During an inspection of the construction site of the Yinba Railway (a branch line of the Baotou-Yinchuan High-Speed Railway from Yinchuan to Bayanhot), it was discovered that China Railway 16th Bureau Group, a subsidiary of China Railway Construction Corporation Limited (601186.SH), may have used substandard rubber materials in bridge construction. Random samples of the installed ethylene propylene diene monomer (EPDM) rubber sheets were easily cut and torn apart. Laboratory tests revealed that their core performance indicators were far below the required standards, and the primary material was not EPDM rubber but isoprene rubber. Experts warn that such substandard materials could reduce the lifespan of certain bridge structures and pose safety risks to railway operations.
The EPDM rubber sheets were installed between concrete cable troughs and steel crossbeams on both sides of the railway to distribute pressure, absorb vibrations, and provide waterproofing. However, on-site tests showed that the rubber sheets could be easily sliced with a knife, and the torn edges appeared rough, resembling compressed irregular particles. Industry experts noted that genuine EPDM rubber products typically have smooth cross-sections, suggesting the material may be a cheaper alternative.
Further testing by a professional rubber inspection agency confirmed that the tensile strength of the sampled rubber sheets was only 1.78 MPa—just 15% of the required standard (≥12 MPa). Material analysis also identified isoprene rubber as the primary component, which has inferior weather resistance compared to EPDM rubber.
When questioned, Zhang Guojun, the project manager of China Railway 16th Bureau Group, stated that he was unfamiliar with the material and could not assess its performance. He claimed that only a small quantity had been used and that the batches had passed random inspections. However, records showed that approximately 9,000 rubber sheets from three batches had already been installed, with a fourth batch scheduled for delivery later in November.
The project’s supervision company, Gansu Xinda Construction Consulting Co., Ltd. (a subsidiary of China Railway Lanzhou Group), asserted that the inspection process was compliant, but no further response was provided regarding the discrepancies in test results.
Experts warned that substandard rubber sheets could accelerate structural wear, potentially leading to safety hazards over time. Zhang Guojun acknowledged that if issues arise, the materials would be replaced, and the supplier held accountable under contractual terms.
Attempts to contact China Railway 16th Bureau Group’s chairman, Wu Yankun, for comment were unsuccessful.
(Reporting by Economic Reference News; investigation tips can be sent to 13810799287@163.com)
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