The Fibertex range of geotextiles, which is designed especially for civil engineering, mining and road construction and maintenance projects, includes a paving fabric – Fibertex AM-2. This flexible needle punched nonwoven paving fabric has been used in a recent road surfacing project in Zambia.

Fibertex paving fabricFibertex AM-2 paving fabric has been used in a recent road surfacing project in Zambia.

“In order to gain access to one of the world’s largest copper mines at Kalumbila on Zambia’s Copperbelt, a network of dirt roads off the main road between Solwezi and Lumwana needed to be constructed. The new mine is situated in a remote location, which meant all road building materials had to be transported over long distances and at great cost,” says Chris Powell of Fibertex South Africa. “High seasonal rainfall in this region has a detrimental effect on roads, substantially increasing maintenance requirements.

“To lower the costly routine maintenance intervals on these roads, they were later upgraded to a surfaced standard, using Fibertex AM-2 paving fabric. Fibertex AM-2 is a flexible needle punched nonwoven fabric, with added thermal bonding on one side only. The purpose of this pre-compressed 140 g/m² polypropylene (PP) bitumen-saturated paving fabric is to prevent the ingress of surface water into the selected layers of the road prism, thereby reducing the bearing capacity of these layers.

“This membrane also act as a Stress Absorbing Membrane Interlayer (SAMI) to prevent surface stress cracking by absorbing stresses imposed by differential loads. This paving fabric also prevents the propagation of stress cracks from lower surface layers (older asphalt or chip seal layers) in the case of a road reseal.”

By including Fibertex AM-2 in the reseal design, the formation of stress cracks and eventual pothole formation is prevented, thus extending the service life of the road surface.

Additionally, when using Fibertex F-grade geotextiles in a separation application below the layer works of the road prism, the road design can be altered to include less of the costly imported engineered fill. This reduces the thickness of the selected layers, resulting in a more cost effective design.

Without the use of a separation fabric in weak subgrade conditions, intermixing of engineered aggregate into the weak subgrade could occur. As a result, the bearing capacity of the base course is reduced, which could lead to base course failure of the road.

The Fibertex AM-2 system can be applied mechanically for large volume installations, as well as manually in cases where narrow width installations are required.