Geocomposites are combinations of two or more geosynthetic materials for

civil engineering Civil engineering is a regulation and licensure in engineering, professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads ...

applications that perform multiple geosynthetic functions; the five basic functions are: separation, reinforcement,

filtration Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filte ...

drainage Drainage is the natural or artificial removal of a surface's water and sub-surface water from an area with excess water. The internal drainage of most agricultural soils can prevent severe waterlogging (anaerobic conditions that harm root gro ...

, and containment. Such composite materials may enhance technical properties of the soil or the geotechnical structure and minimize application costs.

Geotextile-geonet composites

When a

geotextile Geotextiles are versatile permeable fabrics that, when used in conjunction with soil, can effectively perform multiple functions, including separation, filtration, reinforcement, protection, and drainage. Typically crafted from polypropylene or ...

is used on one or both sides of a geonet, the separation and filtration functions are always satisfied, but the drainage function is vastly improved in comparison to

geotextiles Geotextiles are versatile permeable fabrics that, when used in conjunction with soil, can effectively perform multiple functions, including separation, filtration, reinforcement, protection, and drainage. Typically crafted from polypropylene or ...

by themselves. Such geocomposites are regularly used in intercepting and conveying

leachate A leachate is any liquid that, in the course of passing through matter, extracts soluble or suspended solids, or any other component of the material through which it has passed. Leachate is a widely used term in the environmental sciences wh ...

in landfill liner and cover systems and for conducting vapor or water beneath pond liners of various types. These drainage geocomposites also make effective drains to intercept water in a capillary zone where frost heave or salt migration is a problem. In all cases, the liquid enters through the

and then travels horizontally within the geonet to a suitable exit.

Multi-linear drainage composites

A manufactured product composed of a series of parallel single drainage conduits (like perforated mini-pipes) regularly spaced across the width of the product and sandwiched between two or more geosynthetics (more often

). They are used for liquid

gas Gas is a state of matter that has neither a fixed volume nor a fixed shape and is a compressible fluid. A ''pure gas'' is made up of individual atoms (e.g. a noble gas like neon) or molecules of either a single type of atom ( elements such as ...

collection while providing a separation and

function. Such multi-linear drainage composites are not susceptible to creep in compression or geotextile intrusion when confined in the soil, which means that they maintain their flow capacity over time, even under heavy loads. These drainage geocomposites are regularly used in landfill applications for leachate collection layers and cover systems, and in buildings for sub-slab depressurization systems to collect toxic gases (Radon, VOCs, etc.) and prevent their migration into the building.

Geotextile-geomembrane composites

Geotextiles can be laminated on one or both sides of a geomembrane for a number of purposes. The geotextiles provide increased resistance to puncture, tear propagation, and friction related to sliding, as well as providing tensile strength in and of themselves. Geotextiles are of heavy and are of the nonwoven, needle-punched variety. In such cases the geotextile component acts as a drainage medium, since it can conduct water,

or gases away from direct contact with the geomembrane.

Geomembrane-geogrid composites

Some types of

Geomembrane A geomembrane is very low permeability synthetic membrane liner or barrier used with any geotechnical engineering related material so as to control fluid (liquid or gas) migration in a human-made project, structure, or system. Geomembranes are m ...

s and Geogrids are made from the same material, such as

high-density polyethylene High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or " polythene" when used for HDPE pipes. With a high strength-to-density rati ...

(HDPE). This commonality in material allows for them to be effectively bonded together, resulting in a composite system that combines the benefits of both components. By integrating Geomembranes with Geogrids, an impervious membrane barrier is created, which offers enhanced strength and

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...

capabilities. This synergy not only provides superior

tensile strength Ultimate tensile strength (also called UTS, tensile strength, TS, ultimate strength or F_\text in notation) is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials, the ultimate ...

and

durability Durability is the ability of a physical product to remain functional, without requiring excessive maintenance or repair, when faced with the challenges of normal operation over its design lifetime. There are several measures of durability in us ...

but also improves the overall stability and performance of the system in various engineering applications. Such composite barriers are particularly advantageous in projects requiring robust containment solutions, such as

landfill liner A landfill liner, or composite liner, is intended to be a low permeable barrier, which is laid down under engineered landfill sites. Until it deteriorates, the liner retards migration of leachate, and its toxic constituents, into underlying aqu ...

s, mining operations, an
water management systems
The combination of geomembranes and geogrids ensures long-term

reliability Reliability, reliable, or unreliable may refer to: Science, technology, and mathematics Computing * Data reliability (disambiguation), a property of some disk arrays in computer storage * Reliability (computer networking), a category used to des ...

and

efficiency Efficiency is the often measurable ability to avoid making mistakes or wasting materials, energy, efforts, money, and time while performing a task. In a more general sense, it is the ability to do things well, successfully, and without waste. ...

, making them a preferred choice in modern geotechnical and environmental engineering.

Geotextile-geogrid composites

A needle-punched nonwoven geotextile bonded to a geogrid provides in-plane drainage while the geogrid provides tensile reinforcement. Such geotextile-geogrid composites are used for internal drainage of low-permeability backfill soils for reinforced walls and slopes. The synergistic properties of each component enhance the characteristics of the final product.

Geotextile-polymer core composites

A core in the form of a quasi-rigid plastic sheet, it can be extruded or deformed in such a way as to allow very large quantities of liquid to flow within its structure; it thus acts as a drainage core. The core must be protected by a geotextile, acting as a filter and separator, on one or both sides. Various systems are available, each focused on a particular application. * The first type is known as wick drains in the U.S. and prefabricated vertical drains (PVDs) in Europe. The 100mm wide by 5mm thick polymer cores are often fluted for ease of conducting water. A geotextile acting as a filter and separator is socked around the core. The emergence of such wick drains, or PVDs, has all but eliminated traditional sand drains as a rapid means of consolidating fine-grained saturated cohesive soils. * The second type is in the form of drainage panels, the rigid polymer core being nubbed, columned, dimpled or a three-dimensional net. With a geotextile on one side it makes an effective drain on the backfilled side of retaining walls, basement walls and plaza decks. The cores are sometimes vacuum formed dimples or stiff 3-D meshes. As with wick drains, the geotextile is the filter/separator and the thick polymer core is the drain. Many systems of this type are available, the latest addition having a thin pliable geomembrane on the side facing the wall and functioning as a vapor barrier. * The third type within this area of drainage geocomposites is the category of prefabricated edge drains. These materials, typically 500 mm high by 20 to 30 mm wide are placed adjacent to a highway pavement, airfield pavement, or railroad right-of-way, for lateral drainage out of and away from the pavement section. The systems are cost-effective and can be installed quickly.

References

{{Reflist Geosynthetics