Suitability of Selected Bangladesh Sands for the Determination of In-Situ Soil Density
Usually Ottawa sand is used to find out in-situ density of soil by sand replacement method. Ottawa sand is very expensive and it is always imported from abroad. To avoid these difficulties the quality and suitability of locally available sand in and around Khulna district in Bangladesh in lieu of Ottawa sand were assessed for determining in-situ density using sand replacement method. Five samples of sand named by Sylhet sand, Kushtia sand, Fultala sand, Bogjhuri sand and Mongla sand were collected from nearby business centers. Original sand and some graded sands of each sample were under investigation to ascertain their suitability of use in lieu of Ottawa sand in determining in situ soil density. Five gradations were considered and those were (i) passing #16 and retained in #30, (ii) passing #30 and retained in #40, (iii) passing #40 and retained in #50, (iv) passing #30 and retained in #50 sieve and (v) passing #50 and retained in #100 sieve . Each of the original samples has been characterized by determining its index properties, grain size distribution. Specific gravity and density were determined for each sample of original and graded sands. These properties were compared with those recommended by ASTM (1989) for selecting suitable sand in sand replacement method. From this study it was found that original sands of all selected places in Bangladesh did not satisfy the ASTM (1989) criteria of Ottawa sand. In case of graded sands, Sylhet sand satisfied all the required ASTM criteria for four gradations except the gradation passing from #50 to #100 sieve, while Kushtia and Fultala sands satisfied fully for three gradations except the gradations passing from #16 to #30 sieve and passing from #50 to #100 sieve. Bogjhuri and Mongla sands did not satisfy all criteria. So, the graded sands that satisfy the criteria of Ottawa sand as mentioned in investigation may be used in sand replacement method in lieu of costly Ottawa sand.
