Improving granular layer performance

TYPAR^® G-Series Geotextiles prevent the intermixing of aggregate with underlying soils provides a rugged separation and stabilization layer between the road structure and the subgrade soils. The use of  TYPAR in this application goes back over 35 years, and is proven to be an exceptionally durable geotextile.

• Prevents mixing of the valuable road base aggregate with the underlying subgrade soils
  
• Enhances drainage of the subgrade soils while preventing pumping of fine soil particles into the base aggregate
  
• Reduces the required amount of road base aggregate by preventing intermixing
  
• Assures long term prevention of road base deterioration
  
• Reduces the need for costly repairs to paved surfaces

Durability
TYPAR Geotextiles have the only 40+ year study confirming proven performance over this period of time. In the road separation project, dating back to 1972, TYPAR geotextiles have had no noticeable deterioration and at LEAST 90% of original strength. The adjacent image shows tread direction and fabric durability as mechanical wear increases over time. TYPAR geotextiles maintained integrity while the competitive slit film woven fabric deteriorated, resulting in failure of the separation layer.

In extreme projects like the Alaskan Highway, TYPAR geotextiles have been proven time and again to get the job done when your project demands superior durability. 

Radial load requires isotropic properties
The continuous filament design and manufacturing of TYPAR Geotextiles results in uniformity in all orientations. Isotropic fiber distribution creates uniform strength in both machine direction (MD) and cross direction (XD) orientation, with XD being slightly greater. This is in contrast to other geotextiles, which have greatly reduced strength in the XD orientation. As a result, TYPAR geotextiles can be designedand installed in any direction without concerns of reduced integrity, making it the most versatile and consistent fabric available.

Elongation
TYPAR Geotextiles have a high initial modulus, meaning greater amounts of stress are absorbed at much lower elongation and deformation. This is why TYPAR geotextiles feel stiff in comparison to other nonwovens. The high initial modulus results in higher performance at the typical service life stresses experienced in a road design,and as a result, less rutting or deformation will occur at the surface. In highway, road, or reinforcement design,this is imperative, since applications do not allow for high elongation before failure. Designing with TYPAR geotextiles will result in better performance as trips increase under the designed stress.

 TYPAR geotextile tread durability

 TYPAR geotextile isotropic strength

 TYPAR high initial modulus

Filtration
The primary design requirement of a separation layer is the development of a graded aggregate filter layer in the subgrade soil to maintain separation and eliminate the risk of soil mixing or ‘pumping’. TYPAR geotextiles promote development of such filter layers because its unique bonded fibers create a pathway that resembles a well-graded aggregate filter. TYPAR geotextiles provide an effective filter structure since it has both high permeability, which will not change under compaction, and the ability to retain soil particles adjacent to it, minimizing the piping of subgrade soils and reducing fine particles from crossing the filtration layer.

Typical paved and unpaved applications where geotextiles are used beneath granular layers include:

• Paved and unpaved roads
  
• Parking lots
  
• Access Roads
  
• Sidewalks and bike paths
  
• Applications over poor soil conditions