GSB Gradation table

 





GSB Gradation table

  Granular Base is a layer of Highway Road foundation just above the compacted soil  layer  acts a good base for road foundation where no settlement can be happened even in heavy loading by traffic on road. GSB Gradation table required as per is code.  The construction materials basically collected from indigenously which are available locally.

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 Step-1

                                                     Sub Base Specification

Test

Specified Limits

Test Procedure

Limit

Specification

Gradation

As per pavement design

MoRTH Table 400-1

IS 2386 (Part 1)

Liquid Limit

Max  25%

MoRTH Table 400-2

IS 2386 (Part 5)

Plasticity Index

NA

MoRTH Table 400-2

IS 2386 (Part 5)

Moisture Content

 

MoRTH Table 400-3.2

IS 2386 (Part 2)

Proctor Test

 

 

IS 2386 (Part 8)

CBR

Max 30%

MoRTH Table 400-2

IS 2386 (Part 16)

Water Absorption

Max 2%

MoRTH Table 400-2.2

IS 2386 (Part 3)

AIV

Max 40%

 

 


Step-2
II.  Physical Requirement of Granular Sub Base Materials :  (Table 400-1)

Sieve No  (mm)

Test 1

Test 2

Test 3

Average

Specification Limits as per MoRT  Table 400-1

Middle value

Lower Limits

Upper limits

75

100

 

100

100.00

 

 

 

53

100

100

100

100.00

 

100

 

26.5

81.6

80.1

81.3

81.00

70

100

85

9.5

52

50.2

51.3

51.17

50

80

65

4.7

42.6

41.3

42.1

42.00

40

65

52.5

2.36

26.1

25.1

24.3

25.17

30

50

40

0.425

11.5

11.7

11.6

11.60

10

15

12.5

0.075

3.1

3.4

3.3

3.27

<5

 

 

MDD

 

 

 

2.18

 

OMC

 

 

 

7.75

 

Step -3

OMC (%)

Dry Density (gm/cc)

 

Sample1

Sample 1

Sample 1

4.35

1.89

1.78

1.68

6.05

1.992

1.86

1.98

8.32

2.041

2.13

2.18

10.48

2.007

1.92

1.87

12.43

1.913

1.86

1.8

Step-4

                                     Liquid Limit :

Determination Numbers:

1

2

3

Average

Number of Blows

25

25

25

 

Moisture container No

1

2

3

 

Weight of container  (g)

20.12

20.11

20.15

 

Wt. Container + Wet Soil

36.02

35.23

36.12

 

Wt. Container + Oven dry soil

33.6

32.6

33.54

 

Weight of water

2.42

2063

2.58

 

Wight of Dry soil

13.48

12.49

13.39

 

Water Content  (%)

17.95

21.06

19.27

19.43

Step-5
California Bearing Ratio (CBR)

Proving ring factor  :  6.33  (Sample 1)

Penetration

Reading

Load kg

Corrected CBR Value

0.5

27.0

170.91

 

1

54

341.82

 

1.5

81

512.73

 

2

111.4

705.2

 

2.5

135.9

860.2

64.77

4

190.0

1165

 

5

216.0

1290.6

62.80

7.5

230.9

1461.51

 

10

257.9

1632.42

 

1. Standard Unit Load 
2.CBR = Corrected Load standard load) x 100
3. Standard Unit load    : 2.5 mm penetrations' = 1370 kg   
                                                                                              : 5.0 mm :  penetration =
                                                                                               2055

Step-6

Aggregate impact value

SL NO

Description

Sample 1

Sample 2

Average

1

Weight of sample dry passing 12.5 mm IS Sieve and retaining on 10.0 mm IS sieve (gm)   W1

318

320

319

2

Weight of friction retaining on 2.36 mm IS Sieve and after the test     w2

2.66

260

 

3

Weight of friction passing 2.36 mm IS Sieve and after the test     w3 =(w1-w2)

52

60

 

4

Aggregate Impact Value (%)                                    AIV = W3/W1 x 100 

16.34

18.74

17.54

 

Step -7

Sl no

 

                                 Liquid Limit

           Plastic limit

 

1

2

3

4

5

6

 

No of Drops/penetration

13

16

21

26

NA

NA

 

Container No

3

4

5

6

 

 

 

Wt of container

17.37

14.59

12.47

12.17

 

 

 

Cont.+Wet sample

39.12

55.11

45.84

41.31

 

 

 

Cont + Oven D samp  w3

35.81

48.5

39.76

35.44

 

 

 

Wt of water  W4=W2-w3

3.31

6.61

6.08

5.87

 

 

 

Wt of Dry sample  w5

18.44

33.91

27.29

23.27

 

 

 

% of Moisture content

17.95

19.49

22.28

25.23

 

 

 

 

                                             21.24

 

 
                                          Hence Liquid limit (%) 21.24  plastic limit NP      PI (%)     NP

Step-8
Determination of Water absorption

Sl No

 

             Liquid Limit

sample 1

sample 2

Average

1

Wt of SSD Sample in Air (gm) A

2.898

2.796

 

2

Wt of Dry sample (gm) C

2.844

2.702

 

3

Water Absorption (%)   =    (A-C/C)*100

1.899

3.479

 

4

Average Water Absorption (%)

 

1.79

1.16

1.48

 

 

 

 

 



Step-9
SUMMARY OF G.S.B. DESIGN 

                               Mix Proportion :

IS Sieve

Avarage % of Passing

Specified Limit as per MoRTH Table No. 400-1 Grading IV

53.0

100

100

26.5

81

55-75

4.75

42

40-65

0.075

3.27

<5

Physical requirement for GSB

Sl. No.

Parameters

Results

Specified Limit as per MoRTH Table No. 400-2

1

Liquid Limit

19.43%

Max. 25%

2

Plasticity Index

NP

Max. 6%

3

Water Absorption

1.48%

Max. 2%

4

Aggregate Impact value

17.54%

Max. 40%

5

Maximum Dry Density

2.18 g/cc

--

6

Optimum Moisture Content

7.75%

--

7

CBR Value

62.26

Min. 30%

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