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EXPERIMENT NO.7

CYLINDER COMPRESSION TEST

Date of performing experiment : 27/2/2012

Date of submission : 12/3/2012

Submitted by : Farhan Arif

Entry no. : 2010CE10344

Group : 5

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AIM:To test the compressive strength of concrete (cylinder specimen) under AutomaticCompressive Testing Machine.

EXPERIMENTAL SET-UP:

Cylinder Specifications:

Dimensions: 100*200mm

Automatic Compression Testing Machine

The Automatic Compression Testing Machine has all features of Micro Controller based

Compression Testing Machine. In addition:

The machine is available in 500kN, 1000kN, 2000kN, 3000kN ranges. It has an automatic load release facility. It also has facility for transmission of data to the serial port of a computer placed within

200 meters of the loading unit.

THEORY:

The compressive strength of concrete is the most common measure for engineers whichcan be measured by measuring the compressive strength of cylinder specimens.

The compressive strength of concrete is expressed as failure load divided by cross-sectional area resisting the load and represented in MPa in SI units.

The strength of concrete is controlled by the proportioning of cement, coarse and fineaggregates, water, and various admixtures. The ratio of the water to cement is the chief

factor for determining concrete strength.

Due to hydration reaction, the strength of concrete keeps on rising. However, practicallyit is impossible to wait till infinite time to measure the utmost strength of concrete

specimen. Thus, as per the code the maximum strength is taken to be the 28 day strength.

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OBSERVATION:

Sample 1: Grade -M40

Sample Diameter:100(mm)

Sample Area:7850(Sq mm)

Sample Age:28 (Days)

Peak load or FAILURE load= 312.3kN

Estimated failure stress or strength =40+1.65*5=48.25 MPa

Failure stress=312.3kN/7850mm2

= 39.78 MPa , corresponding strain=897

Sample 2: Grade- M40

Sample Shape:Cylindrical

Sample Length:150(mm)

Sample Diameter:100(mm)Sample Area:7850(Sq mm)

Sample Age:28(Days)

Rate Of Loading:0.005 ((mm/Sec))

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Strress vs Strain curve

stress(Mpa)

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Peak load or FAILURE load= 261kN

Estimated strength or failure stress=40+1.65*5=48.25 MPa

Failure stress=312.3kN/7850mm2

= 33.24 MPa , corresponding strain=1324

Sample 3:

Grade: M30

Sample Shape:Cylindrical

Sample Height:200(mm)

Sample Diameter:100(mm)

Sample Area:7850(Sq mm)

Sample Age:28(Days)

Rate Of Loading:0.005 ((mm/Sec))

LOADING: CYCLIC

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Stress(Mpa)

Stress(Mpa)

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RESULT:

For sample 1:

Estimated failure stress or strength =40+1.65*5=48.25 MPa

Failure stress=312.3kN/7850mm2

= 39.78 MPa

For sample 2:

Estimated strength or failure stress=40+1.65*5=48.25 MPa

Failure stress=312.3kN/7850mm2

= 33.24 MPa

DISCUSSION:

Strength of sample 1 is close to 40 MPa or to be precise close to calculated 48.25 MPa. Thus,

declaring it as a good example of M40 casting.

For sample 2, strength is much low as expected. This error might be mainly due to carelessness

while casting as good precaution was taken while preparing design of concrete and mixing the

quantities in proper proportion.

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Stress(Mpa)

Stress(Mpa)