JP2009035900A - Floor slab reinforcing method and concrete finishing device used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve not only quality by enhancing the durability of a floor slab but also reducing vibration and noise generated by construction, while a thickness is smaller than that in a conventional floor slab upper-surface thickness increasing construction method. <P>SOLUTION: The surface of an existing floor slab 1 used for a bridge and a superhighway is ground, polished and cleaned, and soft concrete 2 of a slump of 10 cm or larger is placed for covering the surface of the ground, polished and cleaned floor slab 1, and the soft concrete 2 is compacted and integrated into the existing floor slab 1 by imparting high frequency vibration to a screed plate 12 of a concrete finishing device 10. The soft concrete 2 includes water, a hydraulic setting composition, an aggregate, an expansive admixture and fiber. The hydraulic setting composition uses a material for revealing a compressive strength of 10 N/mm<SP>2</SP>or higher in 2-3 hours after construction as a hardening speed of the soft concrete 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a floor slab reinforcement method and a concrete finishing apparatus used therefor.

Conventionally, a floor slab upper surface thickening method is known as a method for reinforcing a slab when a concrete slab applied to a bridge such as a steel bridge is damaged (see, for example, Patent Documents 1 and 2). In this method, after cutting to a depth of several centimeters from the upper surface of the existing concrete slab, the cut surface is blasted with steel shot, and then reinforced concrete mixed with steel fibers such as steel fibers is paved, and old and new concrete is It is a construction method that reinforces the floor slab by integrating and increasing the thickness.
JP-A-9-59929 JP-A-8-333816

However, the conventional floor slab upper surface thickening method has the following problems.
In other words, an expansion material was added to the concrete to prevent cracking due to shrinkage strain, but the effect was not sufficient, and the shrinkage strain could not be completely eliminated, and there was a risk that the concrete would crack. There was a need to further improve the quality of the concrete in the plate, leaving room for improvement.
In addition, since concrete finishing equipment equipped with an engine is used for paving concrete, the vibration and noise generated from the concrete finishing equipment during paving are large. From the viewpoint of environmental conservation, for example, urban centers such as urban expressways. There was a problem that it was difficult to apply to the floor slab in the department.

The present invention has been made in view of the above-mentioned problems, and is intended to improve the quality of the floor slab by enhancing the durability of the floor slab while being thinner than the conventional floor slab upper surface thickening method. An object of the present invention is to provide a method for reinforcing a floor slab and a concrete finishing device used therefor.
Another object of the present invention is to provide a floor slab reinforcement method and a concrete finishing apparatus used therefor, in which vibrations and noises generated during construction are reduced.

In order to achieve the above object, in the floor slab reinforcement method according to the present invention, a polishing process for cleaning the surface of an existing floor slab, and a surface of the cleaned floor slab is coated with a soft concrete having a slump of 10 cm or more. It is characterized by comprising a construction process and a compacting process in which high-frequency vibration is applied by a screed to compact the soft concrete and integrate it into an existing floor slab.
In the present invention, since soft concrete having a slump of 10 cm or more is used, sufficient strength and flatness can be obtained by compacting while applying high-frequency vibration even when spread on a thin layer. For example, it can be as thin as about 40 mm. Then, by polishing the floor slab, the deteriorated portion of the floor slab upper surface can be removed and the floor slab surface can be roughened, so that the adhesion strength between the old concrete and the new concrete can be increased. Moreover, since the increased thickness becomes a thin layer, the dead load is reduced and the durability of the floor slab can be improved.

In the floor slab reinforcement method according to the present invention, it is preferable that the thickness of the floor slab after compacting the soft concrete is increased in a range of 10 to 50 mm from the thickness of the floor slab before the polishing. .
In the present invention, by increasing the amount of soft concrete thickening within the range of 10 to 50 mm from the thickness of the floor slab before scouring, the level difference between the upper surface of the existing pavement and the asphalt pavement is reduced. Therefore, it is not necessary to rub the steps after finishing work, and the vehicle can be passed as it is, so that it is possible to reduce the time for traffic regulation accompanying the construction.

Moreover, in the floor slab reinforcement method according to the present invention, the high frequency frequency of the screed is preferably 100 to 400 Hz.
In the present invention, by using a high-frequency vibrator or the like to vibrate the screed at a frequency of 100 to 400 Hz and compacting the soft concrete, the vibration and noise are suppressed and the predetermined strength is secured and the thin layer is finished. Can do.

In the floor slab reinforcement method according to the present invention, the screed preferably has a moving speed on the floor slab of 20 to 100 cm / min.
In the present invention, by moving the screed at a speed of 20 to 100 cm / min and compacting the soft concrete, the finish quality can be prevented from being deteriorated and the construction speed can be secured.

In the floor slab reinforcement method according to the present invention, the soft concrete contains water, a hydraulic composition, an aggregate, an expansive admixture, and a fiber, and the hydraulic composition is used as a hardening rate of the soft concrete after construction. It is preferable to express a compressive strength of 10 N / mm ² or more in 3 hours.
In the present invention, since concrete strength that can withstand traffic loads can be obtained in a short time, the construction speed of floor slab reinforcement work can be increased, construction efficiency can be improved, construction period can be shortened, and traffic regulation time can be shortened. can do.

Further, the slab reinforcement method according to the present invention, expandable _{admixture, 3CaO · SiO 2 -2CaO · SiO} 2 -CaO- gap material based composition, 3CaO _· SiO 2 -CaO- gap material based composition, 2CaO A clinker composition comprising one or more compositions selected from SiO ₂ —CaO—interstitial material composition and CaO—interstitial material composition, and having a CaO content of 50 to 92% by weight And gypsum.
In the present invention, since the shrinkage of the concrete is suppressed by the expansive admixture contained in the concrete, and the shrinkage strain of the concrete due to self-shrinkage and drying shrinkage is reduced, cracking occurs in the concrete placed on the floor slab. Can be prevented. In addition, ettringite is generated by the reaction of gypsum contained in the expandable admixture and calcium aluminate, and the shrinkage of concrete can be suppressed by this ettringite, so cracking occurs in the concrete placed on the floor slab. This can be prevented more effectively.

Moreover, in the floor slab reinforcement method according to the present invention, the hydraulic composition comprises (1) calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) 3 to 60% by mass and anhydrous gypsum 1 to 40% by mass. It contains 0.1 to 3.0 parts by mass of lithium carbonate having a specific surface area of 1000 to 4000 cm ² / g, or (2) 3CaO · SiO ₂ , 11CaO · 7Al with respect to 100 parts by mass of the calcium sulfoaluminate composition. ₂ O ₃ · CaF, C ₂ S and the like are preferably included.
In this invention, since the strength of concrete is expressed early by the calcium sulfoaluminate contained in the hydraulic composition, the curing time after placing the concrete on the floor slab can be shortened. In addition, since the shrinkage strain of the concrete can be reduced by lithium carbonate, it is possible to more effectively prevent cracks from occurring in the concrete placed on the floor slab.

  In the floor slab reinforcement method according to the present invention, the existing floor slab is preferably a concrete slab or a steel slab.

Further, the concrete finishing apparatus according to the present invention is a concrete finishing apparatus used in the above-described floor slab reinforcement method, the main body, a screed supported by the main body to spread and compact the concrete, and the screed is subjected to high-frequency vibration. And a towing winch for moving the main body and the screed relative to the floor slab.
In the present invention, a high-frequency vibrator is used for applying vibration to the screed plate and a towing winch that is operated manually or electrically instead of an engine can be used as a power source for the concrete finishing device. Generation of noise can be suppressed. Then, using soft concrete with a slump of 10 cm or more, spreading it on a thin layer and compacting it while applying vibrations with a high-frequency vibrator, the thickness of the floor slab can be reduced to, for example, about 40 mm. Since the increased thickness becomes a thin layer in this way, the dead load is reduced and the durability of the floor slab can be improved. In addition, since it is a small and lightweight concrete finishing device that does not use an engine as a power source, the concrete finishing device can be manually placed on the construction site without using a lifting machine such as a crane. Even if it is a narrow part, it can be easily constructed.

According to the floor slab reinforcement method of the present invention, it is possible to finish the thickening of the floor slab into a thin layer by applying high-frequency vibration to the soft concrete and compacting it. Therefore, the dead load corresponding to the thickness increase is reduced, the durability of the floor slab is enhanced, and the quality can be improved.
Moreover, according to the concrete finishing apparatus used in the floor slab reinforcement method of the present invention, it is possible to use a simple and lightweight concrete finishing apparatus having a high-frequency vibrator attached to a screed by reducing the thickness. It is no longer necessary to use a large concrete finishing device equipped with an engine as in the past, and noise and vibration generated by floor slab reinforcement work can be reduced. For example, in urban areas such as urban highways. It can be adopted even at a construction site.

Hereinafter, a floor slab reinforcement method and a concrete finishing apparatus used therefor according to an embodiment of the present invention will be described with reference to FIGS.
1 is a perspective view showing an outline of a floor slab reinforcement method according to an embodiment of the present invention, FIG. 2 is a front view of the concrete finishing apparatus under construction shown in FIG. 1, FIG. 3 is a plan view of the concrete finishing apparatus, and FIG. (A) is a cross-sectional view taken along line AA shown in FIG. 3, (b) is a cross-sectional view taken along line BB, FIG. 5 is a side view showing a mobile concrete manufacturing apparatus, and FIGS. The figure which shows the construction process of floor slab reinforcement, FIGS. 7-12 is the graph etc. which show the result of Test Example 1. FIG.

  As shown in FIG. 1, the floor slab reinforcement method according to the present embodiment is a concrete manufactured on a floor slab 1 used for a bridge, a highway and the like by a mobile concrete manufacturing apparatus 3 (see FIG. 5) , Soft concrete 2) is laid out by the concrete finishing device 10 and compacted. A specific method for reinforcing a floor slab is that the surface of an existing floor slab 1 is ground, and the surface of the ground floor slab 1 is covered with a soft concrete 2 having a slump of 10 cm or more to form a screed (a screed plate 12 to be described later). Is a method in which high-frequency vibration is applied and the soft concrete 2 is compacted and integrated with the existing floor slab 1.

  Here, in this Embodiment, water, a hydraulic composition, an aggregate, an expansive admixture, and a fiber are used as the material of the soft concrete 2. Note that the floor slab 1 to which the present embodiment is applied is a foundation for bridge pavement, and is a concrete floor slab, a steel floor slab, or the like.

First, the structure of the concrete finishing apparatus 10 is demonstrated based on drawing.
As shown in FIGS. 1 to 4, the concrete finishing apparatus 10 includes a main body 11, a screed plate 12 (scread) supported by the main body 11 for spreading and compacting the soft concrete 2, and a screed plate 12. A high-frequency vibrator 13 for applying vibration to the main body 11 and traction winches 14 and 14 provided in the main body 11 are schematically configured.

  The main body 11 is configured by a substantially rectangular parallelepiped box-shaped member whose front and rear, right and left, and the bottom surface are surrounded by plate members and whose top surface is open. A weight such as a counterweight (not shown) is arranged in the box-shaped member of the main body 11 so as to ensure a reaction force when placing concrete. The length of the main body 11 in the front-rear direction (traveling direction) is sufficiently long so that the finish accuracy of the soft concrete 2 is not affected by the application of vibration to the soft concrete 2 by the screed plate 12 provided in front of the main body 11. For example, it is approximately 50 to 60 cm or more. A first columnar member 15 having an L-shaped cross section is erected inside the front surface of the left and right end portions of the main body 11. The outer bottom surface 11a of the main body 11 is a portion for finishing the placed soft concrete 2 flat, and is formed on a flat and smooth surface.

  The screed plate 12 is constituted by a substantially rectangular parallelepiped box-shaped member whose front and rear, right and left, and the bottom surface are surrounded by plate members and whose top surface is open and whose longitudinal direction is directed in a direction orthogonal to the traveling direction. A base 16 having a pair of angles is provided on the left and right sides of the inner bottom surface of the screed plate 12. A pair of angles on the base 16 are connected to each other through an anti-vibration rubber 19. As a material used for the vibration-proof rubber 19, an appropriate rubber such as natural rubber, styrene butadiene rubber, or chloroprene rubber can be used. The anti-vibration rubber 19 makes it difficult for vibration applied to the screed plate 12 to be transmitted to the main body 11, while it has a function of transmitting the load by the high-frequency vibrator 13 to the soft concrete 2 well. In combination with this, the soft concrete 2 can be flattened sufficiently and the finishing accuracy can be improved.

  A second columnar member 17 is erected on the upper surface of the base 16 with bolts, and the upper portions of the first columnar member 15 and the second columnar member 17 are fixed by connecting members 18. One end portion 18a of the connecting member 18 is attached to the upper portion of the first columnar member 15 so that the screed plate 12 can be moved vertically with respect to the main body 11 by a vise or a bolt. The height position can be adjusted according to the height. Normally, if the finished thickness dimension of the soft concrete 2 is about 40 mm, the height of the outer bottom surface 12 a of the screed plate 12 is adjusted to be approximately 10 mm above the height of the outer bottom surface 11 a of the main body 11.

  Further, the front portion of the outer bottom surface 12a of the screed plate 12 has a tapered surface 12b (FIG. 4) in which the front side in the traveling direction of the concrete finishing apparatus 10 (the direction of arrow E shown in FIGS. 1, 3, and 4 (b)) is high and the rear side is low. (B) is formed, and the material when placing the soft concrete 2 easily enters the outer bottom surface 11a side of the main body 11.

  As shown in FIGS. 3, 4 (a) and 4 (b), the high-frequency vibrator 13 is attached to the center of the inner bottom surface of the box-shaped member of the screed plate 12. The screed plate 12 is vibrated by driving the high-frequency vibrator 13. In the present embodiment, the frequency is preferably 100 to 400 Hz, and the high frequency vibrator 13 employs an adjustable frequency in the range of 100 to 240 Hz.

  As shown in FIGS. 1 and 2, L-shaped brackets 20 are respectively attached to the outer sides of the left and right plate members of the main body 11 by bolts, and the upper surface of each bracket 20 can be wound up manually. A tow winch 14 is provided. That is, the concrete finishing apparatus 10 fixes the end 21a of the wire rope 21 wound around each of the winches 14, 14 to a structure (here, the anchor 22 on the existing floor slab 1) or the like, and then winches. The concrete finishing device 10 moves on the formwork 23, 23 provided so that the upper surface matches the finished height of the soft concrete 2 by rotating the wire 14 with the left and right balance with human power and winding the wire rope 21. It is configured as follows. Here, the winding speed of the winch 14, that is, the moving speed of the screed plate 12 on the floor slab 1 is preferably 20 to 100 cm / min (details will be described later).

The soft concrete 2 of the present embodiment includes water, a hydraulic composition, an aggregate, an expandable admixture, and fibers, and the hydraulic composition is 10 N in 2 to 3 hours after the construction as the setting speed of the soft concrete 2. / Mm ² is a material that develops a compressive strength of ² or more, and as described above, a material that has a slump of 10 cm or more during placement. The material used for the soft concrete 2 will be specifically described below.

(A) Hydraulic composition As a hydraulic composition used for the soft concrete 2 shown in FIG. 1 in the present embodiment, calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) and calcium containing anhydrous gypsum What contains a sulfo aluminate composition and lithium carbonate is preferable. The calcium sulfoaluminate composition contains 3 to 60% by weight of calcium sulfoaluminate and 1 to 40% by weight of anhydrous gypsum, preferably 20 to 40% by weight of calcium sulfoaluminate and 5 to 15% by weight of anhydrous gypsum. Is included. The compounding quantity of the lithium carbonate in a hydraulic composition is 0.1-3.0 mass parts with respect to 100 mass parts of calcium sulfo aluminate compositions, Preferably it is 0.5-1.5 mass parts. When the blending amount of lithium carbonate in the hydraulic composition is less than 0.1 parts by mass, the initial strength of the soft concrete is not sufficiently developed, and when it exceeds 3.0 parts by mass, the effect of reducing the shrinkage strain of the soft concrete is great. There is no change, and the manufacturing cost is expensive.

The specific surface area (Blaine specific surface area) of lithium carbonate contained in the hydraulic composition is 1000 to 4000 cm ² / g, preferably 2000 to 3000 cm ² / g. When the specific surface area is less than 1000 cm ² / g, lithium carbonate particles become coarse, so that when mixed with concrete, lithium carbonate is difficult to uniformly disperse, and the strength of soft concrete decreases. When the specific surface area exceeds 4000 cm ² / g, the effect of reducing the shrinkage strain cannot be obtained sufficiently.

(B) Aggregate Aggregates used for the soft concrete of the present embodiment include fine aggregates and coarse aggregates. As the fine aggregate, natural sand such as river sand, mountain sand and sea sand and artificial sand such as crushed sand and blast furnace slag fine aggregate can be used. The particle size of the fine aggregate is preferably 5 mm or less. The blending amount of the fine aggregate in the soft concrete is preferably 0 to 500 parts by mass and more preferably 100 to 200 parts by mass with respect to 100 parts by mass in total of the hydraulic composition and the expandable admixture. preferable. Gravel and crushed stone can be used as the coarse aggregate. The particle size of the coarse aggregate is preferably 5 to 25 mm, and particularly preferably 5 to 13 mm. The blending amount of the coarse aggregate in the soft concrete is 0 to 500 with respect to a total of 100 parts by mass of the hydraulic composition and the expandable admixture from the viewpoint of mechanical strength after hardening the concrete and workability of the ready-mixed concrete. It is preferable that it is a mass part, and it is more preferable that it is 100-200 mass parts.

(C) Expansive admixture The expansive admixture used for the soft concrete of the present embodiment is preferably one containing a clinker composition and gypsum. Clinker _{composition, 3CaO · SiO 2 -2CaO · SiO} 2 -CaO- gap material based composition, 3CaO _· SiO 2 -CaO- gap material based composition, 2CaO _· SiO 2 -CaO- gap material based compositions and CaO -It contains one or more compositions selected from interstitial material compositions, and the content of CaO is 50 to 92% by mass. Gap substances contained in the clinker composition in expandable admixture is one similar to the mineral filling between the cement clinker minerals in alite (3CaO · SiO ₂₎ and belite (2CaO · SiO _2). Such gap materials, 2CaO _· Fe 2 _{O 3} calcium such as ferrite minerals, calcium aluminate minerals such as _{3CaO · Al 2 O 3, 6CaO} · Al 2 O 3 · Fe 2 O 3, 4CaO · Al 2 O Calcium aluminoferrite minerals such as ₃ · Fe ₂ O ₃ , 6CaO · 2Al ₂ O ₃ · Fe ₂ O ₃ and the like can be mentioned.

  As above-mentioned, the content rate of CaO in a clinker composition is 50-92 mass% with respect to the total mass of a clinker composition. If the CaO content is less than 50% by mass, it may be difficult to develop the early strength of the soft concrete. If the CaO content exceeds 92% by mass, the content of the interstitial material is relatively reduced to reduce the shrinkage of the soft concrete. May be difficult to do.

The expandable admixture contains gypsum together with the clinker composition. Therefore gypsum to produce ettringite _{(3CaO · Al 2 O 3 ·} 3CaSO 4 · 32H 2 O) reacts with the calcium aluminate, the initial strength of the soft concrete with it is possible to suppress the shrinkage of the soft concrete ( Demolding strength during simple steam curing can be increased. The blending amount of gypsum in the expandable admixture is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the clinker composition. When the expansive admixture contains quick lime, the blending amount of gypsum is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the total amount of the clinker composition and quick lime. If the blending amount of the gypsum is less than 5 parts by mass, it is difficult to reduce the shrinkage of the soft concrete and there is a risk that the strength will not be expressed at an early stage, and if it exceeds 50 parts by mass, expansion cracks may occur in the soft concrete. .

  The expandable admixture preferably further contains quick lime. Quicklime expands and generates heat due to the hydration reaction, so that the shrinkage of the soft concrete can be further suppressed, and the calorific value of the expandable admixture as a whole increases and the early strength development of the soft concrete can be further improved. . The content of quicklime when the expandable admixture contains quicklime is preferably 80% by mass or less of the total mass of the clinker composition and quicklime. If the content of quicklime exceeds 80% by mass, the amount of expansion of the soft concrete due to the hydration reaction may increase excessively.

(D) Fiber The fiber contained in the soft concrete of the present embodiment is a metal fiber or an organic fiber. By including these fibers, the soft concrete expanded by the expandable admixture can be restrained to prevent the shrinkage of the soft concrete, and the soft concrete does not expand too much by controlling the expansion of the soft concrete. Can be. Examples of metal fibers include steel fibers, amorphous fibers, and stainless steel fibers. Among these, it is preferable to use steel fibers that can more effectively restrain soft concrete. Examples of the organic fiber include vinylon fiber, polyethylene fiber, polypropylene fiber, polyvinyl alcohol fiber, and cellulose fiber. Of these, it is possible to use vinylon fiber that can more effectively restrain soft concrete. preferable.

It is preferable that the compounding quantity of a metal fiber or an organic fiber is 0.7-2.0 volume% with respect to the volume of soft concrete. If the blending amount of these fibers is less than 0.7% by volume, the strength of the soft concrete may be lowered, and if it exceeds 2.0% by volume, the workability of the kneading operation with the hydraulic composition may be lowered. There is.
The fiber length of the metal fiber or organic fiber is preferably 15 to 60 mm, and more preferably about 30 mm. If the fiber length is less than 15 mm, the soft concrete may not be effectively constrained, and if the fiber length exceeds 60 mm, fiber balls are likely to be generated when the hydraulic composition and metal fibers or organic fibers are kneaded. There is.
The diameter of the metal fiber or organic fiber is preferably 0.62 to 0.90 mm. If the diameter is less than 0.62 mm, the strength of the metal fibers or organic fibers may be insufficient and the fibers may break when subjected to tension. If the diameter exceeds 0.90 mm, the metal in the soft concrete Since the number of fibers or organic fibers is relatively small, there is a possibility that the soft concrete cannot be effectively restrained in any case.

(E) Setting retarder The soft concrete of the present embodiment is 0.5 to 3.0 parts by mass in terms of citric acid with respect to 100 parts by mass in total of the hydraulic composition and the expandable admixture. It further contains citric acid or a salt thereof, 0.05 to 1.5 parts by mass of tartaric acid or a salt thereof in terms of tartaric acid and / or 0.05 to 1.5 parts by mass of heptonic acid or a salt thereof in terms of heptonic acid. It is preferable.

  As a method for kneading the soft concrete according to the present embodiment, the hydraulic composition and the expandable admixture are mixed in advance and water is added to the kneaded mixture, and water is added to the hydraulic composition. In addition, there is a method of kneading and further kneading by adding the expandable admixture. In the present invention, it is preferable to add citric acid (citrate), tartaric acid (tartrate) and / or heptonic acid (heptonic acid salt) as a setting retarder. In particular, tartaric acid (tartrate) and / or heptonic acid (heptonic acid salt) has a setting retarding action similar to citric acid, but the hydraulic composition, expansive admixture, tartaric acid (tartrate) and / or Alternatively, even if heptonic acid (heptonic acid salt) is mixed in advance and water is added thereafter, ettringite is not rapidly formed and rapid setting of soft concrete can be prevented. As a result, sufficient pot life can be ensured and the expandable admixture can be uniformly mixed with the soft concrete, so that the shrinkage strain of the soft concrete can be more effectively suppressed.

When the blending amount of tartaric acid (tartrate) or heptonic acid (heptonic acid salt) with respect to a total of 100 parts by mass of the hydraulic composition and the expandable admixture is less than 0.05 parts by mass in terms of tartaric acid or heptonic acid There is a possibility that the pot life of soft concrete cannot be secured sufficiently. When the blending amount exceeds 1.5 parts by mass, there is a risk that the setting of the soft concrete may not be sufficiently exhibited due to the setting failure or may not be cured in some cases.
The blending amount of tartaric acid (tartrate) is more preferably 0.15 to 1.2 parts by mass with respect to 100 parts by mass in total of the hydraulic composition and the expandable admixture, and 0.2 to 1 Particularly preferred is 0.0 parts by mass. The blending amount of heptonic acid (heptonic acid salt) is more preferably 0.2 to 1.2 parts by mass with respect to 100 parts by mass in total of the hydraulic composition and the expandable admixture, and 0.25. It is especially preferable that it is -1.0 mass part.

  The soft concrete of the present embodiment contains 0.01 to 0.3 parts by mass of boric acid or a salt thereof in terms of boric acid with respect to a total of 100 parts by mass of the hydraulic composition and the expandable admixture. It may be included. By adding boric acid to the soft concrete within the above range, the heat of hydration when the soft concrete hardens can be reduced and the kneading temperature of the soft concrete can be lowered. Even if it exists, the shipment and construction of soft concrete can be performed easily.

  When the blending amount of boric acid (borate) with respect to 100 parts by mass in total of the hydraulic composition and the expansive admixture is less than 0.01 parts by mass in terms of boric acid, the heat of hydration when soft concrete is cured There is a possibility that it cannot be effectively reduced, and if it exceeds 0.3 parts by mass, the strength of the soft concrete may be reduced or a setting delay may occur. The compounding amount of boric acid (borate) is more preferably 0.05 to 0.2 parts by mass with respect to 100 parts by mass in total of the hydraulic composition and the expandable admixture, It is especially preferable that it is -0.15 mass part.

Next, the mobile concrete manufacturing apparatus used for manufacturing the soft concrete described above will be described with reference to the drawings.
As shown in FIG. 5, the mobile concrete manufacturing apparatus 3 includes a concrete material replenishing device 30 and a concrete material kneading device 40, and each is mounted on a vehicle.

  The concrete material supply device 30 stores a first container 31 for storing the hydraulic composition, a first feeder 32 for taking out the hydraulic composition from the first container 31 and transporting the hydraulic composition to the concrete material kneading device 40, and storing the aggregate. The second container 33, the second feeder 34 that takes out the aggregate from the second container 33 and conveys it to the concrete material kneading apparatus 40, and the hydraulic composition taken out from the first container 31 to the concrete material kneading apparatus 40. The first metering device 35 that transports and measures the transport amount of the hydraulic composition and the aggregate taken out from the second container 33 are transported to the concrete material kneading device 40 to measure the transport amount of the aggregate. And a second weighing device 36.

The concrete material kneading apparatus 40 receives the hydraulic composition conveyed from the concrete material supply apparatus 30 and measures the amount of the hydraulic composition received, and the third container 41 receives the hydraulic composition from the third container 41. A third feeder 42 to be taken out, a fourth container 43 for receiving the aggregate conveyed from the concrete material supply device 30 and measuring the amount of the aggregate received, and a fourth feeder 44 for taking out the aggregate from the fourth container 43. The fifth container 45 that receives the supplied water and measures the amount of water received, the hydraulic composition taken out from the third container 41 by the third feeder 42, and the fourth feeder 44 taken out from the fourth container 43. A sixth container 46 for receiving and kneading the aggregate and the water supplied from the fifth container 45, and a raw container obtained in the sixth container 46 disposed below the sixth container 46. And a fifth feeder 47 which discharges the cleat.
The concrete material supply device 30 and the concrete material kneading device 40 may be mounted on separate vehicles as shown in FIG. 5, or both devices may be mounted together in one vehicle.

Next, the construction procedure of the soft concrete 2 using the concrete finishing apparatus 10 of the present embodiment, that is, the floor slab reinforcement method will be specifically described with reference to FIG.
Here, it is a case where it applies to a concrete slab, for example, the construction amount per day shall be about 3.5 m of construction width x about 30 m of construction extension.

First, as shown to Fig.6 (a), the existing bridge surface pavement (asphalt mixture layer 4) is cut and removed by the road surface cutting machine which is not shown in figure. At this time, in order to avoid damage to the existing concrete floor slab 1A and to completely remove the asphalt mixture layer 4, the cutting operation is performed in two layers. Next, a part that hinders adhesion of old and new concrete such as latency on the concrete floor slab 1A is removed by cutting to a depth of about 10 mm with a road surface cutting machine. In FIG. 6 (a), a two-dot chain line denoted by reference numeral 1a indicates a position before cutting, and a solid line denoted by reference numeral 1b indicates a position after cutting.
Thereafter, the surface of the concrete slab 1A is blasted by shot blasting to remove the mortar, and the aggregate is visible on the slab surface (abrasion process). The projection density of the steel ball (steel shot) at this time is about 150 kg / cm ² .

  Subsequently, as shown in FIGS. 6B and 6C, the soft concrete 2 having a slump of 10 cm or more is coated on the surface of the polished concrete floor slab 1A (construction process). Specifically, as shown in FIG. 6 (b), a formwork 23 such as wood is provided around the area where the soft concrete 2 is placed, and the upper surface 23a of the formwork 23 has a finished height of the soft concrete 2. The height is adjusted so as to coincide with the height (position of reference numeral 2a) (see FIG. 2).

  Then, as shown in FIG. 6C and FIG. 1, the concrete finishing device 10 is placed on the formwork 23 of the construction starting point, and the towing winches 14, 14 provided at both ends of the concrete finishing device 10. Then, the wire rope 21 is unwound and its end 21a is fixed to an anchor 22 driven into the existing concrete slab 1A. And the soft concrete 2 manufactured using the mobile concrete manufacturing apparatus 3 (refer FIG. 5) in a construction site is conveyed with a unicycle etc., and it supplies on the existing concrete slab 1A ahead of the advancing direction of the concrete finishing apparatus 10 Then spread it with a rake and spread it.

  Then, as shown in FIG.6 (c), the process which gives high frequency vibration with the screed plate 12 and compacts the soft concrete 2 and integrates it with the existing floor slab 1 is performed (consolidation process). Specifically, as shown in FIG. 1, after driving the high-frequency vibrator 13 of the concrete finishing device 10, the tow winches 14, 14 are rotated by human power with good left-right balance, and the wire ropes 21, 21 are wound up and finished. The apparatus 10 is moved forward (moved in the direction of arrow E shown in FIG. 1) along the mold 23, and the soft concrete 2 is fed backward while being compacted by the screed plate 12 and spread by the outer bottom surface 11 a of the main body 11. As a result, the soft concrete 2 is thickened to a predetermined thickness. Immediately after the placement of the soft concrete 2, the film curing agent is sprayed and the entire surface is covered with a curing mat.

Next, after the soft concrete 2 is cured, a waterproof layer is applied to prevent water from penetrating into the concrete. As the waterproof layer, there are a sheet-type waterproof layer and a coating-type waterproof layer, and those having good waterproofness and adhesion between the asphalt mixture layer and concrete are used.
Then, as shown in FIG. 6D, after the waterproof layer is constructed, the asphalt mixture layer 4 is laid so as to coincide with the height of the existing asphalt mixture layer 4 around the construction region, and the work is completed.

  Thus, in this floor slab reinforcement method, since the soft concrete 2 having a slump of 10 cm or more is used, it is spread on a thin layer and compacted while applying high frequency vibration of 100 to 400 Hz to the screed plate 12 by the high frequency vibrator 13. Thus, the thickness increase of the floor slab 1 can be reduced to, for example, about 40 mm. When the frequency is less than 100 Hz, it is assumed that the material is greatly waved and the soft concrete 2 is insufficiently compacted, and a predetermined concrete strength cannot be obtained. Further, when the frequency exceeds 400 Hz, there arises a problem that noise and vibration increase.

  Then, by polishing the floor slab 1, the deteriorated portion of the floor slab upper surface can be removed and the floor slab surface can be roughened, so that the adhesion strength between the old concrete and the new concrete can be increased. In addition, since the increased thickness becomes a thin layer, the dead load is reduced and the durability of the floor slab 1 can be improved.

  And by making the screed plate 12 (concrete finishing apparatus 10) the moving speed of 20 to 100 cm / min, it is possible to prevent the quality of the finished product from being deteriorated and to secure the construction speed. In addition, if the moving speed is less than 20 cm / min, there is no problem in the quality of the soft concrete 2, but the construction speed is slowed, which affects the construction period. On the other hand, when the construction speed exceeds 100 cm / min, the concrete is not sufficiently compacted, the finished surface is deteriorated, the strength is insufficient, and the quality is deteriorated.

  Here, the thickness of the floor slab 1 after the soft concrete 2 is compacted is preferably set to be increased in the range of 10 to 50 mm from the thickness of the floor slab 1 before the polishing. By constructing in this way, it is possible to reduce the level difference from the upper surface of the existing pavement while finishing the asphalt pavement on the thickened soft concrete 2, so there is no need to rub the level difference after finishing work. Since the vehicle can be passed as it is, the time for traffic regulation accompanying the construction can be shortened. That is, when the increased thickness is less than 10 mm, the level difference from the existing pavement upper surface becomes large, and the finished soft concrete 2 may be too thin to secure the strength to withstand traffic loads. When the increased thickness exceeds 50 mm, the level difference from the existing pavement upper surface increases, and the dead load also increases, and for example, the bridge may not be able to withstand the weight of the floor slab.

Further, since the high-frequency vibrator 13 is used for applying vibration to the screed plate 12 and the towing winch 13 that is operated by human power instead of the engine is used as a power source for the concrete finishing apparatus 10, generation of vibration and noise associated with concrete placement. Can be suppressed. Therefore, it is possible to cope with environmental conservation for the residents in the vicinity of the construction site, and this floor slab reinforcement method can be adopted for urban construction and night construction.
Moreover, since the concrete finishing apparatus 10 has a small and light structure that does not use an engine as a power source, the concrete finishing apparatus can be manually placed on the construction site without using a lifting machine such as a crane. Even if the construction width is narrow, it can be easily constructed.

  Further, in this construction method, since the anti-vibration rubber 19 is attached at an appropriate position between the screed plate 12 and the main body 11, vibrations by the high-frequency vibrator 13 are not easily transmitted to the main body 11 and the screed plate 12 has It is transmitted efficiently, and even with a small number of high-frequency vibrators 13, the soft concrete 2 can be sufficiently flattened and sufficiently compacted, and the generation of noise can be suppressed due to the small number of high-frequency vibrators 13.

Next, although the construction procedure in the case of applying the floor slab reinforcement method of this embodiment to a steel floor slab will be described, it is basically the same construction method as that applied to a concrete floor slab.
First, the existing bridge pavement (surface asphalt mixture layer and base goose asphalt mixture layer) is removed with a road cutting machine. Next, the waterproof layer under the base layer is peeled off by a power shovel equipped with a flat claw bucket. Thereafter, the steel floor slab surface after cutting is polished by shot blasting to remove the remaining waterproof layer. The projection density of the steel shot at this time is about 150 kg / cm ² . After the polishing work is completed, a waterproof layer will be installed to prevent water penetration into the steel slab surface. As the waterproof layer, there are a sheet-type waterproof layer and a coating-type waterproof layer, and those having good waterproofness and adhesion between the asphalt mixture layer and the steel deck are used.

  Next, as shown in FIG. 1, the mold 23 is installed at the place where the soft concrete 2 is placed, and the height is adjusted so that the upper surface 23 a of the mold 23 becomes the finished height of the soft concrete 2. And the concrete finishing apparatus 10 is mounted on the formwork 23 of a construction starting part, The wire rope 21 of the winch 14 provided in the finishing apparatus 10 is unwound, The edge part 21a is put on a steel deck. It fixes to the welded iron bar (equivalent to anchor 22). The soft concrete 2 manufactured using the mobile concrete manufacturing apparatus 3 (see FIG. 5) in the construction site is transported by a unicycle or the like and supplied onto the existing steel slab in front of the finishing apparatus 10. To level and finish to a predetermined thickness and width. Immediately after the placement of the soft concrete 2, the film curing agent is sprayed and the entire surface is covered with a curing mat.

(Test Example 1)
Next, in order to confirm the effect of the thickening reinforcement of the present embodiment described above, the following test was performed.
In this test, thickening reinforcement was performed using the soft concrete 2 of the present embodiment including an expansion material on the upper surface of the RC floor slab that had been damaged in advance, and a static loading test and a wheel load running fatigue test before and after the reinforcement were performed. By carrying out, the reinforcing effect and the degree of fatigue damage were confirmed.

(1) Static loading test The RC floor slab used in this test has a length of 3000 mm in the bridge axis direction, a width of 2000 mm in the direction perpendicular to the bridge axis, a thickness of the floor slab of 160 mm, and a space between the slabs of the test at 1800 mm. It is. D16 and D13 SD295A rebars are used for the main reinforcing bar and the distribution reinforcing bar, respectively, and the arrangement interval of the reinforcing bars in the floor slab is 150 mm for the tensile main reinforcing bar, 300 mm for the compression main reinforcing bar, and 125 mm for the tensile side reinforcing bar. The compression-side distribution reinforcing bar was 250 mm. This RC floor slab was preloaded and damaged in advance, and this was subjected to thickening reinforcement (thickening amount 40 mm) using the soft concrete of the present invention, and then a static loading test was performed.

  The static loading test was performed using a crank type wheel load running tester. This testing machine has a maximum loading capacity of 294 kN, a load travel range of 1000 mm from the center of the floor slab, and a load travel speed of 30 reciprocations / min. A track device was placed in the load travel range. In this loading test, a loading area of 300 mm × 120 mm was secured by the loading block in the apparatus. This is a scale 0.6 times that of the rear wheel (500 mm × 200 mm) of the design B live load, and an acceleration test was realized by adopting this area.

  The RC floor slab support conditions in this loading test were simple support on the two sides in the bridge axis direction and elastic support on the two sides in the direction perpendicular to the bridge axis. The transverse girder stiffness was set so that the behavior of the floor slab was equivalent to that of the semi-infinite plate in the hope that it would show behavior similar to a real bridge in a wheel load running fatigue test. At the four corners of the RC floor slab, a lift prevention device was attached in order to prevent the floor slab end from being lifted when the load was loaded.

  The preliminary loading on the RC slab was carried out by running 50,000 wheel loads at 137.2 kN. FIG. 7 shows the change with time of the deflection of 98 kN in the center of the slab. The figure shows the result of calculating the deflection of the theoretical live load when the entire cross section is effective and when the concrete on the tensile side is neglected, from Huber's plate theory. The deflection of the live load started from the effective of the entire cross section and gradually increased to the neglect of the tensile side, and the loading was finished when the deflection ratio of the active load (the degree of deflection deterioration) with respect to the theoretical deflection when neglecting the tensile side concrete reached 0.99.

  A wheel load was statically loaded at the center of the RC floor slab immediately before and after the thickening reinforcement. From the distribution of the deflection of the live load converted to 98 kN shown in FIG. 8 in the axial direction of the bridge slab center line, it can be seen that the deflection of the live load is reduced by about 56% before and after reinforcement. From this test result, by performing thickening reinforcement using the soft concrete of the present embodiment, the amount of flexure of the floor slab can be reduced and the stress due to traffic load acting on the floor slab 1B can be suppressed, and its durability It can be estimated that the performance is improved.

(2) Wheel load running fatigue test A wheel load running fatigue test was carried out on the RC slab reinforced with thickening using the soft concrete of the present embodiment. The time-dependent change of the deflection at the center of the slab at this time is as shown in FIG. 9. When the theoretical deflection at the time of neglecting the tensile side concrete was exceeded, the deflection increased rapidly and the punching shear fracture occurred. Further, the crack occurrence state on the bottom surface of the RC floor slab is as shown in FIG. 10, and the two-way crack progressed and the crack occurrence state in the actual bridge could be reproduced. The length of the crack is measured to the quantitative evaluation of cracks was determined cracking density C _d by dividing by the area of the slab bottom surface. A result of measuring the crack density C _d is as shown in FIG. 11, following the trend of increasing substantially the same cracking when compared to unreinforced slab.

  As a result of measuring the fatigue durability, it is considered that the floor slab reinforced with the soft concrete and the unreinforced floor slab of the present embodiment followed the same damage process. Plotted in a relationship diagram (see FIG. 12). From this test result, it was confirmed that by performing thickening reinforcement using the soft concrete of the present embodiment, the punching shear strength and fatigue life (durability) are improved as compared with the unreinforced floor slab. .

(Test Example 2)
Next, in order to confirm the noise reduction effect of the present embodiment described above, the following test was performed.
In Test Example 2, the above-described concrete finishing apparatus 10 (see FIG. 1 and the like) was used for leveling (Example), and an off-rail type (tire traveling type) finisher equipped with an engine (concrete finishing). The noise with the case of using the (equipment) was measured at the side of the construction site. As the finisher of the comparative example, “CFM45001” manufactured by Fegel, rated output of 70 ps / DIN, and rated rotational speed of 2,500 rpm were used.

  As shown in Table 1, the measurement locations were three locations, a location 5 m away from the construction location, a location 10 m, and a location 15 m. As a result, it was 77 to 87 dB in the comparative example, whereas it was 68 to 73 dB in the example, and it was confirmed that the example could be reduced by about 10 dB on average from the comparative example. In particular, at a position of 5 m close to the construction site, the difference between the example and the comparative example was 14 to 17 dB, and it was confirmed that the reduction effect was large.

(Test Example 3)
Next, in order to confirm the effect of the above-described embodiment, the following test was performed.
Prepare two concrete slabs of width 1m × length 3m × thickness 0.2m from the above-mentioned floor slab 1 (see FIG. 1 and FIG. 2, etc.) The minute was removed and the aggregate was visible. And the wooden formwork of width 30mm x height 150mm was arrange | positioned around the concrete plate, and it fixed with the anchor.
Table 2 shows the mix of concrete used in this test. Here, the blend A according to the present embodiment is the concrete according to the present embodiment including the expanding material, and the blend B according to the comparative example is a general concrete including no expanding material.

  Concrete placement was performed using the above-described concrete finishing apparatus 10 (see FIGS. 1 to 4). The concrete used in this test was carried out using a mobile concrete production device in which a concrete material supply device and a concrete material kneading device were mounted on the truck bed. After the concrete was placed, the curing surface was sprayed with a curing agent and then covered with a vinyl sheet for curing. Table 3 shows the results of the slump test, the compressive strength test, and the adhesion strength test performed on the concrete thus placed.

  From the test results, the following can be said. In other words, regarding slump, the concrete of the present embodiment including the expansion material has the same value as the general concrete not including the expansion material, and has sufficient workability in placing the concrete. it is conceivable that. Regarding the compressive strength and adhesive strength, the concrete of the present embodiment shows a large value at each age compared to general concrete, and the strength of the concrete is improved by mixing in the expansion material. Conceivable.

  In addition, as shown in Table 3, the slump immediately after being discharged from the mobile concrete manufacturing apparatus is a small value of about 8 cm. This is because of the admixture mixed in the concrete to ensure the fluidity of the concrete. This is because it takes some time for the effect to appear. At the time of placing the soft concrete, a sufficient time has passed after the discharge, and a slump of 10 cm or more of the soft concrete is secured by the effect of the admixture. In other words, it is preferable to place the concrete in about 10 minutes after discharging in the concrete of this test.

As described above, in the floor slab reinforcement method according to the present embodiment, the soft concrete 2 can be subjected to high-frequency vibration and compacted, and the thickening of the floor slab 1 can be finished into a thin layer. Therefore, the dead load corresponding to the thickness increase is reduced, the durability of the floor slab is enhanced, and the quality can be improved.
Moreover, in the concrete finishing apparatus used for the floor slab reinforcement method according to the present embodiment, the concrete finishing apparatus 10 having a simple and lightweight structure in which the high frequency vibrator 13 is attached to the screed plate 12 is used by reducing the thickness. Therefore, it is not necessary to use a large-sized concrete finishing device equipped with an engine as in the past, and noise and vibration caused by floor slab reinforcement work can be reduced. For example, in urban highways It can also be used at construction sites such as in central Tokyo.

As mentioned above, although embodiment of the floor slab reinforcement method and concrete finishing apparatus used for it by this invention was described, this invention is not limited to said embodiment, It changes suitably in the range which does not deviate from the meaning. Is possible.
For example, in this embodiment, as the hydraulic composition, calcium sulfoaluminate composition 100 containing 3 to 60% by mass of calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) and 1 to 40% by mass of anhydrous gypsum. relative to the weight section, but the specific surface area is a material containing 0.1 to 3.0 parts by weight of lithium carbonate 1000~4000cm ² / g, it is not limited thereto, for example, 3CaO · _SiO 2, A fast-hardening cement containing 11CaO · 7Al ₂ O ₃ · CaF, C ₂ S or the like can be employed.

The concrete configuration such as the size and shape of the concrete finishing device 10, the mounting position and quantity of the high-frequency vibrator 13, and the mounting position of the towing winch 14 are optimal in consideration of the construction conditions of the floor slab to be implemented. To design.
In the present embodiment, the formwork 23 is used as a reference for the finished height of the soft concrete (reference numeral 2a shown in FIG. 2), but the present invention is not limited to this. For example, long plate members (end plates) parallel to the traveling direction of the finishing device 10 are provided vertically at both ends of the outer bottom surface 11a of the main body 11 of the concrete finishing device 10, and the height of this plate member is set. The finished thickness of the concrete may be set, and the soft concrete 2 may be placed by advancing the finishing device 10 while bringing the lower end of the plate member into contact with the existing floor slab surface as the construction base surface.

  Further, the pair of left and right tow winches 14 and 14 can always be rotated in conjunction with each other, and can be switched so as to rotate separately on the left and right as necessary. Moreover, the winch 14 is not limited to what is rotated by human power, For example, it is good also as a structure driven with a power source with few noises and vibrations, such as an electric motor.

It is a perspective view which shows the outline | summary of the floor slab reinforcement method by embodiment of this invention. It is a front view of the concrete finishing apparatus in construction shown in FIG. It is a top view of a concrete finishing apparatus. (A) is the sectional view on the AA line shown in FIG. 3, (b) is the sectional view on the BB line similarly. It is a side view which shows a mobile concrete manufacturing apparatus. (A)-(d) is a figure which shows the construction process of floor slab reinforcement. 6 is a graph showing the results of Test Example 1. 6 is a graph showing the results of Test Example 1. 6 is a graph showing the results of Test Example 1. It is a figure which shows the result of Test Example 1. 6 is a graph showing the results of Test Example 1. 6 is a graph showing the results of Test Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Floor slab 2 Soft concrete 3 Mobile concrete manufacturing apparatus 10 Concrete finishing apparatus 11 Main body 11a Outer bottom face 12 Screed plate (screed)
13 High frequency vibrator 14 Towing winch 23 Formwork

Claims (9)

  A polishing process for cleaning the surface of the existing floor slab, a construction process for covering the surface of the cleaned floor slab with a soft concrete having a slump of 10 cm or more, and applying high-frequency vibration by a screed to tighten the soft concrete A floor slab reinforcement method, comprising: a compacting step of solidifying and integrating the existing floor slab.   The floor slab reinforcement method according to claim 1, wherein a thickness of the floor slab after compacting the soft concrete is increased in a range of 10 to 50 mm from a thickness of the floor slab before the polishing.   The floor slab reinforcement method according to claim 1 or 2, wherein the screed has a high frequency of 100 to 400 Hz.   The floor slab reinforcement method according to any one of claims 1 to 3, wherein the screed has a moving speed of 20 to 100 cm / min on the floor slab. The soft concrete includes water, a hydraulic composition, aggregate, an expandable admixture, and fibers, and the hydraulic composition has a hardening rate of the soft concrete of 10 N / mm ² or more in ^{2 to} 3 hours after construction. The floor slab reinforcement method according to any one of claims 1 to 4, wherein the method further exhibits compressive strength. The expandable _{admixtures, 3CaO · SiO 2 -2CaO · SiO} 2 -CaO- gap material based composition, 3CaO _· SiO 2 -CaO- gap material based composition, 2CaO _· SiO 2 -CaO- gap material based composition And a clinker composition and a gypsum having a CaO content of 50 to 92% by weight, comprising one or more compositions selected from CaO-porous material-based compositions. Plate reinforcement method. The hydraulic composition includes (1) 100 parts by mass of calcium sulfoaluminate composition containing 3 to 60% by mass of calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) and 1 to 40% by mass of anhydrous gypsum. On the other hand, it contains 0.1 to 3.0 parts by mass of lithium carbonate having a specific surface area of 1000 to 4000 cm ² / g, or (2) 3CaO · SiO ₂ , 11CaO · 7Al ₂ O ₃ · CaF, C ₂ S, etc. The floor slab reinforcement method according to claim 5 or 6.   The floor slab reinforcement method according to any one of claims 1 to 7, wherein the existing floor slab is a concrete floor slab or a steel floor slab.   A concrete finishing device used in the floor slab reinforcement method according to any one of claims 1 to 8, wherein the main body, the screed supported by the main body, spread and compacted with concrete, and the screed A concrete finishing apparatus, comprising: a high-frequency vibrator for applying high-frequency vibration to a traction winch for moving the main body and the screed relative to the floor slab.

Images