JP4786220B2 - Wood cement board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a wood cement board and a method for producing the same, and more particularly to a wood cement board having high organic matter adsorption performance and excellent in sulfate resistance, and a method for producing the same.

In recent years, from the viewpoints of rationalization of construction technology in the field of construction and civil engineering, labor saving and efficiency improvement, the needs for cement as a raw material used for these have been extremely diversified and compounded.
In particular, recently, for the purpose of making building exterior materials and roofing materials incombustible and incombustible, a mixture of cement, wood fiber and water is formed into a predetermined shape and then cured and hardened. Cement boards have been developed and put into practical use.

In these wood cement boards, wood pulp, wood pieces, wood chips, wood powder, wood wool and the like are used as wood fibers, and the wood cement boards contain many organic substances.
However, when general Portland cement is used for wood cement, the inclusion of organic components contained in wood such as wood pulp, wood chips, wood chips, wood flour, and wood wool, such as acids contained in wood cement Due to the high rate, the strength development is poor in Portland cement.

  This is because when organic Portland cement is used for use as a wood cement board, organic components contained in the wood of the wood cement board raw material are adsorbed on the surface of Portland cement, and the hydration of the cement. This is because the reaction is delayed to inhibit curing, and thus the solidification strength and strength development are deteriorated.

In view of the above points, in order to promote the hydration reaction of the cement composition used for the wood cement board, a hardening accelerator such as calcium chloride or aluminum sulfate is added to improve the solidification performance and strength expression. Yes.
Furthermore, in the production of the wood cement board, the curing reaction is promoted by performing high temperature curing or autoclave curing during curing.
As such a wood cement board, Japanese Patent Application Laid-Open No. 2005-59513 discloses that a raw mixture mainly composed of a hydraulic inorganic material and a wood reinforcing material containing microfibrous cellulose is added and distributed, and a mat is formed. A method for producing a wood cement board in which the mat is compressed, cured and hardened is disclosed.

  In addition, as another method for preventing the strength development from deteriorating, there is a method of excluding organic components contained in wood, for example, a method of washing wood in advance, or adding an organic component adsorbent such as an inorganic porous body There is known a method, or a method in which a large amount of gypsum or the like is included in the cement composition to generate ettringite having a high organic component adsorption ability in the course of cement hydration.

On the other hand, Portland cement is a clinker mineral of 3CaO · SiO ₂ (C ₃ S), 2CaO · SiO ₂ (C ₂ S), 3CaO · Al ₂ O ₃ (C ₃ A) and 4CaO · Al ₂ O ₃ · Fe _2. O ₃ is containing _(C 4 AF), relatively to a ferrite phase containing iron as typified by a one _{4CaO · Al 2 O 3 · Fe} 2 O 3 (C 4 AF) in the mineral It is known to have a high organic matter adsorption capacity.

As containing a large amount of C ₄ AF or the like, _{JP-A-10-330135, Al 2 O 3 / Fe} 2 O 3 ratio in the cement clinker is from 0.52 to 0.62, in the clinker, SO _The cement composition obtained by adding gypsum so that it may become 2 mass% in ₃ quantity is disclosed.
However, it is also known that the organic matter adsorption capacity such as C ₄ AF decreases due to the influence of SO ₃ ^2- ion in the presence of gypsum, and the above cement composition is satisfactory in terms of the organic content adsorption capacity. It was not a thing.

Incidentally, Portland cement specified in JIS, since is impaired strength developing property and Madokayui in the absence of SO ₃ ^2-ion, SO in order to suppress the Madokayui adjust the setting time ₃ It is essential to add gypsum as a source of ^2- ions.
Therefore, it has been difficult to obtain a cement composition having enhanced organic component adsorption ability such as C ₄ AF while ensuring strength development.
Therefore, it has been difficult to use the organic substance adsorbing ability of the ferrite phase containing iron in order to improve the strength development by excluding the organic components contained in the wood in the wood cement board.
JP-A-2005-59513 Japanese Patent Laid-Open No. 10-330135

Accordingly, an object of the present invention is to provide a wood cement board using a cement composition that has improved the adsorptivity of organic components such as C ₄ AF while solving the above problems and ensuring strength development, and a method for producing the same. Is to provide.

The present invention has found that by making the clinker mineral contained in the cement composition specific, it is possible to ensure strength development even when gypsum is not contained, and thus SO ₃ ^{2. -} to achieve ion absence of environmental, wood to give C 4 organics cement composition adsorptivity is increased such _AF, by using this, to use the organic adsorption capacity of the ferrite phase containing iron It is a cement board.

That is, the wood cement board of the present invention contains C ₃ S, C ₂ S and a gap phase as a clinker mineral composition and does not contain C ₃ A, and the C ₃ S is 50% by mass in the clinker mineral composition. It is characterized by using a cement composition which is contained in the above proportion, does not contain gypsum , and has an Fe ₂ O ₃ content of 4.0 to 9% by mass in the clinker mineral .
Preferably, the wood cement board of the present invention is a continuous solid solution in which the interstitial phase does not contain C ₃ A and the average composition is in the range of C ₄ AF to C ₆ AF _2. And
More preferably, in the woody cement board of the present invention, the cement composition is characterized in that Fe ₂ O ₃ / Al ₂ O ₃ in the clinker mineral is 1 or more in molar ratio.
The method for producing a wood cement board of the present invention is characterized in that a cement composition having the above specific composition, wood fiber and water are mixed, the mixture is molded into a predetermined shape, and then cured and cured. And

The wood cement board of the present invention includes a specific cement clinker containing C ₃ S, C ₂ S and a gap phase as a clinker mineral and not containing C ₃ A, and using this as a main component. Even without using gypsum as a setting retarding material, instantaneous fluidization does not occur in initial hydration, and high fluidity can be maintained.

Also contains no gypsum, C 4 large organic substances adsorbed amount of ferrite phase containing iron _AF like, even when manufacturing a wood cement board, the organic delay material causing curing inhibition, C ₄ AF Since the ferrite phase containing iron such as is adsorbed and fixed, sufficient curing can be achieved without using a curing accelerator, and strength development can be ensured.
Furthermore, since it does not contain gypsum and the addition amount of the curing accelerator is reduced or unnecessary, an inexpensive cement composition is obtained, and workability is good and efficient even in the manufacturing process of the wood cement board. Simple manufacturing is possible.

The present invention is illustrated by the following preferred examples, but is not limited thereto.
The wood cement board of the present invention contains C ₃ S, C ₂ S and a gap phase as a clinker mineral composition and does not contain C ₃ A, and the C ₃ S is 50% by mass or more in the clinker mineral composition. The cement composition is contained in a proportion and does not contain gypsum , and the Fe ₂ O ₃ content in the clinker mineral is 4.0 to 9% by mass. The cement composition is preferably a clinker _{F e 2 O 3 / Al 2} O 3 mineral is one or more in molar ratio.
With such a composition, it is possible to accelerate the curing reaction by adsorbing organic matter that inhibits the curing reaction of the cement used in the wood cement board, and it is possible to accelerate the initial hydration reaction without adding gypsum. It is possible to suppress the occurrence of condensation.

First, the clinker of the cement composition used for the wood cement board of the present invention contains C ₃ S, C ₂ S and a gap phase as a clinker mineral phase, and does not contain C ₃ A.
Here, the interstitial phase does not contain C ₃ A, and is particularly preferably a continuous solid solution having an average composition in the range of C ₄ AF to C ₆ AF ₂ .
It is known that when C ₃ A is present in the cement composition, such C ₃ A is known to have high hydration reactivity and a large amount of hydration heat, and in an environment where there is no gypsum, C ₃ A is instantly frozen. Then, since the subsequent hydration reaction is inhibited, it is impossible to ensure strength development.

The composition ratio of the clinker mineral phase is such that the C ₃ S amount is 50% by mass, preferably 60% by mass or more, and the interstitial phase amount is 18 to 21% by mass.
If the amount of C ₃ S is 50% by mass or more, sufficient strength development can be obtained.
If the interstitial phase amount is in the range of 18 to 21% by mass, stable firing can be performed both in terms of operation and quality during clinker production.

To obtain the above cement composition efficiently, as the chemical composition of the clinker mineral phase, _Fe 2 _{O 3} is 4.0 to 9 mass%, it is preferable in particular 4.5 to 9% by weight .
When the proportion of Fe ₂ O ₃ is less than 4% by mass, C ₃ A may be generated, and when it exceeds 9% by mass, the hydration activity of the cement composition may be reduced. This is because sometimes it may be difficult to stabilize the operation.

Further, as the chemical composition of the clinker mineral phase, the ratio of _Fe 2 _{O 3} and _Al 2 _{O 3 is, Fe 2 O 3 / Al 2} O 3 molar ratio is preferably 1 or more.
When the Fe ₂ O ₃ / Al ₂ O ₃ molar ratio is about 1 and the Borg calculation is performed, the interstitial phase is only ferrite (C ₄ AF), and C ₃ A is not generated in the calculation.
Furthermore, by increasing the molar ratio, the interstitial phase changes to ferrite having a C ₆ AF ₂ composition.

As a result, a gap phase formed of a continuous solid solution having an average composition in the range of C ₄ AF to C ₆ AF ₂ can be efficiently obtained, and C ₃ having a high hydration reactivity and a large amount of hydration heat generation. In the environment where gypsum is not used, A is not generated, and the ferrites in the interstitial phase that take up the amount of organic substance exhibit sufficient adsorption performance, and without causing instantaneous hydration at the start of hydration, Expression can be ensured.
Furthermore, as the Fe ₂ O ₃ / Al ₂ O ₃ molar ratio increases, the hydration heat value of the cement decreases and the fluidity improves.

In such an environment where gypsum is not used, the ferrite phase efficiently adsorbs organic substances and does not contain C ₃ A, so there is no instantaneous setting, and the initial hydration activity of alite (C ₃ S) Since strength development can be ensured without being inhibited, it can have excellent strength development even if it contains an organic substance.

Specifically, the clinker contained in such a cement composition is obtained, for example, by firing a mixture of limestone, siliceous raw material, alumina raw material and iron raw material.
By pulverizing the clinker thus obtained, or by adding a cement admixture other than gypsum to the clinker as required, a cement composition used for the production of the wood cement board of the present invention can be obtained. .
Examples of cement admixtures other than gypsum include blast furnace slag, fly ash, and limestone fine powder.

Further, the fineness of the obtained cement composition is not particularly limited, but preferably 2500 to 4500 cm ² / g, and particularly preferably 2800 to 4000 cm ² / g.
This is because if it is less than 2500 cm ² / g, sufficient strength may not be obtained, and if it exceeds 4500 cm ² / g, the production cost is bulky and uneconomical.

In the production of a wood cement board, the added water preferably has a water cement ratio (mass ratio of water to cement) of 50% by mass or more and 300% by mass or less.
The reason is that when the cement / water ratio is less than 50% by mass, the properties of the mixture become hard and the fluidity is deteriorated, and the homogeneity of the obtained cured product is lowered, and 300% by mass. If the ratio exceeds 1, the properties of the mixture will be too soft (the materials will separate), bleeding water will be generated, and the homogeneity of the resulting cured product will be reduced.

As the wood fiber that can be used for the wood cement board of the present invention, wood pulp, wood pieces, wood chips, wood powder, wood hair, wood fiber bundles and the like are preferably used.
It is preferable that the compounding quantity of a wood fiber is 0.5 to 100 mass parts with respect to 100 mass parts of cement. The reason is that if the blending amount of the wood fiber exceeds 100 parts by mass, the properties of the mixture become hard and difficult to be homogenized at the time of kneading, and if it is less than 0.5 part by mass, This is because the effect of addition cannot be obtained.

The mixture may further contain a curing accelerator as necessary, but even if these curing accelerators are not included, the mixture can be sufficiently exerted without inhibiting the curing reaction.
Curing accelerators include magnesium chloride, sodium chloride, potassium chloride, calcium formate, calcium acetate, calcium acrylate, aluminum sulfate, calcium sulfate, sodium sulfate, potassium sulfate, sodium thiocyanate, calcium nitrite, sodium nitrite, water Sodium oxide, potassium hydroxide, calcium carbonate, sodium carbonate, potassium carbonate, diethanolamine, triethanolamine and the like are preferably used.

When mix | blending a hardening accelerator, it may be less than 3 mass parts with respect to 100 mass parts of clinker components in a cement composition.
The reason is that the cement composition used for the wood cement board has the above composition, so that the curing reaction is not inhibited, and a sufficiently high strength can be maintained.

As the admixture, blast furnace slag fine powder, limestone powder, fly ash, silica fume, coal ash, silica stone powder and the like are preferably used.
The blending amount of the admixture is preferably 50 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the clinker component in the cement composition.
The reason is that if the blending amount is less than 50 parts by mass, the additive effect of the admixture cannot be obtained, and the properties of the mixture may not be stable, and if the blending amount exceeds 300 parts by mass, This is because the properties of the mixture may become hard.

  After the above-mentioned wood fiber is defibrated, cement, wood fiber and water are kneaded, and if necessary, a hardening accelerator and / or admixture is further kneaded to prepare a mixture containing cement and wood fiber.

The wood fiber is defibrated by, for example, putting a predetermined amount of wood fiber and water into a mixer having a stirring ability such as a juicer mixer and defibrating the wood fiber at the maximum value of the mixer defibrating ability.
The defibration time is 2 to 4 minutes, for example.
Within this time, the wood fiber can be sufficiently defibrated.
In this way, a dispersion liquid in which the defibrated wood fibers are dispersed in water can be obtained.

Cement, and if necessary, a hardening accelerator and / or an admixture are added to the dispersion.
After the addition, for example, kneading is performed using a mixer having kneading ability such as a Hobart mixer or a hand mixer.
The kneading time is, for example, 1 to 4 minutes.
If it is within this time, it can fully knead | mix.

Next, the obtained mixture is placed in a predetermined mold, cured and cured, and a wood cement board can be produced.
For such curing, any curing method such as wet curing, high-temperature and high-pressure curing, or autoclave curing can be used.

In general, when the organic material contained in the wood material is contained in a high content, the hydration reaction of the cement is significantly delayed, but the hydration reaction promoted in the combination of the present invention is not affected by the wood material. Therefore, the strength can be quickly expressed.
This is because an organic acid such as an organic component of a woody material is adsorbed by a ferrite phase containing iron such as C ₄ AF and C ₆ AF ₂ and calcium aluminate hydrate which is a hydrate thereof. This is because the action of causing SiO ₂ hydration delay is reduced.
Therefore, the amount of the curing accelerator used can be greatly reduced.

The present invention will be described based on the following test examples and examples.
Test Examples 1-4
A mixture prepared from cement clinker raw materials using each reagent was fired at 1450 ° C. for 1 hour in an electric furnace, then taken out of the electric furnace and rapidly cooled in air to obtain a clinker having each composition shown in Table 1. It was.

The obtained clinker was diffracted using an X-ray diffraction device (manufactured by Rigaku Corporation; RAD-rC), and the obtained mineral composition results are shown in Table 2.
The molar ratio of Fe / Al in the mineral ferrite phase is also shown in Table 2.

Next, the clinker 1 to 3 were pulverized with a Blaine specific surface area to a fineness of 3300 cm ² / g to obtain cement compositions of Test Examples 1 to 3.
Further, 3% by mass of dihydrate gypsum was added to the clinker 4 and pulverized with a Blaine specific surface area to a fineness of 3300 cm ² / g to obtain a cement composition of Test Example 4.

To each cement composition, 0.2% by mass of sodium gluconate was added, and water was further added so that the water cement ratio was 50% by mass to obtain a mortar containing an organic retardation substance.
About the obtained mortar, the mortar strength of material age 7 days was measured based on JISR5201-1997 "Physical test method of cement: (5) Strength test".
The results are shown in Table 3.

  From Table 3, Test Examples 1 to 3 show good strength development despite the fact that they do not contain gypsum, and higher strength than Test Example 4 can be obtained under conditions containing an organic retardation substance. I understand that

Example 100 parts by mass of the cement composition of Test Example 3 above, 10 parts by mass of wood flour, 2 parts by mass of a hardening accelerator and 65 parts by mass of water were mixed and molded and cured to obtain a wood cement board of the example. It was.
In the above materials, North American larch was used as the wood flour, and magnesium chloride was used as the hardening accelerator.
Curing conditions were 70 ° C. after molding, air curing for 6 hours as primary curing, and autoclaving curing at 165 ° C., heating for 1.5 hours, holding for 7 hours, and cooling for 1.5 hours after primary curing. .

For wood cement board of this embodiment, the measured strength after similarly primary curing and after autoclave curing the above test example, after the primary curing strength after 1.5 N / mm ² autoclave curing, strength 3.4 N / mm ² , a result having good strength development was obtained.

Since the wood cement board of the present invention has high organic matter adsorption performance, it does not inhibit the curing acceleration reaction and has high strength, so it can be effectively applied to the building field such as exterior materials and roofing materials of buildings. it can.
Furthermore, since it does not contain C ₃ A, it has excellent sulfuric acid resistance, and can be used for civil engineering such as the ocean and oil wells, building materials in the construction field, and the like.

Claims (4)

As a clinker mineral composition, it contains C ₃ S, C ₂ S and a gap phase, and does not contain C ₃ A. The C ₃ S is contained in a proportion of 50% by mass or more in the clinker mineral composition, and further includes gypsum. A wood cement board characterized by using a cement composition which is not contained and has a Fe ₂ O ₃ content of 4.0 to 9% by mass in the clinker mineral . In wood cement board according to claim 1, wherein the gap phase is characterized by C ₃ are those not containing _A, and a continuous solid solution having an average composition is in the range of C ₄ AF or C ₆ AF ₂ , Wood cement board. In wood cement board according to claim 1 or 2, characterized in that _{F e 2 O 3 / Al 2} O 3 in the clinker mineral is one or more in molar ratio, wood cement board. As a clinker mineral composition, it contains C ₃ S, C ₂ S and a gap phase, and does not contain C ₃ A. The C ₃ S is contained in a proportion of 50% by mass or more in the clinker mineral composition, and further includes gypsum. Not containing , mixing the cement composition whose Fe ₂ O ₃ content in the clinker mineral is 4.0 to 9% by mass , wood fiber and water, shaping the mixture into a predetermined shape, and then curing, A method for producing a wood cement board, characterized by curing.