Density and moisture content are, perhaps, the most important parameters a soil engineer has to keep a strict control on, during the construction of earthen dams and embankments. Using the laboratory test data, obtained under controlled conditions. The specifications to be adopted for the fill can be drawn in terms of maximum dry density and optimum moisture content.
Indian standards specify two methods-by light compaction as per IS:2720 (part VII) and by heavy compaction as per IS:2720 (part VIII) for the determination of dry density- moisture content relationship, depending upon the compacting equipment used in the field. The compaction moulds listed here under meet the essential requirements of IS:10074 and the rammers those of IS:9198.
The Automatic Soil Compactor replaces the hand compaction procedure as specified for dry density/moisture content relationship of soil. Both light and heavy compaction tests can be performed by this machine using either 100 mm dia or 150 mm dia compaction moulds. The height of drop of the 50 mm dia rammer can be set either at 310 mm or 450 mm as per requirement.
The machine is provided with a standard rammer weighing 2.6 kg for conducting light compaction and its weight can be increased to 4.89 kg for heavy compaction test by attaching additional rod supplied along with it. While using 100 mm dia mould the rammer carriage is locked in one position and the total area of the mould is compacted in about 25 strokes.
The number of strokes i.e. 25 can be programmed, which are digitally displayed. Locking during the course of test in this stage is through high force solenoids. A selector switch is provided on the control panel for selection between 100 mm dia mould or 150 mm dia mould. For 150 mm dia mould the rammer carriage shifts radially by 25 mm to give about 8 blows within the diameter of 100 mm and 17 blows beyond 100 mm dia that is between 100 mm and 150 mm.
This sequence is repeated till the rammer completes 55 blows after which the machine automatically stops. Safety features like safety lever for preventing rammer falling when the door is open, total cover for moving parts, M.C.B. for overload protection are provided as standard.