In the heart of China’s sprawling railway network, a common yet often overlooked material—fully weathered phyllite—is gaining attention for its potential to revolutionize sustainable transport construction. A recent study led by Aiping Chen from the Sichuan Provincial Engineering Research Center of Rail Transit Lines Smart Operation and Maintenance at Chengdu Vocational & Technical College of Industry has shed light on the viability of using this material, both untreated and stabilized with low-dosage cement, for railway subgrades. The research, published in the journal *Buildings* (translated from Chinese as “Buildings”), offers promising insights for the construction and energy sectors, particularly in terms of cost efficiency and environmental sustainability.
The study, which combines rigorous laboratory investigations with large-scale field trials, provides a comprehensive evaluation of phyllite’s suitability for subgrade fill. “We wanted to bridge the gap between laboratory mix design and real-world field compaction strategies,” Chen explains. “This holistic approach ensures that our findings are not just theoretically sound but also practically applicable.”
The laboratory investigations covered a wide range of properties, including mineralogy, classification, compaction, permeability, compressibility, shear strength, and bearing capacity. Field trials, on the other hand, focused on the influence of loose lift thickness, moisture content, and compaction sequence on subgrade quality. The performance indicators included the degree of compaction and the subgrade reaction modulus K₃₀, defined as the plate load modulus measured with a 30 cm diameter plate.
One of the key findings of the study is the establishment of a recommended cement dosage of 3.5% (by weight of dry soil). This dosage was found to strike a balance between strength development and construction reliability. “Cement stabilization significantly improves the strength, stiffness, and constructability of phyllite, making it a reliable option for the main load-bearing subgrade layers,” Chen notes.
The study also highlights the environmental benefits of using stabilized in-situ phyllite. According to the sustainability analysis, this approach achieves lower costs and approximately 30% lower CO₂ emissions compared to importing crushed rock from 30 km away. This not only promotes resource reuse but also aligns with circular economy and carbon-reduction objectives in railway and road earthworks.
The implications of this research extend beyond the railway sector. The energy sector, in particular, could benefit from the use of locally sourced, stabilized materials for infrastructure projects. This could lead to significant cost savings and a reduced environmental footprint, contributing to the sector’s sustainability goals.
As the world grapples with the challenges of climate change and resource depletion, studies like this one offer a glimmer of hope. By demonstrating the potential of often-overlooked materials like phyllite, Chen and his team are paving the way for more sustainable and resource-efficient infrastructure development. “Our findings support the idea that sustainable construction is not just a possibility but a practical reality,” Chen concludes.
In the quest for low-carbon, resource-efficient infrastructure, this research serves as a testament to the power of innovation and the importance of looking beyond conventional materials. As the construction and energy sectors continue to evolve, the insights from this study could shape future developments, driving the industry towards a more sustainable future.