JP4541916B2 - Synthetic floor slab - Google Patents

Description

  The present invention relates to a composite floor slab that can be used as a floor slab of a building or a bridge, or a pressure-resistant surface structural member of a structure such as the ocean.

  As floor slabs for bridges and the like, precast concrete slabs and composite slabs of precast concrete and on-site cast concrete are known.

  An example is shown in Patent Document 1 below. As shown in FIG. 2, a floor slab unit 15 made of precast concrete having a size corresponding to the interval between the vertical beams 3 or the horizontal beams 4 was used, and adjacent floor slab units 15 on the beam were joined to form a continuous version.

  An end portion of the floor slab unit 15 is formed in an oblique end surface (A), and a U-shaped coupling rebar 16 is projected, and the end portion of the floor slab is disposed on the upper surface of the flange 17 of the vertical and horizontal beams 3 and 4. Thus, the concrete was cast in a continuous manner so that the ends of the adjacent floor slabs were substantially V-shaped (inverted trapezoidal). A stud gibber 18 is welded to the flange 17 of the beam, and the continuous floor slab unit 15 is also connected to the vertical and horizontal beams 3 and 4.

The end portion of the floor slab unit 15 is formed in an inclined end surface (A), and is formed into a substantially V shape (reverse trapezoidal) by the opposing inclined portion (A) of the adjacent floor slab unit 15. Therefore, the floor slab unit 15 can be installed without expanding the flange 17 of the vertical beam 3 or the horizontal beam 4, and the filling property of the bonding concrete 27 can be improved.
JP 2004-183324 A (Repair structure and repair method of existing pile pier)

  As a composite floor slab, a portion of the floor slab unit 15 is formed thinly, and concrete is placed thereon to form a composite floor slab of precast concrete and on-site cast concrete.

  The joint concrete 27 and the concrete cast on the floor are easily cracked together with the floor slab unit 15 which is precast concrete, and there is a possibility that the cracks of the concrete penetrate and a large crack opening is generated.

  As a result, it is necessary to perform re-construction regularly, resulting in an increase in maintenance costs. In this case, the resulting crack opening width reaches 0.6 mm from previous experience.

  Furthermore, since the penetration amount of deterioration factors increases due to the occurrence of cracks, the problem of corrosion of reinforcing bars and steel plates arises. In addition to the negative bending portion, cracking occurs in the concrete due to drying shrinkage and temperature difference, and water enters from that portion, and the fatigue durability of the floor slab is greatly reduced.

  The object of the present invention is to eliminate the inconvenience of the conventional example, and the placement portion is of the same inorganic type as the RC or PC precast plate, can maintain the integrity with the RC or PC precast plate, and is poured. Since construction can be done, laborious work can be saved by omitting complicated processes, and it does not follow cracks with large opening width generated or generated in RC or PC precast plates, suppressing cracks and intruding harmful substances An object of the present invention is to provide a synthetic floor slab that can prevent the above.

In order to achieve the above object, the present invention according to claim 1 arranges RC or PC precast plates as joints on the girders, and has a compressive strength of 30 N / mm on and on these RC or PC precast plates. ² or more, a tensile dispersion of 1.5 N / mm ² or more, and a crack dispersion type in which a tensile strain is 1% or more in a tensile test of a cured product on the 28th day of the material age, and PVA (Polyvinyl Alcohol) of [F1] below Short fibers were added to a formulation matrix of [M1], exceeding 1 and 3 Vol. % High-toughness cement composite material (ECC) that is blended randomly or two-dimensionally at a blending amount of 3%. Further, the high-toughness cement composite material (ECC) is placed on the RC or PC precast plate. The gist is to place approximately 4 to 10 cm .
[M1]
・ Water binder ratio (W / C) 25% or more
-Sand binding material weight ratio (S / C) is 1.5 or less (including 0)
Fine aggregate maximum particle size 0.8mm or less, average particle size 0.4mm or less,
Unit water volume 250 kg / m ³ or more and 400 kg / m ³ or less
High-performance AE water reducing agent amount less than 30kg / m ³
[F1]
Fiber diameter 50μm or less
Fiber length: 5-20mm
Fiber tensile strength: 1500 MPa to 2400 MPa or less

In the invention according to claim 3, RC or PC precast plates are arranged with the ends of the RCs and PC precast plates joined as joints, and a compressive strength of 30 N / mm ² or more and a tensile strength of 1.5 N are placed on these RC or PC precast plates. / mm ² or more compression strength 30 N / mm ² or more, a tensile strength of 1.5 N / mm ² or more, strain tension in the tensile test of the cured product of the wood age 28 days a crack distributed showing 1% or more, The following [F1] PVA (Polyvinyl Alcohol) short fibers are added to the formulation matrix of [M1], exceeding 1 to 3 Vol. % High-toughness cement composite material (ECC) that is blended randomly or two-dimensionally at a blending amount of 3%. Further, the high-toughness cement composite material (ECC) is placed on the RC or PC precast plate. The gist is to place approximately 4 to 10 cm .
[M1]
・ Water binder ratio (W / C) 25% or more
-Sand binding material weight ratio (S / C) is 1.5 or less (including 0)
Fine aggregate maximum particle size 0.8mm or less, average particle size 0.4mm or less,
Unit water volume 250 kg / m ³ or more and 400 kg / m ³ or less
High-performance AE water reducing agent amount less than 30kg / m ³
[F1]
Fiber diameter 50μm or less
Fiber length: 5-20mm
Fiber tensile strength: 1500 MPa to 2400 MPa or less

  According to the first or third aspect of the present invention, instead of concrete, a high toughness cement composite material (ECC) is cast on an RC or PC precast plate and joints thereof, thereby providing a high toughness cement. Since the composite material (ECC) suppresses the crack width, the permeation amount of the deterioration factor is reduced, so that the durability is improved. Durability is improved because cracks due to drying shrinkage and temperature difference are also dispersed. Coarse aggregate is not used, and because it exhibits quasi self-filling properties, it is excellent in filling properties.

  In addition, since this ECC synthesizes precast concrete and bears the tensile force, the cross section can be reduced.

  Furthermore, since the ECC synthesizes the precast concrete and bears the tensile force, the result is that the cross section can be reduced, so that an extremely thin casting of about 4 to 10 cm is required on the RC or PC precast plate. In addition, with a thickness of about 4 to 10 cm, the ECC can sufficiently prevent cracks of the RC or PC precast plate from penetrating to the upper pavement, thereby improving pavement durability.

  In addition to the above effects, high toughness fiber reinforced cement composite material (high toughness FRC material) has a tensile strain exceeding 1% depending on the matrix and fiber content of the formulation, and is almost perpendicular to the loading direction (stress direction). A crack dispersion type destruction phenomenon occurs in which many cracks (multi cracks) are generated in the direction. Therefore, cracks can be reliably controlled to a minute width.

  The gist of the present invention described in claim 2 is that the reinforcing bars protruding from the RC or PC precast plate are connected by a lap joint at the joint.

  According to this invention of Claim 2, a high toughness cement composite material (ECC) can be made to protrude from RC or a PC precast plate, and can be made into a synthetic member with the reinforcement connected by the lap joint.

  The gist of the present invention described in claim 4 is to provide a non-adhesive zone at the interface between the RC or PC precast plate and the high toughness cement composite material (ECC).

  According to the present invention described in claim 4, when the RC or PC precast plate is placed with the end portion butted as a joint, the non-adhesive zone is provided, and the shrinkage amount of the RC or PC precast plate Can be absorbed by this non-adhesive zone.

  According to the fifth aspect of the present invention, on the girder, an installation floor is formed by laying non-shrink mortar between seal members disposed between the girder and the RC or PC precast plate. The gist is that it is placed on the installation floor.

  According to this invention of Claim 5, a sealing performance can be improved by forming such an installation floor part.

  As described above, the composite floor slab of the present invention can prevent cracking of concrete, improve the strength, and has good workability.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal front view showing an embodiment of a composite floor slab of the present invention, in which an RC (steel reinforced) or PC (precast concrete) precast slab 1 is joined to a flange of a beam of a longitudinal beam 3 or a cross beam 4 by a steel frame Arranged as.

  As described above, when the RC or PC precast plate 1 is disposed on the girders, the seal sponge 5 is disposed between the girders and the RC or PC precast plate 1 as a seal member, and the non-shrink mortar 6 is interposed between the seal sponges 5. The installation floor part 7 was formed by spreading the RC or PC precast plate 1 on the installation floor part 7.

  Moreover, the joining reinforcement 8 is protruded from the RC or PC precast plate 1, and the joining reinforcement 8 is connected by a lap joint. It should be noted that the RC or PC precast plate 1 is not limited to this connection, and various other methods can be selected. For example, a U-shaped connecting reinforcing bar is protruded, thereby connecting the reinforcing bars. May be.

  In this way, the RC or PC precast plate 1 which is a precast concrete floor slab unit having a size matched to the interval between the girders is joined to form a continuous plate. As a haunch 1a with a tapered surface, the opening at the joint is widened.

  As another embodiment, as shown in FIG. 5, the RC or PC precast plate 1 may be disposed with its ends abutted on the flange of the beam of the longitudinal beam 3 or the transverse beam 4 made of steel.

Then, the RC or PC precast plate 1 and on the junction of them, compressive strength 30 N / mm ² or more, a tensile strength of 1.5 N / mm ² or more, the elastic modulus 15000 N / mm ² or more high toughness cementitious composites (ECC) 12 was cast to form the composite floor slab of the present invention.

  The high toughness cement composite material (ECC) is placed about 4 to 10 cm on the RC or PC precast plate 1.

  As shown in FIG. 5, when the RC or PC precast plate 1 is disposed with the end portions facing each other, the non-adhesive zone 10 is formed on the boundary surface between the RC or PC precast plate 1 and the high toughness cement composite material (ECC). Is provided. The non-adhesive band 10 can be easily formed by applying a release material with a brush or the like or attaching a tape.

  The non-adhesive band 10 may be installed only on the upper surface side of the RC or PC precast plate 1, but may have a length of the following extent.

ε_ＰＣａ：プレキャス版の収縮ひずみ、ε_ＥＣｃ：ＥＣＣの許容引張ひずみ（１％程度）
例えば、L =６ｍ、ε_ＰＣａ=500×10^-6、ε_ＥＣｃ=１％と仮定すると、
ｌ₂(mm)=Ｌ×ε_ＰＣａ／ε_ＥＣｃ=6,000×0.05／１=３００mm
３０cm程度あれば良い。 If the length of the PCa plate is L and the length of the non-adhesive zone is l ₂ ,
The shrinkage of the PCa plate is absorbed by the non-adhesive zone.

ε _PCa : shrinkage strain of _{precast plate} , ε _ECc : allowable tensile strain of ECC (about 1%)
For example, assuming L = 6 m, ε _PCa = 500 × 10 ⁻⁶ , and ε _ECc = 1%,
l ₂ (mm) = L × ε _PCa / ε _ECc = 6,000 × 0.05 / 1 = 300 mm
About 30cm is enough.

  The casting of the high toughness cement composite material (ECC) 12 is performed by pouring. The high toughness cement composite material (ECC) 12 is kneaded and formed by a mixer, received by a hopper, and poured by a pump. Spraying is also possible.

This high toughness cement composite material (ECC) 12 is a crack dispersion type in which a tensile strain of 1% or more is shown in a tensile test of a cured product on the 28th day of the material age, and the following [F1] PVA (Polyvinyl Alcohol) short fiber 1 to 3 Vol. % Blending amount was three-dimensional random or two-dimensional random.
[M1]
-Water binder ratio (W / C) 25% or more-Sand binder weight ratio (S / C) is 1.5 or less (including 0)
Fine aggregate maximum particle size 0.8mm or less, average particle size 0.4mm or less,
Unit water volume 250kg / m ³ or more and 400kg / m ³ or less Air volume when kneaded 3.5% or more and 20% or less High-performance AE water reducing agent amount Less than 30kg / m ³ [F1]
Fiber diameter 50 μm or less Fiber length: 5-20 mm
Fiber tensile strength: 1500 MPa to 2400 MPa or less

  In the [M1] preparation matrix, the amount of air when kneaded may be 20% or more.

  The tensile strain refers to a strain amount (%) at the maximum tensile stress value in a stress-strain curve obtained by a tensile test of a cured product having a material age of 28 days or more. Actually, it is represented by a tensile strain (%) in a tensile test (for example, a test specimen having a cross section of 30 mm × 13 mm is subjected to a tensile test in an 80 mm test section) on the 28th day of the material age.

  That the tensile strain is 1% or more means that a crack dispersion type fracture phenomenon in which a large number of cracks (multi-cracks) are generated in a direction substantially perpendicular to the loading direction (stress direction).

The vinylon short fiber satisfying the condition of [F1] is preferably a short fiber having an elastic modulus equal to or greater than that of concrete produced from polyvinyl alcohol resin, and a typical one is a fiber length of 12 mm, fiber A high-strength vinylon fiber having a diameter of 0.04 mm and a tensile strength of 1690 N / mm ² is used.

  The materials constituting the high toughness cement composite material (ECC) 12 are cement, admixture, fine aggregate, fiber, and water, and the ratio when the mixing amount is 60 L is as shown in Table 1 below.

  Based on the indoor test results of 18 cases shown in Table 2 below, the cured material properties of the high toughness cement composite material (ECC) 12 will be described below. Case factors were cement type and kneading temperature.

1) Compressive strength and bending strength The compressive strength test was performed in accordance with JIS A 1108 using a specimen of φ100 × 200 mm. The bending strength test was performed in accordance with JIS R 5201 using a 40 × 40 × 160 mm specimen. In both tests, three cases are tested in each case, and the lower limit of the confidence interval (m-1.645σ) that allows a 5% defect rate calculated from the average, standard deviation, coefficient of variation, and this data of all data. Asked. In addition, the test material age was 28 days, and curing was performed in a sealed state in an environment at a temperature of 20 ° C. until then.

The test results are shown in Table 3 above. The average value of the compressive strength is at 44.2N / mm ^2. The standard deviation was 5.0 N / mm ² and the coefficient of variation was 11.4%. Average flexural strength was 12.2N / mm ^2, standard deviation 1.5 N / mm ^2, was 11.8% coefficient of variation. 5% the lower limit of the confidence interval which permits defect rate (m-1.645σ) is, 36.0N / mm ² in compression strength, bending strength 9.9N / mm ^2.

2) Tensile strength and tensile strain The tensile test method is shown in FIG. Since the test method was not standardized for the direct tensile test, the direct tensile test using a dumbbell-shaped specimen (measurement section length 80 mm, width 30 mm, thickness 113 mm) was abandoned. The test material age was 28 days, and curing was performed in a sealed state in an environment at a temperature of 20 ° C. until then.

  The loading speed at the time of the test was 0.5 mm / min, and the tensile strain was evaluated by the average of the two displacement meters 36 attached to both sides of the specimen 35. In the figure, 37 is a displacement meter holder, and 38 is a holder fixing bolt.

  In addition, for the purpose of eliminating the influence of secondary bending, the number of test cases in one case is 5 and the data in which the displacement of one strain gauge is more than twice that of the other is treated as defective data. Not adopted.

  An example of the stress-strain relationship of the high toughness cement composite material (ECC) 12 is shown in FIG. It can be seen that, unlike ordinary cementitious materials, it exhibits pseudo-strain hardening characteristics in which the stress gradually increases with the increase in tensile strain after the initial cracking. Here, the tensile yield strength and ultimate tensile strain of the high toughness cement composite material (ECC) 12 are defined as shown in FIG. That is, the tensile yield strength was defined as a value corresponding to the lowering yield point of the metal material, and the ultimate tensile strain was established as the maximum strain that could ensure the tensile yield strength. By defining the stress-strain curve on the tensile side of the high toughness cement composite material (ECC) 12 as a complete elastoplastic model, the tensile properties of the high toughness cement composite material (ECC) 12 can be used for the design. become.

  Table 4 below shows the tensile yield strength and ultimate tensile strain calculated from the results of all 84 specimens from which effective test results were obtained.

The average value of the tensile yield strength was 3.8 N / mm ^2, standard deviation 0.4 N / mm ^2, was 10.5% coefficient of variation. The average ultimate tensile strain was 3.0%, with a standard deviation of 1.1% and a coefficient of variation of 37.8%. The lower limit (m−1.645σ) of the confidence interval that allows a 5% defect rate is 3.1 N / mm ^{2 in} tensile yield strength and 1.1% in ultimate tensile strain.

  The ultimate tensile strain of the high toughness cement composite material (ECC) 12 is a value that greatly exceeds the strain (about 0.2%) at the yield level of the steel material.

  As described above, the high toughness cement composite material (ECC) 12 has a high ability to restrain cracks caused by fibers, prevents the expansion of cracks, and generates the next crack. Subsequently, since many new micro cracks are generated one after another, even if an apparently very large tensile strain occurs, it can withstand the load.

  Further, since the crack can be controlled to a minute width (for example, 0.05 mm or less), it is also possible to prevent water penetration from the crack. Even if it is not possible to prevent all penetration from cracks, it is said that the penetration amount is proportional to the cube of the crack width, and controlling the crack width can greatly limit the penetration amount.

  And by preventing the penetration of water from cracks, it can be protected from substances such as sulfates and acids that dissolve in water and enter concrete and degrade concrete, which can greatly contribute to the extension of the common life.

It is a vertical front view which shows 1st Embodiment of the synthetic floor slab of this invention. It is a perspective view which shows a prior art example. It is explanatory drawing which shows a direct tensile test method. It is a graph which shows tensile performance. It is a vertical front view which shows 2nd Embodiment of the synthetic floor slab of this invention.

DESCRIPTION OF SYMBOLS 1 ... RC or PC precast plate 1a ... Haunch 3 ... Vertical beam 4 ... Horizontal beam 5 ... Seal sponge 6 ... Non-shrink mortar 7 ... Installation floor part 8 ... Joint reinforcement 10 ... Non-adhesion zone 12 ... High toughness cement composite material (ECC)
DESCRIPTION OF SYMBOLS 15 ... Floor slab unit 16 ... Connection reinforcing bar 17 ... Beam flange 18 ... Stud gibber 27 ... Joining concrete 35 ... Specimen 36 ... Displacement meter 37 ... Displacement meter holder 38 ... Holder fixing bolt

Claims (5)

The RC or PC precast plate arranged Ketajo as joint, the joint and on these these RC or PC precast plate, with compressive strength 30 N / mm ² or more, a tensile strength of 1.5 N / mm ² or more, wood age A crack dispersion type in which tensile strain is 1% or more in a tensile test of a cured product on the 28th, and the following [F1] PVA (Polyvinyl Alcohol) short fiber is added to a mixed matrix of [M1] and exceeds 1 to 3 Vol. % High-toughness cement composite material (ECC) that is blended randomly or two-dimensionally at a blending amount of 3%. Further, the high-toughness cement composite material (ECC) is placed on the RC or PC precast plate. A synthetic floor slab characterized by placing about 4 to 10 cm.
[M1]
・ Water binder ratio (W / C) 25% or more
-Sand binding material weight ratio (S / C) is 1.5 or less (including 0)
Fine aggregate maximum particle size 0.8mm or less, average particle size 0.4mm or less,
Unit water volume 250 kg / m ³ or more and 400 kg / m ³ or less
High-performance AE water reducing agent amount less than 30kg / m ³
[F1]
Fiber diameter 50μm or less
Fiber length: 5-20mm
Fiber tensile strength: 1500 MPa to 2400 MPa or less   The composite floor slab according to claim 1, wherein the reinforcing bars protruded from the RC or PC precast plate are connected by a lap joint at the joint. Butt ends arranged RC or PC precast plate as a joining portion Ketajo, on these RC or PC precast plate, compression strength 30N / mm ² or more, a tensile strength of 1.5 N / mm ² or more compression strength 30N / mm ² or more, a tensile strength of 1.5 N / mm ² or more, a crack decentralized strain tension in the tensile test of the cured product of the wood age 28 days showing the least 1%, PVA of the following [F1] (Polyvinyl Alcohol) short fibers were added to the formulation matrix of [M1], exceeding 1 to 3 Vol. % High-toughness cement composite material (ECC) that is blended randomly or two-dimensionally at a blending amount of 3%. Further, the high-toughness cement composite material (ECC) is placed on the RC or PC precast plate. A synthetic floor slab characterized by placing about 4 to 10 cm.
[M1]
・ Water binder ratio (W / C) 25% or more
-Sand binding material weight ratio (S / C) is 1.5 or less (including 0)
Fine aggregate maximum particle size 0.8mm or less, average particle size 0.4mm or less,
Unit water volume 250 kg / m ³ or more and 400 kg / m ³ or less
High-performance AE water reducing agent amount less than 30kg / m ³
[F1]
Fiber diameter 50μm or less
Fiber length: 5-20mm
Fiber tensile strength: 1500 MPa to 2400 MPa or less   The synthetic floor slab according to claim 3, wherein a non-adhesive zone is provided at an interface between the RC or PC precast plate and the high toughness cement composite material (ECC).   On the girder, an installation floor is formed by laying non-shrink mortar between seal members disposed between the girder and the RC or PC precast plate, and the RC or PC precast plate is placed on the installation floor. The synthetic floor slab according to any one of claims 1 to 4.

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