Geosynthetic products manufacturer and supplier Fibertex says its Fibertex AM-2 is the ideal product for road construction and road maintenance projects in Africa, owing to its being highly durable and resistant to all natural soil alkalis and acids.
“The Fibertex AM-2 is a flexible needle-punched precompressed nonwoven fabric, with added thermal bonding on one side,” explains Fibertex South Africa technical marketing manager Gerard Dirks.
The product is used to avoid the reflective cracking of new asphalt and protect subsoil from water intrusion and, thereby, loss of bearing capacity.
Dirks informs that this product was developed and modified from an existing product that was being used in similar road applications, owing to the African environment requiring modifications be made to ensure optimum performance in harsh conditions. Subsequently, this product was required to be more robust than its predecessor to accommodate the types of aggregates used in road surfacing.
Further, with countries in Africa mainly depending on manual installation, the product had to be configured in such a way that it could be easily handled and placed without the requirement of a heavy plant, and without the possibility of injury risk to the installer.
Dirks extols that, since the first installation of Fibertex AM-2 in 2012, it has met and exceeded all Fibertex’s performance expectations, garnering a “great” response from customers. The product has since been used in several other installations in Africa, having been introduced to road authorities in several developing African countries as a cost- effective solution to road rehabilitation.
“Even though this product can be installed mechanically, it has been widely used in manual installations where the plant is either not accessible or manual installation is preferred.”
One such installation highlighted by Dirks is the Mombasa road rehabilitation project, in Kenya, in 2015. This road reseal project entailed the crack repair and reseal of an urban road that carries heavy traffic.
The Fibertex AM-2 was used as a stress absorbing membrane interlayer. Dirks explains that this fabric was placed on top of the existing crack-repaired wearing course and after being sealed with a bitumen, a new wearing course was added on top of the paving fabric. This paving fabric acts as a waterproof membrane, preventing any water ingress through surface cracks in the wearing course.
Further, this paving fabric also prevents the development of reflective cracking, which is the transfer of cracks from the old to the new wearing course.
Dirks extols that using Fibertex AM-2 for this project prevented surface water from penetrating the bearing course, consequently preventing the washing out of fines and reducing fissures and cracks considerably, which could have led to the development of potholes. As such, this results in the long-term durability of the road wearing course, with a reduction in road-surface maintenance cycles.
He notes that the Fibertex AM-2 is a very simple product to install, but cautions that, when it is installed in regions with extreme climates – as was the case with this project – the grade of bitumen to be used must be considered. He says a tacky latex modified bitumen has proven to generate the best results, whereas ‘cut-back’ bitumen grades are not recommended for the paving fabric installation.
Dirks recommends that local climate always be considered when doing a road seal design, as this will have a great impact on performance and long-term durability.