Geomembranes are low-permeability synthetic membranes used for a variety of containment and fluid barrier applications. With different materials, manufacturing processes, and properties available, selecting the appropriate geomembrane type is crucial for an effective system. This guide provides an overview of the major classes of geomembranes along with their unique advantages.
Thermoplastic Polyolefin (TPO)
TPO is the most common and cost-effective geomembrane option. It is a polymer thermoplastic made from polypropylene and ethylene. TPO offers:
– High puncture and tear resistance
– Good protection against acids, bases, and salts
– Relatively inexpensive compared to other geomembrane types
– Easy installation by welding sheets together
While not suitable for direct UV exposure or volatile organic compounds, TPO works well for landfill liners, mining, and wastewater treatment.
Polyvinyl Chloride (PVC)
PVC geomembranes contain high levels of polyvinyl chloride resin mixed with plasticizers. Benefits of PVC include:
– Excellent chemical resistance, especially acids and bases
– High strength and puncture resistance
– Relatively low cost
– UV light resistance
PVC’s effectiveness against aggressive chemicals makes it ideal for mining, industrial waste containment, and chemical processing. However, plasticizers can leach out over time, becoming brittle.
Polyethylene geomembranes come in two forms:
– High-density polyethylene (HDPE): Higher strength and puncture resistance. Used for landfills and mining.
– Linear low-density polyethylene (LLDPE): More flexible with better elongation. Used for canals and dams.
Overall, polyethylene offers:
– Good chemical resistance except to oils
– High tensile strength
– Low permeability
– Relatively easy installation
Polyethylene geomembranes have a broad range of applications from agriculture to hazardous waste containment.
PP geomembranes are composed of polypropylene resin with added carbon black and stabilizers. Key attributes include:
– High puncture and tear strength
– Resistance to many organic solvents, acids, and bases
– Relatively low cost
– Easy field installation
While prone to UV degradation, polypropylene works well for waste containment and artificial lagoons.
Ethylene Propylene Diene Monomer (EPDM)
EPDM geomembranes contain ethylene, propylene, and a diene monomer. They offer:
– Extreme weathering and UV light resistance
– High elongation and flexibility
– Easy installation even in cold climates
EPDM works well for exposed applications like artificial lakes and irrigation canals. Limitations include sensitivity to oils and limited chemical resistance.
Polyester geomembranes are made of polyethylene terephthalate resin. They provide:
– High tensile strength and puncture resistance
– Resistance to hydrocarbons and microorganisms
– Effective across a wide temperature range
Polyester is a good choice for landfills, mining, and oil and gas applications. But it is prone to hydrolysis and has higher costs.
Other factors like manufacturing process, concrete protection, reinforcement, and thickness further differentiate geomembrane materials. Consulting an expert can help narrow down the appropriate geomembrane choice based on performance, life expectancy, and budget. Proper installation is also critical for effective containment and seam integrity.
As a key component in containment systems, geomembranes act as impermeable barriers against liquids, gases, and contaminants. With a wide array of material options on the market, engineers can select the ideal geomembrane properties to suit the unique needs of any project site. The continued development of geomembrane materials and manufacturing techniques will further enhance capabilities and applications in the future.