MC Bauchemie and Porr have developed a new TBM backfill grout based on a geopolymer that is suitable for use in swelling rock formations. The companies stated that the cement-free filler is sulphate resistant and adequately prevents swelling pressures while providing the usual bedding for securing the tunnel ring. Backfilling materials used fall into one of two categories: single component (1C) and two-component (2C) grouts. The 1C grouts contain cement, additives, aggregates and water. Concrete admixtures are used to create specific application properties.
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