Complaint
Geosynthetic products have become an integral part of the construction process for several key industries. Its price and physical properties are major advantages compared to traditional alternatives. Geosynthetics are manufactured from various man made polymers and are used in conjunction with soil or rock to enhance the stability of terrains. These products are used in civil, mining and transport infrastructure projects because of its ability to solve a range of engineering problems related to soil reinforcement, erosion control and containment. Geosynthetic products are classified into four types. Geomembranes, geotextiles, geocells and geocomposites. The most popular of these types is geomembrane.
Geomembranes are made from impermeable geosynthetic material consisting of thin continuous sheets of polymers. Geomembranes create an impermeable barrier that prevents the leakage of harmful contaminants or dangerous chemicals to surrounding environments. It is also regularly used as containment barriers for potable water and irrigation storage requirements to prevent leakage. Geomembranes are used in conjunction with other geosynthetic products to control fluid movement and provide containment in projects related to mining, sewage treatment and canal construction.
| S/N | Item | Index | ||||||
| Thickness mm | 0.75 | 1.00 | 1.25 | 1.50 | 2.00 | 2.50 | 3.00 | |
| 1 | Density g/cm3 | ≥0.940 | ||||||
| 2 | Tensile yield strength (vertical and horizontal) N/mm | ≥11 | ≥15 | ≥18 | ≥22 | ≥29 | ≥37 | ≥44 |
| 3 | Tensile breaking strength (vertical and horizontal) N/mm | ≥20 | ≥27 | ≥33 | ≥40 | ≥53 | ≥67 | ≥80 |
| 4 | Elongation (vertical and horizontal) % | - | - | - | ≥12 | |||
| 5 | Elongation at break (vertical and horizontal) % | ≥700 | ||||||
| 6 | Tearing load at right angle (vertical and horizontal) N | ≥93 | ≥125 | ≥160 | ≥190 | ≥250 | ≥315 | ≥375 |
| 7 | Anti-puncture strength N | ≥240 | ≥320 | ≥400 | ≥480 | ≥540 | ≥800 | ≥960 |
| 8 | Tensile load stress cracking (tensile method of dead load of the cut) h | _ | ≥300 | |||||
| 9 | Carbon black content % | 2.0~3.0 | ||||||
| 10 | Carbon black dispersion | The number of Level 3 among 10 data is not more than one; Level 4 and Level 5 are not allowed. | ||||||
| Oxidation induction time (OIT) min | Oxidation induction time under normal pressure ≥100 | |||||||
| 11* | Oxidation induction time under disjoining pressure ≥400 | |||||||
| 12 | 85°C thermal aging (retention rate of OIT under normal pressure after 90d) % | ≥55 | ||||||
| 13a | Ultraviolet resistance (retention rate of OIT after 1600h ultraviolet irradiation) % | ≥50 | ||||||
| Note: Technical performance index of thickness specification not listed in the table shall be implemented according to interpolation method. | ||||||||
| For two indexes of Item 11 and Item 13, select one from retention rate of OIT under normal pressure and retention rate of OIT under high pressure and carry out the test. | ||||||||
The growing application of geomembranes is noticeable in different industries due to the versatility of the product. Geomembranes have a wide range of applications in industries such as mining, marine, civil, water treatment and transportation. Some of the applications are detailed below.
Usage of geomembrane in the mining industry started in the 1970s and has increased thereafter. It is used as a lining solution for evaporation ponds, heap leach pads and tailing impoundments.
The design and construction of these heap leach pads are regulated to protect the environment from exposure to harmful chemicals so a lining system, usually a HDPE geomembrane, forms a critical component in construction of these heap leach facilities.
Geomembranes are also used during the end of a mine's lifespan. As a part of mine restoration, HDPE liners are used to seal the mine and prevent waste products from contaminating the surrounding environment. Overall, geomembrane lining is a safe and effective solution to protect the environment from harmful industries.
HDPE geomembranes play a major role in delivering clean water to the community. They are used in services related to drinking water and wastewater including sewage treatment. When canals, dams and reservoirs are sealed with geomembrane liners they avoid contamination from groundwater.
Geomembrane is also used to prevent contamination of potable water from soil and other pollutants as well as preventing loss of water through infiltration of the water into the surrounding soil. Lining a dam or canal can minimise seepage thereby improving the efficiency of storage and transportation. Geomembranes are also used as a secondary containment for underground storage tanks, solar ponds and brine solution.
HDPE geomembranes are used widely in the marine industries, particularly in the construction of floating docks or jetty platforms supported by pontoons. In the construction process, HDPE geomembrane is wrapped around the flotation foam of the pontoon to provide a protective barrier that increases the durability of the product. By lining it with a HDPE geomembrane the foam is protected from damage by marine life, environmental forces and other contaminants in the water.
It also adds additional buoyancy to the pontoons and prevents deterioration from extreme weather conditions, improving the overall longevity of the pontoon. Please refer to Pond and Pontoon Plastic Liner Applications for more information.
HDPE liners are extensively used by farmers in lining dams and ponds as they provide cost effective and reliable containment solutions.
Geomembranes are also used for various applications in nurseries including waterproofing and containment of soils. HDPE liner usage in commercial nurseries is increasing as customers transition from using PVC and LDPE liners. For example, gardeners are now showing an increased interest in HDPE geomembranes as a permanent solution for nursery bed lining and basket lining applications.
Additionally, HDPE liners are used to provide lining for secondary containment in chemical and fertilizer storage tanks due to the immense versatility of the product's applications and its durability.
The process begins by choosing the suitable polymer resin which is normally in pellet form. Next, different additives such as carbon black, plasticizers, antioxidants and lubricants are added. The formulation of resin and additives are then fed into a hopper which leads to an horizontal extruder. This formulation is transported via a continuous screw through feed section, compression, metering and filtering stages, after which it is pressure fed into a die to create sheets of varying widths and thicknesses by calendering.
Additives are added in the formulation to prevent oxidation and increase durability. Carbon black is sometimes added to the formulation to improve its stability under ultraviolet light, making black HDPE one of the most UV resistant products on the market.
Depending on the parent resin used several types of geomembranes are available. The most commonly used geomembranes are listed below.
Several factors affect the degradation of polymers within the geomembranes. Factors like UV exposure, chemical impact, biological contaminants (animal, fungi) and thermal expansion impact the life span of the geomembranes.
Technical expertise is necessary when selecting the right type and thickness for the project. This is generally based on the depth of the containment and the geo technical conditions of the site.
Please see the corresponding depth and thickness chart for a general overview. This is for guidance only, speak to one of our technical consultants for advice relevant to your requirements.
Liquid depth ≤ 1m | 0.5mm thickness |
Liquid depth 1m to 2m | 1.0mm thickness |
Liquid depth 2m to 4m | 1.5mm thickness |
Liquid depth ≥ 4m | 2.0mm thickness |
Determining the best type of geomembrane for your project can be challenging. Several factors such as cost, availability and applicability come into play.
Of all the geomembrane types, HDPE is the most recommended because of its operational advantages. It complies with the environmental sustainability requirements, is cheaper than other geomembrane types and has a variety of applications. With its excellent mechanical qualities and long durability, HDPE geomembrane is a cost-effective solution for seepage control and leakage prevention in reservoirs and dams.
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