Sample lab 3 - Lab report for concrete mix design PDF

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Lab Report N3

Testing Concrete Cylinders in Compression Civ E 302

Table of Contents OBJECTIVE...................................................................................................................................................2 THEORY AND EXPERIMENT SETUP...............................................................................................................2 PROCEDURE.................................................................................................................................................5 DATA............................................................................................................................................................5 CALCULATIONS............................................................................................................................................7 Conclusion...................................................................................................................................................9

Figure 2 Slump Test.........................................................................................................................2 Figure 1 Concrete Molds.................................................................................................................2 Figure 3 Force-Displacement Response in Compression................................................................4 Figure 4 Stress-Strain Response in Compression............................................................................4 Figure 5 Tested Concrete Cylinders.................................................................................................9

1

Testing Concrete Cylinders in Compression OBJECTIVE The main objective of this experiment was to test the behavior of concrete barrels beneath compression on 7th, 14th, 21st and 28th days utilizing MTS pressure compression machine. On each day, 3 concrete barrels will be tried and comes about famous. After 28 days all the results will be calculated, compared and utilized to chart stress-strain reaction compression.

THEORY AND EXPERIMENT SETUP Before testing concrete on compression, we got to make concrete barrels. Concrete compromises of aggregate, cement, sand and water and hydration makes the mass a solid object. After meeting all security supplies, fixings were fit up within the concrete blender and made a something strong object. For the most part, in the lab there were 10 – 10x20cm molds and 8 – 15x30cm molds. First two weeks 10x20cm shapes will be used; hence, 15x30 will be tried on third and fourth weeks. After that, blended object was set within the six 15x30cm and 6 10x20cm estimate molds – all 12 shapes. The proud concrete was packed with the extraordinary rod and exterior the form was tapped by rubber hammer to expel bubbles (made a vibration). After the shapes were filled and prepared, caps set on the mold. For 24 hours concrete molds were set within the curing room and after 24 hours, molds were carefully expelled and put within the water bath for fitting days

Figure 2 Concrete Molds

Figure 1 Slump Test

2

Also, slump test ought to be conducted for the concrete taken from the same blend example are made of. For that we slump cone can be utilized and resolved the uprooting of the blended mass. In case the uprooting will be between 0-5cm concrete will be noted as S1 sort; within the case of 5-10cm – S2; 10-16cm – S3; 16-22cm – S4 On 7th. 14th,21st and 28th days 3 concrete shapes per day were approved beneath compression utilizing MTS pressure compression machine. The stacking cell will record the drive that the concrete stands up to whereas displacements will be expanded at a steady rate. The average of the thee tests performed each week will speak to the quality for a given day. On each day, concrete ought to reach its rate of greatest quality; for illustration, on 7 th day it ought to have 60% of most extreme quality, on 14th – 80%, on 21st – 90% and on 28th day more than 99%. Thus, the compression quality of concrete on 28th day is the most example of perception, as the reason of such concrete is to illustrate its capability to be utilized in greater structures. Separated from that, from the Eq.1 the modulus of versatility can be decided utilizing the extreme quality of concrete on 28th day. E=4700 √ f c ;MPa '

(Eq. 1)

In order to find out the ultimate force, we need to note the ultimate stress of each specimen, which Eq. 2 enables us to do. F=σA ; N

(Eq. 2)

The goal of the experiment is also to find the strain at ultimate stress (Eqn. 3), strain at 50% of ultimate stress, stress at strain 0.003, measured slump for batch of concrete, and axial stiffness (Eq.4). ε=

σ E

(Eq. 3)

K=

AE L

(Eq. 4)

In addition, the density of the concrete should be found (Eq. 5) to determine the strength per cm2. d=

m V

(Eq. 5)

3

Figure 3 Force-Displacement Response in Compression

Figure 4 Stress-Strain Response in Compression

PROCEDURE *Steps 5-7 was repeated for other specimens for 3 weeks* 4

1. Weighing the ingredients (aggregate, cement, sand, water) and mixing them in the mixer. 2. Placing mix in the specimen and placing it in the curing room. 3. Conducting slump test. 4. After 24 hours placing cured shapes in water bath. 5. After one week testing 3 specimens under compression using MTS tension compression machine.

6. Note the ultimate stress of concrete. 7. Stop the test and save the data collected.

DATA Test Sample Concrete Cylinder 1 Concrete Cylinder 2

Diameter (cm) 15 10

Height (cm) 30 20

DATA ON 7 T H DAY: Test Sample Diameter (cm) Mass (g) Fu (kN) Strength of Concrete (MPa) Cut Area (cm2) Volume (cm3) Density (g/ cm3)

Cylinder 1

Cylinder 3

3496.6 142.94

Cylinder 2 10 3479.5 159.44

18.2

20.3

18.9

2.225

78.54 1570.80 2.215

2.209

3471.3 148.44

DATA ON 14 T H DAY: Test Sample Diameter (cm) Mass (g) Fu (kN) Strength of Concrete (MPa) Cut Area (cm2) Volume (cm3)

Cylinder 1

Cylinder 3

3467.9 175.14

Cylinder 2 10 3487.9 193.99

22.3

24.7

23.8

3565.5 186.92

78.54 1570.80 5

Density (g/ cm3)

2.207

2.220

2.270

Cylinder 1

Cylinder 3

10956.3 507.13

Cylinder 2 15 11532.3 531.87

28.7

30.1

27.5

2.067

176.7 5301.44 2.175

2.24

DATA ON 21 S T DAY: Test Sample Diameter (cm) Mass (g) Fu (kN) Strength of Concrete (MPa) Cut Area (cm2) Volume (cm3) Density (g/ cm3)

11865.3 485.92

DATA ON 28 T H DAY: Test Sample Diameter (cm) Mass (g) Fu (kN) Strength of Concrete

Cylinder 1

(MPa) Cut Area (cm2) Volume (cm3) Density (g/ cm3)

Cylinder 3

11917.4 579.58

Cylinder 2 15 11546.3 546.00

32.8

30.9

31.7

2.247

176.7 5301.44 2.178

2.289

12135.2 560.14

CALCULATIONS Cylinder 1− A=π r 2=π x

2

Cylinder 2− A=π r =π x

(

2 10 2 cm =78.54 c m 2

)

(

2 15 cm =176.7 c m2 2

)

Strength of Concrete (Eqn. 2); for example: F 579.58 kN =32.8 MPa σ= = A 176.7 cm2

6

Similarly, it should be done for each data and calculated results are shown above in the table. On 28th day: Test Sample Diameter (cm) Fu (kN) Strength of

Cylinder 1 579.58

Concrete (MPa) Density (g/ cm3)

σ=

Cylinder 2 15 546.00

Cylinder 3

Average

560.14

561.91

32.8

30.9

31.7

31.8

2.247

2.178

2.289

2.238

∑ σ = 95.4 MPa =31.8 MPa n

F u=

3

∑ F = 1685.72 kN =561.91 kN n

3

From Eqn. 1: E=4700 √ f c' =4700 √ 31.8=26.50 MPa From Eqn. 5: m 11917.4 g =2.247 g /cm3 d= = V 5301.44 cm3

From Eqn. 3: σ 31.8 MPa =1.2 cm / cm ε= = E 26.50 MPa From derived numbers from Eqn. 3 we will get the value of yielding strain. ε=

ΔL = 0.0535 =0.0107 cm / cm Li 5

[we have used 0.0003 rule to identify stress at strain 0.003]. From Eqn. 4,

σ =εE=26.50 MPa 0.003=0.0795 MPa

From Eqn. 4: 7

K=

AE 176.7 cm2 ×26.50 MPa =1.56 MPa cm = 30 cm L

Value of Interest Modulus of Elasticity (MPa) Axial Stiffness (MPa*cm) Ultimate Stress (MPa) Ultimate Strain (cm/cm) Strain at 50%of ultimate stress (cm/cm) Stress at strain of 0.003 Measured slump for batch of concrete (cm)

Hot Rolled Coupon 26.50 1.56 31.8 1.2 0.6 0.0795 16; S3

Conclusion The most objective of this laboratory was to test the behavior of concrete barrels beneath compression on 7th, 14th, 21st and 28th days utilizing MTS pressure compression machine. On each day, 3 barrels will be tried and comes about famous. After 28 days all comes about will be calculated, compared and utilizing to chart stress-strain reaction in compression. Cylinder

Value of Interest Modulus of

Cylinder 2

Elasticity, E (MPa) Density (g/cm3) Ultimate Stress

(15x30cm)

(MPa)

Theoretical

Experimental

% Difference

27.58

26.50

3.92

2.24-2.40

2.238

0.089

20-40

31.8

0

From the consequence, it is unmistakable that the concrete barrels proud amid experiment were solid and seem have been utilized on the greater structure. As able to see, the contrasts are immaterial.

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