CN112279585B - Concrete for precast slab track filling layer and preparation method and application thereof - Google Patents
Concrete for precast slab track filling layer and preparation method and application thereof Download PDFInfo
- Publication number
- CN112279585B CN112279585B CN202011115266.2A CN202011115266A CN112279585B CN 112279585 B CN112279585 B CN 112279585B CN 202011115266 A CN202011115266 A CN 202011115266A CN 112279585 B CN112279585 B CN 112279585B
- Authority
- CN
- China
- Prior art keywords
- concrete
- filling layer
- track
- steel fiber
- steel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000004567 concrete Substances 0.000 title claims abstract description 122
- 238000011049 filling Methods 0.000 title claims abstract description 73
- 238000002360 preparation method Methods 0.000 title description 8
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 116
- 239000010959 steel Substances 0.000 claims abstract description 116
- 239000000835 fiber Substances 0.000 claims abstract description 108
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 43
- 238000010276 construction Methods 0.000 claims abstract description 33
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 31
- 239000004568 cement Substances 0.000 claims abstract description 23
- 239000010881 fly ash Substances 0.000 claims abstract description 14
- 238000002156 mixing Methods 0.000 claims abstract description 11
- 239000000843 powder Substances 0.000 claims abstract description 11
- 229910052500 inorganic mineral Inorganic materials 0.000 claims abstract description 10
- 239000011707 mineral Substances 0.000 claims abstract description 10
- 239000004576 sand Substances 0.000 claims abstract description 5
- 239000004575 stone Substances 0.000 claims abstract description 5
- 238000005452 bending Methods 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 21
- 230000008569 process Effects 0.000 claims description 12
- 230000004907 flux Effects 0.000 claims description 7
- 125000002843 carboxylic acid group Chemical group 0.000 claims description 6
- 125000000542 sulfonic acid group Chemical group 0.000 claims description 6
- 239000011398 Portland cement Substances 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 3
- 229920006240 drawn fiber Polymers 0.000 claims description 2
- 238000003306 harvesting Methods 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 22
- 230000009471 action Effects 0.000 abstract description 5
- 230000006835 compression Effects 0.000 abstract description 5
- 238000007906 compression Methods 0.000 abstract description 5
- 239000000203 mixture Substances 0.000 abstract description 5
- 238000005429 filling process Methods 0.000 abstract description 4
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 230000007774 longterm Effects 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 47
- 230000003014 reinforcing effect Effects 0.000 description 15
- 238000013461 design Methods 0.000 description 14
- 238000003756 stirring Methods 0.000 description 14
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 11
- 239000011150 reinforced concrete Substances 0.000 description 9
- 239000011376 self-consolidating concrete Substances 0.000 description 9
- 238000005260 corrosion Methods 0.000 description 8
- 238000005336 cracking Methods 0.000 description 8
- 230000007797 corrosion Effects 0.000 description 7
- 239000002657 fibrous material Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 238000003908 quality control method Methods 0.000 description 5
- 230000002829 reductive effect Effects 0.000 description 5
- 238000007689 inspection Methods 0.000 description 4
- 239000011241 protective layer Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000002356 single layer Substances 0.000 description 4
- 238000009826 distribution Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- DGVVJWXRCWCCOD-UHFFFAOYSA-N naphthalene;hydrate Chemical compound O.C1=CC=CC2=CC=CC=C21 DGVVJWXRCWCCOD-UHFFFAOYSA-N 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 1
- 229920000877 Melamine resin Polymers 0.000 description 1
- 239000004640 Melamine resin Substances 0.000 description 1
- 238000004873 anchoring Methods 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000004746 geotextile Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 125000001624 naphthyl group Chemical group 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000004540 pour-on Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- IIACRCGMVDHOTQ-UHFFFAOYSA-N sulfamic acid Chemical compound NS(O)(=O)=O IIACRCGMVDHOTQ-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- 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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00663—Uses not provided for elsewhere in C04B2111/00 as filling material for cavities or the like
-
- 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
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00724—Uses not provided for elsewhere in C04B2111/00 in mining operations, e.g. for backfilling; in making tunnels or galleries
-
- 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
- C04B2111/90—Electrical properties
- C04B2111/94—Electrically conducting materials
-
- 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)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention provides a steel fiber fine aggregate concrete material for a prefabricated slab track filling layer, which is prepared by mixing water, cement, sand, stone, mineral powder, fly ash, steel fiber and a water reducing agent. The invention has the beneficial effects that: the steel fiber fine aggregate concrete prepared by the composition proportion of the concrete for the track filling layer of the precast slab has excellent fluidity and the slump of the concrete is 200mm +/-20 mm. During construction, the transportation hopper is continuously filled into the filling hole in one side of the track slab or the track slab, the vibrating rod can be adopted to properly vibrate from the filling hole or the two sides of the track slab according to needs in the filling process, air bubbles in concrete can be discharged from the reserved holes and the edges of the track slab, and good compactness can be obtained. On the other hand, the concrete can obviously improve the fatigue and compression strength under the repeated action of long-term fatigue load (namely train load), and the compression and fatigue life of the concrete for the precast slab track filling layer can be expected to be improved by 7.9 to 13.7 times.
Description
Technical Field
The invention belongs to the field of building engineering materials, particularly relates to concrete for a prefabricated slab track filling layer, and particularly relates to steel fiber fine aggregate concrete for the prefabricated slab track filling layer.
Background
The track structure directly bears the load of the train and transmits the load to the lower tunnel lining, which is the key for bearing the upper part and the lower part and ensuring the operation safety and the comfort of passengers. When traditional precast slab tracks are laid, firstly, a reinforced concrete structure is adopted to pour on the inner wall of a tunnel to form a base, then, precast slabs are erected on the base, self-compacting concrete is poured in a space between the precast slabs and the base, and a reinforced bar net is laid to form a self-compacting reinforced concrete filling layer. Finally, the filling layer and the base together form the foundation of the track precast slab.
Traditional precast slab track's foundation construction needs 2 concrete placement at least, 2 times reinforcement construction, and the process is comparatively complicated. The self-compacting concrete in the track filling layer of the precast slab has larger shrinkage, poor volume stability and poor structural crack resistance. Therefore, in view of the above defects, the present inventors have made extensive research and design to provide a casting material for a precast slab track filling layer and a method for preparing the same, which can satisfy the basic performance requirements by using a single concrete casting filling layer, and greatly simplify the construction process.
Due to the influence of space, equipment, transportation and other reasons, the foundation requirements under the prefabricated slab are as follows: 1) mechanical properties (flexural tensile strength); 2) crack resistance (self-cracking); 3) pouring is convenient (self-compaction or slight vibration); 4) the quality control is simple.
The filling mode of the track filling layer of the prefabricated slab is shown in figure 1 at present and divided into two filling modes. The method comprises the steps of firstly constructing a base by adopting common reinforced concrete, and then filling self-compacting concrete between a precast slab and the base. The two filling processes are separated by a geotextile isolating layer.
1. The filling layer uses self-compacting concrete material, makes it under self action of gravity, can flow, closely knit, fills lower part space completely, obtains fine homogeneity simultaneously to do not need additional vibration. This method has the following problems in construction: (1) arranging a steel bar net sheet in the filling layer and placing the steel bar net sheet under the track slab; (2) the reinforcing mesh needs to be fixed and is easy to deviate during pouring; (3) after the self-compacting concrete is dried, the self-compacting concrete shrinks greatly and is easy to crack, and the reinforcing steel bar cannot correspond to the shrinkage crack; (4) the self-compacting concrete loses the bending tensile strength after cracking; (5) the construction performance stability period of the self-compacting concrete is short, and the construction condition requirement is high; (6) the unit price of the self-compacting concrete material is high.
2. The basement is poured by using common concrete, naturally flows and is dense, and is dense by matching with a small amount of vibration measures. This method has the following problems in construction: (1) the aggregate has large particle size, few cementing materials and limited natural fluidity; (2) after cracking, the bending tensile strength is lost, and a reinforcing mesh needs to be configured; (3) the common concrete can generate cracks due to shrinkage, and the reinforcing steel bars cannot correspond to the shrinkage cracks; (4) the reinforcing mesh needs to be fixed, and the designed position is easy to deviate during pouring; (5) the reinforcing mesh blocks the flow of common concrete, and hollows and bubbles are easily generated in a reinforcing steel bar area to influence the quality of a filling layer.
Therefore, in order to effectively solve the problem of laying of the subway track slab, the invention provides concrete for a precast slab track filling layer, and a preparation method and application thereof.
Disclosure of Invention
The invention aims to provide concrete for a prefabricated slab track filling layer, which has self-crack control capability, bending tensile strength after cracking, excellent construction flowability and free flowing filling. During construction, a small amount of tamping measures are matched to fill the structural space, and a compact filling layer structure below the prefabricated slab is formed.
Concrete for a filling layer of a precast slab track, comprising per cubic meter of the concrete for a filling layer of a precast slab track: 300-450 kg of cement, 160-185 kg of water, 650-850 kg of fine aggregate, 960-1210 kg of coarse aggregate, 60-90 kg of mineral powder, 30-80 kg of fly ash, 15-25 kg of steel fiber and 5.0-10.0 kg of water reducing agent.
Preferably, the cement is portland cement.
Preferably, the portland cement strength grade is not less than 42.5 grade.
Preferably, the fine aggregate is medium coarse sand, and the fineness modulus is 2.3-3.3.
The steel fiber material can obviously reduce the fluidity of common fine aggregate concrete, the specific surface area of medium-coarse sand is small, and under the condition of the same cementing material, more slurry can wrap the steel fiber, lubricate the space between the fiber and aggregate, and reduce the influence of the steel fiber on the fluidity. The medium grit with the fineness modulus of 2.3-3.3 can better match the steel fiber with the fluidity required by the performance.
Preferably, the coarse aggregate is crushed stone with 5-16 mm size and continuous grading, and the maximum size is not more than 16 mm.
The concrete for the track filling layer of the precast slab needs higher natural fluidity, and the fine aggregate concrete aggregate with the gravel particle size smaller than 16mm is selected, so that the fluidity is better.
Preferably, the fly ash is first-grade fly ash.
Preferably, the ore powder adopts S95 grade.
Preferably, the water reducing agent should be a high efficiency water reducing agent.
Preferably, the high-efficiency water reducing agent is one or a mixture of a naphthyl high-efficiency water reducing agent, a melamine resin-based high-efficiency water reducing agent, an aminosulfonic acid-based high-efficiency water reducing agent and a sulfonic acid-based carboxylic acid-based high-efficiency water reducing agent.
Preferably, the high-efficiency water reducing agent is a sulfonic acid group carboxylic acid group high-efficiency water reducing agent.
The naphthalene water reducer is a high-efficiency water reducer (accounting for more than 70 percent of the amount of the water reducer) which has the largest output and the widest use in China, and is characterized by higher water reducing rate (15 to 25 percent), no air entraining, little influence on the setting time, relatively better adaptability to cement, capability of being used in combination with other various additives and relatively low price. However, the naphthalene water reducing agent has a high slump loss of concrete, and the adaptability to cement needs to be improved.
The steel fiber has large influence on the fluidity of concrete, a large amount of high-efficiency water reducing agent is needed for blending the fluidity, the use of other additives with weak water reducing capacity can result in overlarge use amount, the concrete is sticky and is not suitable for paving, and the influence on the economy is also caused. Therefore, the sulfonic acid group carboxylic acid group high-efficiency water reducing agent is adopted to better match the required fluidity of the invention.
Preferably, the steel fibers are added in an amount of 18 to 25kg/m3. Where the units are kilograms of the amount of steel fiber that needs to be added per cubic meter of concrete.
The addition amount of the steel fiber has obvious influence on the water-cement ratio, the strength grade, the bending toughness ratio, the concrete slump, the air content and the electric flux. The more the amount of the steel fiber is, the air content and the electric flux can be increased, the excessive air content can influence the strength of the concrete, and the excessive electric flux can influence the conductivity of the track. However, if the doping amount of the steel fiber is too small, the bending tensile strength index is unqualified.
Preferably, the steel fiber is I-type steel wire cold-drawn fiber, the appearance of the steel fiber is that hooks are arranged at two ends, the middle section of the steel fiber is straight, the length of the steel fiber is 30-60 mm, the diameter of the steel fiber is 0.5-1.0 mm, and the tensile strength grade is not lower than 1000 grade.
By contrast, if a steel bar mesh in the original design is to be replaced, I-type steel wire cold-drawn steel wire type fibers are required to replace the steel bar mesh in terms of stress; secondly, in order to ensure that the steel fiber can pull the internal crack of the concrete, the steel fiber needs to keep hooks at two ends to provide anchoring force for controlling the width of the crack; thirdly, the length of the steel fiber is mainly selected according to the construction condition and the requirement of the design bending toughness ratio parameter, the diameter of the transportation pipeline is less than 8cm, and the fiber with the length within the range of 30-50mm is preferably selected; when the diameter of the conveying pipeline is 8-15 cm, the fiber with the length of 50-60mm is preferably selected; the length range can take two aspects into consideration; selecting the diameter to ensure the fiber quantity and the bending toughness ratio; tensile strength is mainly set for preventing the fiber from being pulled apart.
Preferably, the water-cement ratio of the steel fiber fine stone concrete is less than or equal to 0.45, the strength grade is greater than or equal to C40, the bending toughness ratio is greater than or equal to 0.5, the concrete slump is 200 +/-20 mm, the gas content is 2-4%, and the electric flux is less than 1000C.
Firstly, the water-cement ratio is less than or equal to 0.45, and the water-cement ratio is mainly used for ensuring the strength of concrete, reducing the influence of concrete shrinkage as much as possible and reducing the shrinkage rate; the strength grade C40 is mainly used for ensuring the compression-resistant bearing capacity of the structure and also meets the requirements of the original scheme; the bending toughness ratio is more than or equal to 0.5, so that the bending tensile strength of the steel fiber fine aggregate concrete meets the design strength requirement generated by the actual load of the track slab; fourthly, the slump of the concrete is 200 +/-20 mm, so that the concrete is convenient for field transportation and pouring construction; fifthly, the air content is 2-4 percent, which mainly ensures the compactness of the concrete and avoids the problems of bubbles and cavities; the electric flux is less than 1000C, which is to meet the requirement of structure to prevent the diffusion of chloride ion, and belongs to durability index, and the index of 1000C represents that the permeability of chloride ion is very low.
By measuring test pieces with different amounts of steel fibers, different bending toughness ratios are obtained, and the values can be used for calculating a key mechanical property index of the steel fibers, namely a residual bending tensile strength value. According to the invention, the bending toughness ratio is more than or equal to 0.5 as a control index, so that the mechanical property of the prefabricated slab track filling layer not only meets the stress requirement, but also meets the planar structure crack control requirement. The steel fiber is a well-known excellent material for controlling cracks, and the material is used in combination with the fine aggregate concrete, so that the filling layer has good self-crack control capability after being poured. The bending toughness ratio is selected to be more than 0.50, which is far higher than the related crack control requirement in the GB50037-2013 standard.
The steel fiber material has various processes and types and complex shape, and is a recognized crack control material. The I-type steel wire cold-drawn steel fiber is used as a high-strength structural fiber, has the mechanical property of post-crack bending tensile strength in concrete, perfectly replaces the function of a reinforcing mesh, can directly cancel the reinforcing bar design of the original technical scheme, and is not limited by the influences of complicated reinforcing bar preparation, difficult positioning and flow obstruction during construction.
The invention also provides a preparation method of the concrete for the precast slab track filling layer, which comprises the following steps:
s1, scattering steel fibers on the coarse aggregate, and then mixing the fine aggregate, the coarse aggregate and the steel fibers;
and S2, sequentially adding cement, fly ash, water and a water reducing agent, and uniformly mixing to obtain the steel fiber fine aggregate concrete.
Preferably, the preparation method of the concrete for the precast slab track structure comprises the following steps:
s1, using a forced mixer to construct, weighing the fine and coarse aggregates, and conveying and feeding the aggregates through a belt;
s2, in the aggregate transportation process, scattering steel fibers on the surface of the aggregate within 20S by using manpower or special machinery, and feeding the steel fibers into a stirring cylinder through a transportation belt;
s3, feeding the mixture of the fine and coarse aggregates and the steel fibers into a stirring cylinder of a forced mixer, and continuously stirring for 20-30S;
s4, after stirring, continuously adding the water, the water reducing agent, the cement, the fly ash and the mineral powder into the stirring tank;
and S5, after all the components are added, continuously stirring for 90-120S until all the components are uniformly mixed, and obtaining the steel fiber fine aggregate concrete.
The steps S1-S5 are sequentially adopted to prepare the qualified steel fiber fine aggregate concrete finished product with uniformly dispersed steel fibers, and the finished product has excellent fluidity and constructability, so that the requirements of the filling layer can be met.
The invention also provides application of the concrete for the precast slab track filling layer on a precast slab track, and particularly relates to application of the concrete for the precast slab track filling layer on a precast slab track, which is characterized in that a steel fiber fine aggregate concrete material is directly filled in a space between the lower part of the precast slab track and the inner wall of a tunnel, and is poured to the side surface of a track slab for fixing the elevation, as shown in the attached figure 2.
The invention can be directly constructed after the position and elevation of the track slab are fixed, and the steel fiber fine aggregate concrete forming filling layer is continuously poured once. Because the design of two-layer reinforcing bar net piece of traditional scheme has been cancelled because of it, need not during the construction contents such as on-the-spot inspection reinforcing bar quantity, position, fixed measure, only need the hole outer detection steel fibre content, distribution uniformity, concrete mobility index for filling layer construction processes simplifies by a wide margin, and quality control is more simple and convenient, also need not worry reinforcing bar net piece skew scheduling problem.
The invention is further illustrated below:
the component proportion directly determines the compressive strength, durability, construction fluidity and compactness of the concrete finished product, and is a key factor for controlling the construction quality of the filling layer. The components are mixed and stirred in a fixed mode to prepare the steel fiber fine aggregate concrete. The material has the advantages of crack control capability, bending tensile strength after cracking, excellent construction fluidity and free flowing filling. During construction, a small amount of tamping measures are matched to fill the structural space, and a compact filling layer structure below the prefabricated slab is formed. The steel fiber fine aggregate concrete prepared by the composition proportion of the concrete for the track filling layer of the precast slab has excellent fluidity and the slump of the concrete is 200mm +/-20 mm. During construction, the transportation hopper is continuously filled into the filling hole in one side of the track slab or the track slab, the vibrating rod can be adopted to properly vibrate from the filling hole or the two sides of the track slab according to needs in the filling process, air bubbles in concrete can be discharged from the reserved holes and the edges of the track slab, and good compactness can be obtained.
The existing reinforced mesh concrete filling layer structure is arranged as shown in figure 1, a single-layer mesh is generally formed by 10-12 mm diameter HRB400 type reinforcing steel bars in the longitudinal direction of a tunnel, 8mm diameter reinforcing steel bars in the transverse direction and HPB300 type reinforcing steel bars in the transverse direction, and C35 common concrete materials are poured to form the filling layer structure. The reinforcing steel bars of the filling layer are arranged below the precast slab, the number of the reinforcing steel bars is 9-11, and the spacing between the reinforcing steel bars is 200-300 mm.
Compared with the prior art, the invention has the following advantages:
1) steel fiber concrete mechanical property equivalent or superior to single-layer reinforcing mesh design
The steel fiber material is added into the C40 fine-grained concrete, so that the steel fiber fine-grained concrete composite material has higher stress toughness performance. According to the design of the steel fiber mixing amount recommended by the invention, the standard value of the bending tensile strength after cracking can reach 2.1-3.0 Mpa. The section tensile strength of the existing single-layer reinforcing mesh concrete filling layer scheme is only 1.5-2.6MPa, and the bending strength is 1.3-2.3 MPa. Therefore, the steel fiber fine aggregate concrete filling structure with correct mixing amount is selected, the mechanical property of the steel fiber fine aggregate concrete filling structure can completely meet or exceed the existing steel bar distribution scheme, and the steel fiber fine aggregate concrete filling structure can replace a steel bar net to bear the upper load of the track slab.
2) The steel fiber improves the crack control capability of the filling layer
The reinforcing bar net piece that disposes in the existing scheme, the design position is relatively fixed, and must design the plain concrete protective layer of 3-5cm thickness, and this will lead to the net piece to be difficult to carry out the accuse to the structure total cross-section and split the reinforcing, there are more reinforced blind areas in the concrete. In the invention, one or two hundred thousand steel fiber materials are contained in each cubic meter of concrete, and can be widely distributed on the whole cross section of the structure, so that the weak parts of the concrete are reinforced from all directions and all parts. The hooks at the two ends of the fiber and the requirement of high tensile strength can effectively inhibit the expansion of micro cracks in the concrete and prevent the micro cracks from developing into macroscopic cracks visible to naked eyes. According to research results, when the mixing amount of the steel fibers is 30kg, compared with plain concrete, the cracking area of the steel fiber concrete is reduced by 57%, and the number of cracks is reduced by 20%; and the early induced cracking test of the concrete under the condition of manual rapid test also shows that the area of the shrinkage crack of the 30kg mixed amount of the steel fiber concrete is reduced by 40 to 50 percent compared with the surface of plain concrete. The filling layer is poured by adopting the steel fiber concrete material, and the crack control effect is obviously better than that of the existing reinforcing mesh reinforcement design.
3) Steel fiber concrete guarantees structural design life
Along with the increase of the service life of the reinforced concrete structure, under the repeated fatigue action of load and the corrosion of external corrosion factors, the strength of the concrete material can be gradually reduced, and meanwhile, the reinforced material can be slowly corroded to rust, and finally the ultimate service life of the reinforced concrete is reached. However, in the process, the fatigue strength of the concrete is not obviously affected by the steel bars, but the problem of volume expansion after rusting can be solved by squeezing the concrete protective layer, so that the corrosion failure of the concrete protective layer is further accelerated, and the service life of the whole structure can be reduced.
On one hand, the steel fiber material can inhibit the expansion speed of various corrosion factors (such as carbonization corrosion, ion diffusion corrosion and the like) and delay the self-corrosion time by inhibiting the expansion of internal micro-cracks in the concrete. Meanwhile, the volume of the fiber is small, the number of the fibers is large, even if the individual fibers are seriously corroded, the safety of a concrete structure cannot be damaged, chain reaction caused by corrosion cannot occur, and the expected service life of the structure can be guaranteed. On the other hand, the concrete can obviously improve the fatigue and compression strength under the repeated action of long-term fatigue load (namely train load), and the compression and fatigue life of the concrete can be expected to be improved by 7.9-13.7 times. Meanwhile, under the action of dynamic load impact, the impact resistance of the concrete is 2-5 times that of common concrete. Therefore, the steel fiber concrete can not only ensure the design service life of the filling layer, but also promote the extension of the service life.
4) Simplify the construction process and facilitate the rapid construction
The main construction process of the concrete for the precast slab track filling layer is different from the traditional reinforced concrete filling layer structure as follows:
TABLE 1 comparison of construction procedures
Because the base concrete needs 28 days of strength, the process (i) and (iii) can meet the design requirement only after at least 30 to 35 days, and the existing scheme can not meet the requirement of continuous and rapid construction. The material pouring in the invention cancels the processes of (i) and (iii), so that the concrete can be directly poured at the lower part of the track slab, and the continuous and rapid construction condition is provided.
5) Simplify the construction quality control steps and facilitate the quality control
During reinforced concrete construction, a quality inspection department needs to check the diameter, the quantity, the position, the fixing measures, the thickness of a protective layer and other contents of the reinforcing steel bars in a tunnel on site, and also needs to control the workability and the filling quality of common concrete, so that the inspection is time-consuming and labor-consuming, the actual operation is complex and inconvenient, and quality problems such as reinforcing steel bar deviation, untight concrete, cavities and the like easily occur.
The steel fiber fine aggregate concrete prepared according to the component ratio in the part 2 of the invention has excellent fluidity and the slump of the concrete is 200mm plus or minus 20 mm. During construction, the transportation hopper is continuously filled into the filling hole in one side of the track slab or the track slab, the vibrating rod can be adopted to properly vibrate from the filling hole or the two sides of the track slab according to needs in the filling process, air bubbles in concrete can be discharged from the reserved holes and the edges of the track slab, and good compactness can be obtained. The quality inspection department can carry out on-site construction only after detecting the steel fiber content, the distribution uniformity and the concrete workability index outside the tunnel, thereby greatly simplifying the quality control steps and being beneficial to the overall control of the quality.
Drawings
Fig. 1 shows a filling method of a precast slab track in the prior art.
Fig. 2 shows a precast slab track structure of the present invention using fiber fine aggregate concrete as a filling material for a precast slab track filling layer.
Detailed Description
The invention is further described below with reference to specific preferred embodiments, without thereby limiting the scope of protection of the invention.
Example 1
A preparation method of steel fiber fine aggregate concrete for a precast slab track filling layer comprises the following steps:
1) the raw materials are mixed according to the following component ratio: P.O 42.5.5 Cement 325kg/m3175kg/m of water3702kg/m of fine aggregate (medium grit with fineness modulus of 3.3)35-16 grade mountain gravel serving as coarse aggregate 970kg/m3First grade fly ash 67kg/m369kg/m of S95-grade mineral powder3The steel fiber is 15kg/m respectively3、18kg/m3、20kg/m3、21kg/m38.5kg/m of sulfonic acid group carboxylic acid group high-efficiency water reducing agent3(ii) a The steel fiber is I-type steel wire cut-off fiber, wherein hooks are hooked at two ends of the steel fiber, the length of a single side of each hook is 5-10mm, the middle section of each hook is straight, the total length of the steel fiber is 50mm, the diameter of each hook is 0.75mm, the length-diameter ratio of each hook is 67, the nominal tensile strength of each hook is 1230MPa, and each kilogram of the steel fiber is about 5700;
2) construction is carried out by using a forced mixer, fine and coarse aggregates are weighed, and materials are conveyed and loaded through a belt;
3) in the aggregate transportation process, manually or special machinery is used for scattering steel fibers into the aggregates within 20s, and the steel fibers and the aggregates enter a stirring cylinder through a transportation belt;
4) feeding the mixture of the fine and coarse aggregates and the steel fibers into a stirring cylinder of a forced stirrer, and continuously stirring for 20-30 s;
5) after stirring, continuously adding the components of water, a water reducing agent, cement, fly ash and mineral powder into the stirring tank;
6) after all the components are added, continuously stirring for 90-120 s until all the components are uniformly mixed to obtain the steel fiber fine aggregate concrete (C1(15 kg/m)3)、C2(18kg/m3)、C3(20kg/m3)、C4(21kg/m3))；
7) The steel fiber fine aggregate concrete finished product is detected, and various index parameters are shown in the table 2:
TABLE 2 Steel fiber concrete Performance index under different blending amounts
The effect is optimal when the slump is controlled to be 200 +/-20 mm, and if the slump is too low, the effect means that the concrete is dry, the fluidity is not good, and a plurality of bubbles appear at the bottom of the track slab after pouring, so that the track slab is not suitable for a filling layer structure. Too high means that the concrete is very thin, and stones and steel fibers are easy to have uneven layering, thereby seriously affecting the quality of the concrete.
According to the comprehensive performance requirements of water-cement ratio, compressive strength, bending toughness ratio, concrete slump, air content and electric flux, the addition amount of the steel fiber is preferably 18-25kg/m3。
Example 2
1) The raw materials are mixed according to the following component ratio: P.O 42.5.5 Cement 325kg/m3175kg/m of water3702kg/m of fine aggregate (medium grit with fineness modulus of 3.3)35-16 grade mountain gravel serving as coarse aggregate 970kg/m3First grade fly ash 67kg/m369kg/m of S95-grade mineral powder3The steel fiber is 20kg/m3、25kg/m39.22kg/m of sulfonic acid group carboxylic acid group high-efficiency water reducing agent3(ii) a The steel fiber is I-type steel wire cut-off fiber, wherein hooks are hooked at two ends of the steel fiber, the length of a single side of each hook is 5-10mm, the middle section of each hook is straight, the total length of the steel fiber is 33mm, the diameter of each hook is 0.55mm, the length-diameter ratio of each hook is 60, the nominal tensile strength of each hook is 1300MPa, and each kilogram of the steel fiber is 16100.
2) The other procedures were the same as in example 1.
3) Detection of Steel fiber Fine Stone concrete end product (C5(20 kg/m)3)、C6(25kg/m3) And the index parameters are as follows:
TABLE 3 Steel fiber concrete Performance index under different blending amounts and different geometric dimensions
Example 3
A preparation method of steel fiber fine aggregate concrete for a track filling layer of a track traffic precast slab comprises the following steps:
1) the raw materials are mixed according to the following component ratio: P.O 42.5.5 Cement 344kg/m3176kg/m of water3Fine aggregate (medium coarse sand with fineness modulus of 3.3) 713kg/m35-16 grade mountain gravel as coarse aggregate 1065kg/m3First grade fly ash 68kg/m386kg/m of S95 grade mineral powder3Steel fiber 20kg/m39.46kg/m of sulfonic acid group carboxylic acid group high-efficiency water reducing agent3(ii) a The steel fiber is I-type steel wire cut-off fiber, wherein hooks are hooked at two ends of the steel fiber, the length of a single side of each hook is 5-10mm, the middle section of each hook is straight, the length of the steel fiber is 50mm, the diameter of each hook is 0.75mm, the length-diameter ratio of each hook is 67, the nominal tensile strength of each hook is 1230MPa, and each kilogram of the steel fiber is about 5700.
2) The other procedures were the same as in example 1.
3) Detecting the finished product of the steel fiber fine aggregate concrete, wherein the index parameters are as follows: the water-cement ratio is 0.41, the compressive strength is 55.5MPa, the bending toughness ratio is 0.57, the concrete slump is 210mm, and the gas content is 3.8%.
Example 4
The construction of the track filling layer structure of the track traffic precast slab in the prior art comprises the following steps:
1) the raw materials are mixed according to the following component ratio: P.O 42.5.5 Cement 305kg/m3185kg/m of water3702kg/m of fine aggregate35-16 graded coarse aggregate 1083kg/m350kg/m of fly ash375kg/m of mineral powder36.88kg/m of high-efficiency water reducing agent3；
2) Using forced mixer equipment to construct, weighing fine and coarse aggregates, and conveying and feeding materials by a belt
3) And (3) feeding the fine and coarse aggregates into a stirring cylinder of a forced mixer, continuously adding the water, the water reducing agent, the cement, the fly ash and the mineral powder, and continuously stirring until all the components are uniformly mixed after all the components are added to obtain the C35 concrete.
4) Laying 9 HRB400 type steel bars with the diameter of 10mm along the longitudinal direction of the tunnel, wherein the distance is 200-300mm, and the HRB 300 type steel bars with the diameter of 8mm along the transverse direction form a single-layer mesh;
5) positioning the prefabricated track slab;
6) and pouring C35 concrete material to form a filling layer structure.
The properties of the C2, C3, C4, C6 and C7 concrete materials prepared in examples 1 to 3 of the present invention, which were directly cast into a filling layer structure, were compared with those of a structure prepared from prior art reinforced concrete, and the results are shown in Table 4.
Table 4 the performance index of the structure cast according to the invention compared to the conventional reinforced concrete structure is as follows:
therefore, the prepared result is greatly improved in terms of strength, service life and impact resistance, and is obviously superior to the traditional structure.
The above description is only for the preferred embodiment of the present application and should not be taken as limiting the present application in any way, and although the present application has been disclosed in the preferred embodiment, it is not intended to limit the present application, and those skilled in the art should understand that they can make various changes and modifications within the technical scope of the present application without departing from the scope of the present application, and therefore all the changes and modifications can be made within the technical scope of the present application.
Claims (6)
1. The application of the concrete for the filling layer of the precast slab track on the precast slab track is characterized in that the concrete per cubic meter comprises the following components: 300-450 kg of cement, 160-185 kg of water, 650-850 kg of fine aggregate, 960-1210 kg of coarse aggregate, 60-90 kg of mineral powder, 30-80 kg of fly ash, 15-25 kg of steel fiber and 5.0-10.0 kg of water reducing agent;
the water reducing agent is a high-efficiency water reducing agent; the high-efficiency water reducing agent is a sulfonic acid group carboxylic acid group high-efficiency water reducing agent;
the steel fiber is I-type steel wire cold-drawn fiber; the appearance of the steel fiber is that hooks are arranged at two ends, the middle section of the steel fiber is straight, the length of the steel fiber is 30 mm-60 mm, the diameter of the steel fiber is 0.5 mm-1.0 mm, and the tensile strength grade is not lower than 1000 grade;
the water-cement ratio of the concrete for the track filling layer of the precast slab is less than or equal to 0.45, the strength grade is greater than or equal to C40, the bending toughness ratio is greater than or equal to 0.5, the concrete slump is 200 +/-20 mm, the gas content is 2-4%, and the electric flux is less than or equal to 1000C;
the construction process of the concrete for the precast slab track filling layer comprises the following steps:
step 1, positioning, mounting and fixing a prefabricated track slab;
step 2, preparing concrete for the precast slab track filling layer, transporting, pouring, locally tamping and leveling;
and 3, maintaining the finished filling layer.
2. Use according to claim 1, characterized in that the cement is portland cement; the strength grade of the portland cement is not less than 42.5.
3. The use according to claim 1, characterized in that the fine aggregate is medium coarse sand with a fineness modulus of 2.3-3.3.
4. Use according to claim 1, characterized in that the coarse aggregate is crushed stone of 5mm to 16mm continuous gradation, the maximum particle size being not more than 16 mm.
5. Use according to claim 1, wherein the steel fibres are added in an amount of 18-25kg/m for carrying out a high-speed harvest.
6. Use according to claim 1, characterised in that the method for preparing concrete for the filling layer of a precast slab track comprises the following steps:
s1, scattering steel fibers on the coarse aggregate, and then mixing the fine aggregate, the coarse aggregate and the steel fibers;
and S2, sequentially adding cement, fly ash, water and a water reducing agent, and uniformly mixing to obtain the concrete for the precast slab track filling layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011115266.2A CN112279585B (en) | 2020-10-19 | 2020-10-19 | Concrete for precast slab track filling layer and preparation method and application thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011115266.2A CN112279585B (en) | 2020-10-19 | 2020-10-19 | Concrete for precast slab track filling layer and preparation method and application thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112279585A CN112279585A (en) | 2021-01-29 |
| CN112279585B true CN112279585B (en) | 2022-04-19 |
Family
ID=74497779
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011115266.2A Active CN112279585B (en) | 2020-10-19 | 2020-10-19 | Concrete for precast slab track filling layer and preparation method and application thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112279585B (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1915892A (en) * | 2005-12-31 | 2007-02-21 | 大连理工大学 | Anti disruptive self-dense concrete of mixed fiber under high temperature of fire |
| CN101215136A (en) * | 2007-12-29 | 2008-07-09 | 中铁隧道集团有限公司 | Concrete material in tunnel lining C40 super-dense steel concrete and construction method thereof |
| KR20140105965A (en) * | 2013-02-25 | 2014-09-03 | 경북대학교 산학협력단 | Hybrid material of self consolidating concrete(scc) |
| JP2016030707A (en) * | 2014-07-29 | 2016-03-07 | 大成建設株式会社 | High-strength concrete and production method of concrete member |
| CN109678429A (en) * | 2019-01-31 | 2019-04-26 | 青岛市地铁一号线有限公司 | A kind of preparation method of the no muscle steel fiber reinforced concrete segment in the tunnel TBM |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111704402A (en) * | 2020-04-24 | 2020-09-25 | 杨后登 | Application method of concrete for road |
-
2020
- 2020-10-19 CN CN202011115266.2A patent/CN112279585B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1915892A (en) * | 2005-12-31 | 2007-02-21 | 大连理工大学 | Anti disruptive self-dense concrete of mixed fiber under high temperature of fire |
| CN101215136A (en) * | 2007-12-29 | 2008-07-09 | 中铁隧道集团有限公司 | Concrete material in tunnel lining C40 super-dense steel concrete and construction method thereof |
| KR20140105965A (en) * | 2013-02-25 | 2014-09-03 | 경북대학교 산학협력단 | Hybrid material of self consolidating concrete(scc) |
| JP2016030707A (en) * | 2014-07-29 | 2016-03-07 | 大成建設株式会社 | High-strength concrete and production method of concrete member |
| CN109678429A (en) * | 2019-01-31 | 2019-04-26 | 青岛市地铁一号线有限公司 | A kind of preparation method of the no muscle steel fiber reinforced concrete segment in the tunnel TBM |
Non-Patent Citations (1)
| Title |
|---|
| 钢纤维混凝土的力学性能及其在地铁工程中的应用研究;李昭;《中国优秀硕士学位论文数据库 工程科技Ⅱ辑》;20170815(第8期);1.1节、3.1节、图1-3 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112279585A (en) | 2021-01-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Dhonde et al. | Fresh and hardened properties of self-consolidating fiber-reinforced concrete | |
| Lankard | Slurry infiltrated fiber concrete (SIFCON): Properties and applications | |
| CN108529966B (en) | Seepage-proofing anti-cracking pumped concrete component design method and pouring forming method | |
| CN104278841B (en) | The method of casting concrete in steel pipe column | |
| Micelli et al. | Fiber-reinforced concrete and ultrahigh-performance fiber-reinforced concrete materials | |
| CN104499498B (en) | A kind of construction method of mass concrete building | |
| CN111962724A (en) | Wall crack control method | |
| Aslani et al. | Long-term flexural cracking control of reinforced self-compacting concrete one way slabs with and without fibres | |
| CN107640940A (en) | A kind of filler containing polypropylene fibre and its application in mining with stowing | |
| Hossain et al. | Long-term effect of accelerator content on flexural toughness of steel fiber reinforced shotcrete for tunnel construction | |
| CN112279585B (en) | Concrete for precast slab track filling layer and preparation method and application thereof | |
| Okrajnov-Bajić et al. | Self-compacting concrete and its application in contemporary architectural practice | |
| CN114953105A (en) | Non-rib high-doping-amount steel fiber concrete segment and manufacturing method thereof | |
| CN109057822A (en) | A kind of concrete pipe sheet and preparation method thereof containing high active material | |
| Jain et al. | Utilization of marble dust and fly ash in composite mortar as partial cement substitute | |
| Al-Abdalay et al. | Effect of impact load on SIFCON | |
| Kadhim | The Effects of Using Steel Fibers on Self-Compacting Concrete Properties: A Review | |
| CN110698129A (en) | Concrete for steel pipe arch and steel pipe concrete arch bridge | |
| CN105108905B (en) | A kind of construction technology of concrete | |
| Chakeri et al. | Experimental investigation of steel fibers’ effect on the improvement of mechanical properties of concrete segmental lining in mechanized tunneling | |
| Thadaka et al. | Comparative Study on the Mechanical Properties of Steel Fiber Reinforced Self-Compacting Concrete | |
| Ahmed et al. | Experimental Investigation of Strength Characteristics of Foam Concrete | |
| Xueqi | Research on mix ratio of track slab and self-compacting concrete for low-temperature environment in a laboratory | |
| Abubakar et al. | Effects of Water-Cement Ratio on Compressive Strength of Sprayed cured Concrete | |
| Ismael et al. | EFFECT OF CONSTRU STRUCTURAL PERF REINFORCED SELF CONCRETE |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| PE01 | Entry into force of the registration of the contract for pledge of patent right |
Denomination of invention: Concrete for precast slab track filling layer and its preparation method and application Granted publication date: 20220419 Pledgee: Ningxiang sub branch of Bank of Changsha Co.,Ltd. Pledgor: MACCAFERRI (CHANGSHA) ENVIRO-TECH CO.,LTD. Registration number: Y2024980016721 |