Fibertex AM2 is made from polypropylene fibers and is a flexible, needle punched, non-woven fabric added with thermal bonding on one side,in accordance to AASHTO M-288.
Fibertex AM2 avoids reflective cracking of new asphalt and protect the subsoil from water intrusion and thereby loss of bearing capacity. The waterproofing function prevents surface water from entering the bearing courses, thereby increasing the overlay and roadway life, pavement serviceability and decreases roadway maintenance cost. Fibertex AM2 can be used in new road construction as well as in existing road maintenance. Fibertex AM2 has been used in an ADB funded project in Chakdah - Bongaon Road, in West Bengal, a 7 km new road pavement with a width of 10m which was finished with Fibertex AM2 and asphalt overlay. The road is now being used by heavy traffic.
After providing a bituminous tack coat over the asphalt base course, paving fabric (Fibertex AM2) was laid over the tack coat and then a 50 mm thick asphalt overlay on the paving fabric. The asphalt base course is cleaned thoroughly to remove dirt, oil, water and other impurities. Then hot melted bitumen is sprayed over the base course by a tanker. While penetration grade of the bitumen is about 80 (at around 30°C), the applied quantity of bitumen is 1200 g/m2, with the temperature of the back coat being 140°C. Any spillage or excess tack coat should either be removed or sand be sprayed over it. Then paving fabric (Fibertex AM2)is unrolled over the tack coat carefully to avoid wrinkles, particularly in curvatures of the road.
The unrolling can be done manually or mechanically by placing the paving fabric with heat treated side facing up. Once the fabric gets attached to the bituminous tack-coat, then it is not possible to separate the fabric from tack-coat and Wrinkles or folds in excess of 25 mm shall be slit and laid flat.Brooming is required to maximize paving fabric contact with the pavement surface. The overlapping is provided 10 cm in longitudinal direction and 20 cm in transverse direction. Overlaps are added extra tackcoat in between the layers.
While traffic except necessary construction equipment is banned, all areas in which paving fabric is laid would be paved on the same day. Over this paving fabric (50 mm thick) Asphalt overlaid immediately.Sufficient retention heat of the hot asphalt material to soften the underlying bitumen should be ensured for maximum saturation of the fabric.Standard hot mixed asphalt materials have plant temperatures varying between 140 -170°C, which are suitable temperatures for paving fabrics made from polypropylene. If the temperature of the asphalt material exceeds 170°C, a small quantity of the asphalt material should be spread manually before paving to protect the paving fabric. If crawlers or vehicle tyres stick to the paving fabric they may damage the fabric.
To avoid this, some asphalt material has to be spread in the wheel tracks. When backfilling asphalt material in front of the asphalt paver, the truck driver must not use the brakes and must avoid any unnecessary driving at longitudinal overlaps and in spots with plenty of bitumen.
