Dry unit weight of soil (γd) :The dry unit weight (γd) is the weight of solids (Ws) per unit of its total volume (V) (prior to drying) of the soil mass.
(γd) = Ws/ V
Procedure for determination of dry density of field soil by core cutter method.
-Measure the inside dimensions (accurate to 0.25 mm) of the core cutter and calculate its volume.
Find the mass of core cutter (without dolly) accurate to 1 gm i.e. ( W1)
-Expose the soil area, about 30 cm square to be tested and level it. Put the dolly on the top of the core cutter and drive the assembly in to the soil with the help of the rammer until the top of the dolly protrudes about 1.5 cm above the surface.
-Dig out the container from the surrounding soil and allow some soil to project from lower end of the cutter. With the help of straight edge, trim flat the end of the cutter.
-Find the mass of cutter full of soil i.e. (W2)
-Keep some representative specimen of the soil for water content determination.
-Repeat the test at two or three locations nearly and get the average dry density