Chief Executive's Upfront
A Sustainable Concrete Roadmap For The Future

In New Zealand, the case for concrete road pavements (concrete roads) is more compelling than ever.

Rob Gaimster, Chief Executive

Waka Kotahi NZ Transport Agency (NZTA) has adjusted its assessment criteria for future roading projects to favour durable materials, while at the same time evaluating the cause of recent pavement failures on the Waikato and Kapiti Expressways.

Add to this, the fact that Government has made a commitment to huge infrastructure spending post-COVID-19 as well as being zero carbon by 2050, and the scene is set for concrete roads to play a significant role in ensuring a resilient and sustainable New Zealand.

ECONOMIC ADVANTAGES
In 2013 the concrete industry commissioned independent economists Infometrics to study the potential fiscal benefits of using concrete roads instead of bitumen asphalt.

Their report - The Case for Concrete Roads - found that using the NZTA’s then 8 percent discount rate and 30-year service life, a Continuously Reinforced Concrete Pavement was around 25 percent less expensive than Structural Asphaltic Pavement.

Concrete NZ recently asked Infometrics to update the report using the NZTA’s new 6 percent discount rate and 40-year service-life parameters.

They concluded that using this ‘preferred’ scenario a Continuously Reinforced Concrete Pavement is now around 29 percent less expensive than Structural Asphaltic Pavement.

The greater price volatility of bitumen relative to cement/concrete further tilts the economics in favour of concrete roads. As does the uncertainty around bitumen supply, with Refining NZ set to cease production at Marsden Point in early 2020.

The refinery typically produces enough bitumen to meet about 70 percent of the domestic market. While imports will increase to meet demand, potential storage issues created by the new supply model may prompt decision makers to look towards concrete roads.

QUALITY OUTCOMES
In addition to the economic advantages of concrete roads, their capacity to meet durability, reliability and safety criteria is persuasive.

NZTA’s recent Review of State Highway Pavement Delivery report examined delivery requirements for new pavement and rehabilitation construction, and assessed these requirements in terms of value for money to deliver on land transport objectives.

The report concluded that appreciation and confidence amongst a wide range of industry stakeholders of achieving desirable 25-year life reliability using exiting techniques was “marginal”.

Concrete roads typically have an extended service life, during which they require minimal maintenance. In contrast, alternative materials demand regular repairs, more so as vehicle loads and volumes increase, interrupting traffic flow and compromising safety for drivers/passengers and road crews.

In terms of driver/passenger comfort and safety, concrete roads can be textured to provide skid resistance and quietness. They also reflect light to improve driving visibility.

As the NZTA review identified it as critical that procurement and construction of road pavements aim for quality outputs to meet design, reliability and safety expectations, and that innovation and value focus on productivity and quality, concrete roads must be part of the conversation.

LOW CARBON CREDENTIALS
The Cement Association of Canada commissioned a study showing that the primary energy costs of concrete roads over their lifetime are one-third that of asphalt roads.

The difference in New Zealand will be less pronounced with our renewable electricity. However, this is still an important consideration, as is the fact that concrete absorbs atmospheric CO2, especially when crushed.

Tenders for new roads are specifying a lower carbon footprint, up to 30 percent over a time period. Efforts the concrete industry is making to reduce emissions will help in this area.

Measures include replacing a proportion of the fossil fuels in cement production, introducing low-carbon cement replacements such as fly ash, slag and natural pozzolans (such as pumice), improving vehicle efficiency, and greater recycling and reuse of concrete.

Furthermore, concrete roads are ‘rigid’, preventing heavy vehicles from deflecting the road surface and creating the ‘rolling resistance’ experienced with ‘flexible’ alternatives.

Research by MIT in the United States indicated that the result is lower fuel costs per truck journey, which could total about 0.5 percent of transport related emissions over 50 years.

At the end of their long service-life, concrete roads are recyclable. Once crushed, the concrete can be re-used in a range of applications, including road base. This avoids sending end-of-life concrete roading materials to landfill, meeting waste minimisation objectives.

CONCRETE ROADMAP
As New Zealand moves forward, balancing the need for economic stimulus post COVID-19 with carbon zero aspirations, the benefits of concrete will come to the fore.

The Government’s infrastructure investment package is welcomed as a means to kick-start the economy in the wake of the pandemic.

It is an opportunity to future proof our key transport routes by taking advantage of concrete’s cost-competitiveness, durability, safety and environmental attributes.

At the same time, the concrete industry’s commitment to decarbonise, will play a key role in ensuring New Zealand’s aim to be net carbon zero by 2050 remains achievable.