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In Malaysia, geosynthetics are used in constructions that are not classified under national guidelines, such as access roads, parking lots, and forest paths.
They are used for temporary roadways and high-traffic areas.
The use of geosynthetics by engineers has been in existence for many years.
Over 2,000 years ago, road builders used bamboo, straw, small bushes, tree trunks, and stones to stabilize roads. The concept of geosynthetics has been developing in recent years but let us discuss the history of geosynthetics usage on roads.
The first textiles that were used in road construction can be traced to the United States in the 1920s. In the 1960s, woven geotextiles were used to control erosion while in the 1970s, woven and nonwoven geotextiles were used in retaining walls, underdrains, and reinforced-soil applications.
Over the past 40 years, geosynthetics have been used in a wide range of applications on forest roads for constructing drainages, simple walls, and subgrade stabilization. It has also been used in a wide range of applications on USDA Forest Service roads.
Although these early inventions were experimental, over time, geotextile installation applications covered a broader scope, including:
These early efforts were typically experimental until further experiments broadened the scope of geosynthetics.
In the 1970s and mid-way into the 80s, great engineering innovations were recorded in the USDA Forest Service. It was during this period that engineers developed many uses of geosynthetic materials. They applied theories of soil reinforcement and soil mechanics for applications in reinforcement, subgrade separation, and drainage.
By 1980, the use of geosynthetics, or as it was referred back then “geotechnical fabrics,” was gaining more popularity throughout the road construction industry. However, uncertain design criteria and limited performance history were major limitations. You can explore many of the early developments and applications, including the historic wall developments are documented in the following documentations:
In 1973, an opportunity came for the forest service to review the concept of an early prefabricated “filter-fin” subsurface drain discussed in an ASCE Irrigation and Drainage Division journal article by Healy and Long (1972).
This concept was a 1.5 meters (5 ft) prefabricated filter-fin underdrain implemented by Eljen Development. It was used for roadway drainage purposes replacing the conventional gravel vertical trench drain.
This prototype geocomposite drain consists of a nylon chiffon material or a polyester butterfly cloth enveloped around, vinyl plastic reed curtain core material. The result of this design is a modern-day geocomposite drain using a woven or nonwoven geotextile wrapped around an impermeable waffle-like core material.
Back then it was an experiment but today, geocomposite drain has completely replaced conventional gravel underdrain because of its ease of use, geotextile installation, and low-cost.
The first documented construction of a geotextile-reinforced wall in the United States was in 1974 in the Siskiyou National Forest in Oregon. This wall was built using a needle-punched nonwoven geotextile and sandbags for facing to verify laboratory model tests.
In 1975, a second geotextile-reinforced wall was built and monitored on a forest road in the Olympic National Forest near Shelton, Washington DC. Two different geotextiles were used to compare their strength and elongation characteristics. To ensure shoreline protection or sunlight protection, the wall facing was sprayed with an asphalt emulsion.
The performances of these walls were encouraging which led to the construction of several other geosynthetic-reinforced walls in 1979 and 1994. Much of these publications are all over the internet.
In the mid-1970s, geotextiles were made on low-volume forest roads by a procedure known as “subgrade restraint”. This process requires placing a layer of geosynthetic material (for separation) between a lightly cleared path on native soil and then placing aggregate on the roadway through the forest. At that time, this method was intended to limit the movement of the subgrade soil, in turn, increase its bearing capacity. This procedure is still used today to determine aggregate design thickness with a layer of geotextile.
Nowadays, numerous geosynthetic materials have been discovered, with all performing specific functions based on their unique properties. Examples of geosynthetic materials may include geotextiles, geogrids, geofoam, geonets, geocomposites, and geocells. They also include plastic fencing, impermeable membranes and liners, and plastic pipes.
Geosynthetics have become more well-defined as new combinations of materials are being used to develop multilayer filters, geofoam, multilayer filters, geocomposites, and some erosion control applications. Efforts are now invested in quality control and property testing to better improve the materials.
Some of the creative uses of geosynthetics include:
Civil engineering and highway constructions are major beneficiaries of geotextile installation materials but low-volume roads in rural areas still struggle to utilize these resources. The good news is that creative uses of traditional applications can be applied for low-volume roads.
Copyright © Gateway Structure Sdn Bhd (199401025111). All Right Reserved.