Beating the Weather: How We Keep the Roads Intact Through Shoulder Seasons

Turangi, located in Central Waikato, New Zealand, is known for its extreme weather variations. With blisteringly hot days and frigid nights, maintaining road quality can be a daunting task. This high-altitude area only allows for road sealing between December and February, making it crucial to use the right techniques and materials to ensure longevity and durability.

In traditional sealing methods, any residual moisture or rainfall can weaken the bond between the chip and bitumen, leading to significant issues. Especially in cold conditions, like those found in some parts of Waikato, the chip struggles to adhere to the bitumen. This issue is somewhat mitigated by using emulsions, which envelop the chip in a bitumen emulsion, ensuring a better hold once cured. However, curing can be delayed by heavy coats, low temperatures, or nighttime applications, posing a risk of chip loss or stripping when traffic runs over these seals.

The Problem: Traditional Sealing in Challenging Conditions

In colder areas, achieving a fully cured seal becomes more challenging. For Turangi, this means that without the right methods, the likelihood of road damage increases significantly. Road Science has identified that traditional sealing is not sufficient for such environments when moisture or cold conditions prevent the chip from holding onto the bitumen effectively. This often results in a weakened bond, leading to chip loss and stripping.

Innovative Solution: Weather Barriers in Action

In mid-April 2023, Road Science took on the challenge of resealing four sites that could not be delayed any further, despite being late in the season where the cool conditions can increase the risk of stripping. Weather barrier was trialled on two of these sites, while the other two sites did not receive this treatment.

Road Science's evaluation indicated an estimated risk (over 80%) of stripping across the region. However, with the application of weather barriers, this risk dropped dramatically to less than 10%. The weather barrier acts as an additional protective layer, enhancing the seal's ability to cure properly even in less-than-ideal conditions.

The Results: Clear Success with Weather Barriers

Road Science found the two sites that did not utilize the weather barrier experienced significant stripping in the weeks following the reseal. In contrast, the sites that were treated with the weather barrier showed no signs of stripping or chip loss. This clear disparity underscores the effectiveness of weather barriers in maintaining road integrity, especially in regions with challenging weather patterns.

Paving the Way Forward

Turangi Road's story of overcoming weather challenges with innovative sealing solutions serves as an inspiring example for other regions facing similar issues. The use of weather barriers has proven to be a game-changer, reducing the risk of road damage, and ensuring that roads remain safe and functional despite extreme weather conditions.