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Soil Mechanics - II Practical Portion

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**Determination of Relative Density**

Experiment No. 07 Determination of Relative Density of Soil

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**Class Outlines Determination of Field Density Sand Replacement Method**

Determination of Lab Density Standard Proctor Compaction Test Modified Proctor Compaction Test

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**Experiment No. 07(a) Determination of Field Density**

of Soil Using Sand Cone Method

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Designation ASTM: D (1982) AASHTO: T (1996)

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**Apparatus Sand-cone apparatus . Tray with hole Balance Stove or oven.**

Hand chisels for digging test hole Container for moisture samples (tin cans). Container for retaining excavated soil

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Apparatus Excavated test hole ASTM, AASHTO sand-cone apparatus BS sand replacement apparatus

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Procedure Determine the volume of the bottle or cylinder and attachments including the volume of the valve. Determine the bulk density of the sand to be used in the field test Determine the weight of sand required to fill the funnel. Determine the density of soil in place

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**Calculations Calculate the volume of the density apparatus as follows:**

V1 = G Where, V1 = Volume of density apparatus, in cubic centimeters. G = Grams of water required to fill the apparatus. Calculate the density of the sand as follows: W = Grams of sand required to fill the apparatus. V1 = Volume of apparatus in cubic centimeters as determined in 1st step Calculate the in-place density of the soil as follows:

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Calculations Where, V = Volume of test hole or volume of the excavated soil. W2 = Weight of sand used to fill the test hole and funnel. W3 = Weight of sand in funnel W1 = Weight of soil excavated from the test hole Calculate the dry density of the soil in place as follows: Dry density of soil = Where, ‘m’ is the moisture content determined as follows from the sample taken at step (4-g.).

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**Experiment No. 07(b) Determination of Lab Density**

of Soil Using Standard Proctor Compaction Test

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Designation ASTM: D AASHTO: T 99-97

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**Apparatus Mold with detachable collar and detachable base plate .**

Rammer with a mass of 2.5-kg. (5.5–lb) Weighing Balance Drying oven . Straightedge for trimming the soil Sieve No. 4 (4.75-mm.) Containers for moisture content determination

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**Compaction mold and hammers**

Apparatus Compaction mold and hammers

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**Procedure Take 3-kg. soil passing 4.75-mm. (No.4) sieve .**

Thoroughly mix the selected sample with sufficient water to dampen it to approximately 4-percent below the expected optimum moisture content . Compact the soil in the mold with collar attached, in three approximately equal layers to give a total compacted depth of 125-mm. (5-in) . Following compaction of each of the first two layers, any soil adjacent to the mold walls that has not been compacted or extends above the compacted surface shall be trimmed and be evenly distributed on top of the layer

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Procedure Compact each layer by 25 uniformly distributed blows of the rammer dropping free from a height of 305-mm. (12-in.) above the level of the soil . After compaction, remove the collar, trim the compacted soil even with the top of the mold, and determine the weight of mold and soil in kilograms or pounds . For weight recorded in kilograms, multiply the weight of the compacted specimen and the mold, minus the weight of the mold, by 1060, and record the result as the wet density of the compacted soil, γb in kilograms per cubic meter .

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Procedure For weight recorded in pounds, multiply the weight of the compacted specimen and the mold, minus the weight of the mold, by 30, and record the result as wet density of the compacted soil, γb, in pounds per cubic foot . Remove the material from the mold and take a representative sample to find the moisture content Thoroughly break the molded specimen and add to remaining portion of the test sample . Add water to increase the moisture content of the soil by one to two percent and repeat the above procedure for each increment of water added

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Procedure Continue this series of determinations until there is either a decrease or no change in the wet density of compacted soil . If the soil particles are fragile and grain size will be reduced by repeated compaction, separate and new sample shall be used in each test repetition Calculate the moisture content and the dry density of the compacted soil for each trial, and determine the Moisture-Density Relationship as follows .

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**Moisture-Density Relationship**

The dry densities of the soil shall be plotted as ordinates and the corresponding moisture content as abscissas . mopt Water content γd max Dry density

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**Procedure Optimum Moisture Content:**

The moisture content corresponding to the peak of the moisture-density curve is termed the “Optimum Moisture Content” of the soil. Maximum Density: The dry density of the soil at optimum moisture content is termed “maximum density”

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**Observations & Calculations**

Observations for moisture content determination Test data Test repetitions 1 2 3 4 5 6 Row -1 weight of can + wet soil Row -2 weight of can + dry soil Row -3 Wt. of water (row.1-row.2) (gm) Row -4 weight of can, (gm) Row -5 weight of dry soil, (gm) (row.2-row.4) Row -6 Moisture content, m% (row.3/row.5)

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**Observations & Calculations**

Observations for determination of Density = Weight/Volume (kg/m3) Test data Test repetitions 1 2 3 4 5 6 Row -1 Wt. of water added for each trial Row -2 Moisture content, m% Row -3 weight of soil + mold, (gm) Row -4 weight of mold, (gm) Row -5 weight of soil (gm) [kg] (row.3-row.4) Row -6 Wet density (kg/m3) Row.5*1060 Row -7 Dry density (kg/m3)

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Graph

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**Experiment No. 07(b) Determination of Lab Density**

of Soil Using Modified Proctor Compaction Test

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Designation ASTM: D AASHTO: T

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**Apparatus Mold with detachable collar and detachable base plate .**

Rammer 4.54-kg. (10-lb.) Weighing Balance Drying oven . Straightedge for trimming the soil Sieve No. 4 (4.75-mm.) Containers for moisture content determination

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**Compaction mold and hammers**

Apparatus Compaction mold and hammers

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Procedure All the steps are same as in Standard Proctor Compaction Test except; Mould will be filled in five (5) equal layers instead of three(3). Weight of the Rammer used will be 4.54 kg (10lb) instead of 2.5kg (5.5lb). Height of drop of the Rammer will be 18-in instead of 12-in.

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