JPH0780811A - Production of concrete or mortar for immediate removal after pressurization vibration molding - Google Patents

Abstract

PURPOSE:To prevent deformation of a molded piece at the time of removal by a method wherein a water absorptive resin kept in a granular form even after it absorbs water and swells is in a fluid state in a water-absorbing state, and handleable resin-mixed water is used as kneading water in producing a concrete for immediate removal after pressurization CONSTITUTION:A water absorptive resin that is not gelled but kept in a granular form even after it absorbs water and swells is dispersed in kneading water, whereby a part of the kneading water is previously absorbed in the water absorptive resin. Therefore, in kneading materials, such as a cement and a fine aggregate, by a mixer, granulation is prevented. Namely, in the resin in a water-absorbing state in the kneading water, water absorbed at the time of kneading under an alkali atmosphere is temporarily retained, and the same effect as that of reducing an apparent unit water amount is obtained. Thus, granulation can be remarkably reduced. At the time of pressurization vibration molding, the retained water is released, and kneaded material can be ideally loaded. At the time of frame removal, a molded piece is hardly deformed and burred.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a concrete or mortar, that is, a cement-based compound for pressure vibration molding immediate demolding.

[0002]

2. Description of the Related Art The prior art and problems for increasing the strength of concrete or mortar for immediate demolding, which is a superhard kneading, are as follows.

(1) Method by blending and admixture Reduction of water / binder ratio Immediate demolding of pressure vibration molded concrete and mortar suffer from deformation, sag and burrs due to their own weight during demolding after pressure vibration formation. To control, it is necessary to use damp, sandy material. Increasing the unit water content in the formulation,
Although the porosity of the molded body is reduced, when the mold is released after the pressure vibration is formed, there is a problem that deformation due to its own weight, sagging, and burrs occur. On the contrary, when the unit water amount is reduced, the kneaded product becomes dry and the porosity increases without being compacted even when the pressure vibration molding is performed. The unit amount of water, which has good compaction property, can reduce the porosity of the molded body, and can suppress the deformation, sag, and burr of the molded body at the time of demolding, is limited to a narrow range.

The most effective and general method for strengthening concrete or mortar is to reduce the water-binder ratio as much as possible with excellent filling properties so that the porosity of the molded body can be reduced. . However, simply by decreasing the unit water amount or increasing the unit cement amount, the kneaded product becomes dry even if the water binder ratio can be reduced, and the porosity after molding is large, so the molded body is It cannot be effectively strengthened.

It is essential to use a water reducing agent in order to reduce the porosity of the molded body and the water binder ratio by the pressure vibration molding. However, when a water-reducing agent is used and the water-binder ratio is reduced, the amount of unit water should be as small as possible in order to suppress deformation at the time of demolding due to its own weight, and the kneaded product does not become dry and compactable and compacted If the unit water amount is sufficient to reduce the porosity of No. 3, the fine material such as cement or fine aggregate is remarkably granulated during the material kneading in the mixer, which causes a problem that homogeneous kneading cannot be performed. In particular, as the addition amount of the water reducing agent is increased or the strength is increased by using the high-performance water reducing agent having a large water reducing property, the problem that the granulated lumps in the kneaded product become remarkable occurs.

Use of high-strength admixture As an admixture used to increase the strength of pressure vibration molding immediate demolding concrete or mortar, there are inorganic fine powders such as anhydrous gypsum and silica fume. However, even when these admixtures are used, the strength cannot be effectively increased unless a water reducing agent is used in combination and the water binder ratio is reduced. Moreover, since the admixture is a fine powder, the unit water content is as small as possible in order to suppress the deformation at the time of demolding due to its own weight, and the kneaded product does not become dry, compaction is possible and the porosity of the compact is small. The generation of agglomerated lumps of the kneaded product when the unit water amount is sufficient to achieve the problem becomes more remarkable than when no admixture is used.

[0007] As shown in the above, when a water-reducing agent is used to reduce the water-binder ratio to achieve high strength, the unit water amount is made as small as possible in order to suppress deformation at the time of demolding due to its own weight, and When the kneaded material does not become dry and can be compacted and the unit water amount is sufficient to reduce the porosity of the molded body, during the material kneading in the mixer, fine materials such as cement and fine aggregate are significantly granulated. The problem arises. The following problems occur with the occurrence of granulation of the material.

(I) Due to the occurrence of granulation, it is not possible to sufficiently knead the materials into homogeneous concrete and mortar. Further, the granulated mass is mainly composed of a fine powder material such as cement and fine aggregate, and even if the unit cement amount is increased or a fine powder admixture such as silica fume is added, the amount of the granulated mass becomes In many cases, the increase in the unit cement amount and the addition of the finely powdered admixture do not work effectively for increasing the strength.

(Ii) Concrete and mortar in which granulated lumps are generated have a large porosity of the molded body even if subjected to pressure vibration molding as compared with those not granulated, and the void ratio of the molded body is large. Easy to remain. As a result, the molded product is inferior in strength properties, and voids are conspicuous in appearance and inferior in aesthetics.

In order to reduce the generation of granulation, the unit amount of water should be greatly reduced, but since the kneaded product is dry and dry, the compaction property by pressure vibration molding is poor,
Since the porosity of the molded product is remarkably increased, and further, the water required for hydration of cement is not sufficiently supplied, the developability of strength is remarkably poor, and a high-strength molded product cannot be obtained.

On the contrary, even if the unit amount of water is increased for the purpose of reducing the porosity of the molded body and supplying sufficient water for hydration of the cement, the amount of granulated agglomerates also increases accordingly. .
Also, as the unit water volume is increased, the deformation of concrete and mortar due to its own weight becomes noticeable at the time of demolding after pressure vibration molding, causing sagging and blistering, and it is not possible to obtain a predetermined shape as a molded body, and dimensional accuracy Inferior in quality, and burrs are generated on the bottom of the molded body, which causes a serious problem in manufacturing.

(2) Method by compaction The pressure vibration molding method to which the present invention is applied is vibration molding (frequency 2000 to 12000 rpm) under a relatively low pressure (0.1 to 10 kgf / cm ² ). Degree, amplitude 0.2
Is about 2.0 mm) and is a typical and general method for instant demolding compaction for compacting concrete or mortar. The pressure vibration condition has been studied so far, and it has been known that it has an excellent compaction effect and is industrially advantageous.By changing the pressure vibration condition, it is not possible to significantly increase the strength. It will be a disadvantage.

As another compaction method capable of immediate demolding, a high-pressure press molding method (pressurizing pressure: 10 to 500 kgf /
cm ² ). However, the high-pressure pressing method requires a hydraulic device with a large capacity, and it is difficult to apply it to those with a large pressure cross-sectional area and thick molding thickness, and it is not possible to use aggregates with a large particle size. Has the drawback of.

(3) Method by Curing There is a method of increasing the strength by subjecting the molded body after immediate mold release to autoclave curing using a pressure vessel. When silica fine powder is used as an admixture, a strength increase of about 10% can be seen, but this method can only be applied after the compounding and molding problems of (1) and (2) above are eliminated. is there.

(4) Method by impregnation treatment after hardening of molded body There is a method of impregnating and filling a polymer (for example, methylmethacrylate), heated molten sulfur, or the like into voids of a concrete or mortar cured body to increase strength. . This method requires special equipment and processes for drying, heating, degassing, and impregnating the concrete or mortar hardened material that is the base material, and the cost of the impregnating agent is high, so products can be manufactured at low cost. It has the drawback that it cannot.

As described above, according to the conventional technique in which the water binder ratio is reduced by using the water-reducing agent to increase the strength, the moldability suitable for the pressure vibration molding immediate mold release and the shape retention property at the time of mold release are obtained. However, it was not possible to produce a homogeneous concrete and mortar kneaded product that satisfies the above requirements and suppresses granulation of the material during kneading. Therefore, it was not possible to effectively increase the strength by taking advantage of the performance of the material and the composition. Also, due to the influence of the granulated mass, large voids are likely to occur as defects in the molded body, but this is not only disadvantageous in terms of strength, but it is also a major problem that it is not possible to manufacture products with excellent appearance and aesthetics. Met.

However, the strength obtained by the general method of immediate release from pressure and vibration without any special post-treatment such as impregnation of the molded body is about 500 kgf / cm ^{2 in} compressive strength and in bending strength. The limit of about 80 kgf / cm ² was a practical limit that allows easy industrial production.

The present invention does not require a special instant demolding apparatus, and does not impregnate the molded body after molding, and uses a conventional pressure vibration immediate molding machine, The feature is that concrete or mortar can be strengthened by general curing (eg steam curing, autoclave curing, natural curing, etc.), and when a water reducing agent is used to reduce the ratio of water binder to increase the strength, self-weight In order to suppress the deformation at the time of demolding due to, the unit water amount is as small as possible, and the kneaded product does not become dry, and the unit water amount is sufficient for compaction and to reduce the porosity of the molded body. During the mixing of materials, the problem that homogeneous materials cannot be mixed because fine materials such as cement and fine aggregate are remarkably granulated is eliminated, and concrete and mortar with excellent homogeneity and filling properties can be obtained. It is intended to provide a method for efficiently and industrially producing a high-strength, pressure-vibration-molded concrete or mortar for immediate demolding that can suppress deformation and burrs due to its own weight during demolding. is there.

[0019]

A method for producing concrete or mortar for immediate release from pressure vibration molding according to claim 1 is a method for immediate removal from pressure vibration molding including cement, aggregate, water, admixture, water reducing agent and the like. In a method for producing mold concrete or mortar, a water-absorbent resin that does not gel and remains granular after water-swelling is dispersed and suspended in water and mixed with water-absorbent resin that can be handled as a fluid state when the water-absorbent resin absorbs water. It is characterized in that water is used as kneading water.

The method for producing concrete or mortar for rapid vibration molding immediate demolding according to claim 2 is the method according to claim 1, wherein the water mixed with the water-absorbent resin is water containing the water-absorbent resin as kneading water. 1.1 Water absorption capacity of water absorbent resin
It is characterized in that it is water mixed with a water-absorbent resin that can be handled as a fluid state by dispersing and suspending it in twice to 4.0 times as much water.

According to a third aspect of the present invention, in the method for producing concrete or mortar for pressure vibration molding immediate demolding, in the method of the first or second aspect, the admixture is a fine powder inorganic substance.

The method for producing concrete or mortar for pressure vibration molding immediate demolding according to claim 4 is the method according to any one of claims 1 to 3, further comprising reinforcing fibers for concrete or mortar. It is characterized by

[0023]

[Operation] As for the concrete and mortar for pressure vibration molding immediate demolding, it is necessary to use damp sand with a small amount of water in order to suppress deformation, sagging and burrs due to its own weight during demolding. is there. However, when a water reducing agent is used to increase the strength, the unit water content is as small as possible in order to suppress the deformation at the time of demolding due to its own weight, and the kneaded product does not tend to be dry, and compaction is possible with compaction. If the amount of unit water is sufficient to reduce the porosity, a homogeneous concrete or mortar cannot be obtained because the fine material such as cement or fine aggregate is remarkably granulated during the material kneading in the mixer. If the unit water volume is greatly reduced to suppress granulation,
Although granulation is reduced, even if pressure vibration molding is performed, compaction does not occur, the porosity becomes extremely large, and water required for the hydration reaction of cement is insufficient, so high strength cannot be obtained.

According to the present invention, the water-absorbent resin which does not gel even after water-swelling and swelling is dispersed in the kneading water, and a part of the kneading water is preliminarily absorbed by the water-absorbing resin. It is possible to significantly reduce the generation of granulation when kneading the material with the mixer, and to knead the material uniformly. The water-absorbed resin in the kneading water, when kneaded with a material such as cement in the mixer, in an alkaline atmosphere of the kneaded product,
Although it gradually releases the absorbed water, it does not release all the water at the end of the kneading and keeps part of it in a water retaining state. Therefore, apparently, the same effect as that of reducing the unit amount of water is obtained, and the granulation of the kneaded product is significantly reduced.
Further, since the granulation is remarkably reduced, the materials can be uniformly kneaded. Further, according to the present invention, when pressure-kneading the kneaded product, part of the water retained in the water-absorbent resin even after the kneading is released during the pressure-vibration molding,
In order to improve the filling property of the kneaded product, the molded product can have a low porosity. In addition, it also has the effect of reducing deformation of the molded body due to its own weight and occurrence of burrs at the bottom at the time of demolding after pressure vibration molding, so that a high-strength molded body with satisfactory dimensional accuracy as a product can be obtained. .

The water-absorbent resin is dispersed in water which is 1.1 times to 4.0 times, more preferably 1.1 times to 2.0 times, the water absorbing capacity of the water absorbing resin in water used as kneading water. -The effect of the present invention can be obtained by using in a state of being suspended and sufficiently absorbed water. It is not effective to mix the water absorbent resin with water having a water absorption capacity of more than 4.0 times. In addition, the water absorption capacity of 1.
When mixed with less than 1 time of water, it can no longer be industrially handled as a fluid state, the workability is poor, the handling becomes difficult, and the dispersion in the mixer becomes worse.

Although some water-absorbent resins gel when water is absorbed, such water-absorbent resins, on the contrary, increase the viscosity of the kneaded product and, on the contrary, remarkably generate granulated lumps. It cannot be used in the present invention.

Further, it has the following great advantages in industrial handling. That is, since the water-absorbent resin is dispersed and suspended in the kneading water and can be handled as a fluid state, if the kneading water mixed with a predetermined amount of the water-absorbing resin is prepared in the tank, the mixer is charged with the existing kneading water. The supply metering system can be used as is.

[0028]

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

The materials used are as follows.・ Cement: Early strength Portland cement ・ Silica fume: BET specific surface area 21 m ² / g ・ Fly ash: Blaine specific surface area 3800 cm ²
/ G-Aggregate 1: Mixed sand of mountain sand and crushed sand-Aggregate 2: Crushed stone (particle size 2.5 to 10 mm) -Water: Tap water-Water reducing agent: Polycarboxylic acid high-performance water reducing agent-Carbon fiber: PAN-based, fiber length 12 mm-Water-absorbent resin: polyacrylic acid-based spherical powder. The water absorption capacity in pure water is 600 times, and the water absorption capacity in the tap water used is about 240 times.

The kneading and molding methods for the materials and the respective test methods are as follows. Kneading and molding method Kneading is performed by using a forced-bread type mixer, and after kneading solid materials such as cement and aggregate for 30 seconds, kneading water mixed with high-performance water reducing agent and water-absorbent resin is added, and kneading is continued for 3 minutes. I did. The kneading water mixed with the water-absorbent resin can be sufficiently dispersed by adding a predetermined amount of the water-absorbent resin to tap water in a plastic container and stirring.
After suspending, the suspension was allowed to stand for 5 minutes or more to absorb water sufficiently.

In the case of concrete, the amount of water-absorbent resin mixed into tap water was 1/300 with respect to tap water. This is the water absorption capacity of the water absorbent resin in the tap water used.
This corresponds to the addition of 1.25 times the mixture of tap water to 0 times. On the other hand, in the case of mortar, the amount of the water-absorbent resin mixed into tap water was 1/275 with respect to tap water. This corresponds to the addition of 1.15 times more water to the tap water than the water absorption capacity of the water absorbent resin in the used tap water.

In the pressure vibration molding, concrete or mortar is put into a mold of 10 × 20 cm, and a pressing force is 0.25 k.
gf / cm ² , frequency 3140 rpm, amplitude 1.4 m
m, pressurizing time was 8 seconds, and then the molded body was pressed out from the mold with a press plate to produce a molded body having a length of 20 cm, a width of 10 cm, and a height of 8 cm.

Test method Evaluation test method for the amount of granulated lumps The degree of generation of granulated lumps in concrete is determined by sieving the kneaded concrete with a sieve and measuring the amount passing through each sieve to determine the generation state of the granulated lumps. evaluated. The degree of formation of granulated lumps in the mortar was visually evaluated.

Strength Test Flexural strength of mortar and concrete is 10 × 20 ×
Using a pressure vibration molded body of 8 cm, a span of 160 mm and a central one-point loading test method were used. Compressive strength Compressive strength of mortar and concrete is 10 × 20 ×
A φ8 cm × 8 cm core was sampled from the 8 cm pressure vibration molded body, and subjected to a compressive strength test.

Example 1 and Comparative Example 1 Table 1 shows the composition of Example 1 according to the present invention and the composition of Comparative Example 1 in which tap water containing no water absorbent resin was used as a kneading water for comparison. . Concrete was kneaded with the composition of Example 1 and the composition of Comparative Example 1, and a concrete sieving test was performed immediately after kneading. The results are shown in Table 3. Compared with Example 1, Comparative Example 1 had a larger amount of kneaded material with a larger particle size, and the portion passing through the 10 mm sieve had Example 9
Compared with 6%, 78% in Comparative Example 1 and 80% in the portion passing through the 5 mm sieve, and 38% in Comparative Example 1 against 80% in Example 1.
According to the method of the present invention, the degree of granulation could be significantly reduced.

Table 4 shows the observation results of the molded product after the pressure vibration molding immediate demolding, the porosity of the molded product, and the strength test result at 14 days of age. As can be seen from the table, according to the present invention, there is no deformation and burrs due to its own weight after the pressure vibration molding demolding, and the porosity of the molded body can be smaller than that of the comparative example. . Furthermore, the features are that the amount of granulation is extremely small, the concrete is homogeneously kneaded, the strength manifesting ability of the material can be effectively brought out, and large voids that cause a significant decrease in strength can be reduced. Therefore, as shown in Table 4, higher strength can be obtained as compared with the comparative example.

Examples 2 and 3 and Comparative Examples 2 and 3 As an admixture, silica fume which is a fine powder inorganic substance,
Example formulations according to the present invention using ash and fly ash are shown in Examples 1 and 2 of Table 1. Comparative examples 2 and 3 in Table 1 show examples in which tap water containing no water-absorbent resin was used as kneading water for comparison. Table 4 shows the observation results of the molded product after the pressure vibration molding immediate demolding in each example, the porosity of the molded product, and the strength test result at 14 days of age. Also in these examples, granulation during kneading was extremely small, and as shown in Table 4, the molded body was deformed by its own weight,
No burr was generated and the porosity was small, and in the example, high strength was obtained as compared with the comparative example. The finely powdered inorganic substance used as the admixture is not limited to the silica fume and fly ash of this example, and the blast furnace slag fine powder,
It can also be applied when an admixture such as limestone fine powder or silica fine powder is used.

Example 4, Comparative Example 4 It is generally known that when reinforcing fibers are mixed into concrete, granulated lumps and fibre-bar balls are more likely to be formed, as compared with the case where no fibers are mixed. The composition of the examples when carbon fibers are used as the reinforcing fibers are shown in Example 4 of Table 2 and the test results are shown in Table 4. As a comparative example in the case of using tap water containing no water-absorbent resin as the kneading water, the comparative formulation is shown in Comparative Example 4 in Table 2.
Table 4 shows the test results. As is clear from Table 4, according to the present invention, even when reinforcing fibers are mixed, the generation of granulated lumps and fiber balls can be remarkably reduced, and the void ratio of the molded body can be made small. It is possible to obtain a molded product with high strength. The reinforcing fiber is not limited to the carbon fiber of this embodiment, and can be applied to the case of using steel fiber, aramid fiber, glass fiber, vinylon fiber, polypropylene fiber, etc. used for concrete and mortar.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

Example 5 and Comparative Example 5 Also in the case of increasing the strength of a mortar containing a water reducing agent,
According to the present invention, it was confirmed that the same effects as in the case of concrete can be obtained, granulation can be significantly reduced, and a kneaded product excellent in filling property and moldability in pressure vibration molding can be obtained.

Table 5 shows the mortar formulations of Examples and Comparative Examples,
And the observation result of granulation by visual observation is shown. Table 6 shows the test results of the mortar compacts.

[0045]

[Table 5]

[0046]

[Table 6]

[0047]

As described in detail above, according to the method for producing a concrete or mortar for pressure vibration molding immediate demolding according to the present invention, a water reducing agent is used in the production of the concrete for pressure vibration molding immediate demolding or mortar. Used to increase the strength by lowering the cement ratio in water, reduce the generation of granulated lumps and obtain concrete or mortar that is homogeneous and has excellent filling properties.
In addition, it is possible to reduce deformation and burrs due to its own weight at the time of demolding, and to manufacture high-strength pressure vibration molding immediate demolding concrete or mortar efficiently and industrially advantageously. It

According to the method of the second aspect, it is possible to surely obtain a further excellent effect. According to the methods of claims 3 and 4, it is possible to manufacture high-performance, high-performance concrete or mortar by incorporating a fine powder inorganic substance or reinforcing fibers.

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Claims (4)

[Claims] 1. A method for producing concrete for pressure vibration molding immediate demolding or mortar comprising cement, aggregate, water, admixture, water-reducing agent, etc., which retains granularity without gelation even after water swelling. Manufacture of concrete or mortar for pressure vibration molding immediate release, characterized by using water mixed with water-absorbent resin that can be handled as a fluid state when the resin is dispersed and suspended in water and the water-absorbent resin absorbs water Method. 2. The method according to claim 1, wherein the water mixed with the water absorbent resin is 1.1 times to 4.0 times the water absorbing ability of the water absorbent resin in water using the water absorbent resin as kneading water. A method for producing concrete or mortar for rapid vibration molding immediate demolding, which is water mixed with a water-absorbing resin that can be dispersed / suspended in, absorbed in water, and treated as a fluid state. 3. The method for producing concrete or mortar for pressure vibration molding immediate demolding according to claim 1 or 2, wherein the admixture is a finely powdered inorganic substance. 4. The concrete or mortar for pressure vibration molding immediate demolding according to any one of claims 1 to 3, further comprising a reinforcing fiber for concrete or mortar. Manufacturing method.