Geonets: A Comprehensive Guide to Structure, Manufacturing, and Properties

Geonets , a crucial member of the geosynthetic family, are versatile materials designed for in-plane drainage of liquids or gases. In this comprehensive guide, we explore the structure, manufacturing processes, and essential properties of geonets.

Understanding Geonets

Geonets are geosynthetic materials that bear a structural resemblance to geogrids. They are characterized by integrally connected parallel sets of ribs, which overlay similar sets at various angles. This unique design allows for effective drainage within the plane of the material, making geonets indispensable in numerous applications.

Geocomposites: Laminated Versatility

Geonets often undergo lamination with geotextiles on one or both surfaces. When this occurs, they are referred to as drainage geocomposites. These laminations enhance their performance and expand their range of applications. Geonets are a competitive choice among drainage geocomposites, even in the presence of alternatives with different core configurations.

Manufacturing of Geonets

The production of geonets involves a continuous extrusion process that transforms them into a net-like configuration comprising parallel sets of interconnected ribs. Geonets fall into three primary categories:

Biplanar Geonets

Biplanar geonets represent the original and most prevalent type. They consist of two sets of intersecting ribs, each set featuring distinct angles and spacings. The ribs themselves vary in size and shape, offering versatility for various construction styles.

Triplanar Geonets

Triplanar geonets are characterized by parallel central ribs with smaller sets of ribs positioned above and below. This arrangement primarily contributes to geometric stability, making them suitable for specific applications.

Other Geonets

Innovations continue to shape the world of geonets, giving rise to newer structures. Some feature box-shaped channels, while others incorporate protruding columns supported by an underlying network. These variations, often distinguished by thickness, reflect active product development efforts by various manufacturers.

Material Composition

Geonets are exclusively crafted from polyethylene resin. This resin exhibits a density range from 0.94 to 0.96 mg/L, with higher values resulting in more rigid products. It's essential to note that this resin is true high-density polyethylene (HDPE), unlike the density used in HDPE geomembranes, which typically falls under medium density. The resin formulation includes 2.0 to 2.5% carbon black, usually in a concentrated form mixed with a polyethylene carrier resin. Additionally, 0.25 to 0.75% of additives serve as processing aids and antioxidants.

Geonets vs. Geospacers

While geonets serve their unique purpose, the geosynthetic realm also encompasses competitive products known as "geospacers." Geospacers feature drainage cores comprising nubs, columns, cuspations, or intricate 3-D networks of stiff polymer strands. These products find their niche in drainage applications behind retaining walls, plaza decks, and green roofs.

Key Properties

Geonets' primary function is to facilitate in-plane hydraulic flow, known as transmissivity. However, several other properties influence their performance throughout their service life. These include physical, mechanical, endurance, and environmental factors. Understanding these properties is essential for selecting the right geonet for specific construction and drainage needs.

In conclusion, geonets are vital geosynthetic materials with a diverse range of applications in construction and drainage projects. Their unique structure, manufacturing processes, and material composition make them a competitive choice within the geocomposite landscape. As the construction industry continues to evolve, geonets and their innovative variations are poised to play an increasingly important role in ensuring the integrity and longevity of infrastructure projects.