A research team led by Professor Wang Juan from the Department of Civil Engineering at the University of Nottingham Ningbo China (UNNC) has developed an innovative method for transforming construction spoil into high-performance motorway subgrade material, offering a sustainable solution to one of the construction industry’s most persistent environmental challenges.
The team’s integrated three-step process — flocculation, modification and reinforcement — enables waste spoil generated during motorway construction to be fully recycled and reused on site. The technology has already been successfully applied in the Hangzhou–Ningbo Expressway extension project, marking Zhejiang Province’s first large-scale use of engineering spoil in motorway main carriageway construction.
Traditionally, large volumes of excavated spoil are transported over long distances for disposal, creating significant financial and environmental costs. One motorway project alone was expected to generate approximately 400,000 cubic metres of spoil, with conventional disposal costs amounting to tens of millions of RMB. At the same time, new materials would normally need to be purchased separately for roadbed construction.
Professor Wang’s team addressed the challenge by developing a process capable of treating spoil characterised by high moisture content, high compressibility and poor engineering performance. The method first separates solids from liquids in waste slurry before improving the material properties through chemical modification and compaction, ultimately producing roadbed fill that meets motorway engineering standards.
“Applied research should bridge the gap between laboratory innovation and industrial practice,” said Professor Wang. “Our goal is to develop technologies that are practical, affordable and scalable for industry use.”
The project has delivered both economic and environmental benefits. All spoil from the demonstration project was reused on site, eliminating the need for off-site disposal and reducing transport-related carbon emissions. The recycled material also has a lower density than traditional fill materials, helping to reduce subgrade weight, minimise uneven settlement and extend the lifespan of roads.
The achievement earned the team the Second Prize for Scientific and Technological Progress in Ningbo and has since been promoted across multiple motorway projects in the region, contributing to the development of “zero-waste construction sites”.
Currently, the research team is prioritising tackling deep-seated industry pain points and complex technical challenges through interdisciplinary innovation.
Published on 12 May 2026