Shrinkage Test- Result 90 Days

BATULAWA BRIDGE EXTENSION – ALSON CHIN SHRINKAGE TEST INTRODUCTION 1. This paper descripts the results of an experimental investigation carried out to determine the shrinkage of the high strength concrete. 2. To compare the shrinkage strain for in order to choose the better type of concrete in control the shrinkage crack of concrete. Contractor Consultant Concrete Supply Test Periods

: Hart Builders S/B : TCS Consultant : Hailek Concrete S/B : 8th March – 3rd June 2011

PROBLEM IDENTIFICATION Plastic shrinkage normally occurs after the fresh concrete place during the first few days. When the water evaporates from the surface of freshly placed concrete faster than it is replaced by bleed water, the surface concrete shrinks. Paste of rich mixes such as high strength concrete will be more susceptible to plastic shrinkage than normal concrete. The drying shrinkage crack appears as the inevitable especially the under side of the desk slab. It seems common defects for a bridge after long term. It happens after the concrete had already attained its final set and a good portion of the chemical hydration process in the cement gel has been accomplished. Both shrinkages will be measure during this experiment. The dial gauge reading will be taken for the each day for 90 days. The experimental started since 8th March 2011 and end at 3rd June 2011. The changes in length of each specimen were calculated from the different of final and initial dial gauge readings. Then shrinkage strain was calculated. EQUIPMENTS Dial Gauge (X 0.01mm) Frame Pins Test Piece (100mmX 100mm X 600mm)

– 2 nos – 1 no – 2 nos – 2 nos

BATULAWA BRIDGE EXTENSION – ALSON CHIN SHRINKAGE TEST EXPERIMENTAL PROGRAMME Shrinkage of concrete was measured with the help of ‘Shrinkage Apparatus’ as shown below. Then original Concrete beams specimens of 75mm x 75mm in cross section and 280mm length had changed to 100mm x 100mm x 600mm in order scale up the shrinkage rate. Then specimens were cast with 2 different concrete mixes. Both specimens are pump mix design with Grade 40 with high workability. But one of it mixed with Daratard 45 as the retarder to slow down the hydration of concrete.

Dial gauge

100mm

Specimen

600mm

Pin Shrinkage measuring apparatus along with specimen

BATULAWA BRIDGE EXTENSION – ALSON CHIN Pins were embedded at both ends of the specimens to hold them in the shrinkage apparatus. Specimens were cured in water for 7 days before testing for shrinkage. Initial readings of the specimens were taken with the help of dial gauge attached to the apparatus. Then the specimens were air dried for 90 days. Again the final reading of each specimen was taken after the specified period of air drying. The change in length of each specimen was calculated from the difference of final and initial dial gauge readings. Then the shrinkage strain was calculated and compared with the prediction of the shrinkage strain in theory.

COMPOSIION OF MIX 0.3m³ Material Cement (kg)

Pump Mix P40 (Mix 1) 14.1

Pump Mix P40 (with retarder) (Mix 2) 14.1

Water (kg)

3.64

3.65

Total Aggregate (kg)

51.59

51.54

Fine Agg.(kg)

20.59 (39.33%)

20.59 (39.29%)

Coarse Agg.(kg)

30.00 (60.67%)

30.00 (60.73%)

Daracem 100 (L)

0.169

0.169

Daratard 45 (L)

-

0.017

Density of concrete (kg/m³)

2317.8

2317.01

Slump Obtained (mm)

120

120

Table 1: Composition of design mix for deck slab concreting works.

BATULAWA BRIDGE EXTENSION – ALSON CHIN RESULTS The results of the shrinkage strains of various concrete mixes with different mix proportion and use of admixture in order to differences the shrinkage rate of the mixes. Observes the Change in length (∆L) in mm after Days and Shrinkage strain (∆L/L) x 10⁴ after 90 days. Mix Design Days without Daratard 45

Measure Reading (0.01 mm) after days 1 -

2 11.04

3 10.96

4 10.94

5 11.00

6 11.01

7 11.02

8 11.04

9 11.06

10 11.08

11 11.10

12

13

14

15

11.08

11.15

11.17

11.12

with Daratard 45 Days

-

10.90

10.64

10.56

10.47

10.47

10.39

10.40

10.33

10.26

10.25

10.27

10.18

10.16

10.15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

without Daratard 45

11.11

11.10

11.07

11.02

11.02

11.03

11.04

11.05

11.05

11.03

11.01

10.98

11.01

10.99

11.00

with Daratard 45 Days

10.14

10.11

10.08

10.09

10.05

10.04

10.03

10.02

10.01

10.02

10.03

10.00

9.99

9.98

9.97

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

without Daratard 45

11.01

10.98

10.95

10.94

10.98

10.96

10.99

10.97

10.96

10.95

10.94

10.96

10.94

10.94

10.95

with Daratard 45 Days

9.99

9.97

10.00

9.96

9.97

9.97

9.98

9.96

9.98

10.01

9.97

9.97

9.96

9.95

9.99

46

47

48

49

50

51

52

53

54

55

56

without Daratard 45

10.92

10.93

10.96

10.96

10.92

10.93

10.94

10.93

11.04

with Daratard 45 Days

9.96

10.00

9.97

9.96

9.96

9.95

9.96

9.95

61

62

63

64

65

66

67

68

without Daratard 45

10.98

10.99

11.00

10.99

10.95

11.00

10.97

with Daratard 45 Days

9.97

9.95

9.93

9.93

9.90

9.92

76

77

78

79

80

81

without Daratard 45

10.91

10.90

10.93

10.94

10.92

with Daratard 45

9.91

9.92

9.91

9.91

9.90

57

58

59

60

11.09

11.09

11.00

10.99

10.98

9.88

9.88

9.94

9.90

9.91

9.93

69

70

71

72

73

74

75

10.99

10.96

10.98

10.99

11.00

10.93

10.93

10.92

9.91

9.90

9.93

9.95

9.94

9.95

9.92

9.91

9.92

82

83

84

85

86

87

88

89

90

10.91

10.91

10.89

10.89

9.91

9.94

9.92

9.93

Table 2: Test results of shrinkage of concrete Measure Reading (0.01 mm) after days

BATULAWA BRIDGE EXTENSION – ALSON CHIN

Mix Design

Change in length Δ L (0.01 mm) after days

Days

1 day

2

3

4

5

6

7

8

9

10

11

12

13

14

15

without Daratard 45

-

-

0.08

0.10

0.04

0.03

0.02

0.00

-0.02

-0.04

-0.06

-0.04

-0.11

-0.13

-0.08

with Daratard 45 Days

-

-

0.26

0.34

0.43

0.43

0.51

0.50

0.57

0.64

0.65

0.63

0.72

0.74

0.75

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

without Daratard 45

-0.07

-0.06

-0.03

0.02

0.02

0.01

0.00

-0.01

-0.01

0.01

0.03

0.06

0.03

0.05

0.04

with Daratard 45 Days

0.76

0.79

0.82

0.81

0.85

0.86

0.87

0.88

0.89

0.88

0.87

0.90

0.91

0.92

0.93

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

without Daratard 45

0.03

0.06

0.09

0.10

0.06

0.08

0.05

0.07

0.08

0.09

0.10

0.08

0.10

0.10

0.09

with Daratard 45 Days

0.91

0.93

0.90

0.94

0.93

0.93

0.92

0.94

0.92

0.89

0.93

0.93

0.94

0.95

0.91

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

without Daratard 45

0.12

0.11

0.08

0.08

0.12

0.11

0.10

0.11

0.00

-0.05

-0.05

0.04

0.05

0.06

with Daratard 45 Days

0.94

0.9

0.93

0.94

0.94

0.95

0.94

0.95

1.02

1.02

0.96

1.00

0.99

0.97

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

without Daratard 45

0.06

0.05

0.04

0.05

0.09

0.04

0.07

0.05

0.08

0.06

0.05

0.04

0.11

0.11

0.12

with Daratard 45 Days

0.93

0.95

0.97

0.97

1.00

0.98

0.99

1.00

0.97

0.95

0.96

0.95

0.98

0.99

0.98

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

without Daratard 45

0.13

0.14

0.11

0.10

0.12

0.13

0.13

0.15

0.15

with Daratard 45

0.99

0.98

0.99

0.99

1.00

0.99

0.96

0.98

0.97

Table 3: Test results of shrinkage of concrete Change of length (0.01 mm) after days

BATULAWA BRIDGE EXTENSION – ALSON CHIN Mix Design

Shrinkage strain, (ΔL/L)x 10 ⁴ after days

Days

1 day

2

3

4

5

6

7

8

9

10

11

12

13

14

15

without Daratard 45

-

-

1.325

1.656

0.662

0.497

0.331

0

-0.33

-0.66

-0.99

-0.66

-1.82

-2.15

-1.32

with Daratard 45

16 -1.15894 12.6036 31 0.49669 15.0912 46 1.98675 15.5887 61 0.99338 15.4229 76 2.15 16.42

17 -0.99 13.1 32 0.993 15.42 47 1.821 14.93 62 0.828 15.75 77 2.32 16.25

4.312 18 -0.5 13.6 33 1.49 14.93 48 1.325 15.42 63 0.662 16.09 78 1.82 16.42

5.638 19 0.331 13.43 34 1.656 15.59 49 1.325 15.59 64 0.828 16.09 79 1.66 16.42

7.131 20 0.331 14.1 35 0.993 15.42 50 1.987 15.59 65 1.49 16.58 80 1.99 16.58

7.131 21 0.166 14.26 36 1.325 15.42 51 1.821 15.75 66 0.662 16.25 81 2.15 16.42

8.458 22 0 14.43 37 0.828 15.26 52 1.656 15.59 67 1.159 16.42 82

8.292 23 -0.17 14.59 38 1.159 15.59 53 1.821 15.75 68 0.828 16.58 83

9.453 24 -0.17 14.76 39 1.325 15.26 54

10.61 25 0.166 14.59 40 1.49 14.76 55 0 16.92 70 0.993 15.75 85 2.48 16.25

10.78 26 0.497 14.43 41 1.656 15.42 56 -0.83 16.92 71 0.828 15.92 86

10.45 27 0.993 14.93 42 1.325 15.42 57 -0.83 15.92 72 0.662 15.75 87

11.94 28 0.497 15.09 43 1.656 15.59 58 0.662 16.58 73 1.821 16.25 88 2.48 16.09

12.27 29 0.828 15.26 44 1.656 15.75 59 0.828 16.42 74 1.821 16.42 89

12.44 30 0.662 15.42 45 1.49 15.09 60 0.993 16.09 75 1.987 16.25 90

without Daratard 45 with Daratard 45 without Daratard 45 with Daratard 45 without Daratard 45 with Daratard 45 without Daratard 45 with Daratard 45 without Daratard 45 with Daratard 45

69 1.325 16.09 84 2.15 15.92

length , L for mix 1 = 604mm length , L for mix 2 = 603mm + value indeicated shrinkage & - value indicated expansion for the concrete Table 4: Test results of shrinkage strain of concrete after days

BATULAWA BRIDGE EXTENSION – ALSON CHIN

TEST RESULT OF THE SHRINKAGE WITH MIX 1 (WITHOUT DARATAD 45) AND MIX 2 (WITH DARATARD 45) LENGTH OF SPECIMEN 600mm

SHRINKAGE STRAIN (ΔL/L) x 10 ⁴ after days

20.00

15.00

10.00 Mix 1 Mix 2 Poly. (Mix 1) 5.00

Poly. (Mix 2)

0.00 0

-5.00

10

20

30

40

50

60

70

80

90

100

DAYS

Figure 1 : Variation of shrinkage strain of concrete with Mix 1 & Mix 2 versus age (days)

BATULAWA BRIDGE EXTENSION – ALSON CHIN DISCUSSION OF RESULTS This discussion will be separated to 2 parts, mainly discussed on the plastic shrinkage and drying shrinkage crack. Results shown from day first to 7th days been observed for the plastic shrinkage until the final set observed. Then remaining results shall use for extracting shrinkage strain for drying shrinkage crack. Mix 1 is the Pump mix with design of concrete strength G40 used of super plasticizer Daracem 100 and Mix 2 indicated the same design strength but use the admixture ( Daracem 100 and Daratard 45) Part 1: Plastic Shrinkage crack (1 day to 7 days) From the results it is concluded that the shrinkage strain for Mix 1 decreases with time from then day 1 to days 3 and it turned to negative value at days 4 to days 7, it mean then concrete shown expansion with time after 3 days. Mix 2 which added with Daratard 45 shown shrinkage increase with time from then 1 day to 7 days. The shrinkage strain was larger compare to mix 1.

The cement has higher-than-normal quantities of tricalcium aluminate (C3A) and calcium sulfate. Expansion is caused by the hydration of these materials. Expansion can occur if concrete is cured by immersing in water. Daracem 100 allowed develops of early strength process hydration during the 1st 3 days. Then water (H2O) need for the process hydration and after 3rd day the water is sucked into the concrete to counteract self desiccation and to swell and hydrate the CSH phases in Mix 1. Cement chemist notation Standard notation Balanced

: C3S + H → C-S-H + CH : Ca3SiO5 + H2O → (CaO)·(SiO2)·(H2O)(gel) + Ca(OH)2 : 2Ca3SiO5 + 7H2O → 3(CaO)·2(SiO2)·4(H2O)(gel) + 3Ca(OH)2

BATULAWA BRIDGE EXTENSION – ALSON CHIN Meanwhile Mix 2 with presents of admixture Daratard 45, the shrinkage strain increase with time and gradually slower rate as show as figure 1 The retarder was used to slower the initial and final setting time of the concrete. For initial setting, it extends the setting time by 2-3 hours at 21°C to insure sufficient delivery, placement, vibration or compaction time, such as in hot weather concreting transit mix concrete and prestressed concrete. Daratard 40 is also used in special applications, as in bridge decks where it extends plastic characteristics of the concrete until progressive deflection resulting from increasing loads is completed. For final setting, Retarders help to reduce the possibility of early dry-shrink cracking and reduce the maximum temperature rise in mass concreting, by extending the heat-dissipation period. The superplasticiser for the high workability concrete, Daracem 100 had used as the high range water reducer specially formulated for extended slump life. It provides improved slump retention in flowable concrete and it is ideal for low water cement ratio concrete designed for high early compressive and flexural strengths with exceptional workability and flow characteristics.

Daratard 45 retards the initial and final set of concrete. At the usual addition rate of 300 ml /100 kg cementitious material it will extend the initial setting time of portland cement concrete by 2 to 3 hours at 21°C. Daratard 45 is used wherever a delay in setting time is required to insure sufficient delivery, placement, vibration or compaction time, such as in hot weather concreting transit mix concrete and pre-stressed concrete Daratard 45 is also used in special applications, as in bridge decks where it extends plastic characteristics of the concrete until progressive deflection resulting from increasing loads is completed. Part 2 Drying Shrinkage Test (7 days to 90 days) Refer to the Figure 1: Variation of shrinkage strain of concrete with Mix 1 & Mix 2 versus age (days). Mix 1 (Without Daratard 45) The Shrinkage strain for days It is concluded that the shrinkage strain for Mix 1 increase with time form 0.166E4 to 2.48E4 since the 25th days to 88th days which indicated the shrinkage after the final setting. The overall shrinkage strain was desired and low compared to the Mix 2 which achieves 16.09E4 at days 88th. After the final set, the curing process occurs and the concrete mix begins to gain strength The majority of chemical reactions between admixtures and other concrete components take place during this phase. There should be a constant shrinkage rate with the slower or minor hydration process. Mix 2 (with Daratad 45) Mix 2 which added with Daratard 45 shown shrinkage increase with time from then 7th day to 28th days. Then high rate of shrinkage rate increase from 8.29E4 (8th days) to 15.09E4 (28th days) It was believed, the retarder have slows the process of hydration and the shrinkage strain from 28th days to 88th days only increase 1.00E4 which shows the concrete specimen achieved the final set.

BATULAWA BRIDGE EXTENSION – ALSON CHIN CONCLUSION On the basis of test results the following major conclusions can be drawn: 1. The use of trial mix 1 (without Daratard 45) as approved design mix for deck slab concreting works. (Attached with the Trial Mix Design) 2. After drying for 7 days, there is obvious difference between the shrinkage of Mix 1 and Mix 2 made with Daratard 45, the add of retarder causes a high increase in the shrinkage stains of Mix 2. 3. Both the shrinkage strain of the concrete increases with time from 28th to 88th days but the shrinkage strains of the Mix 2 (with Daratard 45) is higher then Mix 1 (without Daratard 45)