However, the trial didn’t perform as hoped with the woven geotextile not developing the interlock that would be achieved by a geogrid.
It was therefore decided to use a MultiTrack NW9 non-woven geotextile as a separator/filter on the sub-grade with layers of ‘punched and drawn’ SX Grid 3030 geogrid above to provide the reinforcement and stabilisation for the road.
Following training, AMEC’s temporary works design team became competent in using Wrekin’s ‘Sub Save’ calculation software to calculate the required road cross sections. The software calculated the stone depth and number of layers of geogrid required and also the saving in stone that the geogrid provided – typically between 35-45% against an unreinforced solution. The road cross sections varied due to the varying ground conditions across the challenging and remote terrain, but also the varying volume and type of construction traffic that would be using each section of road.
With a required road width of 4m, and taking the roads shoulders into consideration, standard width rolls required 2 roll widths of each product to achieve full coverage at sub-grade level. This would result in a much slower construction rate and potentially a large amount of product waste. Wrekin removed this potential for waste, and delivered further savings in cost and time to AMEC by supplying the geotextile and geogrid as wide rolls in excess of 5m width.
