Structural relining of culvert under rail

Problem:

The 50-year-old rail line connecting this mine to the port is a vital component of the mining company's infrastructure and its safe operation crucial to their operations.  Routine inspections of the rail line including bridges and culverts are conducted. In January 2024, a badly deteriorated culvert was discovered. The culvert was judged to be structurally unsound and emergency repairs were fast tracked. Ironstone Civil was mobilised to site to carry out repairs in early February 2024.

Solution:

Ironstone Civil proposed the installation of a sprayed geopolymer liner, GeoCast, to structurally replace the existing corrugated steel culvert. Consulting engineers completed a 50-year design, and a minimum design thickness was determined. The GeoCast geopolymer is sprayed onto the deteriorated culvert using a robotic sprayer in 15 to 20mm layers until the designed thickness is achieved. No reinforcing steel is required and once the designed thickness is achieved the liner becomes “the structure” taking over from the original culvert.

Ironstone Civil worked around the 4 to 5 rail movements each day ensuring no delays to trains. Temperatures peaked well above 40 degrees during the works. Like all cementitious grouts the long-term properties of Geopolymers are essentially set in the first 24 hours after batching and placing. So given the conditions preventative measures to protect the freshly sprayed GeoCast and ensure efficient curing were crucial.