Advancements in Cold In Place Recycling Using Foamed and Emulsified Bitumen with Field Demonstration in Guigang China

Nov 11,2025 04:00

According to WPB, the city of Guigang in the Guangxi Zhuang Autonomous Region of southern China recently hosted a major technical demonstration dedicated to innovative road‑maintenance technologies, with a central focus on cold in‑place recycling using foamed bitumen and emulsion‑based cold recycling. This event attracted highway‑maintenance experts, contractors, and engineers from across Guangxi, aiming to showcase cutting‑edge, energy‑efficient, and environmentally responsible methods for rehabilitating and preserving existing pavements. The meeting was jointly organized by the Guigang Municipal Transportation Bureau and several highway‑maintenance technology companies, highlighting China’s continuous shift toward low‑carbon and resource‑efficient construction practices. Participants observed live demonstrations of foam‑bitumen cold recycling (known locally as “泡沫沥青就地冷再生”) and emulsion‑based cold recycling, both of which allow the reuse of existing pavement materials without requiring high‑temperature processes.
China’s expanding highway network faces mounting challenges from aging pavements and escalating maintenance costs. Traditional hot‑mix rehabilitation consumes significant energy, generates emissions, and requires transporting large amounts of aggregate and binder. In response, the Ministry of Transport and several provincial departments have promoted the adoption of the “Four New Technologies” framework — new materials, new equipment, new processes, and new management models — with cold recycling as a flagship solution. The Guigang event exemplifies how these initiatives are implemented on the ground, offering on‑site machinery demonstrations and technical briefings that allowed attendees to compare step‑wise (分步式) and integrated (一体式) cold recycling methods. The step‑wise approach performs milling, binder injection, and compaction sequentially, while the integrated approach uses continuous trains of specialized equipment to execute all operations simultaneously, enhancing efficiency and quality control.
Cold in‑place recycling (CIR) reconstructs deteriorated asphalt pavements directly on the roadbed by pulverizing the existing surface, adding binding agents such as foamed bitumen or bitumen emulsion, mixing, reshaping, and compacting. Laboratory and field research indicate that critical factors for success include binder type, reclaimed asphalt content (RAP/RAI), compaction degree, curing conditions (especially moisture escape), and environment. For instance, studies show that emulsion‑based mixtures often outperform foamed‑bitumen mixes in water stability and overall performance. Moreover, curing that fails to account for field evaporation and moisture conditions can lead to lower strength and higher void content. These findings underline the importance of rigorous mix design, simulation of in‑situ conditions in laboratory testing, and careful field implementation.
Field trials in Guangxi, including sections of Highway S204 in Pingnan County, have applied foam‑bitumen CIR and achieved improvements in crack‑resistance, surface smoothness and early traffic loading capacity, thereby extending pavement service life. Feedback from practitioners underlined that shorter project times, lower heat energy inputs, and reduced traffic disruption were tangible advantages.
Stakeholders – including municipal and provincial highway agencies, contractors and equipment manufacturers – must internalize that adopting CIR is not simply about purchasing new machinery, but about holistic process change: specifying the right binder, controlling moisture and compaction, ensuring curing meets environmental conditions, and aligning with lifecycle‑cost goals. For municipal agencies, this means shorter project cycles, less traffic impact and optimized capital use. For contractors and manufacturers, the shift opens new business models around cold‑recycling equipment, modular crews, and maintenance‑focused contracts. Policymakers benefit via aligned environmental targets, reduced embodied emissions, and more resilient infrastructure.
Challenges remain: cold recycling requires precise compaction and curing; if water evaporation is insufficient or voids too high, performance suffers. Performance in the field typically lags laboratory predictions, so field monitoring and quality assurance are crucial. Also, lower temperature crack resistance remains a concern for some CRM types. Nonetheless, the Guigang demonstration provides a strong model for other provinces and international practitioners seeking to adopt low‑carbon, resource‑efficient and durable pavement‑rehabilitation solutions.
In summary, the Guigang cold‑recycling demonstration reflects a broader trend in China toward sustainable, energy‑efficient road maintenance. By leveraging foamed‑bitumen CIR and emulsion‑based cold recycling methods grounded in recent research, municipal and provincial authorities can extend pavement life, reduce environmental impact, and improve operational efficiency. The event not only showcased technical innovations but also reinforced the strategic importance of integrating advanced recycling technologies into routine infrastructure management.