10) Core Cutter Method

Density of the soil in place by the Core Cutter Method Introduction:

This test method sets out the procedure for the determination for the in-situ dry density of  compacted soils in earth works and pavement layers. The core cutter method consists of driving a core cutter of known volume (1000 cm 3) into the soil after placing it on a cleaned soil surface. The core cutter is usually provided with 2 mm high dolly. The driving of the core cutter is usually done !y hitting the dolly mounted on top of the cure cutter with a suita!le hammer. Then the cutter filled with soil is removed and the e"cess soil trimmed off. The cutter with the is weighed. The volume of the cutter is calculated from the dimensions of the cutter and the in-situ unit weight is determined !y dividing the weight of the soil in the cutter !y the volume of the cutter. #f the water content of the soil in the cutter is determined in the la!oratory$ the dry unit weight of the soil can also !e computed. %or construction control$ this test method is often used as the !ase for acceptance of material compacted compacted to a specified density or to a percentage of a ma"imum ma"imum unit weight determined !y a standard la!oratory test method. Objectives: •

&!'ective of this test is to determine the field density !y core cutter method.

Apparatus:

The following apparatus are reuired (%igure 1). 1) The standard standard density density apparatus apparatus consisting consisting of of steel cylinder cylinder and detacha!l detacha!lee collar. collar.

%igure 1 - pparatus for *ore *utter +ethod. 2)  !alance !alance of 10 kg$ kg$ capacity capacity reada!le reada!le and accurate accurate to at at least 0.01 0.01 g. 3) +iscellaneou +iscellaneouss euipment euipment such as rammer$ straight straight edge$ edge$ chisels for digging digging surroundin surrounding g soil.

,) mall containers for moisture content determination. ) rying &ven /  thermostatically controlled oven capa!le of continuously maintaining a temperature of 10 / 110 *0$ throughout the drying cham!er. Procedure:

1) The core cutter was weighted (1) and calculated the internal volume from its dimensions (). 2) The surface of the location to !e tested was prepared. 3) The core cutter with the collar on top was placed on the prepared surface and it was driven into the soil with a help of a hammer. ,) The surrounding soil was dug to take out the core cutter. ) The !oth ends of core cutter were leveled off with a straight edge and then it was weighted (2). ) The soil sample was removed from the core cutter and the material was mi"ed thoroughly secured and weighed with a representative$ sample for moisture determination. ) ample was kept in the oven for water content determination and after 2, hours it was weighed. Observation: •

&!servations are given in nne" 1.

Calculations and result:

1.

olume of the density apparatus in millimeters.

2.

#n-situ density of the soil (at least for two trails) 4ulk ensity of the soil

3.

5 !ulk  6 (2 / 1 ) 

The ater *ontent of the oil and then the ry ensity of the oil ater *ontent w 6 + + ry ensity 5dry 6 5 !ulk  (1 + w)

Specimen Calculation: •

in kg7m3

olume of the density apparatus a) Trail 8o9 01

6

•

•

#n-situ density of the soil +ass of wet soil

6 6

4ulk ensity of the soil

6 6

The +oisture *ontent of the oil

*an 8o9, +oisture content

6 6

*an 8o91: +oisture content

6 6

•

verage moisture content

6 6

• •

The ry ensity of the oil The +a" ry ensity ry ensity

6 6

•

The +a" ry ensity

6

•

;elative *ompaction

6 6

a) Trail 8o9 02 •

#n-situ density of the soil +ass of wet soil

6 6

4ulk ensity of the soil

6 6

•

The +oisture *ontent of the oil

*an 8o9 +oisture content

6 6

*an 8o92, +oisture content

6 6

•

verage moisture content

6 6

•

The ry ensity of the oil ry ensity

6 6

•

The +a" ry ensity

6

•

;elative *ompaction

6 6

Discussion: 1 !he "imitations of this !est#

&ne of the common methods of determining field density of fine-grained soils is core cutter method. 4ut this method has a ma'or limitation in the case of soils containing coarse-grained particles such as gravel$ stones and aggregates$ as the presence of coarsegrained particles will adversely affect the test results.

$ Compare the Core Cutter %ith other Methods of &ield Density Determinations#

' (hy is it important to measure the field density) *ive e+amples#

The dry density of the compacted soil or pavement material is a common measure of the

amount of the compaction achieved during the construction.