A Guide for Using Geosynthetic Products
Geosynthetic products are derived from polymeric materials and are widely used in Civil and Structural Engineering. The purpose of geosynthetic products is: prevent soil erosion, act as barrier and reinforcement, containment, drainage, and separation. There are several geosynthetic types, which include geotextiles, geogrids, geomembranes, geofoam, geosynthetic clay liners, geocomposites, and geopipes.
This is a combination of more than one geosynthetic, which allows the user to benefit from various features at a minimal cost. The use of geosynthetic material allows for more functionality, increasing the speed of construction compared to other alternatives.
Adhesive bonding uses an adhesive to make the materials bond together. Several methods can be used to apply the adhesive to the substrate, but the common ones include bath and roller, spray, and pressure. Heat lamination involves passing thermoplastics over a source of heat to create a layer of molten polymer. Then, the material is quickly pressed against the counterpart material while still in molten form.
Stitching consumes a lot of time in the manufacturing process but is the only method that allows the effective combination of geosynthetic materials. Just like in textile stitching, high-strength geosynthetic yarns are stitched together. Ultrasonic welding technique is used in combining thermoplastics. An expert welder can create a robust solid-state material using high-frequency acoustic vibrations.
Geogrids function as reinforcement of soil and grass in construction works. Geogrids have apertures that permit aggregate to get through, providing interlock and confinement. Thus, the geogrids maintain modulus values and minimize the movement of aggregate. To withstand inclement and harsh weather conditions, the geogrids must be filled with gravel or grass. They can be used in car parks, reinforcing the foundation of a structure, industrial yards, and working platforms.
Geogrids can be knitted from yarns, welded, or punching patterns of holes in sheets stretched to form a grid. There are three categories of geogrids: homogenous geogrids that originated in the UK, the textile woven geogrids, and geogrids formed as a result of laser bonding.
These are categorized as either woven or non-woven. Geotextiles are highly porous. Their function is to reinforce, separate, filter, drain, and protect the soil. Non-woven geotextiles are characterized by fiber, bonding system, web formation, and finishing treatment. Woven geotextiles are made by interlocking two similar elements at 90-degrees to form one single solid structure. They cannot be bio-degraded easily due to the high-quality synthetic fibers that make them.
Geotextiles must physically possess the right weight, gravity, density, and stiffness to perform their specific function. They also should be able to be resistant to abrasion and have the correct clogging dimensions. Geotextiles can be manufactured from either natural or synthetic fibers, which defines their function. Natural fibers like ramie and jute are used in projects that require them to biodegrade quickly. Synthetic fibers such as polyethylene and polymers can be used in a variety of civil and environmental projects.
Geosynthetic Clay Liner (GCL)
A GCL is defined as a layer of sodium bentonite in the middle of two layers of geotextiles. When it is soaked in water, the Geosynthetic Clay Liner swells to seal and heal itself around a puncture or rip. The geotextiles are industrially bonded using needle punching, stitching, or inert adhesive process. It requires a lot of expertise in the manufacturing process to ensure the layer of bentonite is uniform. This offers protection and ensures no holes or voids can allow water. Sodium bentonite acts as a liner, and the GCL can swell up to ten times its dry volume.
GCLs with lower hydraulic conductivity retain more sewage in landfills. This is effective in preventing water contamination which can cause ecological and environmental problems.