AU2020103012A4

AU2020103012A4 - Steel fiber polymer concrete composite structure as well as preparation method and application thereof

Info

Publication number: AU2020103012A4
Application number: AU2020103012A
Authority: AU
Inventors: Zhanbiao CHEN; Xinyan GUO; Peiyan HUANG; Wen Li; Xiaohong ZHENG
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2020-10-26
Filing date: 2020-10-26
Publication date: 2020-12-24
Anticipated expiration: 2028-10-26

Abstract

The disclosure belongs to the field of civil construction and traffic engineering, and discloses a steel fiber polymer concrete composite structure as well as a preparation method and application thereof. The method for preparing the composite structure comprises: determining tension and shearing parts in the composite structure, using a steel fiber polymer structure concrete material in the tension and/or shearing parts, and using ordinary high-strength concrete material in other parts; then successively pouring a bottom member, a middle member and an upper member and curing to obtain the steel fiber polymer concrete material composite structure. The steel fiber polymer structure concrete material composite structure and the ordinary high-strength concrete material have a compressive strength difference of < 2MPa. The obtained composite structure has high strength, high tendency, good deformation coordination, wearing resistance, permeation resistance, alkaline tolerance, weather tolerance, crack resistance, fatigue resistance, impact resistance and durability. DRAWINGS SFpSC Ordinary high strength concrete L Ordinary high strength concrete L FIG.1 (aI) FIG.1b Box girder with tensed roof Box girder with tensed bottom plate Ordinaryhighstrengthconcrete Ordinary high strength concrete ,SFPSC SFPSC FIG.1(c) FIG.1(dJ Box girder with shearing force stressed on the web Box girder with tensed bottom plate and sheared web SSFPSC sost SFPSC FIG.1e) FIG.1 f) FIG.1(g) Box girder with seriously stressed cross sections I-shaped beam with tensed upper wing flange I-shaped beam with tensed lower wing flange SPCSFPSC SFPSC S FPSC FIG.1() FIG.1 (i) FIG.1(j) I-shaped beam with large shearing force I-shaped beam with tensed lower wing flange I-shaped beam with seriously stressed on the rib and sheared rib cross sections 1/3

Description

DRAWINGS

SFpSC Ordinary high strength concrete L

Ordinary high strength concrete L

FIG.1 (aI) FIG.1b

Box girder with tensed roof Box girder with tensed bottom plate

Ordinary high strength concrete Ordinaryhighstrengthconcrete

,SFPSC SFPSC

FIG.1(c) FIG.1(dJ Box girder with shearing force stressed on the web Box girder with tensed bottom plate and sheared web

SSFPSC

sost SFPSC

FIG.1e) FIG.1 f) FIG.1(g) Box girder with seriously stressed cross sections I-shaped beam with tensed upper wing flange I-shaped beam with tensed lower wing flange

SPCSFPSC SFPSC S FPSC

FIG.1() FIG.1 (i) FIG.1(j) I-shaped beam with large shearing force I-shaped beam with tensed lower wing flange I-shaped beam with seriously stressed on the rib and sheared rib cross sections

1/3

STEEL FIBER POLYMER CONCRETE COMPOSITE STRUCTURE AS WELL AS PREPARATION METHOD AND APPLICATION THEREOF

TECHNICAL FIELD The disclosure belongs to the field of civil construction and traffic engineering, and particularly relates to a steel fiber polymer concrete composite structure as well as a preparation method and application thereof. BACKGROUND For a superstructure of a long-span concrete bridge, during the construction or service period, structure parts, such as 0# block, 1# block, 1/4# block, span-middle nearby segments and closure segments of a continuous rigid frame bridge, are in a complicated stress state and large pull stress or shear stress occurs to cause crack and influence the durability of the structure. Many engineering practices show that if ordinary high-strength concrete materials are used, the crack resistance and durability requirements of the above bridge structure cannot be met only depending on improvement of the strength of the material. High strength and high toughness are development trends of civil construction and transportation field on material and structure performance requirements. At present, there are three types of high strength or high toughness concrete: ordinary high strength concrete, steel fiber reinforced concrete, steel fiber reinforced polymer modified concrete; the composite structure is mainly steel-concrete composite structure. Although the ordinary high-strength concrete has high strength, low cost and wide application, it is prone to dry shrinkage cracking, fatigue and impact load cracking, which can not meet the requirements of concrete structures such as bridges in complex stress states on crack resistance and durability. Steel fiber concrete has higher tensile strength, bending strength and shearing strength than ordinary concrete, and its fatigue resistance, impact resistance and durability are also greatly improved. However, the contribution of steel fiber to the prevention of concrete initial crack is not great; the impermeability, alkaline resistance, weather resistance and deformation resistance of steel fiber concrete are poor, and the ordinary steel fiber is easily corroded in the concrete, so that the outer surface of the structure is damaged prematurely; the stainless steel fiber is relatively expensive in price, and is difficult to popularize and apply. Although the previous steel fiber reinforced polymer modified concrete has good adhesion, impermeability, alkaline resistance, weather resistance and large deformation capacity, the current steel fiber reinforced polymer modified concrete belongs to medium and low strength concrete, and can not be applied to the bearing structure which needs high strength, such as the upper structures of concrete bridge beams. The steel-concrete composite/combined structure mainly includes a steel-concrete composite beam, a steel reinforced concrete structure, a concrete-filled steel tube structure and a profiled steel plate concrete composite plate. The advantages are that the steel-concrete composite/combined structure can reduce the height and weight of the structure, has good ductility and stiffness, and has good impact resistance, fatigue resistance and stability. However, the deformation coordination property between the steel structure and the concrete component is poor, and its junction is the soft spot of this composite/combined structure. Moreover, the construction is poor and the cost is relatively high. The alkaline resistance, weather resistance and durability of the steel structure need to be improved.

SUMMARY In order to solve the defects and shortages of the prior art, the main objective of the disclosure is to provide a steel fiber polymer concrete composite structure. Another objective of the disclosure is to provide a method for preparing the above steel fiber polymer concrete composite structure. Another objective of the disclosure is to provide application of the above steel fiber polymer concrete composite structure. The objectives of the disclosure are realized through the following technical solution: Provided is a steel fiber polymer concrete composite structure, wherein the tension and/or shearing parts of the composite structure use a steel fiber polymer structure concrete material (SFPSC), and other parts use an ordinary high-strength concrete material; the steel fiber polymer concrete structure composite material and the ordinary high-strength concrete material

has a compressive strength difference of < 2MPa.

The composite structure comprises a box girder, an I-shaped beam, a T-shaped beam, a rectangular beam and a hollow slab girder. The composite structure is as shown in Fig.1. The steel fiber polymer structure concrete material is prepared from the following components in percentage by mass: 41%-45% of gravel, 25%-28% of medium stand, 18%-21% of cement, 6.3%-7.3% of water, 2.1%-3.1% of steel fiber, 0.21%-0.29% of a water reducing agent, 0.25%-0.29% of latex and 0.10%-0.40% of coal ash. Preferably, the steel fiber is an impressed or wave-shaped fiber.

Preferably, the water reducing agent is polycarboxylic high-performance water reducing agent. Preferably, the latex is butylbenzene latex, which can disperse vinyl acetate/ethylene copolymer glue powder after encountering water. Provided is a method for preparing the steel fiber polymer concrete composite structure, comprising the following steps: (1) determining tension and shearing parts in the composite structure, using a steel fiber polymer structure concrete material in the tension and/or shearing parts, and using ordinary high-strength concrete material in other parts; (2) configuring a bottom plate or bottom flange plate or other materials located on the bottom member and pouring, and curing for 4-24 h according to a method for ordinary concrete, and directly entering into step (3) if no bottom member is present; (3) configuring a web or rib or other materials located on the middle member and pouring, and then curing for 4-24 h according to the method for ordinary concrete; and (4) configuring a top plate or upper flange plate or other materials located on the upper member, and then maintaining the entire composite structure according to the method for ordinary concrete to obtain the steel fiber polymer concrete composite structure. Preferably, the steel fiber polymer structure concrete material is prepared by the following steps: (1) putting gravel, medium sand and steel fiber into a blender for dry blending based on mass percent; (2) adding cement, latex and coal ash, and then carrying out dry blending; (3) adding water and a water reducing agent and then carrying out wet blending; and (4) putting the concrete subjected to wet blending into a mixing device, and discharging after uniformly stirring, so as to obtain the steel fiber polymer structure concrete material. Preferably, in step (1), the dry blending time in the blender is 2-5 min. Preferably, in step (2), the dry blending time is 1-2 min. Preferably, in step (3), the wet blending time is 2-5 min. The above steel fiber polymer concrete composite structure is subjected to wet curing for -7 days after pouring and then enters into the dry curing phase, and then used for traffic. The steel fiber polymer concrete composite structure can be used for bridges, tunnels, roads, ports and house concrete structures. Compared with the prior art, the disclosure has the following advantages and beneficial effects: (1) The steel fiber polymer structure concrete material (SFPSC) in the composite structure of the disclosure and ordinary high strength concrete have the compressive strength difference of <2MPa, thereby achieving excellent deformation coordination property;

(2) according to the stress conditions, each part of the composite structure can flexibly adopt the steel fiber polymer structure concrete material or ordinary strength concrete material, preparation method and concise technology; (3) the composite structure has balanced basic mechanical properties and deformation resistances, such as tensile strength, compression resistance, shear resistance and torsion resistance, and the structure is more reasonable; (4) the steel fiber polymer structure concrete material used in the composite structure of the disclosure is better wear resistance, alkaline resistance, weather resistance, tensile strength, deformation resistance, crack resistance, fatigue resistance, impact resistance and durability than the ordinary high-strength concrete material; (5) the steel fiber polymer structure concrete used in the composite structure of the disclosure has better wear resistance, alkali resistance, weather resistance, tensile strength, deformation resistance, crack resistance, fatigue resistance, impact resistance and durability than the ordinary high-strength concrete material; has higher tension resistance, compression resistance, shearing resistance strength and better fatigue resistance, impact resistance and durability than steel fiber enforced polymer modified concrete.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a structural diagram of a composite structure (a material not shown in the figure is ordinary high strength concrete, SFPSC is steel fiber polymer structure concrete) of the disclosure. Fig. 2 is an S - N fatigue life experiment curve graph of steel fiber polymer structure concrete material SP60 and C60 concrete prepared in example 1. Fig. 3 is an S - N fatigue life experiment curve graph of steel fiber polymer structure concrete material SP55 and C55 concrete prepared in example 2.

DESCRIPTION OF THE EMBODIMENTS The disclosure will be further described in detail in combination with embodiments and drawings, but these embodiments of the disclosure are not limited thereto. Example 1 A preparation method of a C60 grade composite box girder with a tensioned roof and a compressed bottom plate (for example, 0# block and 1# block of a main box girder of a rigid frame bridge, as shown in Fig. 1 (a)) is as follows: (1) the material used in each part of the composite box girder was determined. It was determined according to the stress condition of the composite box girder that the roof was prepared by using the steel fiber polymer structure concrete, and the web and bottom plate were prepared by using C60 concrete; (2) the C60 concrete was prepared to pour the bottom plate and the web of the composite box girder, and curing was carried out for 8 h after pouring was finished; (3) the steel fiber polymer structure concrete was prepared according to the compressive strength of the C60 concrete, and the preparation method was as follows: 1) medium sand and stones were washed and kept in a dry state; 2) gravel, medium sand and steel fiber were put into a blender for dry blending for 2 min according to a mix ratio shown in Table 1; 3) cement, styrene butadiene latex and fly ash were added, and then stirred for 2 min; 4) water and a polycarboxylic high-performance water reducing agent were added for wet blending for 2 min; 5) after the mixture is relatively uniform, the concrete was put into a mixing device to be mixed evenly to discharge the material, namely the steel fiber polymer structure concrete (SP60) was prepared. (4) The prepared steel fiber polymer structure concrete was transported to the mold of the composite box girder, the roof was poured, and the whole box girder is cured for 7 days after pouring and initial setting to obtain the steel fiber polymer concrete composite structure. The main mechanical properties of the steel fiber polymer structure concrete SP60 and C60 concrete prepared in this example are shown in Table 2; the S-N fatigue life test curve is shown in Fig. 2 Table 1 Amounts of various materials of steel fiber polymer structure concrete (wt%) Water Cemen Steel reducing Coal Gravel Sand t water fiber agent Latex ash 41.2 28.0 21.0 6.80 2.10 0.30 0.30 0.30 Table 2 Main mechanical properties of steel fiber polymer structure concrete SP60 and C60 concrete

Cleavage Compres Breaki and breaking Fractur Fatigue Materials ive strength ng strength strength e toughness limit /MPanm" (ratio / MPa /MP:a °/MPa

C60 77.3 8.2 5.0 1.54 1.0

SP60 78.9 15.8 10.4 2.45 1.32

Example 2 A preparation method of a C55 grade composite box girder with a tensioned roof and a compressed bottom plate (for example, a span middle nearby segment box girder of a main bridge of a rigid frame bridge, as shown in Fig. 1 (b)) is as follows: (1) The material used in each part of the composite box girder was determined. It was determined according to the stress condition of the composite box girder that the roof and the web were prepared by using C55 concrete, and the bottom plate was prepared by using steel fiber polymer structure concrete; (2) the steel fiber polymer structure concrete was prepared according to the compressive strength of the C55 concrete, and the preparation method was as follows: 1) medium sand and stones were washed and kept in a dry state; 2) gravel, medium sand and steel fiber were put into a blender for dry blending for 2 min according to a mix ratio shown in Table 3; 3) cement, styrene butadiene latex and fly ash were added, and then stirred for 1.5 min; 4) water and a polycarboxylic high-performance water reducing agent were added for wet blending for 2 min; 5) after the mixture is relatively uniform, the concrete was put into a mixing device to be mixed evenly to discharge the material, namely the steel fiber polymer structure concrete (SP55) was prepared. (3) The prepared steel fiber polymer structure concrete was transported to the mold of the composite box girder, the bottom plate was poured, the whole box girder is cured for 4 h after pouring; (4) C55 concrete was prepared to pour the roof and web of the composite box girder, the whole box girder was cured for 7 days after pouring to obtain the steel fiber polymer concrete composite structure. The main mechanical properties of the steel fiber polymer structure concrete SP55 and C55 concrete prepared in this example are shown in Table 4; the S-N fatigue life test curve is shown in Fig. 3. Table 3 Amounts of various materials of steel fiber polymer structure concrete (wt%) Water Grave Ceme Steel reducing Coal I Sand nt water fiber agent Latex ash 44. 28. 19. 6.3 1.9 0.2 0.2 0.3

0 0 0 0 0 3 5 2

Table 4 Main mechanical properties of steel fiber polymer structure concrete SP55 and C55 concrete

Cleavage Compres Breaki and breaking Fractur Fatigue Materials ive strength ng strength strength e toughness limit

/MPa /MP:a °/MPa /MPanml" (ratio

C55 69.0 5.3 4.1 1.82 1.0

SP55 70.0 10.7 8.6 2.85 1.55

Example 3 Engineering application of steel fiber polymer concrete composite structure Engineering examples and application effects of the steel fiber polymer concrete composite structure of the disclosure and the preparation method thereof are briefly described as follows: Engineering example 1: from July 2007 to January 2008, the composite structure of the disclosure was applied to the 0# block of a main bridge box girder of a pre-stressed continuous rigid frame bridge with a span combination of 112 + 2x200 + 112 meters on a highway in Guangdong Province. The specific application method and construction steps are as follows: (1) the form of the composite structure was determined. The working conditions in the construction and operation stages were stimulated to analyze the forces of the overall structure and local structure of the main bridge to determine that all the 0#box girders of the main bridge (two frames) adopt the steel fiber polymer concrete composite structure shown in Fig. 1 (a), namely, the bottom plate and webs adopt the ordinary high-strength concrete, the roof adopts the steel fiber polymer structure concrete. The grades of the two concretes are both C60; (2) sand and stones were washed kept in dry state; (3) C60 concrete was prepared according to the standard, and the bottom plate and web of the composite box girder were poured on site and then cured for 24 hours after pouring; (4) the gravel, medium sand and steel fiber were put into the blender for dry blending for 5 min in a ratio of "cement (wt): medium sand (wt): gravel (wt): water (wt): water reducing agent (wt): steel fiber (wt): polymer latex (wt): fly ash (wt) = 1: 1.33:1.96:0.324:0.0143:0.100:0.0143:0.0143"; (5) cement, styrene butadiene latex and fly ash were added and stirred for 2 min; (6) water and the water reducing agent were added for wet blending for 5 min;

(7) after the mixture is relatively uniform, the concrete was put into the mixing device to be stirred evenly and then discharge the material, and the concrete was delivered to the above box girder segment by using a remote pumping method to pour roof on site; (8) the whole box girder was cured for 7 days by using an ordinary concrete curing method. Engineering example 2: from July 2014 to July 2015, the composite structure of the disclosure was applied to the a span closure segment and left and right two box girder segments of a pre-stressed continuous rigid frame bridge with 90+ 150 + 90 meters on a highway in Guangdong Province. The specific application method and construction steps are as follows: (1) the form of the composite structure was determined. The working conditions in the construction and operation stages were stimulated to analyze the forces of the overall structure and local structure of the main bridge to determine that the span closure segment and left and right two box girder segments of the main bridge (two frames) adopt the steel fiber polymer concrete composite structure shown in Fig. 1 (b), namely, the bottom plate and webs adopt the ordinary high-strength concrete, the roof adopts the steel fiber polymer structure concrete. The grades of both concretes are C55; (2) sand and stones were washed kept in dry state; (3) the gravel, medium sand and steel fiber were put into the blender for dry blending for min in a ratio of "cement (wt): medium sand (wt): gravel (wt): water (wt): water reducing agent (wt): steel fiber (wt): polymer latex (wt): fly ash (wt) =

1:1.47:2.32:0.332:0.0121:0.100:0.0132:0.0168"; (4) cement, styrene butadiene latex and fly ash were added and then stirred for 2 min; (5) water and the water reducing agent were added for wet blending for 5 min; (6) after the mixture is relatively uniform, the concrete was put into the mixing device to be stirred evenly and then discharge the material, and the concrete was delivered to the above box girder segment by using a remote pumping method to pour roof on site; after pouring, the concrete was cured for 8 h by using the ordinary concrete curing method; (7) the C55 concrete was prepared according to the standard to pour the webs and roof of the composite box girder on site; (8) the whole box girder was cured for 7 days. Engineering example 3: from January 2014 to June 2014, the composite structure of the disclosure was applied to the continuous box girder segments of a span combination with 35+ + 35 meters on a highway in Guangdong Province. The specific application method and construction steps are as follows: (1) the form of the composite structure was determined. The working conditions in the construction and operation stages were stimulated to analyze the forces of the continuous box girder to determine that all the segments of the continuous box girder adopt the steel fiber polymer concrete composite structure shown in Fig. 1 (e), namely, all the cross sections adopt the steel fiber polymer structure concrete. The grade of the concrete is set as C55; (2) sand and stones were washed kept in dry state; (3) the gravel, medium sand and steel fiber were put into the blender for dry blending for 5 min in a ratio of "cement (WT): medium sand (wt): gravel (wt): water (wt): water reducing agent (wt): steel fiber (wt): polymer latex (wt): fly ash (wt) =

1:1.47:2.32:0.332:0.0121:0.100:0.0132:0.0168"; (4) cement, styrene butadiene latex and fly ash were added and then stirred for 2 min; (5) water and the water reducing agent were added for wet blending for 5 min; (6) after the mixture is relatively uniform, the concrete was put into the mixing device to be stirred evenly and then discharge the material, and the concrete was delivered to the above box girder segment by using a remote pumping method to pour roof on site; after pouring, the concrete was cured for 7 days by using the ordinary concrete curing method. The above three engineering practices show that the steel fiber polymer concrete composite structure of the disclosure has excellent tension resistance, compression resistance, bending resistance and shearing resistance strengths as well as alkali resistance, weather resistance, deformation resistance, crack resistance, fatigue resistance and durability. At the same time, the steel fiber polymer structure concrete of the disclosure has good flow performance, and can realize long-distance (more than 100 meters) pumping. Spot check test results (Table 2, Table 4 and Fig.3) indicate that the concrete of the disclosure has excellent tension resistance, bending resistance and shearing resistance strengths as well as deformation resistance, crack resistance and fatigue resistance performances. After the continuous rigid frame bridge in engineering example 1 operates for 6.5 years, by detection via the inspection organization and the long-term bridge health monitoring unit, the results show that, there are no cracking and corrosion in the composite structure of the disclosure; furthermore, the maximum deflection (vertical deformation) of 200 m main span is only 10 cm, which is reduced by about 50% compared with the expected maximum deflection. The rigid frame bridges and continuous box girder bridges in engineering examples 2 and 3 have also been opened to traffic, there are no cracks, corrosion and other phenomena currently, their deformation is small. This shows that the composite structure and steel fiber polymer structure concrete of the disclosure and the preparation method are very effective and feasible. The above examples are preferred embodiments of the disclosure, but the embodiments of the disclosure are not limited by the above examples. Other any changes, modifications, substitutions, combinations and simplifications made without departing from the spiritual essence and principle of the disclosure should be equivalent replacement modes, and are all included in the protection scope of the disclosure.

Claims

Claims WHAT IS CLAIMED IS:

1. A steel fiber polymer concrete composite structure, wherein the tension and/or shearing parts of the composite structure use a steel fiber polymer structure concrete material, and other parts use an ordinary high-strength concrete material; the steel fiber polymer structure concrete material composite structure and the ordinary high-strength concrete material have a compressive strengths difference of G 2MPa.

2. The steel fiber polymer concrete composite structure according to claim 1, wherein the composite structure comprises a box girder, an I-shaped beam, a T-shaped beam, a rectangular beam and a hollow slab girder.

3. The steel fiber polymer concrete composite structure according to claim 1:

wherein the steel fiber polymer structure concrete material is prepared from the following components in percentage by mass: 41%-45% of gravel, 25%-28% of medium stand, 18%-21% of cement, 6.3%-7.3% of water, 2.1%-3.1% of steel fiber, 0.21%-0.29% of a water reducing agent, 0.25%-0.29% of latex and 0.10%-0.40% of coal ash;

wherein the steel fiber is an impressed or wave-shaped fiber; the water reducing agent is polycarboxylic high-performance water reducing agent; the latex is butylbenzene latex.

4. A method for preparing the steel fiber polymer concrete composite structure according to any one of claims 1-3, comprising the following steps:

(1) determining tension and shearing parts in the composite structure, using a steel fiber polymer structure concrete material in the tension and/or shearing parts, and using an ordinary high-strength concrete material in other parts;

(2) configuring a bottom plate or a lower flange plate or other materials located on the bottom member and pouring, and curing for 4-24 h according to a method for ordinary concrete, and directly entering into step (3) if no bottom member is present;

(3) configuring a web or rib or other materials located on the middle member and pouring, and then curing for 4-24 h according to the method for ordinary concrete; and

(4) configuring a top plate or upper flange plate or other materials located on the upper member, and then curing the entire composite structure according to the method for ordinary concrete to obtain the steel fiber polymer concrete composite structure.

5. The method for preparing the steel fiber polymer concrete composite structure according to claim 4, wherein the steel fiber polymer structure concrete material is prepared by the following steps:

(1) putting gravel, medium sand and steel fiber into a blender for dry blending;

(2) adding cement, latex and coal ash, and then carrying out dry blending;

(3) adding water and a water reducing agent and then carrying out wet blending; and

(4) putting the concrete subjected to wet blending into a mixing device, and discharging after uniformly stirring, so as to obtain the steel fiber polymer structure concrete material;

in step (1), the dry blending time of the blender is 2-5 min; in step (2), the dry blending time is 1-2 min; in step (3), the wet blending time is 2-5 min;

wherein the steel fiber polymer concrete composite structure is subjected to wet curing for 5-7 days after pouring and then enters into the dry curing phase, and then used for traffic.