Cracking under stress?

The Project

The Musgrave and High Street Intersection in Rockhampton had been experiencing its fair share of repairs and periodic maintenance due to soft patches of subgrade and cracking asphalt. As part of planned maintenance works for Rockhampton Council, Roadtek Operations required a solution to repair and reinforce the existing damage.

The Challenges

Cracking of asphalt overlay is a common problem on roads. Causes of cracking range from soft subgrade to long-term creep deformation and fatigue. If the pavement cracks are not addressed, the penetration of water and moisture under the overlay can lead to large pot holes and further deteriorate the underlying base and sub-base. The main factors leading to the acceleration and propagation of cracks (and costly maintenance) are time, temperature variations and moisture.

Soft subgrade causes excessive deflection of the pavement layers (including the asphalt wearing course). This can result in large cracks and undermine the integrity of the overlay. Similarly, old and brittle aging asphalt which is prone to small micro-cracks can lead to larger pot holes.

The Solution

Polymeric bitumen-coated high-tensile strength TerraGrid® 6060C was chosen to reduce the maintenance cycle and lengthen the road’s effective life span. TerraGrid® 6060C‘s pavement-reinforcing composite assists with alleviating the tensile stresses of the asphalt overlay caused by excessive subgrade deflection.

The TerraGrid® 6060C reinforcement was installed by :

• milling out the existing damaged surface,
• applying a corrector layer and bitumen tack coat then
• rolling out the TerraGrid® 6060C over the corrective layer.

Once the TerraGrid® 6060C had been firmly brushed into the tack coat, a minimum thickness of 40mm of asphalt overlay was placed by paver directly over the top of the geogrid composite.

The Result

The bitumen-coated TerraGrid® 6060C ‘s low profile and high-bonding capability made the overlay installation a quick and easy process with no sign of movement of the reinforcement apparent during paving operations.

TerraGrid® 6060C is a biaxial material providing equal tensile strength (TS= 60kN/m) in both the roll and cross roll directions, thus allowing applied stresses along and across the road to be resisted and dispersed with maximum efficiency.

For more information regarding this product please contact Raymond Chow (Technical Support Engineer)

*This material complies with all the road authorities including the newly revised MRTS104