"The proof is in the pudding", or the proof roll!

Contractor: Drapers Civil Contracting. , Ash Whittaker
Consultant: Beveridge Williams , Ryan Cross
Date: 25th Oct 2021

Drapers Civil faced a difficult problem to construct a pavement over very soft, saturated subgrade at Horseshoe Bend Rd in Armstrong Creek. The presence of a gas main and rock floaters at shallow depth ruled out the possibility of over-excavation so Drapers considered installing DUX CG30 composite geogrid.

One layer of CG30 was installed at subgrade followed by 175mm capping layer of Type A granular fill. Because some movement was still being experienced a second layer of CG30 was then installed followed by 290mm of Class 3 aggregate. Research has shown the reinforcing effect of geogrid to extend approx 250mm above and below the grid, so the presence of this second layer of grid at mid-pavement further reinforces the pavement. The proof roll showed no visible movement or cracking. A further 160mm of crushed rock and asphalt wearing course completes this main road pavement. DUX CG30 passes another great test with flying colours and provides contractors with a cost-effective alternative to deep dig-out and replacement or cement/lime stabilisation !