This standard specifies the designation, general requirements, technical requirements, test methods, inspection rules, marking, packaging, storage and transportation of natural sodium bentonite geosynthetic clay liner.
This standard is applicable to needle-punched film-coated geosynthetic clay liner (GCL-OF) made of natural sodium bentonite as the main raw material for waterproofing in the rail transportation engineering.
This standard is not applicable to rail transportation engineering with high-concentration electrolyte solutions.
2 Normative references
The following referenced 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.
GB/T 328.14-2007 Test methods for building sheets for waterproofing - Part 14: Bitumen sheets for waterproofing-flexibility at low temperature
GB/T 2791-1995 Adhesives, T peel strength test method for a flexible-to-flexible test specimen assembly
GB/T 4666-2009 Textiles - Fabrics - Determination of width and length
GB/T 5005-2010 Specifications of drilling fluid materials
GB/T 13760-2009 Geosynthetics - Sampling and preparation of test specimens
GB/T 15788-2005 Geosynthetics - Wide-width tensile test
GB/T 17690-1999 Geosynthetics - Plastic woven film yarn geotextile
GB/T 19978-2005 Geotextiles and geotextile-related products - Determination of the puncture resistance
GB/T 20973-2007 Bentonite
3 Designation
The product designation consists of this standard number, product type: GCL-OF (needle-punched film-coated geosynthetic clay liner), bentonite variety: N (natural sodium bentonite), mass per unit area, length and width.
Example: A natural sodium bentonite geosynthetic clay liner with a length of 30 m, a width of 6 m and a mass per unit area of 5,000 g/m2 may be designated as:
GB/T 35470-2017 GCL-OF/N/5000/30-6
4 General requirements
4.1 Nonwoven geotextile with a mass per unit area of 220 g/m2 should be used.
4.2 The plastic woven film yarn geotextile used in the product shall meet the requirements of GB/T 17690-1999, and UV resistant plastic woven film yarn geotextile with a mass per unit area of 110 g/m2 should be used.
4.3 The polyethylene geomembrane used in the product shall meet the requirements of GB/T 17643-2011, and its thickness shall not be less than 0.15 mm.
5 Technical requirements
5.1 Technical requirements for bentonite
Technical indicators of bentonite shall meet those specified in Table 1.
Table 1 Bentonite properties
No. Test item Indicator
1 Content % of bentonite particle (with a size of 0.2 mm ~ 2 mm) ≥ 80
2 Swelling index /(mL/2 g) ≥ 24
3 Durability /(mL/2 g) ≥ 20
4 Methylene blue index /(g/100 g) ≥ 30
5 Filtrate volume /mL ≤ 18
6 Identification of natural sodium bentonite particles Identified as natural sodium bentonite particles
5.2 Appearance quality
The product shall have flat surface, uniform thickness, and uniform stitch spacing without holes, broken edges or residual broken needles.
5.3 Length and width tolerance
The negative deviation shall not be greater than 1% of the nominal value.
5.4 Physical and mechanical properties
Foreword i 1 Scope 2 Normative references 3 Designation 4 General requirements 5 Technical requirements 6 Test method 7 Inspection rules 8 Marking, packaging, storage and transportation Annex A (Normative) Identification test method of natural sodium bentonite Annex B (Normative) Test method for permeability coefficient Annex C (Normative) Test method for resistance to hydrostatic pressure
