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Requirements for FSMRs

Compressive strength must be determined in accordance with the principles of BS EN 12390-3, with the following exceptions or options:
  1. Test specimens may be prepared at the time of placement by casting within a test mould or recovered from site after placement by extracting cores from the reinstatement.
  2. Specimen shape and dimensions must be in accordance with BS EN 12390-1 with the addition that specimens may also be manufactured with an aspect ratio of 1. FSMR moulds may be manufactured from cellular foam (preferably polystyrene) and include a cellular foam lid. The samples must not be compacted except for minimal tamping to allow the mould to be filled without leaving excessive areas of voids.
  3. The top and bottom surfaces of the extracted core may be grouted to provide flat and parallel loading surfaces.
  4. Following preparation or recovery, the test samples must be stored upright at either 20°C or 40°C depending on the nature of the material, and tested in compression at 28 days after placement of the material on site.
FSMRs must achieve the required performance without being tamped or compacted.
In excavations containing water, the minimum recommended density for FSMRs is 1050 kg/m3.
FSMRs are unlikely to provide adequate load bearing capacity for several hours after placement, depending on several variables including temperature and set time of the mix.