We have three types of Geogrids; extruded, woven and bonded.
Extruded geogrids are flat structures in polymer (usually high density polyethylene or polypropylene) that are extruded and then pulled: this may be done in one direction (mono-oriented geogrids), or in the two main directions (bi-oriented geogrids). They are used in soil and road paving reinforcement.
Woven Geogrids are flat structures in the shape of a net made of high module synthetic fibres, that may also be coated with a further protection layer, using synthetic material (usually PVC or other polymer).
Bonded Geogrids are flat structures, where two or more series of strip elements made of polyester coated with polyethylene, are linked at regular intervals by means of bonding.
Based on which direction the stretching is done during manufacture, geogrids are classified as
These geogrids are formed by the stretching of ribs in the longitudinal direction. So, in this case, the material possesses high tensile strength in the longitudinal direction than on the transverse direction.
Here during the punching of polymer sheets, the stretching is done in both directions. Hence the function of tensile strength is equally given to both transverse and longitudinal direction.
Applications of Geogrid in Pavement Construction
The Geogrid construction in pavement construction have following features:
Improvement of subgrade: The subgrade, which is the most important load bearing strata, is made solid and strong by the geogrids. The problem of soft subgrade can be solved by this method.
Reinforcement of pavement base: The thickness of base if increased would increase the stiffness of base. But increasing thickness enormously is not economical. The reinforcement to a given base layer would give adequate stiffening that helps in reduction of thickness and time of construction. This also helps in increasing the life of the pavement.
Fig.1: Laying the Geogrids over leveled soil sub-base as reinforcement
Fig.2:Placing Aggregates over the Geogrid layer
Fig.3: Final Compacted and rolled
Advantages of Geogrids in Construction
Ease of Construction: he Geogrid can be installed in any weather conditions. This makes it more demanding.
Land Optimization: This method of Geogrid installation in soils makes an unsuitable area suitable for preparing it to meet desired properties for construction. Geogrid thus helps in proper land utilization.
Geogrid promotes soil stabilization
A higher strength soil mass is obtained
Higher load bearing capacity
It is a good remedy to retain soil from erosion
No requirement of mortar. The material is implemented dry.
No difficulty in material availability
Geogrids are flexible in nature. They are known for their versatility.
Geogrids have high durability reducing maintenance cost. They are highly resistant against environmental influences.
Materials are tested based on standard codes and regulations.
