Contents
Purpose and Application Range
Woven geotextile enables increasing the road pavement service life, shortening inter-repair spans, reducing operation costs, accelerating construction, enhancing surface resistance to dynamic and static loads, decelerating occurrence of ruts, cracks, potholes and dents.
The application range of woven geotextiles is wide and goes beyond the construction industry. The most common applications include:
- reinforcement of weak foundations in construction of permanent and quick roads, oil & gas facilities, airports, car parking lots, heavy-load sites and construction sites;
- separation of pavement and base layers while constructing permanent and quick roads;
- layer separation to reinforce railbeds;
- construction of soil reinforcement systems;
- erosion protection and reinforcement of slopes, bridge abutments, viaducts, dams and banks.
Production process
Woven geotextile is made of polypropylene and polyester fibers by loom bonding of longitudinal warp yarn and perpendicular weft yarn. Woven geotextile is represented in Geospan range by two brands:
Geospan GT PP is a woven geotextile loom-made of strong polypropylene fibers. It is used for road pavement reinforcement, soil base strengthening and layer separation.
Geospan PET is a woven geotextile loom-made of polypropylene fibers to provide the material with high strength (up to 1,600 kN/m2). It is used for construction of embankments with weak foundations and unusual slopes, etc.
Laying techniques
To be used in motorway construction, renovation and overhaul, woven geotextile should meet the requirements of the regulatory documents specified in the compliance certificate.
Prior to geotextile fabric laying, the soil surface and reinforcements should be graded. In case of reinforcement layer installation on a weak soil, such grading may be waived if there is no fabric damage. Potholes and ruts, if any, should be filled and leveled by a grader or a bulldozer. Shrubs and trees should be cut off at the soil surface level. If there is any surface water on site, a leveling sand layer should be filled in.
With all the prep done, fabrics shall be laid in the longitudinal or transverse direction towards the embankment axis. Rolls shall be unrolled manually in case of installation of protective interlayers along the subgrade. With initial meters unrolled, the fabric edges shall be fixed to the ground with anchor rods. While unrolling, the geofabric shall be evened and stretched from time to time before it is anchor attached to the ground. The fabrics shall be overlapped by at least 0.2 m and stitched together, if necessary.
When laying fabrics in the direction across a road axis, the recommended thickness of intermediate soil layer varies from 0.5 m to 1.5 m. The geofabrics are rolled into an open half-casing from each side, followed by anchoring. Such method envisages geofabric overlapping by 0.5 m.
Finally, the geofabric is topped with sand or macadam in the travel direction. The filled layer thickness shall be at least 15 cm in case of solid soil, with 20 cm in case of weak soil. The filler should be spread by a bulldozer.
Track record
During 2008 to 2022, Geospan materials were utilized in over 80 federal projects and over 650 regional projects, including the following:
Spaceport Vostochny near Tsiolkovsky town, the first Russian civil spaceport, aimed at obtaining an independent access to the outer space and secured fulfilment of international and commercial space programs. Geospan GT PP 80 geomaterial was used in the project.
Refurbishment of the bridge crossing of river Chumysh at 150th km to 158th km section of Chuisky Tract R-256 motorway. The section was burdened with heaving soil. Gexa engineers calculated the road pavement design to find that Geospan GT PP 80 application would increase the road structure elastic modulus and the subgrade shear reserve.
Lena M-56 motorway renovation at 4th km to 38th km section. Transproject design institute in Kazan recommended the usage of Geospan GT PP 80 woven geotextile for reinforcement of the embankment bed of excavated permafrost soil to increase the bearing capacity.
Refurbishment of Belgorod – Pavlovsk motorway in Belgorod region. Based on calculation results, Geospan GT PP 80 woven geotextile was chosen for the embankment bed reinforcement, while Geospan PET 300 high-strength polyester geotextile fabric was selected to reinforce the embankment body. This is just a short list of Geospan material applications.
Woven geotextile application in road construction is justified if it is based on design calculations and geotechnical profile.
Conclusions
Woven geotextile use based on geotechnical research and development aids in solving the challenges of road construction in a most variable geology environment.
