GOVERNMENT ENGINEERING COLLEGE DETERMINATION OF INDEX PROPERTIES PRESENTED BY:- 130200106025

METHOD OF DETERMINATION OF DRY DENSITY OF SOIL Sand replacement method Core cutter method Water displacement method Rubber ballon method

Core cutter method It is a field method to find out the unit weight of soil. It is called drive sample method. it consists of using a steel cutter to take out sample from the ground to determine its bulk density. Core cutter consists of a steel cutter 10c.m. in diameter and about 13c.m. High. A 12.5c.m. High dolly is placed above the cutter.

procedure Clean a small area of about 30c.m. Square of ground and level it. Take weight of cutter say W1. Place the cutter with dolly over the ground. Push down the cutter in the ground with the help of rammer till 1c.m. Of dolly projects above the ground surface.

Take out the cutter and remove the dolly Take out the cutter and remove the dolly. Trim of extra soil present if any. Weight the soil with cutter. say W2. Calculate the volume of cutter with its known dimensions.

Determine bulk unit weight of soil as: bulk unit weight =W2-W1/Vn Here W1=weight of empty cutter W2=weight of cutter with soil V=volume of cutter # This method works very good for soft, fine grained soil . However it can not be used on stoney, gravelly soils.

Sand replacement method The equipment in this method consists of (1) Sand pouring cylinder mounted over a pouring cone and separated by shutter. (2) Calibrating container. (3)Supplementary items like chisel, scoop, balance etc.

Calibration of the cylinder This is done to compute the bulk density of sand used in the cylinder. the steps involve in this are: (1) Fill the cylinder with uniform dry sand and weight it. Say this weight is W1. (2) Place the pouring cylinder above calibrating container and open the shutter. Sand fills the calibrating container and the cone.

(3) Close the shutter and weigh the cylinder say weight is W2. (4) Refill the cylinder equal to the original weight W1. (5) Allow the sand to run out of the cylinder to fill calibrating container only and shutter is closed.

(6) Place the cylinder over a plane surface and open the shutter. (7) Allow the sand to run out to fill the cone below. (8)Remove the cylinder and weigh the sand filling the cone only. Say its weight W3.

(9) Calculate unit weight of sand as under: = W1-W2-W3/Vc Here W1=initial weight of cylinder with sand W2= weight of cylinder after filling sand into the cone and container W3= weight of sand filling cone only Vc=volume of the container

Calculating bulk density of soil Following steps are involved in this: (1) Clean the site and level it. Exacavate a test hole in the ground of depth equal to that of calibration container. (2) Collect the soil in tray and weigh it. Say its weight is W. (3) Place the cylinder centrally over the excavated hole.

(4) Open the shutter and allow the sand to fill in the cone. (5) Measure the weight of remaining sand and cylinder. Say its weight is W4. (6) Determine the volume of hole as under Volume of hole=W1-W4-W3/Weight of sand

Here, W1=weight of cylinder+sand before pouring to hole W2= weight of sand in cone only W3= weight of cylinder after pouring sand into the hole. (7) Determine the bulk density of soil as Bulk density= weight of soil in hole/volume of hole

Specific gravity determination The specific gravity of soil material can be determined in laboratory by any of the following methods: (1) Density bottle method (2)Pycnometer method (3) Measuring flask method (4) Gas jar method

Density bottle method The density bottle method is the most accurate and suitable for all types of soils. Specific gravity is determined using the principle that: specific gravity of soil= dry weight of soil/weight of water equal to the volume of soil

procedure (1) weight the empty dry bottle say its weight W1. (2) An oven dried soil sample is placed in bottle and its weight is determined, say this weight is W2. (3) Fill the remaining portion of bottle with gradually. Remove the trapped air either by vaccum or shaking the bottle.

(4) Weight of bottle + water is taken. Say this is W3 (4) Weight of bottle + water is taken. Say this is W3. (5) Empty the bottle completely and wash it through with clean water. (6) Now fill the bottle completely with water and weight it. Say this weight is W4.

Specific gravity is determined as below: Here W1= weight of empty bottle W2=weight of bottle + dry soil W3= weight of bottle + soil + water W4=weight of bottle+water Hence weight of dry soil=W2-W1 weight of water=W4-W1 weight of water at third stage=W3-W2.

Now weight of water equal to the volume soil solids=(W4-W1)-(W3-W2) Now weight of water equal to the volume soil solids=(W4-W1)-(W3-W2). Specific gravity=weight of dry soil/weight of water equal to volume of solids G=W2-W1/(W4-W1)-(W3-W2)

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