Contents
What is geomat?
Geomat is a geosynthetic material with through, changeable-shape cells of dimensions exceeding the maximal size of rib cross section, made by extrusion or rib intertwinement. According to GOST R 55028-2012, various types of geosynthetics can be used for the road construction, namely geotextile, geocomposites, geogrids and so on, including geomats.
Geomat application
In accordance with GOST R 55028-2012, geomats can perform the functions of separation and erosion protection. Road structure layer separation is prevention of a road structure contacting layers material particles from interpenetration.
The current road structures must comply with all the existing requirements and standards of the road industry. At the present time, a motorway inter-repair span is equal to 12 years, with 24 years specified for overhaul. Correspondingly, motorway projects are characterized by enhanced requirements to the quality of structures installed. Building a reliable heavily loaded structure lasting over 12 years without road pavement layer separation is hardly possible.
Erosion protection is prevention or limitation of migration of soil or other particles on the structure surface. Erosion should be understood as a combination of soil destruction, migration and deposition caused by water and wind.
The following may be treated as the road erosion main factors:
- terrain modification (construction of embankments, vertical leveling, etc.);
- vegetation change;
- water evacuation variation (post-precipitation water evacuation failure, stagnation of floodwater, etc.);
- Moreover, road erosion is caused by other geological processes, such as decay, land slide, karst and so on. Also, land cultivation is considered as a factor contributing to road erosion. Erosion growth is also caused by vegetation diminishment and land development.
Geomat-assisted structures are a reliable barrier to soil erosion widely used in road construction.
Road geomat properties:
- Increase in the whole structure strength;
- Aid in vertical load distribution;
- Prevention of road pavement sliding;
- Aid in maintaining the aggregate level.
Application range:
- Road construction and repair;
- Railroad construction;
- Bank reinforcement;
- Hydraulic construction;
- Landscaping.
Geomat classification
According to GOST R 55028-2012, geomats are divided by manufacturing type into:
- Knitted geomats made by knitting with one or many threads.
- Braided geomats.
- Geomats of synthetic polymer made by extrusion.
By material type:
- Fiberglass geomats with high strength and low elasticity.
- Basalt geomats, bitumen emulsion impregnated to enhance performance.
- Polypropylene geomats.
- Polyester geomats.
- Polymeric geomats made by extrusion.
Transportation and storage
Proper storage and transportation are an important condition of maintaining the geomat stress-strain behavior. The relative air humidity in a warehouse storing the material should be maintained at a level of up to 80%. Geomat package should have no mechanical damage. Geomats can be transported by enclosed carriers of any type with transportation rules followed.
Installation
There are several techniques of a geonet installation:
- Laying along the whole surface width and length;
- Partial laying, used during a road repair when cracks and potholes need to be patched;
- Combined laying, when, besides all-over laying, geonet segments are placed at interfaces and in problem zones.
When selecting a geonet, one should follow the following recommendations:
- Geonet rupture strength should not be less than 40 kN/m;
- Cell size calculation should follow the formula, the apertures size should be 2 to 2.5 times more than the aggregate size;
- The mixture of asphalt and concrete should be in compliance with GOSTu (9128-97).
Conclusions
Geomat is a geosynthetic material widely used in road construction as separation interlayers. Geomat is also used for erosion protection.
Geospan AS is a geomat (geonet) made of polyester filaments impregnated with bitumen emulsion with or without a needle punched textile underlying pad. It is used for road pavement reinforcement.
