As soil and stones have been involved in many projects for years, in this circumstance, different methods have been created and applied in stabilizing, sealing, and protecting the raw soil. Geomembranes definitely reflect the development of modern technology for converting compacted ground into useful rooms. Tinhy’s geomembrane can not only work below the layers of gravel, and asphalt, but is also durable, climate-resistant, and flexible for applying as tarpaulins and custom-made covers. This article mainly talks about the usual applications of geomembranes produced by Tinhy Geosynthetics and you may find the right type of geomembrane for your anti-seepage and waterproof projects.
What Are Geomembranes?
Geomembranes are a type of impermeable sheet that can be used for protecting, stabilizing, or sealing exposed soil. Tinhy’s geomembranes are usually made of woven or non-woven polymeric materials while other kinds of membranes can’t take a good effect as geomembranes, for they can not be directly installed onto the soil.
The methods applied in producing geomembranes consist of calendaring, coating, and sheet extruding. The main features of geomembranes of most types, including flexibility, UV resistance power, reinforcement grades, and absolute polymer ingredients, vary enormously among different products. Our geomembranes can be applied in many industries, such as waste management(landfills), water management(dams, tailings), agriculture, aquaculture, etc.
Geomembrane Types
Nowadays, more and more geomembrane products can be applied for any use of liners. Required characteristics can be provided by numerous single-layer or co-polymeric membranes blending two or even more polymeric materials. Geomembrane products are also produced in the form of geo-composites with two or more geosynthetic materials(geomembranes with geotextiles) mingled together or reinforced with fabrics. Some Additives like plasticizers are usually added to the geomembranes so as to extend the lifespan as well as the durability of the products.
Most polymer materials that are applied in the production of geomembranes are thermoplastics which are much easier to weld and repair. The membranes commonly used in landfill anti-seepage and watertight projects are polyethylenes(PET) because of their great resistance to a variety of chemicals.
As the geomembranes are mostly made of polymer materials with great molecular weight, in this circumstance, Tinhy’s Geomembranes have high density and strength while the liner is also thick enough to keep these characteristics. The installation process of geomembranes has to be handled under the condition of gradual uplifting temperatures because of the generation of heat from the waste’s biological degradation, which leads the temperature from 40℃ to 70˚C. The data of test properties can only be obtained at an increasing temperature that amounts to 50℃ at least. Once you are not quite sure whether the geomembrane fits your waterproof projects of landfills, dams, roads, or bridges, you need to follow the suggestions of experienced engineers or technicians.
According to the difference in polymer materials, geomembranes can mainly be divided into PE Geomembranes, PVC Geomembranes, EVA Geomembranes, TPO Geomembranes, CPE Geomembranes, CSPE Geomembranes, and EPDM Geomembranes, etc. Considering the practical application in the anti-seepage or waterproof projects, PE Geomembranes(Tinhy’s Geomembranes are made of HDPE Materials) and PVC Geomembranes are more often applied in the projects of landfills, reservoirs, dams, and roads, etc. What’s more, in accordance with our own cases, Composite Geomembranes(also known as geo-composites) are quite popular with our customers while the lifespan of these geomembranes can effectively be extended.
Permeability
Liquids and gases can permeate geomembranes in the form of vapors or gases on a molecular scale by diffusion. The permeation rate depends on the solubility of the liquid as well as the diffusibility of the dissolved molecule in the geomembrane. A molecular concentration or partial pressure gradient across the geomembrane will be the driving force for the direction and rate of transfer while the hydraulic head drives the soils and clay in a totally different way.
Gas permeability varies enormously in accordance with its nature as well as different types of geomembrane. Our continuous experiments have proved the permeability of geomembranes to organics aqueous solutions, simulating leachates containing small amounts of organics. Essential quantities of organic compounds can permeate through a geomembrane, even if these organic compounds are existing in the leachate with low concentrations.
Physical Stress
Geomembranes will be greatly affected by physical stresses during the process of transportation, installation, and their whole lifespan, some of which can be evaluated from the liner design steps(such as the arrangement of anchorages). Other stresses may occur due to the temperature such as induced expansion or contraction. Geomembranes are capable of burdening the physical, biological, or chemical pressures during the whole installation course.
Chemical Stress
The influences of chemical stress placed on the liner system should be taken into primary consideration in the long run because of the wastes that are likely to exist in a landfill. These influences that may take decades of years to appear to include:
– The degradation of fundamental polymers
– Inevitable depolymerization
– The assimilation of waste in any forms
– The extraction of components(i.e. antioxidants)
EPA Method 9090 is effective in determining the influences of leachate materials on the physical properties of geomembrane liners. Continuous experiments of immersing the liner material in leachate chemicals may last at least 4 months going with a temperature of 50°C. What’s more, comparisons of measurements on HDPE Geomembrane‘s physical properties are used for evaluating the compatibility of the liner contacting with the fluid waste over time.
Biological Stress
As geomembrane sheets have to contact with soil or liquid when being applied in the anti-seepage projects of landfills, reservoirs, and ponds, biological stress will affect the use of geomembranes to some extent. In accordance with the data from our lab and our construction field, biological substances have been found to negatively affect the performance of geomembranes.
Frankly Speaking, high molecular materials can take a great effect on resisting the process of biodegradation. What’s more, the biological attack can be monitored with composite geomembranes due to the susceptibility of plasticizers and other monomeric constituents. The resin material existing in the geomembrane is quite effective in resisting the bacteria, as the bacteria can not survive under the condition without a carbon source.
How to Select Adaptable Geomembranes
High-density polyethylene (HDPE) materials have been quite popular nowadays and widely used for basal lining. At the same time, linear low-density polyethylene (LLDPE) materials can also adapt to the anti-seepage or waterproof projects of landfills, reservoirs, tailing dams, etc. Due to their high resistance against chemical abrasion, both HDPE and LLDPE geomembranes can be applied in landfills of many countries. However, other polymeric materials should also be considered for use while HDPE liners are not always suitable for different projects.
By far, a great number of polymer materials have been applied specifically in landfills as qualified liners because of their great abrasion resistance, reasonable strength, perfect flexibility, and temperature stability. The performance and chemical resistance of HDPE geomembranes or geomembranes made of other polymeric materials should be considered when you want to apply them in the waterproof or anti-seepage projects of dams, landfills, reservoirs, fishing ponds, etc. Geomembranes that provide adequate tensile strength should be specially chosen for application in the above-mentioned projects.
Tips About Delivery and Handling
CQA engineers must follow up on the delivery process of the HDPE liner materials, including the unloading and discharge for safe storage. Necessary machinery appliances are demanded to uplift and transport the geomembrane. Geomembranes can never be handled with the tines of forklift machines, the bucket of excavators, or any similar types of equipment so that the possible damage can be minimized to a certain degree.
Something You Need to Know About Designing
Slopes are restricted by subgrade preparation while the sheets can be installed against steep vertical walls which are not smooth enough to contact with the geomembrane. This problem has been gradually solved by many geo-experts, for gabions, rock-bolted frames and vertical formers are put into use so as to provide some space for installing the sheet. As is known to all, not all geomembranes can adapt to vertical or sub-vertical installation. Due to the poor quality design and installation, lots of errors may occur in sub-vertical systems. In this circumstance, designers, as well as engineers, should provide additional technical information on sheet properties.
The shearing strength of the soil interface is low enough to enable the design of steeper slopes in landfills, and the creation of available space for waste disposal. In this circumstance, textured HDPE geomembranes have come about, including roughness or protuberances on one or both sides of the geomembrane. The texturing process should adapt to the membrane, which can perform quite well in slope stability. Different texturing procedures may bring different shear strengths and friction angles between the geomembrane and other materials like geotextiles can be obtained in this way.
Stresses can be imposed on the geomembrane because of many factors during transportation and installation. Potential sources and magnitudes of the above-mentioned stresses must be considered when designing the whole waterproof or anti-seepage project, and lining materials and elements can be applied in eliminating these stresses. At the same time, leachate monitoring and extraction points must be designed so that the stress can be loaded while the geomembrane will relieve from the damage of overstress or puncture.
