Backfilling and Plinth Filling

Backfilling and Plinth Filling

Backfilling shall be done after the foundation has completely set.Backfilling shall be carried out in layers and each layer shall be thoroughly compacted.Inadequate compaction is likely to cause settlement of backfilling resulting in development of cracks in flooring.Mechanicl rammers are preferable to hand rammers.Use hand rammers where the area is inaccessible to mechanical rammers.Filling layers not exceeding 250mm in thickness.

  • Backfilling work shall not start until Site Engineer gives his approval to do so. Material used for backfilling shall be any one or combination of soil types mentioned
  • Back filling shall be done in layers of thickness not exceeding 30 to 45cm depending on compaction equipment and method (loose soil before compaction). The soil layer shall then be watered adequately and compacted to minimum 90% to 95% of Standard Proctor Density for soil other than sand and 85% in case of sand. Compaction shall be carried out at optimum moisture content (OMC). Soil after compaction shall be free from pockets underneath.
  • After the compaction of final layer of soil, at least 3 cores shall be taken from the areas directed by Site Engineer and the soil shall be tested in laboratory for the degree of compaction achieved. Results shall be matched above.
  • If the soil is excessively wet, it shall be allowed to dry sufficiently before compaction. (Approximately OMC should be maintained)
  • Compaction shall be done with suitable mechanical equipment such as plate vibrator, vibratory or tendon roller, or 10 Tonnes Power Roller as suitable for the area to be compacted. In areas where mechanized compaction cannot be done, hand compaction shall be resorted to as directed by the Site Engineer. Overall compacted thickness of soil shall be as per drawing.
  • Over the compacted ground, rubble soling shall be done. Stones shall be hand packed as close as possible and bedded firmly on broadest base. Void shall be filled with chips and small stones.
  • Backfilling around water retaining structures shall be done only after testing of structures against leakage is done.
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