What are the procedure to fill Sand in the Building Back Fill or Basement Work?

SAND FILLING AND COMPACTION FOR THE BUILDING

 Approved material shall be used for back filling. Soil with liquid limit exceeding 65% and plasticity index exceeding 35% cannot be used. High clay soil is not preferred for back filling.Imported fill shall be selected - graded hard granular fill with 100% free stones larger than 100mm, up to 50% passing 5mm mesh and not more than 20% passing a 75 micron sieve.Compaction is done in layers of 150mm. Choose the compaction equipment based on the nature of soil. Soil with organic material, construction debris, susceptible for spontaneous combustion, soft clay, and moisture content greater than optimum value to be avoided as back fill material. Insitu field densities of compacted material should be 95% of maximum dry density or as specified by the consultant. Test should be conducted 10m centre-to-centre and before the anti-termite treatment is done. Sand replacement method can be used to ascertain insitu field density. If removal and replacement of the weak strata with strong compact material is necessary, check the compatibility

of the proposed fill material with the existing chemical ground conditions.The checks that need to be made before work starts include the stability and levels of the original ground or foundations at the base or top of embankments, selection of suitable fill material and the stability and profiles of side slopes. The stability of slopes to cuttings and embankments (in all weather conditions) is critical to safety on site.  If in doubt, the Project-in-charge must be consulted and the decisions taken to be recorded. Know your soil conditions before starting any large-scale earth moving operations.Unit of measurement of back fill material should be clear before the work starts.For volumetric calculations cater for 30% quantity more of loose back fill to compacted volume.

Regards,

J.Jaya Ruban,

Land Valuer in Tamilnadu,

Chennai.