Wherever low/poor bearing capacity soils met with, the Architects and also certain Builders think and believe that If the bearing strength of soils become weak or low, RC Structural slabs & Beams may be arranged at plinth level (GF-Finished floor level) with the purpose of preventing settlement of foundation and subsequent development of cracks in walls.
By applying your own experience and expertise in foundation structure, it is possible to have clear idea on the behavior of weak bearing soil if loaded heavily. The foundation cost is raised by 50% with the inclusion of the cost of setting up RC Structural Slabs & Beams.
But the provision of RC structural slabs and Beams at plinth level may not be considered as useful solution to get rid of foundation settlement and subsequent cracks. Rather it will be treated as extra expenses that is incurred on the construction of structure.
It is recommended to apply the following measures to resist the settlement of foundation systems and wall cracks efficiently.
The foundation soil at a depth of 00 m to 2.70m (if it belongs to a weak bearing soil like soft/medium clay) should be artificially reinforced with Geogrids/Geotex layers supported with Quarry dust:Gravel Mix 1:3 or cement.
Quarry dust 1:10 mix in 4 or 5 layers of 200 mm thick will enhance the SBC of soil at 2.00m/1.80m level to 200kN/m2 from 100kN/m2.
Arrange an extra layer of Geogrid/Geotex over and then apply the PCC 1:5:10 for 100 mm. Over which the foundation system should be provided as designed-combined strip Raft/combined/isolated footings as per situation. Inspite, under reamed piles with pile cap may be arranged directly.
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