China’s Pavement Crisis Meets Eco-Innovation

China’s road infrastructure, with over 5.25 million kilometers of highways, is facing widespread degradation. From rutting to cracks and potholes, asphalt roads are buckling under the pressure of rising vehicle loads. Traditional solutions like full removal & reconstruction offer structural reliability but demand heavy resources, time, and cost. Meanwhile, the government’s Dual Carbon goals, peak emissions by 2030 & carbon neutrality by 2060, have made environmental sustainability an imperative in road repair technologies.

The Advent of FDR-PC in Road Rehabilitation

Full-depth reclamation with Portland cement has emerged as a novel technique with immense promise. Unlike conventional methods, FDR-PC rejuvenates damaged roads by pulverizing and stabilizing existing layers in place using cementitious binders. This eliminates the need for hauling materials, reducing carbon emissions and fuel use. As such, FDR-PC aligns seamlessly with China's "1 + N" policy system that supports low-carbon technologies in transportation and construction sectors.

Study Design: A Scientific Scrutiny

To examine the environmental credentials of FDR-PC, a team led by Haiwei Zhang and colleagues undertook a comparative study using life cycle assessment models. The researchers designed pavement structures for three rehabilitation methods, removal & reconstruction, cold central plant recycling, and FDR-PC, under uniform service life conditions using 3D-Move Analysis software. Carbon emission models were created for each scenario to estimate emissions and energy usage across the entire lifecycle.

Carbon Footprint: FDR-PC Shows Lower Emissions

Results showed that FDR-PC generates only 92% of the carbon emissions compared to removal & reconstruction, and 90% compared to cold recycling when limited to pavement base layers. In energy terms, FDR-PC consumed just 60% of the energy used by removal & reconstruction and 70% of that used in cold recycling. Transportation-related emissions during FDR-PC operations were particularly low, at just 4% of those from removal & reconstruction and 6% of cold recycling, underscoring the environmental benefit of in-place treatment.

Sensitivity Analysis Reveals Cement’s Dual Role

The sensitivity analysis revealed that cement content was the most influential factor affecting carbon emissions in the FDR-PC process. While more cement improved strength and durability, it also increased emissions due to cement production’s high carbon intensity. Thus, a balance must be struck to optimize performance and environmental impact. The study also found that compaction methods, curing temperature, and duration played secondary but noteworthy roles in altering the final carbon output.

Reinforcing the Case for FDR-PC

The study situates itself among a growing body of global literature endorsing recycling-oriented pavement rehabilitation. For instance, previous research in Virginia and Brazil demonstrated that stabilized FDR reduces greenhouse gas emissions by up to 51% and energy consumption by 64% compared to conventional methods. The Chinese study enriches this discourse by offering performance-equivalent comparisons using standardized LCA methods, thus enabling more equitable benchmarking across technologies.

Strategic Implications for Policymakers

The findings from Zhang and colleagues have significant implications for infrastructure planning under China's green development agenda. By validating the carbon efficiency of FDR-PC, the study encourages highway authorities to shift from traditional reconstruction methods to more sustainable, performance-equivalent technologies. Additionally, it informs material choices, especially in optimizing cement content to balance durability with decarbonization.

Paving the Way for Low-Carbon Transport Futures

With China’s transport sector facing pressure to decarbonize rapidly, scalable, and proven interventions like FDR-PC can act as pivotal enablers. By retaining old materials and minimizing transport, FDR-PC cuts down not only emissions but also project timelines and costs. The study reaffirms that innovation and environmental stewardship need not be mutually exclusive, particularly when bolstered by rigorous data and lifecycle methodologies.

Key Takeaways:

• FDR-PC reduced base-layer carbon emissions to 92% of removal & reconstruction and 90% of cold recycling, with only 60%–70% of the energy consumption.

• Transportation emissions during FDR-PC were just 4%–6% of those in traditional methods, making it highly energy-efficient.

• Cement content was the most sensitive factor impacting emissions, requiring a balance between strength and sustainability.