JP6974819B2 - Stucco, plaster panel and manufacturing method of plaster panel - Google Patents

Description

The present invention relates to a plaster that is lightweight and has excellent toughness, a plaster panel using the plaster, and a method for manufacturing the plaster panel.

Since plaster is made entirely of natural materials, it is extremely friendly to the living environment, and it has been confirmed in past experiments that it has excellent effects on fire protection, earthquake resistance, soundproofing, and living environment. It can be said that it is a suitable building material.

Conventional general plaster is made by adding lime, susa made of hemp, straw, etc., adhesive obtained from herbs and seaweed, sand, water, etc., and kneading them to cure while absorbing carbon dioxide. It is a stucco material. Since the plastering is a wet method in which the plasterer applies and finishes it, it takes time from application to drying. Another problem with plaster is that it takes time to exhibit high strength and hardness.

In order to solve these problems, the present inventor has developed a plaster material which is excellent in strength development and can exhibit a predetermined strength and hardness at an early stage (see, for example, Patent Document 1). In addition, attempts are being made to expand the range and applications of plaster by developing new products that focus on the original characteristics of plaster, such as humidity control function and formaldehyde adsorption / decomposition function, as opposed to conventional plaster. (See, for example, Patent Document 2).

Japanese Patent No. 4843733 Japanese Unexamined Patent Publication No. 2007-284294

By using the plaster material developed by the present inventor, the problem of exhibiting a predetermined strength and hardness at an early stage can be solved, but the problem of plaster construction and the like remains. If plaster can be made into a panel like gypsum board, problems related to construction can be solved, and it is expected that the applications will be further expanded.

Stucco panels can be manufactured by forming plaster into a plate shape and hardening it, but in order to use it as a wall material or the like, resistance to shearing and bending is required. In addition, since conventional plaster has a high density, it is heavy and difficult to transport and handle simply by making it into a panel.

An object of the present invention is to provide a plaster that can obtain a stucco panel that is lightweight and has high strength and toughness, a stucco panel that is lightweight and has high strength and toughness, and a method for manufacturing the plaster panel.

The present invention is a plaster containing lime, fine aggregate and kneaded water as main components, the lime being fresh lime and / or slaked lime, and the fine aggregate being crushed into sand and fibrous bamboo chips. The weight ratio of the bamboo chips to the lime is 40 to 80%, the weight ratio of the bamboo chips to the sand is 10 to 30%, the kneaded water is a high Ca ion-containing aqueous solution, and the high Ca ion content. It is a plaster characterized in that the Ca ion concentration contained in the aqueous solution is 2 to 20 g / L.

The plaster of the present invention is characterized in that the length of the bamboo chip is 3 to 15 mm.

In the plaster of the present invention, the volume when the plaster is poured into a 40 × 40 × 160 mm prismatic mold and demolded after 24 hours has passed is V ₀ , and after demolding, carbon dioxide gas curing is performed for 1 to 8 days. When the volume of the cured body of the plaster obtained by curing for 41 days in total _{is V, (V-V 0} ) / V ₀ is 0 to + 0.6%. It is characterized by that.

Further, the present invention is a plaster panel obtained by curing the plaster.

Further, the present invention is a plaster panel obtained by curing the plaster using a wood grain as a base.

Further, the present invention is a decorative board characterized in that the plaster panel is surface-finished.

Further, the present invention is a method for manufacturing the plaster panel or the decorative board, which comprises the aerial curing step and the carbon dioxide gas curing step as the curing step. ..

Further, the method for producing a plaster panel or a decorative board of the present invention is characterized in that the carbon dioxide gas curing step is carried out prior to the aerial curing step.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a plaster that can obtain a stucco panel that is lightweight and has high strength and toughness, a stucco panel that is lightweight and has high strength and toughness, and a method for manufacturing the plaster panel.

It is a figure which shows the manufacturing procedure of the stucco panel or the decorative board of this invention. It is a volume increase / decrease rate measurement result of the bamboo chip high Ca sand stucco hardened body described in the Example of this invention. It is the density measurement result of the bamboo chip high Ca sand stucco hardened body described in the Example of this invention. It is a bending strength measurement result of the bamboo chip high Ca sand stucco hardened body described in the Example of this invention. It is the compressive strength measurement result of the bamboo chip high Ca sand stucco hardened body described in the Example of this invention. It is a figure which shows the neutralization progress state of the bamboo chip high Ca sand stucco hardened body described in the Example of this invention. It is a figure which shows the rebound amount at the time of curing of the bamboo chip high Ca sand stucco hardened body described in the Example of this invention.

Various plasters are defined as follows in the embodiments and examples of the present invention. Similar to conventional plaster, a material obtained by kneading lime, mountain sand, etc. with water is called a sand plaster composition, and a material used for producing a sand plaster composition is called a sand plaster material. Therefore, the sand plaster material contains kneaded water, and the sand plaster material is kneaded to form the sand plaster composition. Further, a sand plaster composition obtained by combining a sand plaster composition and a sand plaster material, and further curing and curing the sand plaster composition is called a sand plaster cured product.

High Ca sand plaster composition, high Ca sand plaster material, high Ca sand plaster using an aqueous solution containing high Ca ions (high Ca ion containing aqueous solution) in kneading water instead of water in the same manner as the above sand plaster etc. , High Ca sand plaster hardened body.

Furthermore, those containing bamboo chips in sand plaster, bamboo chip sand plaster composition, bamboo chip sand plaster material, bamboo chip sand plaster, bamboo chip sand plaster hardened body, and those containing bamboo chips in high Ca sand plaster , Bamboo chip high Ca sand plaster composition, bamboo chip high Ca sand plaster material, bamboo chip high Ca sand plaster, bamboo chip high Ca sand plaster hardened body.

The plaster of the first embodiment of the present invention is a plaster containing lime, fine aggregate and kneaded water as main components, the lime is fresh lime and / or slaked lime, and the fine aggregate is crushed into sand and fibrous form. It is a bamboo chip, and the kneaded water is a high Ca ion-containing aqueous solution. According to the above definition, the plaster of the first embodiment is a bamboo chip high Ca sand plaster containing a bamboo chip high Ca sand plaster composition and a bamboo chip high Ca sand plaster material, and bamboo chips are added to the sand plaster. Stucco using a high Ca ion-containing aqueous solution for kneading water.

Further, in the plaster of the present embodiment, the amount of bamboo chips added is specified, and the concentration of Ca ions contained in the high Ca ion-containing aqueous solution is specified.

In addition to the above components, the plaster of the present embodiment may contain hemp fibers and straw fibers (susa) generally used in plaster, an adhesive obtained from herbs and seaweed, or an adhesive made of synthetic resin. Even in that case, the main components are lime, fine aggregate and kneaded water. The plaster of the present embodiment can be composed only of quicklime and / or slaked lime, sand, bamboo chips, and a high Ca ion-containing aqueous solution.

In the plaster of the present embodiment, as the lime, quick lime or slaked lime or a mixture of quick lime and slaked lime can be used. As a material for quicklime or slaked lime, calcined shells such as oyster shells and scallops can also be used.

The sand, which is one of the fine aggregates, is not particularly limited, and mountain sand, river sand, lime sand, etc., which have been generally used for sand plaster, can be used.

Bamboo chips are obtained by crushing bamboo into fibers using a crusher or the like. The type of bamboo that is the raw material for bamboo chips is not particularly limited. The crusher for crushing bamboo is not particularly limited, but it is preferable that the bamboo is sufficiently crushed to obtain a fine fibrous material. When bamboo is crushed, not only fibrous substances but also lumpy substances and powdery substances are discharged together, but the amount of lumpy substances and powdery substances should be as small as possible. It is preferable to appropriately pass the pulverized material through a sieve, a screen, or the like to remove lumps and / or powders, or classify the crushed material to obtain only a fibrous material having a predetermined size. The length of the bamboo chips is preferably 3 to 15 mm, more preferably 3 to 8 mm, and even more preferably 3 to 6 mm. The thickness of the bamboo chips is preferably 1 mm or less.

In the plaster of the present embodiment, the bamboo chips have a weight ratio of 40 to 80% with respect to lime and 10 to 30% by weight with respect to sand. As a result, it is possible to obtain a stucco panel that is lightweight and has high strength and toughness when formed into a panel. Further, this plaster panel is a well-balanced panel having an appropriate density and strength.

The high Ca ion-containing aqueous solution means a liquid containing a high concentration of Ca ions. According to publicly available data (eg http://www.takenet-eco.co.jp/pages/jitsurei/sokai_senjo.html, http://www.questions.gr.jp/chem/odoroki1.htm) Quicklime (CaO) and slaked lime (Ca (OH) ₂ ) are said to be dissolved in pure water at a weight percentage concentration of about 0.2%. In the plaster of the present embodiment, one in which CaO or Ca (OH) ₂ is dissolved in an amount of more than 0.2% is used.

Therefore, for example, first, a stock solution in which CaO is easily dissolved in an acetic acid aqueous solution or the like is produced. Then, this undiluted solution or an aqueous solution obtained by diluting this undiluted solution with water is produced, and these are added to lime or the like containing bamboo chips and kneaded. The water used in the high Ca ion-containing aqueous solution and the water for diluting the water are not particularly limited, and may be clean water, ionized water, pure water, or the like.

As the high Ca ion-containing aqueous solution, for example, when a 10% acetic acid aqueous solution is used, CaO can be dissolved at room temperature at a weight percentage concentration of about 3.2% (32 g / L) based on Ca. If it is difficult to dissolve CaO or Ca (OH) _{2 , sodium hydrogen carbonate (NaHCO 3} ) can be added. _{Further, CaO and / or Ca (OH) 2} may be dissolved by using an acidic aqueous solution such as a citric acid aqueous solution or a formic acid aqueous solution in addition to the acetic acid aqueous solution. However, an acetic acid aqueous solution is preferable in consideration of dissolution ability and the like. In addition, the pH of the high Ca ion-containing aqueous solution can be adjusted during use.

_{The CaO and / or Ca (OH) 2} used in the production of the high Ca ion-containing aqueous solution is not limited to the specific CaO and / or Ca (OH) ₂ , and is as shown in Examples described later. Calcium husk powder baked at 900 to 1200 ° C. can be used. Instead of oyster shells, other shells can be fired and used.

In the lacquer of the present embodiment, the amount of Ca ions in the high Ca ion-containing aqueous solution can be such that Ca ions are about 2 to 20 g / L, and among them, high Ca ions having a Ca ion concentration of 5 to 20 g / L can be used. An ion-containing aqueous solution can be preferably used.

The plaster of the present embodiment is a plaster having a small volume increase / decrease rate when made into a cured product, and the larger the content of bamboo chips, the smaller the volume change when made into a cured product. In particular, as shown in Examples described later, plaster with a bamboo chip content of 80% (BTR 80%) (bamboo chip high Ca sand plaster) is poured into a mold (40 × 40 × 160 mm prism) and demolded after 24 hours have passed. However, in the case of a stucco cured product (bamboo chip high Ca sand plaster cured product) that can be cured for a total of 41 days by first curing with carbon dioxide gas and then curing in the air in the curing process, the volume increase / decrease rate is about 0 to +0. It was 6%, and the volume changed little or slightly expanded during curing.

The density of the bamboo chip high Ca sand plaster cured product obtained by curing the plaster of the present embodiment is considerably smaller than the density of the sand plaster cured product. Specifically, as shown in Examples described later, plaster (bamboo chip high Ca sand plaster) is poured into a mold (square column of 40 × 40 × 160 mm), demolded after 24 hours, and carbonized first in the curing process. Comparing the density ρ of the stucco hardened body (bamboo chip high Ca sand stucco hardened body) obtained by gas curing and then aerial curing for a total of 41 days with the density ρ ₀ of the sand stucco hardened body, the bamboo chip content rate. The stucco cured product with 40% has a density ratio of ρ / ρ ₀ ≈ 0.81, and the stucco cured product having a bamboo chip content of 80% has a density ratio of ρ / ρ ₀ ≈ 0.75. Further, the density of the bamboo chip high Ca sand plaster hardened body decreases linearly in proportion to the bamboo chip content.

Further, the strength of the stucco hardened body obtained by hardening the stucco of the present embodiment is considerably higher than the strength of the sand stucco hardened body. Specifically, as shown in Examples described later, the plaster of the present embodiment is poured into a mold (a prism of 40 × 40 × 160 mm), demolded after 24 hours have passed, and then cured with carbon dioxide gas first in the curing step. _{Comparing the bending strength σ B} of the stucco cured product that can be cured in the air for a total of 41 days with _{the bending strength σ B0} of the sand plaster cured product, the strength ratio is σ _B / σ _B0 > 6.0 or more. rice field.

Similarly, when the compressive strength σ _c of the stucco cured product of the _{present embodiment is compared with the compressive strength σ C0} of the sand plaster cured product, the strength ratio is σ _C / σ _C0 > 5.5 or more. rice field.

As described above, the plaster of the present embodiment has a small volume increase / decrease rate when it is made into a cured product, so that cracks, gaps and the like are less likely to occur, and the plaster is suitable as plaster for panels. In addition, it is possible to obtain a hardened plaster body that is about 20% lighter than conventional sand plaster but has a strength of 5.5 times or more, and it can be said that it is very promising as a material for promoting panelization. It has a good balance between lightness and strength, has excellent toughness, and can be said to be a material with characteristics not found in plaster currently on the market.

Next, a plaster panel (board) or a decorative board using the plaster (bamboo chip high Ca sand plaster) of the present embodiment will be described. The plaster panel or decorative board obtained by curing the plaster (plaster composition) of the present embodiment is lightweight and has excellent strength and toughness, so that it can be suitably used as a building material such as a wall material. Bamboo is known to have a bactericidal action and a sterilizing action, and in this respect as well, the stucco panel or decorative board can be said to be a preferable building material.

The size of the plaster panel is not particularly limited, but it is convenient if the thickness is 9 mm or 12 mm and the width × length is 910 mm × 2400 mm, 910 mm × 1820 mm, 910 mm × 910 mm.

The decorative board is a plaster board with a finely finished surface, and unlike a general plaster panel whose surface is not particularly finely finished, it is not necessary to apply a finishing material to the surface. The dimensions of such a decorative board are not particularly limited, but it is convenient if the thickness is 9 mm, 12 mm or 15 mm, and the width × length is 300 mm × 600 mm and 400 mm × 800 mm.

The plaster panel or decorative board may be used as a plaster panel or a decorative board by curing the plaster without using a base material, or a plaster panel by applying plaster on the plaster using Komai or wood shaving as a base material. Alternatively, it may be used as a decorative board.

Next, FIG. 1 shows a procedure for manufacturing a hardened stucco body. It should be noted that this method is not limited to a plate material such as a plaster panel or a decorative plate, and can be widely used for producing a cured body of plaster.

As a first step, a predetermined amount of lime, sand, bamboo chips and a high Ca ion-containing aqueous solution are kneaded to produce bamboo chips high Ca sand plaster (composition). Next, the bamboo chip high Ca sand plaster is filled in the mold (step S2), and the mold is removed after 24 hours have passed (step S3). Subsequently, the demolded plaster is cured with carbon dioxide gas (step S4). Here, a carbonation reaction occurs between calcium hydroxide and Ca ions in the plaster and carbon dioxide gas.

The carbon dioxide curing time depends on the size of the plaster panel or the decorative board, but may be about 2 to 3 days in consideration of the examples described later. After the carbon dioxide gas curing is completed, aerial curing is performed (step S5).

In the production procedure shown in FIG. 1, carbon dioxide gas curing is performed immediately after demolding, but aerial curing may be performed prior to carbon dioxide gas curing. Since the aerial curing performed prior to the carbon dioxide curing is mainly for the purpose of drying the plaster, the aerial curing period may be appropriately determined depending on the air temperature, humidity, the size of the plaster panel or the decorative plate, and the like. Although it depends on the size of the plaster panel or the decorative board, the aerial curing period may be about 3 to 7 days in consideration of the examples described later.

When producing a cured product using the plaster of the present embodiment as described above, it is preferable to include the carbon dioxide gas curing step and the aerial curing step in the curing step, and in particular, immediately after the demolding shown in FIG. The method of performing carbon dioxide curing and then performing aerial curing is suitable for producing a plaster panel or a decorative board. Considering the physical stability of the plaster panel or the decorative board and the manufacturing cost, it is preferable to perform carbon dioxide gas curing for about 2 to 3 days as the first curing step, and then perform aerial curing. As a result, plaster panels or decorative boards can be easily manufactured and shipped at factories and the like.

As described above, the preferred embodiment has been described, but those skilled in the art will easily assume various changes and modifications within a trivial range by looking at the present specification. Therefore, such changes and amendments are construed as being within the scope of the invention as defined by the claims.

Example: Bamboo chip high Ca sand stucco composition The preparation procedure is shown. 100 parts by weight of quicklime (manufactured by Nakayama Lime Industry Co., Ltd .; particle size 0.15 mm or less) shown in Table 1, 300 parts by weight of lime sand, and 40 parts by weight of fibrous bamboo chips with a length of 3 mm or less are prepared by the following procedure. 110 parts by weight of the high Ca ion-containing aqueous solution was mixed to obtain a bamboo chip high Ca sand plaster composition. The bamboo chip content (BTR) is 40% and the water-lime ratio is 110%. Bamboo chips were used after passing through a sieve having an opening of 3 mm and removing the top of the sieve. The Ca ion concentration of the high Ca ion-containing aqueous solution was 10 g / L. In the same manner, a bamboo chip high Ca sand plaster composition having a bamboo chip content of 80% was obtained.

The high Ca ion-containing aqueous solution was prepared as follows. White color obtained by calcining oyster shells at 1200 ° C. in an acetic acid aqueous solution (10% by mass concentration) in which 100 g of acetic acid (first grade manufactured by Wako Pure Chemical Industries, Ltd., code No. 014-00266) is added to 900 g of pure water. 30 g of the powder of Wako Pure Chemical Industries, Ltd. was added in several portions and completely dissolved. After leaving this solution for half a day, the supernatant was collected and used as a high Ca ion-containing aqueous solution (stock solution). Water was added to the undiluted solution to obtain a high Ca ion-containing aqueous solution. Table 2 shows the component analysis results of the white powder obtained by firing the oyster shell at 1200 ° C.

Further, using fibrous bamboo chips having a length of 6 mm or less, a bamboo chip high Ca sand plaster composition having a bamboo chip content of 40% was produced. This plaster composition was cured by the curing pattern 2 described later to obtain a test body (bamboo chip high Ca sand stucco cured body).

Comparative Example: High Ca Sand Stucco As a comparative example, a high Ca sand plaster composition containing no bamboo chips was prepared in the following manner. A high Ca sand plaster composition is prepared by mixing 100 parts by weight of quick lime (manufactured by Nakayama Lime Industry Co., Ltd .; particle size 0.15 mm or less) shown in Table 1, 300 parts by weight of lime sand, and 110 parts by weight of a high Ca ion-containing aqueous solution. Obtained. The water-lime ratio is 110%. The Ca ion concentration of the high Ca ion-containing aqueous solution was 10 g / L.

Hardened Bamboo Chip High Ca Sand Stucco As a test piece for measuring the physical properties of bamboo chip high Ca sand plaster, a hardened bamboo chip high Ca sand plaster prepared in the following manner was used. Pour the above plaster composition (hereinafter referred to as plaster) into a triple formwork to about half, poke it evenly with a stick so that the plaster spreads to every corner of the formwork, and then pour the plaster to the full formwork. , I pierced evenly until the bottom of the stick was 1/3 of the previous depth. Further, plaster was poured and left for 4 hours until the surface of the mold was hidden. Then, the upper part of the mold was cut with a parallel bar, and after being cured in the air for 24 hours, it was taken out from the mold, placed in a curing case, and cured in the following manner to obtain a test piece. The test piece is a 40 × 40 × 160 mm prismatic shape. During curing, the weight of the test piece and the length, width and height of the test piece were measured daily using a digital caliper.

Curing pattern 1
Curing after demolding was performed as follows. After demolding, as the first curing step, the air was cured in the air curing room for 0 to 8 days. Then, as the second curing step, it was cured in a carbon dioxide curing room for 8 days. Furthermore, as the third curing step, the air was cured until the day before the destruction test (strength test). This is referred to as curing pattern 1. The destructive test was performed 39 days after the demolding.

Curing pattern 2
Curing after demolding was performed as follows. After demolding, it was cured in a carbon dioxide curing room for 0 to 8 days as the first curing step. Furthermore, as the second curing step, aerial curing was performed until the day before the destruction test. This is referred to as curing pattern 2. The destructive test was performed 42 days after the demolding.

2 and 3 show the measurement results of the volume increase / decrease rate and the density of the test pieces obtained in the curing pattern 1 and the curing pattern 2 on the day before the fracture test. The number of days of the first curing on the horizontal axis of FIGS. 2 and 3 represents the number of days of the first curing step, and the description of the reference numeral indicates whether the first curing step is aerial curing or carbon dioxide curing, and further indicates the content of bamboo chips. .. For example, "Aerial Curing BTR40", which is a code description of a black circle in FIG. 2, is a test body in which the first curing step is aerial curing, that is, a test piece cured by the curing pattern 1, and the bamboo chip content is 40. Indicates that it is%. The same applies to other figures.

The volume increase / decrease rate (volume change rate) is obtained by measuring the length, width, and height of the test piece on the day before the fracture test using a digital caliper, and obtaining the volume V of the test piece based on these, and the volume at the time of demolding. It was obtained by using the formula (1) with V _{0 as a reference.}
Volume increase / decrease rate (%) = (Volume on the day before the fracture test-Volume at the time of demolding) / Volume at the time of demolding
× 100 ・ ・ ・ (1)

The density was determined by measuring the weight W of the test piece on the day before the fracture test and dividing the weight by the volume V calculated in the above procedure.

As shown in FIG. 2, the volume increase / decrease rate was smaller as the bamboo chip content was larger, regardless of the curing pattern. In relation to the number of first curing days, the amount of change in the volume increase / decrease rate during the first curing days of 1 to 8 days was about 2.5% at the maximum. In relation to the curing pattern, in the curing pattern 1 in which the first curing step was aerial curing, the volume contraction tended to increase in proportion to the number of first curing days. On the other hand, in the curing pattern 2 in which the first curing step was carbon dioxide gas curing, the volume increase / decrease rate tended to be almost the same or slightly increased (expanded) regardless of the number of days of the first curing.

In the case of a test piece with a bamboo chip content of 80%, when cured by curing pattern 2 in which carbon dioxide gas curing is performed after demolding, the amount of change in the volume increase / decrease rate is very small in the first curing days 1 to 8 days, and is about 0 to 0. It was a slight expansion of + 0.6%.

As shown in FIG. 3, the density decreases as the bamboo chip content increases regardless of the curing pattern. When the bamboo chip content is 80%, the density is about 1.42 to 1.51 g / cm ³ , and the bamboo chip content. At 40%, the density was about 1.55-1.64 g / cm ³ .

When the density of this test piece (bamboo chip high Ca sand plaster hardened body) is compared with the density of the sand plaster hardened body, the density of the sand plaster hardened body is 1.9 to 2.0 g / cm ³ , so that the bamboo chip The hardened sand plaster with a high Ca sand lacquer content of 80% is about 0.5 g / cm ³ smaller than the hardened sand plaster by about 25%. Similarly, the bamboo chip high Ca sand plaster cured product having a bamboo chip content of 40% is about 0.35 g / cm ³ smaller than the sand plaster cured product by about 19%.

Looking at the density of this test piece from the curing pattern, when curing is performed in the curing pattern 1 in which aerial curing is performed immediately after demolding and then carbon dioxide gas curing and aerial curing are performed, the density does not depend on the bamboo chip content. It tended to increase in proportion to the number of first curing days. On the other hand, when curing was performed in the curing pattern 2 in which carbon dioxide gas curing was performed immediately after demolding, the density became stable after the first curing day was 2 days regardless of the bamboo chip content, and remained almost constant thereafter.

4 and 5 show the strength test results of the test pieces obtained in the curing pattern 1 and the curing pattern 2. The strength test was carried out according to JIS A1171 (test method for polymer cement mortar).

As shown in FIG. 4, the bending strength was about 0.95 to 1.9 N / mm ² at a bamboo chip content of 40% and about 1.25 at a bamboo chip content of 80% in the first curing days 1 to 8 days. It was ~ 1.87 N / mm ^2. Since the bending strength of the test piece (40 × 40 × 160 mm prismatic) obtained by aerial curing of sand plaster for about 40 days is about 0.2 N / mm ² , the bending strength of the bamboo chip high Ca sand plaster hardened body Is about 5 to 9.5 times the bending strength of the hardened sand plaster.

As shown in FIG. 4, the bending strength of the bamboo chip high Ca sand plaster hardened body having a bamboo chip content of 40% was almost the same regardless of the curing pattern. The bending strength of the bamboo chip high Ca sand plaster hardened body having a bamboo chip content of 80% was almost the same regardless of the curing pattern when the first curing days were 4 to 7 days.

As shown in FIG. 5, the compressive strength was about 2.3 to 6.4 N / mm ² when the bamboo chip content was 40% and about 3.9 when the bamboo chip content was 80% in the first curing days 1 to 8 days. It was ~ 7.9 N / mm ^2. In the case of the first curing days of 2 to 8 days, the bamboo chip content was 40% and was about 3.9 to 6.4 N / mm ² . Since the bending strength of the test piece (40 × 40 × 160 mm prismatic) obtained by aerial curing of sand plaster for about 40 days is about 0.7 N / mm ² , the first curing period is 2 to 8 days. The bending strength of the bamboo chip high Ca sand plaster hardened body is 5.5 to 11 times the bending strength of the sand plaster hardened body.

Looking at the compressive strength in relation to the curing pattern, when cured by the first curing pattern, the number of days of the first curing increased in the range of 1 to 8 days as compared with the number of days of the first curing regardless of the bamboo chip content. On the other hand, when cured by the second curing pattern, the compressive strength increased until the first curing day was 2 days regardless of the bamboo chip content, but became almost the same value after 2 days. In particular, in the case of a test piece having a bamboo chip content of 80%, the compressive strength was stabilized at an early stage when the test piece was cured by the curing pattern 2 in which carbon dioxide gas curing was performed after demolding.

FIG. 6A is a diagram showing the progress of neutralization of the bamboo chip high Ca sand plaster hardened body (test piece) obtained by the curing pattern 1, and phenol is formed on the bending fracture cross section of each test piece by the strength test. It is a figure obtained by spraying a phthalein liquid. Similarly, FIG. 6B is a diagram showing the progress of neutralization of the bamboo chip high Ca sand plaster hardened body (test piece) obtained by the curing pattern 2. The white part is the neutralized part and is calcium carbonate. The red part is the part that has not been neutralized yet and is calcium hydroxide.

6 (a) and 6 (b) include specimens having a first curing day of 0 to 8 days. The arrangement of the test bodies is from the bottom left to the top right in each figure, and the number of first curing days is increasing. Specifically, the test piece on the leftmost side of the bottom row and the test piece to the right of it has 0 days of first curing day, and the test piece on the rightmost side of the bottom row and the test piece to the left of it has 2 days of first curing day. , The test piece on the leftmost side of the middle row and the test piece to the right of it has the first curing day of 3 days, and the test piece on the rightmost side of the middle row and the test piece to the left of it has the first curing day of 5 days. The test specimens on the right and to the left of it have a first curing day of 8 days.

As can be seen from FIG. 6, in the relationship between the bamboo chip content and the neutralization progress state, it can be seen that the higher the bamboo chip content is, the more the neutralization is progressing in both the curing pattern 1 and the curing pattern 2. Regarding the relationship between the number of first curing days and the progress of neutralization, both curing pattern 1 and curing pattern 2 are being neutralized as the number of first curing days increases. In particular, the test piece having a bamboo chip content of 80% obtained in the curing pattern 2 has a first curing period of 2 days, and neutralization has progressed to the central part.

FIG. 7 is a diagram showing the relationship between the number of first curing days and the amount of rebound. The rebound amount is the amount of change in weight when switching from the first curing step to the second curing step. Specifically, it is the difference between the weight of the test piece on the first day of the second curing process and the weight of the test piece on the last day of the first curing process. According to the data of 2 days, when the first curing process is aerial curing and the curing days are 2 days, and the second curing process is carbon dioxide gas curing and the weight is measured on the first day, the weight increases by 10 g in one day of carbon dioxide curing. Show that you did.

The amount of rebound is as follows: in the curing pattern 1 in which the first curing process is aerial curing, the first curing days are 2 days or later, and in the curing pattern 2 in which the first curing process is carbon dioxide gas curing, the first curing days are 0 days or later. , All became positive.

When curing was performed according to the curing pattern 1, the amount of rebound increased in proportion to the number of days of the first curing. From this, it can be seen that if carbon dioxide gas curing is performed after the product has been sufficiently dried, carbon dioxide gas absorption and carbonation reaction proceed. Both the bamboo chip content of 40% and the bamboo chip content of 80% showed the same tendency, but the value of the rebound amount was larger for the bamboo chip content of 40%.

In the case of curing according to the curing pattern 2, the amount of rebound increased in proportion to the number of the first curing days up to the first curing day of 2 days, but became almost constant after the 1st curing day of 2 days. Both the bamboo chip content of 40% and the bamboo chip content of 80% showed the same tendency, but the value of the rebound amount was larger for the bamboo chip content of 80%.

Comparing the rebound amount according to the curing pattern, the rebound amount was higher in the curing pattern 2 than in the curing pattern 1 until the first curing day 3 days, but this relationship was reversed after the first curing day 3 days. From FIGS. 5 and 7, it can be seen that the relationship between the first curing days and the rebound amount shows the same tendency as the relationship between the first curing days and the compressive strength.

Claims (8)

It is a plaster whose main components are lime, fine aggregate and kneaded water.
The lime is quick lime and / or slaked lime.
Bamboo chips in which the fine aggregate is crushed into sand and fibers.
The weight ratio of the bamboo chips to the lime is 40 to 80%, and the weight ratio of the bamboo chips to the sand is 10 to 30%.
The kneaded water is a high Ca ion-containing aqueous solution.
Stucco characterized in that the Ca ion concentration contained in the high Ca ion-containing aqueous solution is 2 to 20 g / L. The plaster according to claim 1, wherein the bamboo chips have a length of 3 to 15 mm. When the plaster was poured into a 40 × 40 × 160 mm prismatic mold and demolded after 24 hours, the volume was V ₀ , and after demolding, carbon dioxide gas curing was performed for 1 to 8 days, and then in the air. _{A claim characterized in that (V-V 0} ) / V ₀ is 0 to + 0.6%, where V is the volume of the hardened stucco obtained after curing for a total of 41 days. The plaster according to item 1 or claim 2. A plaster panel obtained by curing the plaster according to any one of claims 1 to 3. A plaster panel obtained by curing the plaster according to any one of claims 1 to 3 using a wood grain as a base. A decorative board according to claim 4 or 5, wherein the plaster panel is surface-finished. The method for manufacturing a plaster panel according to claim 4 or claim 5 or a decorative board according to claim 6.
As a curing process, an aerial curing process, a carbon dioxide gas curing process, and
A method for manufacturing a plaster panel or a decorative board, which comprises. The method for manufacturing a plaster panel or a decorative board according to claim 7, wherein the carbon dioxide gas curing step is carried out prior to the aerial curing step.

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