JP4431432B2 - Manufacturing method of concrete molded product - Google Patents

Description

The present invention relates to a method for producing a concrete molded article using a slurry obtained by kneading Portland cement, silica sand and water.

Conventionally, lightweight cellular concrete (ALC) and other concrete molded products have been used for construction and civil engineering materials.
In order to produce this concrete molded article, generally, Portland cement, α-quartz (quartz) as silica sand, water, and additives are kneaded to produce a slurry, which is then poured into a mold, and further this slurry It is done by curing. The curing process includes autoclave curing performed under high temperature and high pressure steam.

A concrete molded product is required to have high strength and high heat resistance. In order to satisfy this requirement, it is necessary to produce plate-like crystalline tobermorite in the molded product.
In conventional concrete moldings, α-quartz is used as silica sand, and other additives such as fibers are also added. Therefore, the temperature of autoclave curing is required to produce plate-like crystalline tobermorite. Must be at a high temperature of 180 ° C. or higher.
In order to perform autoclave curing at a high temperature, a large amount of energy (fuel) is required, and the cost is also high.

An object of the present invention is to provide a method for producing a concrete molded article having high strength and high heat resistance at a low energy cost.

A method for producing a concrete molded article as a related technique of the present invention is to produce a slurry by kneading Portland cement, quartz sand containing quartz and fused silica, and water, pouring the slurry into a mold, It is characterized by curing the slurry in an autoclave.

Here, the mixing ratio of the Portland cement and the silica sand is set to an appropriate value, for example, 6: 4.
Furthermore, although the mixing ratio of water and the powder containing Portland cement and silica sand is set to an appropriate value, it is, for example, 3: 7 to 5: 5.
In the invention of this configuration, since plate-like crystalline tobermorite is generated in the molded article, the silica sand contains not only quartz (for example, α-quartz) but also fused silica (FS). In contrast to the conventional example containing only α-quartz that must be autoclaved at a temperature of 180 ° C. or higher, in the present invention, plate-like crystalline tobermorite can be produced by autoclave curing at about 170 ° C.
Therefore, even if the temperature in the autoclave curing is lower than that in the past, it is possible to produce plate-like crystalline tobermorite in the concrete molded product, so that the energy cost can be reduced.

In the related art of the present invention, the quartz preferably has a particle size of 600 to 10,000 cm 2 / g, and most preferably 8000 cm 2 / g.
When the particle size of the quartz is less than 6000 cm 2 / g, the generation of plate-like crystalline tobermorite is small, and the same result is obtained even when it exceeds 10000 cm 2 / g.
Further, a configuration in which the weight ratio of the quartz and the fused silica is approximately 50%: 50% is preferable.

Further, the method for producing a concrete molded article of the present invention is to produce a slurry by kneading Portland cement, silica sand containing at least one of silica fume and rice husk and quartz, and water using a mixer. The slurry is wet-stirred with a ball mill, the wet-stirred slurry is poured into a mold, and the slurry is wet-cured and then autoclaved.
In the present invention, the weight ratio between the quartz and the silica fume is appropriately set. For example, 90%: 10% to 80%: 20% is preferable, and 87.5%: 12.5% is more preferable.
Silica fume and rice husk both have a small particle size, and the main constituent compound is SiO ₂ glass, so that they react almost equally.

  Silica sand containing Portland cement, quartz and silica fume (SF) and water are kneaded to produce a slurry and then cured (wet air curing) to produce a dense gel because the dissolution rate of silica fume and rice husk is fast, In this state, when autoclave curing is performed, crystal formation is inhibited, but in the present invention, the slurry is wet-stirred with a planetary ball mill before autoclave curing, so that plate crystalline tobermorite is generated even when autoclave curing is performed at a low temperature. Energy costs can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a manufacturing apparatus for carrying out the method for manufacturing a concrete molded product according to the first embodiment.
In FIG. 1, a manufacturing apparatus 10 includes a tank (storage device) 11 for storing each material (described later) and taking out a predetermined amount, and a slurry 1 obtained by kneading each material measured in the tank 11 with a concrete mold 2. The slurry mixer 12 to be placed on the surface, the wet air curing device 13 for curing the concrete slurry with wet air, and the autoclave curing device 14 for curing the wet air cured concrete with an autoclave are configured.

Each tank 11 includes a cement tank 11A for storing ordinary Portland cement, a silica sand tank 11B for storing silica sand, an additive tank 11C for storing various additives, and a water storage tank 11D for storing suction. I have.
Portland cement stored in the cement tank 11A has a chemical composition such as SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , CaO, SO ₃ , and f.CaO, and has an appropriate particle size (for example, 3000 cm ² / g). The mineral composition of this Portland cement is C ₃ S, C ₂ S, C ₃ A, C ₄ AF and others.
The silica sand stored in the silica sand tank 11B contains quartz and fused silica (FS), and the weight ratio thereof is approximately 50%: 50%. As the quartz, α-quartz having a particle size of 600 to 10,000 cm ² / g is used, and this α-quartz is composed of components such as SiO ₂ , Al ₂ O ₃ , Fe ₂ O _{3 and the} like. Portland cement and silica sand are configured in an appropriate ratio (for example, 6: 4).
Additives stored in the additive tank 11C include polyoxyethylene sulfonic acid-based foaming agents, polycarboxylic acid-based water reducing agents (for example, high-performance AE water reducing agents), retarders composed of organic acids and salts thereof, hollow shapes Fly ash, fiber material made of heat-resistant polypropylene fiber, rapid hardening material made of calcium aluminate compound, and other materials.

The wet air curing device 13 is a device for curing the concrete slurry at a predetermined temperature (for example, 40 ° C.) and a predetermined humidity (for example, 100% humidity) for a predetermined time (for example, 10 hours).
The autoclave curing device 14 hydrothermally cures concrete subjected to air and humidity curing at a predetermined temperature for a predetermined time (for example, 8 hours).

Next, a method for producing the concrete molded product of the first embodiment will be described.
First, silica sand containing Portland cement, α-quartz and fused silica (FS), an additive, and water are supplied from each tank 11 to a slurry mixer 12, and these materials are kneaded by the mixer 12 to obtain slurry 1. To manufacture.
The slurry 1 is poured into the mold 2, and the slurry 1 is wet-cured for a predetermined time with the wet-air curing device 13, and then autoclaved with the autoclave curing device 14 at a predetermined temperature for a predetermined time. Thereby, a concrete molded product is manufactured.

  Therefore, in the first embodiment, since silica sand includes not only α-quartz but also fused silica (FS), it is possible to generate plate-like crystalline tobermorite even if autoclave curing is performed at a lower temperature than the conventional example. It was.

Next, Example 1 for confirming the effect of the first embodiment will be described.
[Example 1]
(1-1) Portland cement chemical composition ratio (%)
SiO ₂ : 21.6, Al ₂ O ₃ : 5.08, Fe ₂ O ₃ : 2.93, CaO: 64.5, SO ₃ : 1.95, f.CaO: 0.4
Mineral composition (Bogue formula%) ratio
C ₃ S: 52.81, C ₂ S: 22.19, C ₃ A: 8.50, C ₄ AF: 8.92, Others: 7.58
Particle size 3000cm ² / g
(1-2) Silica sand
(1-2-1) α-quartz
Chemical composition ratio (%)
SiO ₂ : 95.9, Al ₂ O ₃ : 1.54, Fe ₂ O ₃ : 0.99
Particle size 8000cm ² / g
(1-2-2) Fused silica (FS)
Chemical composition ratio 99.8%
Particle size 10μm or less
(1-3) Additives Use high-performance AE water reducing agent as water reducing agent.
(1-4) Ratio of material Ratio of α-quartz to fused silica is 50%: 50%
The ratio of Portland cement to quartz sand is 6: 4
Water powder contrast (W / P) It experimented in two cases of 0.5 and 0.3.
(1-5) Molding procedure The material is stirred for 3 minutes to produce a slurry, which is then placed in a mold. Thereafter, wet curing was performed for 10 hours at 40 ° C. and humidity (RH) 100%, and then autoclave curing was performed at each set temperature of 170 ° C. and 160 ° C. to prepare a test specimen.
It was investigated whether tobermorite was produced or calcium silicate compound (CSH) was produced in the prepared test piece.
Calcium silicate compounds are gel-like hydrates and have a large amount of crystal water that dissociates when dried, and the amount of shrinkage associated therewith is large, which causes cracks in concrete.
The results of Example 1 are shown in Table 1.
In the following tables including Table 1, “◎” is very large, “◯” is confirmed, “Δ” is small, growing, and “−” is not present.

According to Table 1, when autoclave curing was performed at 170 ° C., it was confirmed that a large amount of plate-like crystals of tobermorite could be produced in two cases where the water powder contrast (W / P) was 0.5 and 0.3. Furthermore, it was also confirmed that no calcium silicate compound (CSH) was produced.
On the other hand, when autoclave curing is performed at 160 ° C., tobermorite in the form of plate crystals cannot be produced even in two cases where the water powder contrast (W / P) is 0.5 and 0.3, and conversely, calcium silicate compounds It was confirmed that was generated.

[Comparative Example 1]
(1-1) Portland cement Same as Example 1
(1-2) Only silica sand α-quartz is used.
The chemical composition ratio of α-quartz is the same as in Example 1. However, particle size 3300cm ² / g
(1-3) Material ratio Same as Example 1
(1-4) Molding procedure Basically the same as Example 1.
However, the set temperatures of the autoclave curing were 180 ° C., 170 ° C., and 160 ° C., and test specimens were produced under these conditions.
In the same manner as in Example 1, it was examined whether tobermorite was produced on the test piece or whether a calcium silicate compound was produced. The results are shown in Table 2.

According to Table 2, it was confirmed that the plate-shaped tobermorite can be produced in an extremely large amount in an example in which the autoclave curing is performed at 180 ° C. and the water powder comparison (W / P) is 0.5. Furthermore, it was also confirmed that no calcium silicate compound (CSH) was produced when autoclave curing was performed at 180 ° C.
On the other hand, the autoclave curing was performed at 170 ° C., and in the example where the water powder contrast (W / P) was 0.5, it was confirmed that the tobermorite of the oriented fiber was generated until the tobermorite of the plate crystal could not be generated. It was also confirmed that a calcium silicate compound was produced. In other cases, it was not only possible to confirm the generation of plate crystals and tobermorite of oriented fibers, but also the formation of calcium silicate compounds.

[Comparative Example 2]
The basic configuration is the same as that of Comparative Example 1, but is different from Comparative Example 1 in that the α-quartz particle size is 8000 cm ² / g.
In the same manner as in Example 1 and Comparative Example 1, it was examined whether tobermorite was produced on the test piece or whether a calcium silicate compound was produced. The results are shown in Table 3.

  According to Table 3, Comparative Example 2 in which the particle size is smaller than Comparative Example 1 shows a slight improvement in the production of tobermorite, but the most important plate-like tobermorite has not been produced. Calcium silicate compounds have been produced.

[Comparative Example 3]
(1-1) Portland cement Same as Example 1
(1-2) Silica sand Use only fused silica.
The particle size is the same as in Example 1.
(1-3) Material ratio Same as Example 1
(1-4) Molding procedure Same as Example 1.
The experimental results are shown in Table 4.

  According to Table 4, Comparative Example 3 using fused silica instead of α-quartz used in Comparative Example 1 shows no improvement in the production of tobermorite. Calcium silicate compounds have not decreased.

[Comparative Example 4]
(1-1) Portland cement Same as Example 1
(1-2) Silica sand
(1-2-1) α-quartz
Same as Example 1
(1-2-2) Silica fume (SF)
Chemical composition ratio (%)
SiO ₂ : 98.7, Al ₂ O ₃ : 0.12, Fe ₂ O ₃ : 0.01, CaO: 0.08, SO ₃ : 0.14
Particle size 0.1μm or less
(1-3) Additive Same as Example 1
(1-4) Ratio of materials Ratio of α-quartz to silica fume is 87.5%: 12.5%
The ratio of Portland cement to quartz sand is 6: 4
Water powder contrast (W / P) It experimented in two cases of 0.5 and 0.3.
(1-5) Molding procedure Same as Example 1.
The results are shown in Table 5.

  According to Table 5, Comparative Example 4 shows a slight improvement in the production of tobermorite compared to Comparative Example 1, but the most important plate-like crystal tobermorite has not been produced, and conversely, the calcium silicate system. A compound has been produced.

As described above, Example 1 in which α-quartz and fused silica were mixed as silica sand produced plate-like tobermorite at a lower autoclave curing temperature than Comparative Example 1 in which α-quartz was alone or Comparative Example 3 in which fused silica was alone. Is done.
This can be confirmed from the graph shown in FIG. FIG. 2 is a graph showing the relationship between autoclave time and reaction ratio. In this graph, looking at the reaction rate of α-quartz, it can be seen that the reaction rate Q in the case of mixing with fused silica is higher than the single reaction rate Q ′. Similarly, the reaction rate of fused silica is seen. It can be seen that the reaction rate Fs in the case of mixing with α-quartz is higher than the single reaction rate Fs ′. As described above, when α-quartz and fused silica are mixed, the reaction rate becomes high, so that plate-like tobermorite is easily generated.

Next, a second embodiment of the present invention will be described with reference to FIG. Here, in description of 2nd Embodiment, the component similar to 1st Embodiment attaches | subjects the same code | symbol, and abbreviate | omits or simplifies description. In FIG. 3, in 2nd Embodiment, the silica sand stored in the silica sand tank 11B contains quartz and silica fume (SF), The weight ratio is 90%: 10% -80%: 20%. Yes, preferably about 87.5%: 12.5%.
A planetary ball mill 15 is disposed between the slurry mixer 12 and the wet air curing device 13. This planetary ball mill 15 is a known one.

Next, a method for producing the concrete molded product of the second embodiment will be described.
First, silica sand containing Portland cement, α-quartz and silica fume (SF), additives, and water are supplied from each tank 11 to the slurry mixer 12, and these materials are kneaded by the mixer 12 to produce slurry 1. To do.
The slurry 1 is wet-stirred by the planetary ball mill 15, the wet-stirred slurry 1 is poured into the mold 2, and the slurry 1 is wet-cured for a predetermined time by the wet-air curing device 13 as in the first embodiment. Thereafter, the autoclave curing device 14 performs autoclave curing at a predetermined temperature and a predetermined time. Thereby, a concrete molded product is manufactured.

  Therefore, in the second embodiment, the slurry 1 is wet-stirred by the planetary ball mill 15 before the autoclave curing, so that plate-like crystalline tobermorite can be generated even when the autoclave is cured at a low temperature. Therefore, the energy cost can be reduced.

Next, Example 2 for confirming the effect of the second embodiment will be described.
[Example 2]
(1-1) Portland cement Same as Example 1.
(1-2) Silica sand
(1-2-1) α-quartz
Same as Example 1
(1-2-2) Silica fume (SF)
Chemical composition ratio (%)
SiO ₂ : 98.7, Al ₂ O ₃ : 0.12, Fe ₂ O ₃ : 0.01, CaO: 0.08, SO ₃ : 0.14
Particle size 0.1μm or less
(1-3) Additive Same as Example 1
(1-4) Ratio of materials Ratio of α-quartz to silica fume is 87.5%: 12.5%
The ratio of Portland cement to quartz sand is 6: 4
(1-5) Molding procedure The material is stirred for 3 minutes to prepare a slurry, and this slurry is wet-stirred in a planetary ball mill 15 for 5 hours and placed in a mold. Thereafter, wet curing was performed for 10 hours at 40 ° C. and humidity (RH) 100%, and then autoclaving was performed at a set temperature of 160 ° C. to prepare a test specimen.

It was investigated whether tobermorite was produced or calcium silicate compound (CSH) was produced in the prepared test piece.
As a result, it was confirmed that plate-like crystals of tobermorite were generated, and formation of calcium silicate compounds was not confirmed.
This is because silica fume is replaced as a part of silica sand, and the slurry is wet-stirred with a planetary ball mill and pulverized and hydrated to increase the reaction rate of the entire silica sand.

FIG. 4 is a graph showing the relationship between autoclave time and reaction ratio. In this graph, when looking at the reaction rate of α-quartz, the reaction rate Q1 of pulverization hydration in Example 2 is higher than the reaction rate Q2 of static hydration (which is left without wet stirring with a planetary ball mill). Similarly, looking at the reaction rate of silica fume, the reaction rate Sf1 of pulverized hydration in Example 2 is higher than the reaction rate Sf2 of stationary hydration.
By increasing the reaction rate of the entire silica sand, crystalline metagenite (C ₆ S ₉ H ₇ ) is produced by pulverization and hydration after wet-air curing, which reacts with the SiO ₂ component in autoclave curing (hydrothermal reaction). It can be inferred that it was inhibited.

The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the second embodiment, quartz and silica fume (SF) are used as silica sand. However, in the present invention, instead of silica fume, or in addition to silica fume, rice husk may be used. That is, in the present invention, the silica sand only needs to contain at least one of silica fume and rice husk and quartz. Rice husk has the same particle size and properties as silica fume, and therefore can provide the same effect as silica fume.

  The present invention is widely applicable to concrete members in the field of architecture and civil engineering.

It is a schematic block diagram which shows the manufacturing apparatus for enforcing the manufacturing method of the concrete molded product which concerns on 1st Embodiment of this invention. It is a graph which shows the relationship between autoclave time and reaction ratio in 1st Embodiment. It is a schematic block diagram which shows the manufacturing apparatus for enforcing the manufacturing method of the concrete molded product which concerns on 2nd Embodiment of this invention. It is a graph which shows the relationship between autoclave time and reaction ratio in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Slurry 2 Formwork 11 Tank 12 Slurry mixer 13 Wet air curing device 14 Autoclave curing device 15 Planetary ball mill

Claims (1)

Portland cement, silica sand containing at least one of silica fume and rice husk and quartz, and water are kneaded using a mixer to produce a slurry. The slurry is wet-stirred with a planetary ball mill, and the wet-stirred slurry is molded. A method for producing a concrete molded product, which is poured into a frame, and further subjected to autoclave curing after the slurry is wet-air cured .

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