Vibro compaction (VC) is the most economical deep compaction technique for densifying loose granular soils. The basic principle behind the process is to rearrange loose deposits into denser state by means of vibration. Optimized design spacing of vibro compaction will be usually determined based on field trials comparing pre & post penetration tests (esp. CPT or SPT). Recent fills or river deposits having clean sands with fines less than 10% demonstrate considerable improvement after compaction, while presence of calcareous material significantly influences the post treatment results (Al Homound and Wehr in Geotech Geol Eng 24:757–774, 2006). Studies done in the past stated that cone tip resistance in pure sand is clearly different from that found in calcareous sand at constant relative density and in-situ stresses. Shell correction factor shall be applied to assess the post improvement cone tip resistance in the presence of calcareous material. Pre and post improvement penetration tests were conducted to assess the extent of improvement at one of the project sites having the presence of shell content. Samples were extracted through borehole investigation to estimate percentage of calcareous content. The present study illustrates the established shell correction factor and the influence of calcareous content on cone tip resistance.