Cement Material

        Portland Cement
           Cement content is controlled by the strength requirements in relation to the max. aggregation size.
           Exposed to soil or water high in soluble sulfate Type II or V

       Pozzolan
           To improve long-term strength & lower permeability
           To improve workability (pumpability)
           To increase resistance to sulfate attack
           To reduce expansion caused by the alkali-silica

       Silica Fume
           Over 85% silicadioxide, 100 times finer than portland cement
           To improve strength & durability
           To fill the microscopic void => To reduce permeability & increase the density of the shotcrete

      Aggregate
           Final product must meet specified strength
           Well graded w/o gaps
           Lightweight-agg. shotcrete :dry-mix

      Water
          Reasonable clean & free from suspended silt and organic matter and from alkali and other dissolved mineral salts.

      Water-reducing
          Not used in dry-mix shotcrete

      Accelerator
          Rapid strength & set (Tunnel support)
          To reduce rebound
          2~6% of cement content by weight

     Polymers (Latex emulsion)
         To increase tensile & flexural strength
         To improve bonding
         To decrease permeability