Asphaltic concrete (asphalt) and chipseal are the two surfacing options most commonly used on our roads.
Read more about why we resurface roads, and how we decide which option to use.
Differences between chipseal and asphalt
Structural improvement: Asphalt provides structural benefits to the road which chipseals can’t. Asphalt is a paved layer where chipseal is a surface coating.
Rideability of the road: Asphalt improves the levels of the road providing a smoother ride quality to the road users. Because chipseal is a surface coating it has very little influence on the levels of the road surface.
Watertightness: Asphalt is quite sponge like when applied in the thicknesses required for our flexible pavements in the Wellington area. Chipseal is a great water proofer and is critical to the survival of our roads.
Texture of final surface: Most asphalts used in Wellington have a smooth surface. Chipseal has a textured surface that can vary from only marginally rougher than asphalt to extremely coarse, depending on the need.
Skid resistance and safety: Asphalt has lower skid resistance than Chipseal. Thus, chipseal is safer from a vehicle breaking perspective. Good to have a chipseal on the approach to a pedestrian crossing for example.
Environmental impact: Asphalt uses a lot more aggregate and bitumen than chipseal. Depending on the thickness of the asphalt this can vary anywhere from four times to twenty times. Chipseal is thus significantly more environmentally friendly and has a much lower carbon footprint.
Life expectancy: Asphalt between 10 and 20 years depending on the traffic loading. Chipseal between 8 and 15 years depending on traffic loading.
Cost: Asphalt uses a significant amount more aggregates and bitumen than chipsealing. Thus, it is any considerably more expensive, generally around four times more than chipseal.
Aftercare: Asphalts have very little to no aftercare. Chipseal takes a time to embed and cure. There will be loose stones on the road for the first few weeks. This is managed by increased sweeping intervals.