GB/T 23453-2025Natural limestone slab for building (English PDF)

4.1 Classification

4.1.1 Classified by density.

a) Low-density limestone. density not less than 1.76 g/cm3 and less than 2.16 g/cm3;

b) Medium-density limestone. density not less than 2.16 g/cm3 and less than 2.56 g/cm3;

c) High-density limestone. density not less than 2.56 g/cm3. 4.1.2 Classified by shape.

a) Polished slate (MG);

b) Standard type sheet (PX);

c) Irregularly shaped plate (YX).

4.2 Level

Classified by processing and appearance quality.

a) The rough-finished boards are classified into three grades. A, B, and C, based on their thickness deviation, flatness tolerance, and appearance quality.

b) Standard boards are classified into three grades, A, B, and C, based on dimensional deviations, flatness tolerances, angular tolerances, and appearance quality.

4.3 Marking

4.3.1 Name. Use the name or number specified in GB/T 17670.

4.3.2 Marking order. name, category, size, grade and standard number.

Example. 600mmx600mmx20mm standard type, grade A slabs processed from Guangxi silver-line limestone blocks are marked as follows.

5.1 General Rules

5.1.1 The board material shall be protected with a suitable protective agent, which shall meet the requirements of GB/T 32837.

5.1.2 The common size series of the sheet metal is shown in Table 1.The specifications and dimensions of irregular-shaped sheets and standard sheets with special requirements shall be determined by the supplier and the buyer through negotiation.

5.2 Processing quality

5.2.1 The flatness tolerance and thickness allowable deviation of the roughened board shall conform to the provisions of Table 2.

5.2.2 The allowable deviations in the dimensions of standard steel plates shall conform to the provisions of Table 3.

5.2.3 The flatness tolerance of the standard plate is shown in Table 4.

5.2.4 The angular tolerances for standard plates are shown in Table 5.

5.2.5 The angle between the front and side of a standard sheet should not exceed 90°.

5.2.6 The surface finish and specular gloss requirements of the sheet metal shall be determined through negotiation between the supplier and the buyer.

5.2.7 The effective dimensions and geometric tolerances of irregularly shaped plates shall be determined through negotiation between the supplier and the buyer. The allowable thickness deviation shall conform to the thickness requirements in Table 3.

The surface tolerances, based on the external outline dimensions, should conform to the requirements of Table 4.

5.3 Appearance Quality

5.3.1 The color tones of boards from the same batch should be basically harmonious, and the patterns should be basically consistent.

5.3.2 The appearance defects on the front of the sheet material shall conform to the provisions of Table 6.

5.3.3 The boards are permitted to be bonded and repaired. Bonding and repair should not affect the decorative effect of the boards, nor should they reduce the physical properties of the boards.

5.4 Physical Properties

The physical properties of the sheet material should conform to the requirements in Table 7.

5.5 Product Application Performance

The performance characteristics of the sheet material should conform to the specifications in Table 8.If the project has special requirements, they should also conform to the design and construction requirements of the project.

6.1 Processing quality

6.1.1 Rough board

6.1.1.1 Flatness Tolerance

Place a 1000mm steel straightedge with a flatness tolerance of 0.1mm naturally at a distance of 15mm from the edge of the board and on both sides of the surface being inspected.

On the diagonal, use a feeler gauge to measure the gap between the gauge face and the board surface. When the length of the side being inspected or the diagonal length is greater than 1000mm, use a steel straightedge along the edge.

The length and diagonal sections should be inspected separately, with the overlap not less than 1/3 of the steel straightedge length. The plane of the roughened board is represented by the measurement of the maximum gap.

The tolerance is 0.05 mm, and the measured value is accurate to 0.05 mm.

6.1.1.2 Thickness Deviation

Measure the thickness of the roughened board using vernier calipers or other measuring instruments that meet the required precision, measuring the midpoints of the four sides (see Figure 1).

Do not use the maximum and minimum values of the deviation between the measured value and the nominal value to represent the dimensional deviation of the roughened board thickness; the measured value is accurate to 0.1 mm.

6.1.2 Standard Type Plate

6.1.2.1 Dimensional Deviations

Measure the length, width, and thickness of the sheet metal using a vernier caliper or other measuring instrument that meets the required accuracy. Length, width Measure the thickness at three points. along the centerline of the board and 10mm from the edge (see Figure 2). Measure the thickness at the midpoints of all four edges (see Figure 1).

Do not use the maximum and minimum deviations between measured and nominal values to represent dimensional deviations in length, width, and thickness; the measured values should be accurate to [missing value]. 0.1mm.

6.1.2.2 Flatness Tolerance

Place a 1000mm steel straightedge with a flatness tolerance of 0.1mm at a distance of 10mm from the edge of the board and on two opposite corners of the surface being inspected.

Online, use a feeler gauge to measure the gap between the gauge face and the board surface. When the side length and diagonal length of the inspected surface are greater than 1000mm, use a steel straightedge along the perimeter.

And diagonal segment detection.

The flatness tolerance of the board is expressed as the measured value of the maximum gap, accurate to 0.05 mm.

6.1.2.3 Angle tolerance

Use a 90° steel angle ruler with an interior angle perpendicularity tolerance of 0.13mm and an interior angle side length of 500mm x 400mm for inspection. Tighten the short side of the angle ruler.

Place the board against its short side, with its long side against the long side of the board, and use a feeler gauge to measure the maximum gap between the long side of the board and the long side of the square. Measure using the method described above.

Measure the four corners of the board.

The angular tolerance of the sheet metal is expressed as the measured value of the maximum gap, accurate to 0.05 mm.

6.1.2.4 Angle between front and side views

Using a 90° steel angle ruler with an interior angle perpendicularity tolerance of 0.13mm and an interior angle side length of 500mm x 400mm, place the short side of the angle ruler close to the decoration.

Place the long side of a square against the side and observe the position of the gap to determine the size of the included angle.

6.2 Appearance Quality

6.2.1 Color scheme and pattern

Place the boards to be inspected side by side on the ground and stand 1.5m away from the boards for visual inspection.

6.2.2 Appearance defects

Use vernier calipers or other measuring instruments that meet the accuracy requirements to measure the length and width of the defect, with the measurement accurate to 0.1 mm.

6.3 Physical Properties

6.3.1 Bulk density and water absorption rate

Test according to the provisions of GB/T 9966.3.When the specimen size specified in GB/T 9966.3 cannot be met, a representative plate should be used.

Prepare a 50mmx50mmxplate thickness sample from the material, and proceed with the rest in accordance with the provisions of GB/T 9966.3.

6.3.2 Compressive strength

Test according to the provisions of GB/T 9966.1.When the specimen size specified in GB/T 9966.1 cannot be met, a specimen of a considerable size may be prepared from the plate.

For cubic specimens measuring 20mm x 20mm x 20mm, the number of specimens was doubled. The specimen size specified in GB/T 9966.1 was not adopted.

When providing the sample, the actual sample dimensions should be noted.

6.3.3 Bending strength

Test according to Method A in GB/T 9966.2-2020.

6.3.4 Abrasion resistance

Test according to Method A in GB/T 9966.4-2020.

6.4 Product Application Performance

6.4.1 Freeze-resistant properties

According to the test specifications of GB/T 9966.1, the arithmetic mean of the compressive strength after freeze-thaw cycles and the arithmetic mean of the water-saturated compressive strength are compared.

The ratio is expressed as a percentage and retained to two significant figures.

6.4.2 Impact resistance

For products using actual thickness, tests shall be conducted in accordance with the provisions of GB/T 9966.14.

6.4.3 Ground anti-slip coefficient

Test according to the provisions of JC/T 1050.

6.4.4 Stain Resistance

Test according to the provisions of Appendix A in GB/T 18601-2024.

6.4.5 Impermeability

Ordinary cement-based adhesive conforming to GB/T 24264 is used, and cement mortar is prepared by mixing according to the specified proportions. The cement mortar is then placed...

Place the container in a suitable container, lined with a plastic film, and smooth with cement mortar to a thickness of at least 5mm. The dimensions should be at least 300mm x 100mm.

Three 300mm thick boards are placed flat inside the container with the decorative side facing up, the edges of the boards at least 10mm from the container wall, and the cement mortar is poured to the specified height.

The sample should not exceed half the thickness of the stone. When taking samples from large slabs, the sides of the sample should be protected with the protective agent used on the slab.

After the stone has been protected and the specified curing time has been reached, a test will be conducted. Seal the exposed sides of the stone and the perimeter of the container with plastic tape, and place...

7 days. Observe the color change and the presence of water spots on the sample surface every other day, and record any abnormalities.

6.4.6 Dimensional stability

Test according to the specifications in Appendix B of GB/T 18601-2024.When taking samples from large-format plates, the sides of the sample should be protected with a protective film.

The material is protected with a protective agent and tested after the specified curing time has been reached.

6.4.7 Durability

Test according to the provisions of Appendix C in GB/T 18601-2024.

6.4.8 Cement bond strength

Test according to the provisions of Appendix D in GB/T 18601-2024.

7.1 Factory Inspection

7.1.1 Inspection Items

The factory inspection items are shown in Table 9.

7.1.2 Batching

A batch of boards of the same variety, category, grade and the same supply batch is considered as one batch, or boards from consecutive installation locations are considered as one batch.

7.1.3 Sampling

Samples were drawn according to Table 10.

7.1.4 Determination

If all the test results of a single board meet the corresponding grade in the requirements, then the board is deemed to meet that grade.

Based on the sample inspection results, if the number of grade nonconforming items found in the sample is less than or equal to the acceptance number (Ac), then the batch is deemed nonconforming.

If the number of nonconforming items of a given grade found in the sample is greater than or equal to the rejection number (Re), then the batch is deemed not to meet the grade.

7.2 Type Testing

7.2.1 Inspection Items

The type test items are shown in Table 11.

7.2.2 Inspection conditions

Type testing shall be conducted under any of the following circumstances.

a) When a new factory goes into operation;

b) When there are significant changes in raw materials or production processes;

c) During normal production, this is conducted once a year.

7.2.3 Batching

Same as factory inspection.

7.2.4 Sampling

Sampling for processing quality and appearance quality is the same as for factory inspection. Samples for physical properties and product application performance are randomly selected from the inspection batch.

Prepare double the number of test samples according to the specifications and quantities required by the test method, and keep one sample as a backup. Physical properties and product application performance are then tested.

The samples and methods are shown in Table 12.

7.2.5 Determination

If all test results meet the requirements of 5.4 and 5.5, the batch of boards is deemed to be qualified in terms of the above properties; if two or more of the test results do not meet the requirements of 5.4 and 5.5, the batch is deemed qualified.

If any item fails to meet the requirements of 5.4 or 5.5, the batch of boards is deemed unqualified; if any item fails to meet the requirements of 5.4 or 5.5, the item is re-inspected using a reserve sample, and the re-inspection result is...

If the requirements are met, the batch of boards is deemed合格 (qualified) in terms of the above performance; otherwise, the batch is deemed不合格 (unqualified). Judgment of other test results. Same as factory inspection.

8.1 Marking

8.1.1 The outer packaging box of the sheet metal shall be marked with the company name, trademark, and logo, and shall have "This Side Up" and "Handle with Care" markings and comply with GB/T 191. According to the regulations.

8.1.2 For boards with specific installation sequence requirements, the installation sequence number should be marked.

8.2 Packaging

8.2.1 Packaging should be done separately according to board type, category, and grade, and accompanied by a product certificate (including product name, specifications, grade, batch number, inspector, and...). (Date of manufacture).

8.2.2 Packaging shall meet the requirements for safe loading, unloading and transportation under normal conditions.

8.3 Transportation

During the transportation of the boards, collisions, rolling, and tipping should be prevented.

8.4 Storage

8.4.1 Boards should be stored indoors, and those stored outdoors should be covered.

8.4.2 Stack the boards separately according to their type, category, grade, or installation location.

GB/T 23453-2025. Natural Limestone Building Panels ICS 91.100.15 CCSQ21 National Standards of the People's Republic of China Replaces GB/T 23453-2009 Natural limestone building slabs Published on 2025-04-25 Implemented on 2025-11-01 State Administration for Market Regulation The State Administration for Standardization issued a statement.