JP2008194883A - Concrete product and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a concrete product enhanced in productivity, good in work environment, producing no sludge and having excellent aesthetic surface by solving the point at issue inherent to the concrete product like a concrete pipe or the like having a synthetic resin in its inside and a steel material in its outer peripheral surface. <P>SOLUTION: In the manufacturing method of the concrete product having the synthetic resin in its inner peripheral surface and the steel material in its outer peripheral surface, highly flowable concrete with a slump flow of 65 cm or above is prepared and the prepared concrete is cast on the space between the inside form comprising the synthetic resin which constitutes the inner surface side of the concrete product and the outside form comprising the steel material which constitutes the outer surface side of the concrete product without detaching both forms after the concrete is cast and molded in the state that both forms are allowed to stand stationarily. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a concrete product and a concrete product, and in particular, a method for producing a concrete product such as a concrete tube having a synthetic resin tube provided on the inner peripheral surface for imparting a corrosion prevention function, and a concrete product, The present invention relates to a method for manufacturing a concrete product that does not require conventional centrifugal molding or vibration pressure molding, and a concrete product obtained by the manufacturing method.

  In general, when a concrete product is manufactured, a basic process of placing concrete in a mold is included, but depending on the type of concrete product, various methods are adopted. For example, as a concrete pipe manufacturing method, conventionally, concrete placed in a mold is compacted using a large centrifugal force generated by high-speed rotation (also referred to as centrifugal molding method), or concrete is filled. At this time, a method of compacting by applying strong vibration to the mold (also referred to as a vibration molding method) is known.

  However, in the above-mentioned centrifugal molding method, it takes about 1 hour for one centrifugal molding, and even when a commonly used triple centrifugal molding apparatus is used, only three pieces can be produced per hour. It has the problem of low productivity. Further, there is a problem that the noise generated by the centrifugal molding apparatus is extremely large and the working environment is extremely bad. Furthermore, there is a problem in that a large amount of sludge, called Noro, is generated by centrifugal molding from the peripheral surface of the pipe, and excess water, fine particles of cement, and mud in the aggregate are mixed. is there.

On the other hand, in the vibration pressure molding method, since it is possible to use a concrete with a low water cement ratio, immediate demolding from the mold is possible, and the productivity is high compared to the centrifugal molding method, There is an advantage that no sludge is generated.
However, the amount of cement paste is reduced so as not to cause deformation, deformation, sagging, etc. after molding, and because it uses solid concrete with a low water-cement ratio, it is insufficiently filled even under strong vibrations. As a result, the surface of the concrete pipe obtained by the vibration pressure forming method has a problem that corners, voids such as bean plates, etc. are likely to occur.

  By the way, a synthetic resin pipe may be provided on the inner peripheral surface of the concrete pipe as described above in order to provide an anticorrosion function, and the outer peripheral surface of the concrete pipe is bent when used as a propulsion pipe. A steel pipe may be provided in order to provide a function of increasing resistance to a load and improving external pressure strength, and the manufacturing method of a concrete pipe having such a configuration requires another manufacturing process. However, as a method of manufacturing a concrete pipe having such a configuration, the centrifugal molding method or the vibration pressure molding method as described above is basically employed, and the above-described problems similarly occur. .

  In addition, there are problems inherent to the synthetic resin pipe provided on the inner peripheral surface. That is, in the case of the centrifugal molding method, after forming the concrete pipe by compacting using centrifugal force as described above, a synthetic resin pipe is attached to the inner surface side of the concrete pipe. Since the synthetic resin pipe is attached as the inner pipe, there is a problem that it takes time.

In addition, when a synthetic resin tube is installed in advance as an inner mold rather than retrofitting and centrifugal molding is performed, there is a risk of mold displacement and distortion due to high-speed rotation. In addition, since the concrete is tightened to the outer mold side by centrifugal molding, there is a high possibility that a gap is generated between the inner mold and the concrete. As a result, the synthetic resin pipe and the concrete cannot be kept together, and there arises a problem that the function of the synthetic resin pipe as the inner pipe cannot be achieved.
On the other hand, as a method of manufacturing a concrete pipe in which a synthetic resin pipe is provided on the inner peripheral surface, and employing a vibration pressure forming method, there is a technique as described in Patent Document 1 below. In this Patent Document 1, a synthetic resin pipe is erected in the longitudinal direction so as to be an inner surface of a concrete pipe to form an inner mold, and an adhesive is applied to the outer peripheral surface of the synthetic resin pipe. A method is disclosed in which an outer mold frame is erected on the outside of the inner mold frame at a predetermined interval in parallel with the inner mold frame, and then concrete is placed between the inner mold frame and the outer mold frame.

JP 2001-260124 A

  However, since the vibration pressure forming method imparts vibration to the mold as described above, it is necessary to attach a fixture or the like so that the synthetic resin pipe as the inner mold does not shift. Installation and removal work is required, which takes time. In the method disclosed in Patent Document 1, a special adhesive is applied to the outer peripheral surface of the synthetic resin pipe for adhesion to the concrete pipe, and such an adhesive application step is necessary. This also complicates the manufacturing process.

  Furthermore, in the method disclosed in Patent Document 1, it is assumed that only general-purpose concrete is placed. However, the general-purpose concrete disclosed in Patent Document 1 is poor in self-filling property, and this When performing the vibration pressure forming method using concrete with poor self-filling properties, the problems of the vibration pressure forming method such as the above-mentioned corner chipping and voids such as bean plate occur, and the necessary strength for the concrete pipe is obtained. It may not be possible.

Further, shown as a unique problem due to the steel pipe is provided on the outer peripheral surface, if the integrity of the steel and the concrete is not maintained, the same deformation behavior of steel and concrete against a load due to the effect of peanut brittle and voids As a result, there also arises a problem that the external pressure strength is reduced.

  The present invention has been made to solve the problems caused by the conventional centrifugal molding method and the vibration pressure molding method as described above, and has high productivity, a good working environment, and no sludge. Another object of the present invention is to provide a method for producing a concrete product capable of producing a concrete product with excellent product solidity. Another object of the present invention is to solve problems inherent in a concrete product such as a concrete pipe having a synthetic resin on the inner peripheral surface and a steel material on the outer peripheral surface.

  The present invention is a method for producing a concrete product having a synthetic resin on the inner peripheral surface and a steel material on the outer peripheral surface, wherein a high-fluidity concrete having a slump flow of 65 cm or more is prepared and removed after placing the concrete. The prepared concrete is placed between an inner frame made of synthetic resin that constitutes the inner surface side of the concrete product and an outer frame made of steel material that constitutes the outer surface side of the concrete product without being removed after placing the concrete. A method for producing a concrete product is provided, wherein the concrete is molded while being placed and the inner frame and the outer frame are left stationary.

In the method for producing a concrete product according to the present invention, it is preferable that the high fluidity concrete has a slump flow 50 cm arrival time of 5 to 10 seconds. Preferably, an expansion material is added to the high fluidity concrete. More preferably, the expansion material is added so that the expansion amount of the concrete is 150 × 10 ^{−6 to} 700 × 100 ⁻⁶ . More preferably, the expansion material is a calcium sulfoaluminate-based expansion material, and the amount of the expansion material added is 20 to 50 kg per 1 m ^{3 of} concrete.

  The present invention also provides a concrete product manufactured by the method for manufacturing a concrete product as described above.

High-fluidity concrete with a slump flow of 65 cm or more is excellent in self-filling properties, so such high-fluidity concrete is placed between an inner frame made of synthetic resin and an outer frame made of steel. By doing so, a concrete product in which the space between the inner frame and the outer frame is filled densely can be obtained. Moreover, since such a dense concrete product can be obtained without adopting the centrifugal molding method or the vibration pressure molding method, the centrifugal molding method is used between the synthetic resin provided on the inner peripheral surface and the concrete. Therefore, it is possible to produce a concrete product excellent in the integrity of concrete and synthetic resin and concrete and steel without using an adhesive.
In addition, since no special equipment such as centrifugal molding or vibration pressure molding is required, the productivity is high and the working environment is good. Simple concrete products can be manufactured easily.

Further, when high-fluidity concrete to which an expansion material is added is placed between an inner frame made of synthetic resin and an outer frame made of steel, shrinkage of the concrete is suppressed or the concrete expands. Therefore, it is difficult for gaps to occur between concrete and synthetic resin, or between concrete and steel, and the integrity between concrete and synthetic resin, and between concrete and steel can be improved without taking measures such as adhesives. It can be further enhanced.
Furthermore, the concrete product according to the present invention is in a solid filling state and is low in manufacturing cost.

  The method for producing a concrete product according to the present invention, as described above, prepares a high-fluidity concrete having a slump flow of 65 cm or more, and forms an inner side made of a synthetic resin that constitutes the inner surface side of the concrete product without removing it after placing the concrete. By placing the prepared concrete between a frame and an outer frame made of steel, and molding the concrete while leaving the inner frame and the outer frame stationary, A concrete product having a synthetic resin and a steel material on the outer peripheral surface is manufactured.

The high-fluidity concrete having a slump flow of 65 cm or more used in the present invention is obtained by measuring the slump flow of fresh concrete by the method specified in “Method of testing slump flow of concrete” in JIS A 1150. It is a concrete whose average value of the measurement results is 65 cm or more.
Therefore, for example, when the measurement result obtained by the test method described in the above JIS is a slump flow of 70.0 × 69.0 (cm × cm), the average value is 69.5 (cm ) Is the slump flow in the present invention.

Further, in the high fluidity concrete having a slump flow of 65 cm or more used in the present invention, it is preferable that the time for the slump flow to reach 50 cm (also referred to as the slump flow 50 cm arrival time in the present invention) is 5 to 10 seconds. .
Use of such a high-fluidity concrete has an effect that the mold can be filled uniformly without causing material separation.

The composition of such high fluidity concrete is not particularly limited, for example, adjustment of water / binder ratio, addition of admixtures such as silica fume, fly ash, blast furnace slag fine powder, limestone fine powder, or It can be obtained by adjusting the fluidity by adding an admixture such as a water reducing agent, a high performance water reducing agent, and a high performance AE water reducing agent.
The water / binder ratio here refers to the weight of water relative to the total weight of cement as a binder and cement admixture (silica fume, fly ash, blast furnace slag fine powder, etc.) having pozzolanic activity or hydraulic properties. Ratio (%).

  In particular, in the present invention, it is preferable to prepare a high-fluidity concrete having a predetermined slump flow by blending silica fume.

  When silica fume is used, specifically, it is preferably blended so as to have a replacement amount of 5 to 25% by weight with respect to the cement, and more preferably blended so as to have a replacement amount of 10 to 20% by weight. preferable.

From the viewpoint of increasing the strength of the concrete product to be produced, it is preferable that the silica fume, water reducing agent, etc. are blended to make the water / binder ratio 40% or less.
That is, by preparing high-fluidity concrete by blending silica fume, water reducing agent, etc., the fluidity in the fresh state can be enhanced while keeping the water / binder ratio low, and therefore the strength of the concrete product after curing is increased. There is an effect that it can be increased.

  Although it does not specifically limit as said silica fume, The thing which has silicon dioxide as a main component and contains a zirconium oxide (henceforth a specific silica fume) can be used suitably. The specific silica fume is obtained mainly as a silica fume by-produced in the production process of zirconia, and has a larger average particle size and a lower pH than a conventional general silica fume. Therefore, such a specific silica fume has the property that most of the particles are present in the state of primary particles and hardly agglomerate, and the effect of delaying the setting of the concrete is moderately exerted and the fluidity is hardly lowered. have.

  In addition, when such a specific silica fume is used in combination with an expansion material, it becomes a high fluidity concrete that does not cause material separation and has good self-filling properties. Then, the concrete is prepared at a water / binder ratio of 30% or less, placed in a mold, and the concrete is molded while the mold is left standing, thereby providing conventional molding such as centrifugal molding and vibration molding. It becomes possible to manufacture a concrete product having strength and aesthetics equivalent to or higher than the manufacturing method described above.

  The specific silica fume is not particularly limited with respect to its production method, raw material, and the like, but those mainly produced as a by-product in the production process of zirconia can be preferably used. Further, the silica fume does not have to satisfy the quality defined in JIS A 6207 “Silica fume for concrete”.

  The amount of silicon dioxide that is the main component of the specific silica fume is preferably 85% by weight or more, and more preferably 90% by weight or more. Further, the content of zirconium oxide as one component of the specific silica fume is preferably 1 to 10% by weight, more preferably 3 to 5% by weight.

The specific silica fume preferably has a specific surface area of 10 m ² / g or less, more preferably 9 m ² / g or less. Conventionally, silica fume generally used as an admixture for cement has a specific surface area of 15 m ² / g or more, whereas the silica fume has a relatively small specific surface area as described above. .

  The specific silica fume preferably has an average particle size of 0.5 to 1.5 μm, more preferably 0.8 to 1.2 μm. If the average particle size of the specific silica fume is in the above range, the aggregation of the specific silica fume is suppressed, the dispersibility in the concrete is good, and the predetermined fluidity is exhibited even when used in combination with an expansion material. As with conventional silica fume, it is possible to produce dense concrete with high strength by the microfiller effect and the pozzolanic reaction.

  The average particle size of silica fume is measured based on the Japan Cement Association “Standard Test Method (CAJS K-03-1982 / Friction Test Method Using Air Jet Sieve Device)”.

In addition, when silica fume is blended in the present invention, the silica fume preferably has a pH of 2.5 to 6.5, more preferably 4.0 to 5.0. If the pH of the silica fume is in the above range, the setting delay action of the concrete is adequately exerted, so the flow loss is reduced, the workability at the time of construction is improved, and the denser and higher strength concrete. There is an effect that can be manufactured.
The pH of silica fume is measured based on JIS Z 8802-1986 “pH measurement method”.

  Furthermore, in the present invention, it is preferable to add an expansion material to the high fluidity concrete. The type of the expansion material is not particularly limited, and a conventionally known expansion material can be used. Among them, an expansion material having a quality defined in JIS A 6202 “Expansion material for concrete” can be preferably used. it can.

  Specifically, as the expanding material, calcium sulfoaluminate-based and quicklime-based expanding materials can be used alone or in combination.

When adding the expansion material to the high fluidity concrete, it is preferable to add the expansion material so that the expansion amount of the concrete is 150 × 10 ^{−6 to} 1000 × 10 ⁻⁶ , and the expansion amount of the concrete is 500 it is preferable to add an expansion member so as × a 10 ^-6 ~800 × 10 ^-6. When the amount of expansion of the concrete is within the above range, the concrete expands appropriately due to the action of the expansion material, and the synthetic resin and the concrete are better integrated. In particular, it is particularly effective that the length change of the concrete after hardening is not contracted but on the expanded side even after three months.
In addition, the amount of expansion of concrete is converted to a ratio of “length change rate L _r (%)” obtained based on method B of JIS A 6202 Annex 2 “Testing Method for Restrained Expansion and Shrinkage of Expanded Concrete”. That is, the value obtained by dividing the “length change rate L _r (%)” by 100.

When the expansion material is a calcium sulfoaluminate-based expansion material, the addition amount of the expansion material is preferably 20 to 50 kg, more preferably 30 to 40 kg per 1 m ^{3 of} concrete. By setting the upper limit of the amount to be added as described above, it is possible to reduce the risk of the unreacted expansion material expanding slowly and destroying concrete.

  Moreover, when using a silica fume and an expansion material together, it is preferable that the mixing ratio (weight ratio) of a silica fume and an expansion material shall be silica fume: expansion material = 60: 40-70: 30, and a silica fume: expansion material = 60: It is more preferable to set it as 40-65: 35.

  In addition, the cement used in the present invention is not particularly limited. Examples of the cement include normal, early strength, ultra-early strength, white, sulfate-resistant salt, moderate heat, low heat, and other Portland cements, the Portland cement. Examples thereof include mixed cement obtained by mixing blast furnace slag, fly ash, etc., jet cement, alumina cement and the like.

The amount of water in preparing the concrete is preferably such that the water / binder ratio is 40% or less, more preferably 15 to 30%, and particularly preferably 10 to 20%.
By setting the water / binder ratio in such a range, it was possible to perform demolding in a short time after filling while maintaining excellent self-filling property when filling into the frame, and manufactured. Concrete products have high compressive strength and external pressure strength.
In particular, by producing a high-strength concrete pipe with a water / binder ratio of 10 to 20%, the produced concrete pipe can be laid in the ground using a propulsion pipe method. .

  When preparing concrete, various materials as described above are kneaded using various conventionally known concrete mixers.

  A concrete product can be obtained by placing the concrete prepared as described above between an inner frame and an outer frame, and molding and curing the concrete while the frame is left standing. . In the present invention, various synthetic resin molded products such as synthetic resin pipes are used as the inner frame, and various steel materials such as steel pipes are used as the outer frame.

  That is, when a concrete product having a desired shape such as a concrete pipe is manufactured according to the present invention, an inner frame made of a synthetic resin pipe and an outer frame made of a steel pipe are installed in advance, and the inner frame and the outer A concrete product having a predetermined shape can be obtained by placing the concrete prepared as described above between the frames, molding the concrete while leaving the formwork still, and curing the concrete. .

  Here, as the synthetic resin, for example, a thermoplastic resin made of polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl chloride, fluorine resin, ABS resin, AS resin, or the like can be used. The synthetic resin is selected according to the application of the concrete product to be manufactured.

  On the other hand, as said steel material, what consists of stainless steel, iron, etc. can be used, for example.

  These inner and outer frames can be of any configuration depending on the intended concrete product. In particular, the high-fluidity concrete used in the present invention has high self-filling property as described above, and it is not necessary to apply centrifugal molding or strong vibration during filling. Therefore, these frames are also subjected to centrifugal molding and strong vibration. It is not necessary to use a material that can withstand high rigidity. Also, the shape of the frame can be any shape, and the type of concrete product is not limited to the concrete pipe, and can be products of various shapes.

  The high-fluidity concrete used in the present invention has a slump flow of 65 cm or more as described above and has a high self-filling property. Therefore, when filling the concrete into the frame, centrifugal molding or strong There is no need to apply vibration. However, vibrations may be applied within a range in which material separation does not occur from the viewpoint of surely preventing corner chipping, bean plate, and soot from occurring on the concrete surface.

  Moreover, it is also possible to shape | mold as a concrete product containing reinforcing bars, such as a reinforced concrete pipe, by arranging a reinforcing bar in the frame beforehand.

  Specifically, the concrete self-filled in the frame has a strength capable of handling the product in at least 24 hours.

As described above, according to the method for producing a concrete product according to the present invention, it is not necessary to use a high-rigid formwork that has been used in the conventional production method, and thus the steel material that reinforces the formwork is omitted. This can greatly reduce the production cost of the formwork.
Further, according to the method for producing a concrete product according to the present invention, a large noise is not generated at the time of molding, so that the working environment is improved and no sludge is generated, so that the processing cost is not required.
Further, since a large-sized device such as a centrifugal molding device or a vibration molding device is not required, there is an advantage that the cost required for capital investment is lower than that in the past.
In addition, there is an advantage that a concrete product excellent in the integrity of the steel material provided on the outside, the synthetic resin provided on the inside, and the concrete filled therebetween is provided.

  The materials shown in Table 1 below were kneaded with the composition shown in Table 2 below using a biaxial forced kneading mixer with a capacity of 55 liters to prepare concretes of Preparation Examples 1 to 5.

(Measurement of fresh properties)
Regarding the concretes of Preparation Examples 1 to 5, the slump flow defined in JIS A 1150 “Concrete slump flow test method” was measured as a fresh property when the concrete was prepared. The measurement results are shown in Table 3 below.

(Compressive strength test)
Based on the test method defined in JIS A 1108 “Testing method for compressive strength of concrete”, the compressive strength of the concrete of Preparation Examples 1 to 5 on the 14th day of the φ10 × 20 cm specimen was measured. The measurement results are shown in Table 3 below.

(Measurement of concrete expansion)
The expansion amount of the concrete was measured based on the method B of JIS A 6202 Annex 2 “Testing Method for Restrained Expansion and Shrinkage of Expanded Concrete”. The results are shown in Table 3 below.

  Next, concrete pipes were prepared using the concretes of Preparation Examples 1 and 3, and the integrity of the concrete, the synthetic resin pipe, and the steel pipe was evaluated.

(Example)
A synthetic resin pipe (outer diameter 114 mm, pipe thickness 3.1 mm, effective length 300 mm) is set as the inside, and a steel pipe (outer diameter 200 mm, pipe thickness 2.3 mm, effective length 300 mm) is set as the outside. The concrete of Examples 1 and 3 was cast. When placing, both the synthetic resin pipe and the steel pipe were placed so that the effective length direction was vertical, and the concrete was poured from above at a speed of 100 mm / sec. Next, after 24 hours had passed from the placement, concrete sheets of Examples 1 and 2 were produced by sealing with a vinyl sheet and curing in a thermostatic chamber at 20 ° C. for 13 days after sealing.

(Integrity evaluation between concrete, synthetic resin pipe and steel pipe)
When installed in a pressure tester so that a load is applied in the radial direction of the obtained concrete pipes of Examples 1 and 2, when the load was applied at a loading speed of 0.5 mm / min, cracks were confirmed in the concrete pipe. The load at the time was measured. The results are shown in Table 4 below.

  According to the results shown in Table 4, the concrete pipes of Example 1 and Example 2 both have excellent strength in the radial direction, which is between the inner synthetic resin pipe and the outer steel pipe. It is considered that the filled concrete exhibited excellent integration with these synthetic resin pipes and steel pipes. In particular, the concrete pipe of Example 2 using concrete added with an expanding material has a markedly improved radial strength compared to the concrete pipe of Example 1 using concrete without adding an expanding material. It is recognized that That is, in the concrete pipe of Example 2, due to the expansion of the concrete, the integrity of the inner synthetic resin pipe, the outer steel pipe, and the concrete filled therebetween is further improved, thereby significantly increasing the strength in the radial direction. This is thought to be an improvement.

  The method for producing a concrete product according to the present invention is not limited to products such as rebars or unreinforced concrete pipes conventionally produced by centrifugal molding, but also various cements 2 such as box culverts, retaining walls, water tanks, gutters, and RC segments. It can also be applied to the production of next products.

Claims (6)

  A method for producing a concrete product having a synthetic resin on the inner peripheral surface and steel on the outer peripheral surface, wherein a high-fluidity concrete having a slump flow of 65 cm or more is prepared and the concrete product is removed without being removed after placing the concrete. Placing the prepared concrete between an inner frame made of synthetic resin that constitutes the inner surface side and an outer frame made of steel that constitutes the outer surface side of the concrete product without removing after the concrete is cast, A method for producing a concrete product, wherein the concrete is molded while the inner frame and the outer frame are left stationary.   The method for producing a concrete product according to claim 1, wherein the high fluidity concrete has a slump flow 50 cm arrival time of 5 to 10 seconds.   The method for producing a concrete product according to claim 1 or 2, wherein an expansion material is added to the high fluidity concrete. The method for producing a concrete product according to claim 3, wherein the expansion material is added so that the amount of expansion of the concrete is 150 × 10 ^{−6 to} 1000 × 10 ⁻⁶ . 5. The method for producing a concrete product according to claim 3, wherein the expansion material is a calcium sulfoaluminate-based expansion material, and the amount of the expansion material added is 20 to 50 kg per m ³ of concrete.   A concrete product manufactured by the method for manufacturing a concrete product according to any one of claims 1 to 5.