GB/T 17656-2018Plywood for concrete form (English PDF)

3.1 Plywood for concrete form

The plywood that can pass the boiling test and be used as concrete forming molds.

5.1 Wood species

5.1.1 The wood species of plywood used for concrete form can be masson pine, Yunnan pine, larch, radiata pine, poplar, eucalyptus, birch, Schima superba, sweetgum, Alniphyllum fortunei, Lauan, Okoume, Apitong, etc.

5.2 Structure of the plywood

5.2.1 The wood grains of two adjacent layers of veneer shall be perpendicular to each other. The veneers of the symmetrical layers at both sides of the central layer shall be of the same wood species or wood species with similar physical properties, and the thicknesses shall be the same.

5.3 Adhesives

5.3.1 The adhesive of plywood for concrete form shall be phenolic resin or resin with equivalent performance.

5.3.2 The resin used for surface treatment shall be phenolic resin or resin with equivalent performance.

5.3.3 The resin used for coating shall be phenolic resin or resin with equivalent performance.

5.4 Specifications and deviations

5.4.3 Verticality

The verticality of plywood for concrete form shall not exceed 0.8 mm/m.

5.4.4 Edge straightness

The edge straightness of plywood for concrete form shall not exceed 1 mm/m.

5.4.5 Flatness

The flatness of plywood for concrete form shall not exceed 20 mm.

5.5 Appearance quality

5.5.3 The adhesive-coated board is divided into two grades according to the visible processing defects on the finished board. first-class products and second-class products; the permissible defects shall meet the requirements in Table 4.

5.5.5 The surface of the board shall be sanded or scraped, and it can be sanded (scraped) on one side or not sanded (scraped) as agreed upon by both the supplier and the buyer.

5.5.6 There is no limit to the number of surface splicing veneers of plywood used for concrete form, but the splicing shall comply with the provisions for splicing of surface veneers in Table 3. Similar textures are required for the splicing.

5.5.7 The adhesive-coated board shall be coated with resin on both sides. If the grades of the two sides are different, they shall be clearly marked.

5.5.8 The film-coated board shall be coated on both sides. If the grades of the two sides are different, they shall be clearly marked.

5.6 Physical and mechanical properties

5.6.1 The physical and mechanical properties of plywood for concrete form shall meet the requirements of Table 6.

6.1 Specification and dimension measurement

6.1.1 Measuring tools

The measuring tools include.

6.1.2 Measurement of length, width and thickness of boards

Carry out according to the relevant regulations in GB/T 19367.

6.1.3 Squareness measurement

Carry out according to the relevant regulations in GB/T 19367.

6.2 Sampling and size specification of specimens

6.2.1 Instruments and measuring tools

The instruments and measuring tools include.

6.2.2 Sawing of specimens

6.3 Inspection method

6.3.1 Appearance quality

6.3.1.1 Measure the appearance defects of plywood by visual inspection or with a steel ruler (the accuracy shall be 0.1 mm).

6.3.1.6 Determination of results. Check the plywood for concrete form one by one, inspect the appearance defects, and then determine whether the plywood is qualified or not.

6.3.2 Moisture content

The moisture content inspection shall be carried out according to the provisions of 4.3 in GB/T 17657-2013.

7.1 Inspection classification

7.1.1 Product inspection is divided into factory inspection and type test.

7.1.2 The factory inspection includes the following items.

7.1.3 Type test includes appearance quality inspection (5.5), specification and dimension inspection (5.4) and inspection of all physical and mechanical properties (see Table 6). Type test shall be carried out when one of the following situations happens.

7.2 Sampling inspection

7.2.1 Appearance quality inspection

Appearance quality sampling inspection shall be carried out in accordance with the provisions of 7.2.1 in GB/T 9846-2015.

7.3 Judgment Rules

7.3.1 Judgment rules for appearance quality and size

When the appearance quality, size and deviation meet the requirements of 5.4, 5.5, 7.2.1 and 7.2.2, the appearance quality and specifications of the batch of samples shall be judged as qualified; otherwise, it shall be downgraded or judged as unqualified.

7.3.2 Rules for determining physical and mechanical properties

7.3.2.3 If the arithmetic means of the static bending strength and elasticity modulus of each plywood meet the requirements of the index value, and the minimum value is not less than 80% of the index value, then the static bending strength and elasticity modulus are qualified; otherwise, re-inspection shall be carried out.

7.4 Comprehensive judgment

When the appearance quality, specification and deviation, and physical and mechanical properties of the samples all meet the requirements of the corresponding grade, the batch of products is judged as qualified. Otherwise, the batch shall be downgraded or judged as unqualified.

7.5 Measurement of products

Finished products are measured and calculated in cubic meters, and their allowable tolerances shall not be included. When measuring a single board, the result can be accurate to 0.00001 m³; when calculating a batch of boards, the result can be accurate to 0.001 m³.

8.1 Logo

At the lower right corner of the back veneer of each board, or the side, stamp the signs to indicate the product name, grade, and to remind users of the direction of the board (longitudinal and transverse).

8.2 Packaging

Products shall be properly packaged according to different types and specifications.

Each package shall be accompanied by an inspection label indicating the product name, wood species and thickness of the surface veneer, category, grade, manufacturer's name, trademark, size, quantity, product standard number, etc.

8.3 Transportation and storage

The product shall be protected from moisture, rain, the sun and deformation during transportation and storage. […]