fiber.

The milling type steel fiber is used for ultra-high performance concrete, and has the advantages of high strength, good toughness, rough surface and end hooks. Compared with the common milling type steel fiber, the steel fiber has the characteristics of high strength, high toughness and the like, and can effectively improve the initial cracking strength of the ultra-high performance concrete.

The invention further aims to provide the application of the milled steel fiber in ultra-high-performance concrete and ultra-high-performance concrete wear-resistant terraces.

The invention aims at realizing the following technical scheme:

A milling type steel fiber is obtained by milling a high-strength steel ingot or steel plate and comprises a steel fiber body with a circular arc-shaped or approximately rectangular cross section, wherein the steel fiber body is straight, arched or wavy, the upper surface and the lower surface or the whole surface of the steel fiber body are rough, and two ends of the steel fiber body are provided with end hooks.

Preferably, the tensile strength of the milled steel fiber is 1500-2500 MPa, the surface of the milled steel fiber body is rough, the contact area between the milled steel fiber body and a cement matrix is greatly increased, the bonding strength of the steel fiber and the matrix is greatly improved, and the two ends are provided with end hooks, so that the anchoring force of the steel fiber is further enhanced, the mechanical properties of the steel fiber are fully exerted, and the initial cracking strength of the ultra-high-performance concrete can be improved.

Preferably, the milling type steel fiber has the length of 12-22 mm, the section width of 2-3 mm, the section thickness of 0.2-0.4 mm and the length of the end hook of 1-2 mm.

Preferably, the steel fiber body is straight, the length of the straight part of the steel fiber body is more than or equal to 2/3 of the total length of the fiber, the steel fiber body is arched, the arch radian is 25-45 degrees, more preferably 25-35 degrees, the steel fiber body is wavy, 2 wave crests are arranged, and the wave height is 0.6-1.2 mm.

Preferably, the steel fiber body is straight, the two ends of the steel fiber body are provided with end hooks, the end hooks are in a fold line shape, the straight line part can be twisted, the mechanical biting force of the steel fiber is greatly enhanced, and the interface bonding strength of the steel fiber and the matrix is further improved.

Compared with straight steel fiber bodies, the arched steel fiber bodies have better grinding energy consumption capability, can fully exert the toughness advantages of fibers, improve the cooperative work of the fibers and a concrete matrix, and realize the purposes of reinforcing and toughening.

The wavy steel fiber is provided with 2 wave crests, the wave height is 0.6-1.2 mm, the contact area of the steel fiber and the matrix is enlarged, the bonding efficiency of the steel fiber is improved, the uniformity of anchoring force in all directions is facilitated, and the anchoring force of the steel fiber and the matrix is further enhanced.

Preferably, the alloy steel material for milling the steel fibers comprises the following components of Mn=7.3-9.9%, C=0.2-0.4%, al=1.3-2.1%, S=0-0.016%, P=0-0.012%, and the balance of Fe and unavoidable impurities.

Preferably, the milling type steel fiber surface can be subjected to rust-proof treatment, and the corrosion resistance of the steel fiber is greatly improved by preparing the anti-corrosion layer on the steel fiber body surface, so that the milling type steel fiber can be used in more complex and severe environments.

The milling type steel fiber is applied to ultra-high-performance concrete and ultra-high-performance concrete wear-resistant terraces.

The milling type steel fiber is singly doped or mixed with the microfilament steel fiber to be doped in the ultra-high performance concrete and the ultra-high performance concrete wear-resistant terrace component, wherein the volume doping amount of the milling type steel fiber is 1-10%, and the volume doping amount of the microfilament steel fiber is 0-4%.

More preferably, the volume doping amount of the milled steel fibers is 1-6%, and the volume doping amount of the microfilament steel fibers is 1-4%.

The utility model provides an ultra-high performance concrete wear-resisting terrace, includes ordinary concrete basic unit, reinforcing bar rack and above-mentioned milling shaped steel fibre reinforcing ultra-high performance concrete surface course, wherein mills steel fibre volume and mix the volume and be 1~6%, reinforcing bar rack is located ultra-high performance concrete in situ to be connected with ordinary concrete through the connecting piece.

Preferably, the thickness of the milling type steel fiber reinforced ultra-high performance concrete surface layer is 30-100 mm.

Compared with the prior art, the invention has the following advantages:

(1) The milling type steel fiber has the advantages that the surface is rough, the contact area between the milling type steel fiber and the ultra-high performance concrete matrix is greatly increased, and the bonding strength between the milling type steel fiber and the ultra-high performance concrete matrix is greatly improved.

(2) According to the milling type steel fiber with the tensile strength of 1500-2500 MPa, the flat, arched or wavy structure is adopted, and the end hooks are arranged at the two ends, so that the cooperative work of the milling type steel fiber and an ultra-high-performance concrete matrix can be improved, the mechanical properties of the steel fiber are fully exerted, the initial cracking strength of the ultra-high-performance concrete is improved, the toughness advantage of the steel fiber is fully exerted, and the purpose of reinforcing and toughening is achieved.

(3) The milling type steel fiber surface is subjected to rust prevention treatment, so that the corrosion resistance of the steel fiber is greatly improved, and the milling type steel fiber can be used in more complex and severe environments.

(4) When the invention is applied to the field of ultra-high performance concrete wear-resistant floors, the impact resistance of the wear-resistant floors under the fatigue action can be enhanced without using interlayer adhesives, and the generation of tiny cracks and the possible bulge under the impact can be reduced.

By combining the characteristics, the milling type steel fiber can effectively improve the cracking resistance and the shock resistance of the ultra-high performance concrete, and is not easy to generate micro cracks, so that the requirements of cracking resistance and shock resistance of the ultra-high performance concrete under extreme environment and special requirements are met, the service life of the structure is prolonged, and the economic benefit, the social benefit and the environmental benefit are remarkable.

Drawings

Fig. 1 is a schematic view of a milled straight steel fiber according to the present invention, in which the end hook 1, the upper surface 2 of the cross section, and the lower surface 3 of the cross section are shown.

Fig. 2 is a schematic view of a milled arch steel fiber according to the present invention, in which the end hooks 1, the inner arc surface 4, the outer arc surface 5 and the arc radian α are shown.

Fig. 3 is a schematic diagram of a milled wavy steel fiber, in which the end hooks 1 and wave crests 6 are shown.

Fig. 4 is a schematic cross-sectional view of milled steel fiber in the present invention, in which (a) is an approximately rectangular cross-sectional milled steel fiber upper surface 2 and lower surface 3, and (b) is an arc-shaped cross-sectional milled steel fiber intrados 4 and extrados 5.

Fig. 5 is a schematic diagram of the whole structure of milled steel fiber used for the ultra-high performance concrete wear-resistant terrace, wherein the general concrete base layer 9, the reinforced steel bar net frame 8, the milled steel fiber reinforced ultra-high performance concrete surface layer 7, the transverse steel bars 10, the longitudinal steel bars 11 and the short steel bars 12 for reinforcing connection are shown in the figure.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but embodiments of the present invention are not limited thereto.

The specific conditions are not noted in the examples of the present invention, and are carried out according to conventional conditions or conditions suggested by the manufacturer. The raw materials, reagents, etc. used, which are not noted to the manufacturer, are conventional products commercially available.

Example 1

As shown in fig. 1 and fig. 4 (a), the milled steel fiber for ultra-high performance concrete has a flat appearance, a tensile strength of 1500MPa, a length of 12mm, a cross section of approximately rectangular width of 2.5mm, a thickness of 0.2-0.4 mm, and an end hook length of 1mm, and is obtained by milling a steel plate, wherein the alloy steel material comprises mn=7.5%, c=0.3%, al=1.5%, s=0.012%, p=0.01%, and the balance Fe and unavoidable impurities.

Example 2

As shown in fig. 2 and fig. 4 (b), the milled steel fiber for ultra-high performance concrete has an arch shape, the tensile strength is 2000MPa, the chord length is 22mm, the section is arc-shaped, the width is 2mm, the thickness is 0.2-0.4 mm, the end hook length is 2mm, the radian alpha is 33 degrees, the milled steel fiber is obtained by milling steel ingots, and the alloy steel material comprises mn=8.0%, c=0.25%, al=1.8%, s=0.008%, p=0.01%, and the balance is Fe and unavoidable impurities.

Example 3

As shown in fig. 3 and fig. 4 (b), the milled steel fiber for ultra-high performance concrete has a wavy appearance, the tensile strength is 2500MPa, the length is 16mm, the section is arc-shaped, the width is 3mm, the thickness is 0.2-0.4 mm, the length of the end hook is 1.5mm, 2 wave crests 6 are arranged, the wave height is 0.6mm, the milled steel fiber is obtained by milling steel ingots, and the alloy steel material comprises mn=9.0%, c=0.2%, al=2%, s=0.008%, p=0.01%, and the balance of Fe and unavoidable impurities.

Comparative example 1

The microfilament steel fibers for comparison were supplied by Guangdong Gatery New Material Co., ltd., copper plated flat, 0.22mm in diameter, 13mm in length, and 2700MPa in tensile strength.

The advantages of the invention are reflected in the application of the ultra-high performance concrete, so the steel fibers of the examples 1-3 are doped into the ultra-high performance concrete and compared with the proportion 1, and the mechanical property difference is analyzed.

The ultra-high performance concrete substrate adopts 42.5R silicate cement, quartz sand with the maximum grain diameter of 1.18mm, silica fume as raw ash, polycarboxylate water reducer aqua and tap water.

The ultra-high performance concrete mixture ratio of 4 groups of the ultra-high performance concrete mixed with different types of steel fibers is designed, the proportion of each group of the ultra-high performance concrete mixture ratio is given in table 1, each component is given in parts by weight, and table 2 shows the performance of each numbered milled steel fiber ultra-high performance concrete.

TABLE 1 ultra-high Performance concrete mix ratio

Sequence number	Cement and its preparation method	Silica fume	Sand and sand	Water reducing agent	Water and its preparation method	Steel fiber
							1. Microfilament steel fiber (comparative example 1)	800	200	1195	50	157	150
2. Milling straight section steel fiber (example 1)	800	200	1195	50	157	150
							3. Milling arch steel fiber (example 2)	800	200	1195	50	157	150
4. Milling wave shaped steel fiber (example 3)	800	200	1195	50	157	150

TABLE 2 ultra high Performance concrete Properties

Sequence number	Initial cracking strength (MPa)	Compressive strength (MPa)	Relative wear amount (%)
				1. Microfilament steel fiber (comparative example 1)	9.2	150	100
2. Milling straight section steel fiber (example 1)	11.3	161	88.5
				3. Milling arch steel fiber (example 2)	12.1	157	87.1
4. Milling wave shaped steel fiber (example 3)	12.8	159	89.3

In the four groups of ultra-high-performance concrete, the initial cracking strength of the UHPC is greatly enhanced due to the good interface bonding performance of the milled steel fibers and the UHPC, wherein the initial cracking strength of the wavy milled steel fibers is highest.

Example 4

As shown in fig. 5, the milled steel fiber for ultra-high performance concrete of the present invention can be used in the field of wear-resistant terraces, which comprise a milled steel fiber reinforced ultra-high performance concrete surface layer 7, a reinforced steel bar net frame 8, a common concrete base layer 9, transverse steel bars 10, longitudinal steel bars 11 and short steel bars 12 for reinforcing connection.

The ultra-high performance concrete mix ratios and properties of this example are shown in tables 1 and 2. The abrasion resistance test adopts a mass loss method according to the Highway engineering cement and cement concrete test procedure (JTGE-2005), the dimensions were measured using 150X 150mm cube standard test pieces, 3 groups of test pieces were prepared for each mix and averaged.

And pouring a common concrete base layer, placing a bound reinforcing steel bar net frame, and rapidly pouring and milling the steel fiber reinforced ultra-high performance concrete to form a surface layer, wherein the thickness of the milled steel fiber reinforced ultra-high performance concrete surface layer is 80mm.

The specification of the transverse steel bars 10 and the longitudinal steel bars 11 in the reinforced steel bar net frame is 12@200, the transverse steel bars 10 are U-shaped, the longitudinal steel bars 11 are positioned at the U-shaped opening, and the reinforced steel bar net frame is suitable for milling the steel fiber reinforced ultra-high performance concrete surface layer with the thickness of 60-100 mm.

As shown in table 2, in this embodiment, the mass abrasion of the wear-resistant terrace under the fatigue effect is reduced without using an interlayer binder in ultra-high performance concrete by doping milled steel fibers, and the generation of fine cracks and possible damage caused by impact are reduced.

The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.

Claims

1. A milling steel fiber for ultra-high performance concrete, characterized in that it is obtained by milling a steel ingot, the steel fiber body is arched, its tensile strength is 2000MPa, the chord length is 22mm, the cross section is arc-shaped, the width is 2mm, the thickness is 0.2-0.4mm, the end hook length is 2mm, and the arc α is 33°;

Or it is obtained by milling from a steel ingot. The steel fiber body is wavy, with a tensile strength of 2500MPa, a length of 16mm, an arc-shaped cross-section, a width of 3mm, a thickness of 0.2-0.4mm, a hook length of 1.5mm at the end, 2 wave peaks, and a wave height of 0.6mm.

2. The milling steel fiber according to claim 1 is characterized in that the alloy steel material used for the milling steel fiber is composed of the following components: Mn=7.3~9.9%, C=0.2~0.4%, Al=1.3~2.1%, S=0~0.016%, P=0~0.012%, and the remainder is Fe and unavoidable impurities.

3. The milling steel fiber according to claim 1 is characterized in that the surface of the milling steel fiber is subjected to anti-corrosion treatment by preparing an anti-corrosion layer on the surface of the steel fiber body.

4. Use of the milling steel fiber according to any one of claims 1 to 3 in ultra-high performance concrete and ultra-high performance concrete wear-resistant flooring.

5. The use of the milling steel fiber in ultra-high performance concrete and ultra-high performance concrete wear-resistant floor according to claim 4 is characterized in that the milling steel fiber is added alone or mixed with microfilament steel fiber into the ultra-high performance concrete and ultra-high performance concrete wear-resistant floor components, wherein the volume content of the milling steel fiber is 1-10%, and the volume content of the microfilament steel fiber is 0-4%.

6. The use of the milling steel fiber in ultra-high performance concrete and ultra-high performance concrete wear-resistant floor according to claim 5 is characterized in that the milling steel fiber and the microfilament steel fiber are mixed and added to the ultra-high performance concrete and ultra-high performance concrete wear-resistant floor components, wherein the volume content of the milling steel fiber is 1-6%, and the volume content of the microfilament steel fiber is 1-4%.

7. An ultra-high performance concrete wear-resistant floor, characterized in that it includes an ordinary concrete base, a reinforced steel grid and a milled steel fiber reinforced ultra-high performance concrete surface layer, wherein the volume content of the milled steel fiber is 1 to 6%, the reinforced steel grid is located in the ultra-high performance concrete surface layer, and is connected to the ordinary concrete base layer through a connecting piece, the milled steel fiber is the milled steel fiber according to any one of claims 1 to 3, and the thickness of the milled steel fiber reinforced ultra-high performance concrete surface layer is 30 to 100 mm.