A HIGH-STRENGTH composite geotextile that tolerates high pres- sures as it dissipates pore water has been used on a contract to build a new approach road for the Harbour industrial estate in Belfast. The road has to cross a stretch of wasteland with a high water table and poor ground conditions.
The area was reclaimed by dumping dredged material from the Belfast Lough. Consultant WDR & RT Taggart, working for Belfast Harbour Commissioners, has built 5km of roads in the area using a geotextile fabric beneath the fill with a geogrid reinforce- ment. But for this contract it was decided to use Rock PEC devel- oped by geosynthetic manu- facturer Polyfelt Geosynthetics.
Rock PEC is a composite mat- erial of a polypropylene geo- textile, reinforced by high ten- acity polyester yarns. It features high-tensile strength and allows pore water pressure to be dis- sipated through the fabric, essen- tial for the conditions on this site.
Along most of the 1.5km long alignment, overburden and un-suitable fill material was excavated down to the underlying silty clay. A total of 25,000m2 of the geotextile was then laid by main contractor FP McCann. Where more material had to be removed, the geotextile was overlaid with around 1m of rock fill.