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GB/T 25998-2020Mineral wool decorating and acoustic ceilings (English PDF)

矿物棉装饰吸声板

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

June 2, 2020

Implementation date

April 1, 2021

Scope

GB/T 25998-2020 is the English-translated version of 矿物棉装饰吸声板.

A suspended ceiling is the one surface in an office, a classroom or a hospital corridor that is large, flat and out of reach, which makes it the natural place to put the sound absorption a room needs. Mineral wool boards do that job because the felted slag, rock or glass fibres leave an open pore network in which air movement is damped by friction, so that speech energy is dissipated instead of being reflected back into a room where the same hard surfaces reflect it again. The engineering problem is that everything which makes the board absorbent works against every other property it must have. Open porosity means low density and weak bending strength, so a 600 mm tile spanning a grid sags under its own weight and sags further when it takes up moisture from humid air. The binders and coatings that give strength and a decorative face can emit formaldehyde into the same enclosed room, and organic content raises the fire load of a surface directly above the occupants. This document sets the classification, designation, requirements, test methods and inspection rules that hold those competing demands together for wet-process and dry-process mineral wool ceiling boards used indoors.

Document preview — GB/T 25998-2020

National Standard of the People's Republic of China

ICS: 91.060.30
Classification: Q 25
Replacing: GB/T 25998-2010

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

1 Scope
2 Normative references
3 Terms and definitions
3.1 Mineral wool decorating and acoustic ceilings
3.2 Wet-process ceilings
3.3 Dry-process ceilings
3.4 Nominal size
3.5 Actual size
3.6 Right angle deviation
3.7 Pin holes
4 Classification and designation
4.1 Classification
4.2 Specifications
4.3 Product designation
5 Requirements
5.1 General requirements
5.1.1 Appearance quality
5.1.2 Permissible dimensional deviations
5.1.3 Bulk density
5.1.4 Burning behaviour
5.1.5 Radionuclide limits
5.1.6 Formaldehyde emission
5.1.7 Asbestos phase
5.2 Wet-process boards
5.2.1 Bending breaking load and thermal resistance
5.2.2 Noise reduction coefficient
5.2.3 Deflection after exposure to damp
5.2.4 Moisture content by mass
5.3 Dry-process boards
5.3.1 Bending breaking load and thermal resistance
6 Test methods

Foreword

GB/T 25998-2020 was issued on 2 June 2020 by the State Administration for Market Regulation and the Standardization Administration of the People's Republic of China, and has been in force since 1 April 2021. It is classified under ICS 91.060.30 and under Chinese Standard Classification code Q 25. It replaces GB/T 25998-2010, Mineral wool decorating and acoustic ceilings, which was the only previous edition.

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

Compared with GB/T 25998-2010, apart from editorial changes, the main technical changes are the following: the field of application was added (see Clause 1, and Clause 1 of the 2010 edition); the definitions of mineral wool decorating and acoustic ceilings, of wet-process ceilings and of dry-process ceilings were revised (see 3.1, 3.2 and 3.3, and 3.1, 3.2 and 3.3 of the 2010 edition); the content of the product designation was revised (see 4.3, and 4.3 of the 2010 edition); the bulk density requirement was revised (see 5.1.3, and 5.3 of the 2010 edition); the classification requirement for burning behaviour was revised (see 5.1.4, and 5.6 of the 2010 edition); the formaldehyde emission requirement was revised (see 5.1.6, and 5.10 of the 2010 edition); the technical requirements for products made by the different production processes were revised (see 5.2 and 5.3, and 5.3, 5.5, 5.6, 5.7 and 5.10 of the 2010 edition); the noise reduction coefficient requirement was revised (see 5.2.2 and 5.3.2, and 5.7 of the 2010 edition); the bending breaking load requirement for dry-process boards with a rock wool substrate was revised (see 5.3.1, and 5.5.2 of the 2010 edition); the test method for right angle deviation was revised (see 6.2, and 6.2 of the 2010 edition); the test method for the noise reduction coefficient was revised (see 6.7, and 6.7 of the 2010 edition); the test method for formaldehyde emission was revised (see 6.10, and 6.10 of the 2010 edition); Annex B was deleted (see Annex B of the 2010 edition); and the method of taking the value of the bending breaking load of dry-process boards was revised (see C.5.6, and C.5.6 of the 2010 edition).

This standard was proposed by the China Building Materials Federation and is under the jurisdiction of the National Technical Committee on Thermal Insulation Materials of Standardization Administration of China (SAC/TC 191).

The drafting organisations of this standard are: Nanjing Fiberglass Research and Design Institute Co., Ltd.; Beixin Group Building Materials Co., Ltd.; Xingpai USG Building Materials Co., Ltd.; Armstrong Building Products (Suzhou) Co., Ltd.; Changzhou Beiyang Building Materials Co., Ltd.; Shanxi Dongfang Resources Development Co., Ltd.; Guangde Paluofeng Fibre Products Co., Ltd.; Hebei Guomei New Building Materials Co., Ltd.; and the National Quality Supervision and Inspection Centre for Glass Fibre Products.

The main drafters of this standard are: Tang Jian, Wang Jiaqing, Teng Weiguang, Zhang Tongkun, Zhou Jianquan, Kang Jing, Zhang Jian, Yu Shengli, Zhang Hanqing, Wu Jun, Li Peng, Gao Shiyi, Li Guojun, Hou Peng, Wei Shanzhi, Ding Qing, Pan Yang, Qu Huili, Cui Jun and Zhang Jianhong.

1 Scope

This standard specifies the classification and designation, the requirements, the test methods, the inspection rules, and the marking, labelling, packaging, transport and storage of mineral wool decorating and acoustic ceilings, hereinafter referred to as acoustic ceilings.

This standard applies to mineral wool decorating and acoustic ceilings produced by the wet process or the dry process and used for indoor suspended ceilings. Mineral wool decorating and acoustic ceilings for other uses may also refer to this standard.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document, including any amendments, applies.

The documents cited are: GB/T 191 on pictorial marking for handling of goods; GB/T 2918 on standard atmospheres for conditioning and testing; GB/T 3947 on acoustical terminology; GB/T 4132 on terms relating to thermal insulating materials; GB/T 5480 on test methods for mineral wool and its products; GB 6566 on limits of radionuclides in building materials; GB/T 8170 on rounding off of numerical values and the judgement of limiting values; GB 8624-2012 on the classification of burning behaviour; GB/T 10294 and GB/T 10295 on the determination of steady-state thermal resistance by the guarded hot plate and by the heat flow meter apparatus; GB/T 14402 on the determination of the gross heat of combustion; GB/T 17657-2013 on test methods for wood-based panels and surface decorated wood-based panels; GB 18580 on the limit of formaldehyde emission of indoor decorating materials; GB/T 20247 on sound absorption measurement in a reverberation room; GB/T 20284 on the single burning item test; GB/T 20313 on the determination of moisture content by drying at elevated temperature; and HJ/T 206 on the technical requirements for asbestos-free building products carrying the environmental label.

3 Terms and definitions

For the purposes of this document, the terms and definitions given in GB/T 3947 and GB/T 4132 and the following apply.

3.1 Mineral wool decorating and acoustic ceilings

A decorative sound-absorbing board made mainly from slag wool, rock wool, glass wool or similar raw materials, processed by the wet or the dry production route.

Note: mineral wool decorating and acoustic ceilings are commonly used to improve the acoustic performance inside a building, while also providing a decorative function and improving the thermal insulation of the building.

3.2 Wet-process ceilings

A mineral wool decorating and acoustic ceiling board made mainly from granulated wool and similar materials, processed by pulping, forming, drying, cutting, surface treatment, edge milling and coating.

3.3 Dry-process ceilings

A mineral wool decorating and acoustic ceiling board made from a rock wool board or glass wool board as the substrate with a glass fibre tissue or similar material as the facing, processed by lamination, milling, edge sealing, coating and drying.

3.4 Nominal size

The size used to designate the specification of the product.

3.5 Actual size

The size used for production control in the factory.

3.6 Right angle deviation

The degree to which two adjacent edges depart from a right angle, expressed as the ratio of the maximum gap between the try square and the board to the length of the edge.

3.7 Pin holes

The perforations in the decorative face of a wet-process board.

4.1 Classification

According to the production process, products are divided into dry-process boards and wet-process boards.

According to the method of installation, products are divided into composite adhesive-bonded boards, semi-concealed grid boards, concealed grid boards and exposed grid boards, the last comprising flat boards and tegular boards.

4.2 Specifications

The nominal sizes of the commonly used specifications are given in Table 1, in millimetres: length 600, 1 200 and 1 800; width 300, 400 and 600; thickness 9, 12, 14, 15, 16, 18 and 20.

4.3 Product designation

The product designation consists of the installation method, the product name, the number of this standard, the production process, whether the board is pin-holed, the installation method, the applicable humidity and the size specification; a commercial code may be added after them.

Where the nominal size and the actual size of the product differ, both the nominal size and the actual size shall be marked; for the way sizes are marked see Annex A.

The highest ambient relative humidity for which the product is suitable is expressed by the letters RH followed by the value of the relative humidity. A product that is not so marked is treated as RH80.

Note: RH is a reference indicator for the application of the product, and the producer is responsible for making it clear to the user. It means the upper limit of the relative humidity of the environment in which the product is to be used; for example, a product marked RH80 is recommended for use in an environment at a relative humidity of 80 per cent or below.

Example 1: a wet-process mineral wool decorating and acoustic ceiling with a nominal length of 600 mm and actual length of 593 mm, a nominal width of 600 mm and actual width of 593 mm, a nominal thickness of 15 mm and actual thickness of 12 mm, pin-holed, for exposed grid installation, suitable for an ambient relative humidity of 90 per cent or below, is designated: exposed grid tegular mineral wool decorating and acoustic ceiling GB/T 25998 wet process pin-holed RH90 600(593) x 600(593) x 15(12) (commercial code).

Example 2: a board with a nominal and actual length of 600 mm, a nominal and actual width of 600 mm, a nominal thickness of 15 mm, without pin holes, for concealed grid installation and suitable for an ambient relative humidity of 90 per cent or below, is designated: concealed grid glass wool decorating and acoustic ceiling GB/T 25998 dry process RH90 600 x 600 x 15 (commercial code).

5.1.1 Appearance quality

The front face of the acoustic ceiling shall be free from stains, scratches, uneven colour, incomplete patterns and other defects that impair the decorative effect. The product shall be free from cracks, breakage and distortion, and free from missing corners and edges that impair its use or its decorative effect.

5.1.2 Permissible dimensional deviations

The permissible dimensional deviations shall comply with Table 2. For composite adhesive-bonded boards and concealed grid boards the deviation of the actual length and width is plus or minus 0.5 mm and that of thickness plus or minus 0.5 mm; for semi-concealed grid boards the length deviation is plus or minus 2.0 mm, the width deviation plus or minus 0.5 mm and the thickness deviation plus or minus 1.0 mm; for exposed grid tegular boards the length and width deviation is plus or minus 1.5 mm and the thickness deviation plus or minus 1.0 mm; for exposed grid flat boards the length and width deviation is plus or minus 2.0 mm and the thickness deviation plus or minus 1.0 mm. The right angle deviation shall be not greater than 1 mm/m for composite adhesive-bonded, concealed grid and semi-concealed grid boards, not greater than 2 mm/m for exposed grid tegular boards and not greater than 3 mm/m for exposed grid flat boards.

5.1.3 Bulk density

The bulk density shall be not greater than 380 kg/m3.

5.1.4 Burning behaviour

The burning behaviour shall be not lower than the classification declared by the manufacturer, and shall be not lower than the class B1 requirement specified in GB 8624-2012.

5.1.5 Radionuclide limits

The product shall meet the requirements for class A decorating and finishing materials specified in GB 6566: the internal exposure index IRa shall be not greater than 1.0 and the external exposure index Ir shall be not greater than 1.3.

5.1.6 Formaldehyde emission

The product shall meet the class E1 requirement specified in GB 18580, and the formaldehyde emission shall be not greater than 0.124 mg/m3.

5.1.7 Asbestos phase

The product shall not contain asbestos fibres.

5.2.1 Bending breaking load and thermal resistance

The bending breaking load and the thermal resistance shall comply with Table 3. For a product with an embossed relief pattern, the bending breaking load and the thermal resistance shall meet the values corresponding to the board thickness measured with the relief pattern excluded.

Table 3 gives, by nominal thickness in millimetres, the minimum bending breaking load in newtons and the minimum thermal resistance in square metres kelvin per watt at a mean temperature of 25 degrees C: thickness not greater than 9, load 40 N, resistance 0.14; 10, 47 N, 0.16; 11, 53 N, 0.17; 12, 60 N, 0.19; 13, 70 N, 0.20; 14, 80 N, 0.22; 15, 90 N, 0.23; 16, 103 N, 0.25; 17, 117 N, 0.26; thickness not less than 18, 130 N, 0.28.

5.2.2 Noise reduction coefficient

The noise reduction coefficient shall be not lower than the value declared by the manufacturer and shall comply with Table 4: for pin-holed wet-process boards the noise reduction coefficient shall be not less than 0.50, and for other wet-process boards not less than 0.30.

5.2.3 Deflection after exposure to damp

The deflection after exposure to damp shall be not greater than 3.5 mm.

5.2.4 Moisture content by mass

The moisture content by mass shall be not greater than 3.0 per cent.

5.3.1 Bending breaking load and thermal resistance

The bending breaking load and the thermal resistance shall comply with Table 5.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 17 pages — is available in the English PDF.

Referenced standards

Normative references

GB/T 2918 Plastics - Standard atmospheres for conditioning and testing · GB/T 4132 Terms relating to thermal insulating materials · GB/T 10294 Thermal insulation - Determination of steady-state thermal resistance and related properties - Guarded hot plate apparatus · GB/T 10295 Thermal insulation - Determination of steady-state thermal resistance and related properties - Heat flow meter apparatus · GB/T 14402 Reaction to fire tests for building materials and products - Determination of the gross heat of combustion · GB/T 20247 Acoustics - Sound absorption measurement in reverberation room · GB/T 20313 Hygrothermal performance of building materials and products - Determination of moisture content by drying at elevated temperature · HJ/T 206 Technical requirement for environmental labelling products - Asbestos-free building products

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