Gypsum board with high nail pull and method of making

Abstract

The embodiment of the present application provides a kind of high nail holding force gypsum board and preparation method thereof, the gypsum board includes: 60 parts by weight to 80 parts by weight gypsum, 2 parts by weight to 15 parts by weight cement, 2 parts by weight to 10 parts by weight mineral powder, 2 parts by weight to 10 parts by weight fly ash, 2 parts by weight to 3 parts by weight calcium oxide, 0.1 parts by weight to 0.5 parts by weight crystal modifier, 0.1 parts by weight to 0.5 parts by weight fluorine silicon emulsion, 0.5 parts by weight to 0.8 parts by weight water reducing agent, 0.1 parts by weight to 0.5 parts by weight retarder.The gypsum board provided by the embodiment of the present application has the characteristics of strong nail holding force, low cost, green environmental protection and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to, but is not limited to, the field of building materials, and in particular to a high-nail-holding-strength gypsum board and a preparation method thereof. BACKGROUND

[0002] Gypsum board has the advantages of light weight, flame retardation, heat preservation and insulation, and is applied to indoor buildings as wall and decoration materials. However, the gypsum products still have defects such as low strength, poor water resistance and easy breakage, which limit their utilization. In indoor decoration, wood structures are still mostly used, and a large amount of artificial boards are used as roof boards, partition boards and roof beams. The large use of artificial boards is not only not conducive to green and sustainable development, but also releases excessive harmful substances such as formaldehyde, which is harmful to human health. Therefore, it is very urgent to improve the performance of gypsum board to expand its utilization in the field of indoor decoration.

[0003] At present, there are relevant reports on the improvement of the performance of gypsum board at home and abroad. For example, there are many reports on improving the mechanical strength, wear resistance and antibacterial property of gypsum board, but there are few reports on improving the nail holding strength of gypsum board. SUMMARY

[0004] The following is a summary of the subject matter of the detailed description herein. This summary is not intended to limit the scope of protection of the present application.

[0005] The embodiments of the present application provide a high-nail-holding-strength gypsum board and a preparation method thereof, which has the characteristics of strong nail holding strength, low cost, green and environmental protection, etc.

[0006] The embodiments of the present application provide a high-nail-holding-strength gypsum board, which comprises:

[0007]

[0008]

[0009] In the embodiments of the present application, the crystal modifier can be selected from any one or more of maleic acid and aluminum sulfate.

[0010] In the embodiments of the present application, the cement can be a sulphoaluminate cement.

[0011] In the embodiments of the present application, the gypsum can be semi-hydrated desulfurization gypsum.

[0012] In the embodiments of the present application, the average particle size of the gypsum can be 20 μm to 60 μm.

[0013] In the embodiments of the present application, the specific surface area of the gypsum can be 1.253 m 2 / g-1.582 m2 / g.

[0014] In the embodiments of the present application, the mineral powder contains silicate, aluminate and calcium oxide, the total mass percentage of silicate and aluminate in the mineral powder can be 45% to 55%, and the mass percentage of calcium oxide in the mineral powder can be 35% to 40%.

[0015] In the embodiments of the present application, the average particle size of the mineral powder can be 7 μm to 10 μm.

[0016] In the embodiments of the present application, the average particle size of the fly ash can be 10 μm to 20 μm.

[0017] In the embodiments of the present application, the mass percentage of solids in the fluorosilicon emulsion can be 40% to 50%, and the average particle size of solids can be 70 nm to 150 nm.

[0018] In the embodiments of the present application, the water reducing agent can be selected from any one or more of polycarboxylic acid superplasticizer and naphthalene series water reducing agent.

[0019] In the embodiments of the present application, the retarder can be selected from any one or more of sodium citrate and protein-based retarder.

[0020] The embodiments of the present application also provide a preparation method of the high-nail-holding force gypsum board as described above, and the preparation method comprises:

[0021] dispersing the crystal modifier, the fluorosilicon emulsion, the water reducing agent and the retarder in water to obtain an admixture solution;

[0022] mixing the gypsum, the cement, the mineral powder, the fly ash, the calcium oxide, water and the admixture solution, and controlling the water-gypsum ratio to be 0.4 to 0.5 to obtain a slurry;

[0023] casting the slurry in a mold, shaping, curing to obtain the high-nail-holding force gypsum board.

[0024] The technical scheme of the embodiments of the present application can obtain the following beneficial effects:

[0025] (1) The present application introduces a crystal modifier into the gypsum board, which can convert the crystal form of gypsum into a short column shape, improve the compactness of the base structure, and improve the nail holding force of the gypsum board;

[0026] (2) The present application introduces cement (for example, sulphoaluminate cement, mineral powder, fly ash into the gypsum board, which can increase the compactness of the gypsum base at an early stage and the effective lap joint points, thereby improving the nail holding force of the gypsum board;

[0027] (3) The main raw materials of the gypsum board of the present application include gypsum, mineral powder, and solid waste such as fly ash, so that the raw material cost is greatly reduced, the resource utilization rate is increased, the pressure on the environment is reduced, the preparation process is simple, and the gypsum board is easy to produce and popularize, which has energy-saving and environmental protection significance and economic benefits;

[0028] In summary, the gypsum board of the embodiments of the present application has the characteristics of strong nail holding force, low cost, green environmental protection, and can be widely used in the field of indoor decoration and other building fields, replacing wooden structures, improving indoor air environment, and benefiting human health.

[0029] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the present application. Other advantages of the present application can be realized and obtained by the solutions described in the specification. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present application more clear, the embodiments of the present application will be described in detail below. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other arbitrarily without conflict.

[0031] The embodiments of the present application provide a high-nail-holding-force gypsum board, which comprises:

[0032]

[0033] In the embodiments of the present application, the high-nail-holding-force gypsum board is composed of the following components:

[0034]

[0035] In the embodiments of the present application, the high-nail-holding-force gypsum board can comprise:

[0036] 60-80 parts by weight of gypsum, for example, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, or 80 parts by weight of gypsum;

[0037] 2-15 parts by weight of cement, for example, 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight, 10 parts by weight, 12 parts by weight, 14 parts by weight, or 15 parts by weight;

[0038] 2-10 parts by weight of mineral powder, for example, 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight, or 10 parts by weight of mineral powder;

[0039] 2-10 parts by weight of fly ash, for example, can include 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight or 10 parts by weight of fly ash;

[0040] 2-3 parts by weight of calcium oxide, for example, can include 2 parts by weight, 2.5 parts by weight or 3 parts by weight of calcium oxide;

[0041] 0.1-0.5 parts by weight of a crystallization modifier, for example, can include 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight or 0.5 parts by weight of the crystallization modifier;

[0042] 0.1-0.5 parts by weight of a fluorosilicon emulsion, for example, can include 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight or 0.5 parts by weight of the fluorosilicon emulsion;

[0043] 0.5-0.8 parts by weight of a water reducing agent, for example, can include 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight or 0.8 parts by weight of the water reducing agent;

[0044] 0.1-0.5 parts by weight of a retarder, for example, can include 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight or 0.5 parts by weight of the retarder.

[0045] In the embodiments of the present application, the crystallization modifier can be selected from any one or more of maleic acid and aluminum sulfate. The purity of the crystallization modifier can be ≥ 99%, which is an analytically pure product.

[0046] In the embodiments of the present application, the cement can be a sulphoaluminate cement, for example, a fast-hardening sulphoaluminate cement.

[0047] In the embodiments of the present application, the gypsum can be semi-hydrated desulfurization gypsum.

[0048] The average particle size of the gypsum can be 20-60 μm; the specific surface area can be 1.253 m 2 / g-1.582 m 2 / g; the purity can be 95%-98%; the water content can be 2.6%-5.3% by mass percentage.

[0049] In the embodiments of the present application, the mineral powder contains silicates, aluminates and calcium oxide, and the total mass percentage of the silicates and aluminates in the mineral powder can be 45%-55%, and the mass percentage of the calcium oxide in the mineral powder can be 35%-40%.

[0050] In the embodiments of this application, the mineral powder can be ultrafine mineral powder, for example, its average particle size can be 7μm to 10μm, and its specific surface area can be 400cm². 2 / g to 450cm 2 / g.

[0051] In the embodiments of this application, the average particle size of the fly ash can be from 10 μm to 20 μm. The density of the fly ash can be 1.32 g / cm³. 3 Up to 1.53 g / cm 3 .

[0052] In the embodiments of this application, the raw materials for synthesizing the fluorosilicone emulsion may mainly include butyl acrylate, methyl methacrylate and acrylic acid.

[0053] In the embodiments of this application, the mass percentage of solids in the fluorosilicone emulsion can be 40% to 50%, and the average particle size of the solids can be 70 nm to 150 nm.

[0054] The viscosity of the fluorosilicone emulsion can be from 80 mPa·s to 100 mPa·s.

[0055] In the embodiments of this application, the water-reducing agent may be selected from any one or more of polycarboxylate superplasticizers and naphthalene-based water-reducing agents.

[0056] In the embodiments of this application, the retarder may be selected from any one or more of sodium citrate and protein-based retarders.

[0057] This application also provides a method for preparing high nail-holding power gypsum board as described above, including:

[0058] A crystallizing agent, fluorosilicone emulsion, water-reducing agent, and retarder are dispersed in water to obtain an admixture solution;

[0059] Gypsum, cement, mineral powder, fly ash, calcium oxide, water, and the admixture solution are mixed, and the water-to-gypsum ratio is controlled to be 0.4 to 0.5 to obtain a slurry.

[0060] The slurry is poured into a mold, shaped, and cured to obtain the high nail-holding power gypsum board.

[0061] In the embodiments of this application, the curing process may include: placing the gypsum board product in an environment with a temperature of 50°C to 80°C and a humidity of 60% to 90% for 12 to 24 hours; and then transferring it to an environment with a room temperature of 20±2°C and a humidity of 50±2% for curing until the corresponding age.

[0062] The technical solution of this application will be described in detail below with reference to the embodiments.

[0063] In the following examples and comparative examples, the gypsum powder used is semi-hydrated desulfurization gypsum powder with an average particle size of 30 μm, a specific surface area of 1.264 m 2 / g, a purity of 98%, and a water content of about 2.7% by mass;

[0064] The fly ash used has an average particle size of 13 μm and a density of 1.32 g / cm 3 ;

[0065] The aluminum sulfate used as a crystal modifier has a purity of more than 99%;

[0066] The cement used is fast-hardening sulphoaluminate cement 42.5 produced by Huaxin Cement Co., Ltd.;

[0067] The mineral powder used is V500-I slag powder produced by Wuhan Weishen Technology Development Co., Ltd., with an average particle size of 8 μm, a specific surface area of 400 cm 2 / g, a total silicate and aluminate content of 50% by mass, and a calcium oxide content of 35%;

[0068] The fluorosilicon emulsion used is JL-S02 fluorosilicon emulsion produced by Changsha Jianglong Chemical Technology Co., Ltd., with a viscosity of 100 mPa.s, a solid content of 50%, and an average particle size of 80 nm;

[0069] The water reducing agent used is ZY-HPWR-S polycarboxylic acid high-efficiency water reducing agent produced by Hunan Zhongyan Building Materials;

[0070] The retarder used is HN-302 protein-based retarder produced by Hebei Xiezong Chemical Co., Ltd.

[0071] Example 1

[0072] The high-nail-holding gypsum board of this example is prepared from the following raw materials by mass:

[0073] The powder material includes: gypsum powder: 80 parts by weight; cement: 10 parts by weight; mineral powder: 2 parts by weight; fly ash: 5 parts by weight; calcium oxide: 3 parts by weight;

[0074] The admixture includes: aluminum sulfate: 0.15 parts by weight; fluorosilicon emulsion: 0.1 parts by weight; water reducing agent: 0.5 parts by weight; retarder: 0.1 parts by weight;

[0075] Water: to make the water / gypsum ratio 0.45.

[0076] The powder material is mixed uniformly in proportion, the admixture is uniformly dispersed in part of the water in advance to form an admixture solution, the uniformly mixed powder material, the admixture solution, and the remaining water are stirred uniformly, and then molded and cured.

[0077] Curing system: the formed gypsum board is cured in an environment with a temperature of 80℃ and a humidity of 90% for 12h; then the gypsum board is transferred to an environment with a room temperature of 20±2℃ and a humidity of 50±2% for curing to the corresponding age.

[0078] Example 2

[0079] The high-nail-holding gypsum board of the present example is prepared from the following raw materials by mass percentage:

[0080] The powder material includes: gypsum powder: 75 parts by weight; cement: 13 parts by weight; mineral powder: 5 parts by weight; fly ash: 4 parts by weight; calcium oxide: 3 parts by weight;

[0081] The additive includes: maleic acid and aluminum sulfate in a mass ratio of 1:1, together 0.2 parts by weight; fluorosilicon emulsion: 0.15 parts by weight; water reducing agent: 0.5 parts by weight; retarder 0.15 parts by weight;

[0082] Water: the water-gypsum ratio is 0.43.

[0083] The powder material is mixed uniformly in proportion, the additive is uniformly dispersed in part of the water in advance to form an additive solution, the uniformly mixed powder material, the additive solution and the remaining water are stirred uniformly, molded by injection, and cured.

[0084] Curing system: the formed gypsum board is cured in an environment with a temperature of 80℃ and a humidity of 90% for 12h; then the gypsum board is transferred to an environment with a room temperature of 20±2℃ and a humidity of 50±2% for curing to the corresponding age.

[0085] Example 3

[0086] The high-nail-holding gypsum board of the present example is prepared from the following raw materials by mass percentage:

[0087] The powder material includes: gypsum powder: 70 parts by weight; cement: 13 parts by weight; mineral powder: 7 parts by weight; fly ash: 7 parts by weight; calcium oxide: 3 parts by weight;

[0088] The additive includes: maleic acid: 0.25 parts by weight; fluorosilicon emulsion: 0.1 parts by weight; water reducing agent: 0.55 parts by weight; retarder 0.1 parts by weight;

[0089] Water: the water-gypsum ratio is 0.42.

[0090] The powder material is mixed uniformly in proportion, the additive is uniformly dispersed in part of the water in advance to form an additive solution, the uniformly mixed powder material, the additive solution and the remaining water are stirred uniformly, molded by injection, and cured.

[0091] Curing system: the formed gypsum board is placed in an environment with a temperature of 80°C and a humidity of 90% for curing for 15 hours; then the gypsum board is transferred to an environment with a room temperature of 20±2°C and a humidity of 50±2% for curing to the corresponding age.

[0092] Example 4

[0093] The high nail-holding force gypsum board of the present example is prepared from the following raw materials by mass percentage:

[0094] The powder material includes: gypsum powder: 65 parts by weight; cement: 15 parts by weight; mineral powder: 5 parts by weight; fly ash: 2 parts by weight; calcium oxide: 3 parts by weight;

[0095] The admixture includes: aluminum sulfate: 0.3 parts by weight; fluorosilicon emulsion: 0.3 parts by weight; water reducing agent: 0.6 parts by weight; retarder: 0.15 parts by weight;

[0096] Water: the water / gypsum ratio is 0.40.

[0097] The powder material is mixed uniformly in proportion, the admixture is uniformly dispersed in part of the water in advance to form an admixture solution, the uniformly mixed powder material, the admixture solution and the remaining water are stirred uniformly, injection molding is performed, and curing is performed.

[0098] Curing system: the formed gypsum board is placed in an environment with a temperature of 80°C and a humidity of 90% for curing for 12 hours; then the gypsum board is transferred to an environment with a room temperature of 20±2°C and a humidity of 50±2% for curing to the corresponding age.

[0099] Example 5

[0100] The high nail-holding force gypsum board of the present example is prepared from the following raw materials by mass percentage:

[0101] The powder material includes: gypsum powder: 75 parts by weight; cement: 15 parts by weight; mineral powder: 3 parts by weight; fly ash: 5 parts by weight; calcium oxide: 2 parts by weight;

[0102] The admixture includes: aluminum sulfate: 0.4 parts by weight; fluorosilicon emulsion: 0.35 parts by weight; water reducing agent: 0.5 parts by weight; retarder: 0.15 parts by weight;

[0103] Water: the water / gypsum ratio is 0.48.

[0104] The powder material is mixed uniformly in proportion, the admixture is uniformly dispersed in part of the water in advance to form an admixture solution, the uniformly mixed powder material, the admixture solution and the remaining water are stirred uniformly, injection molding is performed, and curing is performed.

[0105] Curing system: the formed gypsum board is placed in an environment with a temperature of 80°C and a humidity of 90% for 12h; then the gypsum board is transferred to an environment with a room temperature of 20±2°C and a humidity of 50±2% for curing to the corresponding age.

[0106] Comparative Example 1

[0107] The gypsum board of the present comparative example is prepared from the following raw materials by mass percentage:

[0108] The powder material includes: gypsum powder: 80 parts by weight; cement: 10 parts by weight; fly ash: 5 parts by weight;

[0109] The admixture includes: aluminum sulfate: 0.15 parts by weight; fluorosilicon emulsion: 0.1 parts by weight; water reducing agent: 0.5 parts by weight; retarder 0.1 parts by weight;

[0110] Water: the water / gypsum ratio is 0.45.

[0111] The powder material is mixed uniformly in proportion, the admixture is uniformly dispersed in part of the water in advance to form an admixture solution, the uniformly mixed powder material, the admixture solution and the remaining water are stirred uniformly, injection molding, curing;

[0112] Curing system: the formed gypsum board is placed in an environment with a temperature of 80°C and a humidity of 90% for 12h; then the gypsum board is transferred to an environment with a room temperature of 20±2°C and a humidity of 50±2% for curing to the corresponding age.

[0113] Comparative Example 2

[0114] The gypsum board of the present comparative example is prepared from the following raw materials by mass percentage:

[0115] The powder material includes: gypsum powder: 75 parts by weight; cement: 13 parts by weight; mineral powder: 5 parts by weight; calcium oxide: 3 parts by weight;

[0116] The admixture includes: aluminum sulfate: 0.2 parts by weight; fluorosilicon emulsion: 0.15 parts by weight; water reducing agent: 0.52 parts by weight; retarder 0.15 parts by weight;

[0117] Water: the water / gypsum ratio is 0.43.

[0118] The powder material is mixed uniformly in proportion, the admixture is uniformly dispersed in part of the water in advance to form an admixture solution, the uniformly mixed powder material, the admixture solution and the remaining water are stirred uniformly, injection molding, curing;

[0119] Curing system: the formed gypsum board is placed in an environment with a temperature of 80°C and a humidity of 90% for 12h; then the gypsum board is transferred to an environment with a room temperature of 20±2°C and a humidity of 50±2% for curing to the corresponding age.

[0120] Comparative Example 3

[0121] The gypsum board of the present comparative example was prepared from the following raw materials by mass percentage:

[0122] The powder material included: gypsum powder: 80 parts by weight; cement: 10 parts by weight; mineral powder: 2 parts by weight; fly ash: 5 parts by weight; calcium oxide: 3 parts by weight;

[0123] The admixture included: fluorosilicon emulsion: 0.1 parts by weight; water reducing agent: 0.5 parts by weight; retarder: 0.1 parts by weight;

[0124] Water: the water-gypsum ratio was 0.45.

[0125] The powder material was mixed uniformly in proportion, the admixture was uniformly dispersed in part of the water to form an admixture solution, the uniformly mixed powder material, the admixture solution and the remaining water were stirred uniformly, and then the gypsum board was formed by injection molding and cured.

[0126] Curing system: the formed gypsum board was placed in an environment with a temperature of 80℃ and a humidity of 90% for curing for 12h; then the gypsum board was transferred to an environment with a temperature of 20±2℃ and a humidity of 50±2% for curing to the corresponding age.

[0127] The nail holding force of the gypsum board was tested according to the American standard ASTM C473-17 “Standard Test Methods for Physical Testing of Gypsum Board Products”; the compressive strength of the gypsum board was tested according to the Chinese national standard GB / T 17669.3-1999 “Determination of Mechanical Properties of Building Gypsum”; the softening coefficient was calculated according to the compressive strength; and the test results are shown in Table 1.

[0128] Table 1 Performance test results of the gypsum board of the examples and comparative examples

[0129]

[0130]

[0131] Note: The dry bending strength and the dry compressive strength are the bending strength and the compressive strength of the red rock of the gypsum board.

[0132] By comparing the performance of the gypsum board of Comparative Example 1 and Example 1, it can be seen that the gypsum board of Comparative Example 1 does not add mineral powder and calcium oxide, and the nail holding force and the board strength of the gypsum board are significantly lower than those of the gypsum board of Example 1.

[0133] By comparing the performance of the gypsum board of Comparative Example 2 and Example 2, it can be seen that the gypsum board of Comparative Example 2 does not add fly ash, and the nail holding force and the board strength of the gypsum board are significantly lower than those of the gypsum board of Example 2.

[0134] It can be seen from the performance of the gypsum board of comparative example 1 and comparative example 3 that the gypsum board of comparative example 3 does not add crystal modifier, and the nail holding force and the board strength of the gypsum board are obviously lower than those of the gypsum board of example 1;

[0135] Therefore, the introduction of the mineral powder, the calcium oxide, the fly ash and the crystal modifier is beneficial to improve the nail holding force and the board strength of the gypsum board, and in addition, does not affect the deformation resistance of the gypsum board.

[0136] Although the embodiments disclosed in the present application are as above, the content described is only the embodiments adopted for the convenience of understanding the present application, and is not used to limit the present application. Any person skilled in the art of the present application can make any modification and change in the implementation form and details without departing from the spirit and scope of the present application, but the protection scope of the present application shall be subject to the scope defined by the appended claims.

Claims

1. A high nailing strength gypsum board, characterized by, The raw materials include: gypsum 60-80 parts by weight cement 2-15 parts by weight mineral powder 2-10 parts by weight fly ash 2-10 parts by weight calcium oxide 2-3 parts by weight crystal modifier 0.1-0.5 parts by weight fluorosilicon emulsion 0.1-0.5 parts by weight water reducing agent 0.5-0.8 parts by weight retarder 0.1-0.5 parts by weight The crystal modifier is aluminum sulfate, or aluminum sulfate and maleic acid.

2. The high nailing force gypsum board of claim 1, wherein, The cement is sulphoaluminate cement.

3. The high nailing force gypsum board of claim 1, wherein, The gypsum is semi-hydrated desulfurization gypsum.

4. The high nailing force gypsum board of claim 3, wherein, The average particle size of the gypsum is 20-60 μm.

5. The high nailing force gypsum board of claim 3, wherein, The specific surface area of the gypsum is 1.253 m 2 / g-1.582 m 2 / g.

6. The high nailing force gypsum board of claim 1, wherein, The mineral powder contains silicates, aluminates and calcium oxide, the total mass percentage of silicates and aluminates in the mineral powder is 45-55%, and the mass percentage of calcium oxide in the mineral powder is 35-40%.

7. The high nailing force gypsum board of claim 6, wherein, The average particle size of the mineral powder is 7-10 μm.

8. The high nailing force gypsum board of claim 1, wherein, The average particle size of the fly ash is 10-20 μm.

9. The high nailing force gypsum board of claim 1, wherein, The mass percentage of solids in the fluorosilicon emulsion is 40-50%, and the average particle size of the solids is 70-150 nm.

10. The high nailing force gypsum board of claim 1, wherein, The water reducing agent is selected from any one or more of polycarboxylic acid superplasticizer and naphthalene-based water reducing agent.

11. The high nailing force gypsum board of claim 1, wherein, The retarder is selected from any one or more of sodium citrate and protein-based retarder.

12. The method of making a high nailing force gypsum board according to any one of claims 1 to 11, characterized in that, The method comprises: dispersing the crystal modifier, fluorosilicon emulsion, water reducing agent and retarder in water to obtain an additive solution; mixing the gypsum, cement, mineral powder, fly ash, calcium oxide, water and the additive solution, and controlling the water / gypsum ratio to be 0.4-0.5 to obtain a slurry; casting the slurry in a mold, shaping, curing to obtain the gypsum board with high nail holding force.

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