CHAPTER 4: RESULTS AND DISCUSSION
4.2 COMPRESSIVE STRENGTH TEST
Table 14 : Compressive Strength for control mix w/c 0.45 WATER CEMENT RATIO : 0.45 (control)
34 Curing
(day)
Date Cured
Date Test
Max Load (kN)
Compressive Strength (MPa)
Average CS (kN)
3 6-Oct 9-Oct 46.4 18.55
15.70
3 6-Oct 9-Oct 33.8 13.51
3 6-Oct 9-Oct 37.6 15.03
7 6-Oct 13-Oct 65.0 25.98
24.75
7 6-Oct 13-Oct 58.8 23.51
7 6-Oct 13-Oct 61.9 24.75
14 6-Oct 20-Oct 68.1 27.36
27.78
14 6-Oct 20-Oct 78.5 31.41
14 6-Oct 20-Oct 61.4 24.58
28 6-Oct 3-Nov 83.68 33.47
29.60
28 6-Oct 3-Nov 73.1 29.18
28 6-Oct 3-Nov 65.4 26.14
Figure 8 : Compressive Strength for control mix w/c 0.45
Table 15 : Compressive Strength for control mix w/c 0.55 WATER CEMENT RATIO : 0.55 (control)
Curing (day)
Date Cured
Date Test
Max Load (kN)
Compressive Strength (MPa)
Average CS (kN) 15.7
24.75
27.78 29.6
0 5 10 15 20 25 30 35
0 7 14 21 28
Compressive Strength (MPa)
Curing (Day)
Water Cement Ratio : 0.45 (control)
35
3 11-Oct 14-Oct 38.9 15.55
11.60
3 11-Oct 14-Oct 22.8 9.11
3 11-Oct 14-Oct 25.4 10.15
7 11-Oct 18-Oct 47.9 19.14
19.10
7 11-Oct 18-Oct 42.8 17.11
7 11-Oct 18-Oct 52.4 20.95
14 11-Oct 25-Oct 72 28.81
26.55
14 11-Oct 25-Oct 60.7 24.28
14 11-Oct 25-Oct 66.3 26.55
28 11-Oct 8-Nov 87.2 34.87
31.24
28 11-Oct 8-Nov 75.4 30.15
28 11-Oct 8-Nov 71.8 28.72
Figure 9 : Compressive Strength for control mix w/c 0.55
Table 16 : Compressive Strength at 5% Replacement-Sundried Seaweed Granules WATER CEMENT RATIO : 0.45 (5 % replacement) X-series
11.6
19.1
26.55
31.25
0 5 10 15 20 25 30 35
0 7 14 21 28
Compressive Strength (MPa)
Curing (Day)
Water Cement Ratio : 0.55 (control)
36 Curing
(day)
Date Cured
Date Test
Max Load (kN)
Compressive Strength (MPa)
Average CS (kN)
3 16-Nov 19-Nov 24.8 9.91
9.81
3 16-Nov 19-Nov 26.45 10.58
3 16-Nov 19-Nov 22.31 8.94
7 16-Nov 23-Nov 27.3 10.91
12.23
7 16-Nov 23-Nov 33.95 13.58
7 16-Nov 23-Nov 30.5 12.2
14 16-Nov 30-Nov 31.98 12.79
13.22
14 16-Nov 30-Nov 29.3 11.73
14 16-Nov 30-Nov 37.8 15.13
28 16-Nov 14-Dec 47.2 18.95
21.75
28 16-Nov 14-Dec 58.7 23.48
28 16-Nov 14-Dec 57.01 22.82
Figure 10 : Compressive Strength at 5% Replacement- Sun dried Seaweed Granules
Table 17 : Compressive Strength at 5% Replacement-Oven dried Seaweed Granules
37
WATER CEMENT RATIO : 0.45 (5 % replacement) Curing
(day)
Date Cured
Date Test
Max Load (kN)
Compressive Strength (MPa)
Average CS (kN)
7 16-Nov 23-Nov 23.8 9.56
8.29
7 16-Nov 23-Nov 18.57 7.42
7 16-Nov 23-Nov 19.7 7.88
14 16-Nov 30-Nov 30.56 12.22
11.79
14 16-Nov 30-Nov 25.9 10.41
14 16-Nov 30-Nov 31.84 12.74 28 16-Nov 14-Dec 38.15 15.26
17.43 28 16-Nov 14-Dec 42.05 16.82
28 16-Nov 14-Dec 50.53 20.21
Figure 11 : Compressive Strength at 5% Replacement- Oven dried Seaweed Granules
Table 18 : Compressive Strength at 5% Replacement- Seaweed Ashes
38
WATER CEMENT RATIO : 0.45 (5 % replacement) Y-series Curing
(day)
Date Cured
Date Test
Max Load (kN)
Compressive Strength (MPa)
Average CS (kN)
7 16-Nov 23-Nov 44.1 17.63
17.19
7 16-Nov 23-Nov 38.5 15.39
7 16-Nov 23-Nov 46.4 18.55
14 16-Nov 30-Nov 51.21 20.5
21.05
14 16-Nov 30-Nov 49.6 19.92
14 16-Nov 30-Nov 56.8 22.72
28 16-Nov 14-Dec 69.4 27.77
28.79 28 16-Nov 14-Dec 74.53 29.81
28 16-Nov 14-Dec 71.9 28.79
Figure 12 : Compressive Strength at 15% Replacement- Seaweed Ash
Table 19 : Compressive Strength at 15% Replacement-Sundried Seaweed Granules
39
WATER CEMENT RATIO : 0.45 (15 % replacement) S series Curing
(day)
Date Cured
Date Test
Max Load (kN)
Compressive Strength (MPa)
Average CS (kN)
3 1-Nov 4-Nov 19.6 7.86
8.35
3 1-Nov 4-Nov 26.7 10.67
3 1-Nov 4-Nov 16.3 6.52
7 1-Nov 8-Nov 37.5 14.98
13.16
7 1-Nov 8-Nov 29.6 11.83
7 1-Nov 8-Nov 31.7 12.68
14 1-Nov 15-Nov 33.8 13.51
15.57
14 1-Nov 15-Nov 39.6 15.8
14 1-Nov 15-Nov 43.5 17.4
28 1-Nov 29-Nov 53.75 21.5
19.07
28 1-Nov 29-Nov 45.1 18.04
28 1-Nov 29-Nov 44.2 17.68
Figure 13 : Compressive Strength at 15% Replacement-Sundried Seaweed Granules 8.35
13.16
15.57
19.07
0 5 10 15 20 25 30 35
0 7 14 21 28
Compressive Strength (MPa)
Curing (Day)
15% Replacement-Sundried Seaweed Granules
40
Table 20 : Compressive Strength at 15% Replacement- Oven dried Seaweed Granules
WATER CEMENT RATIO : 0.45 (15 % replacement) Curing
(day)
Date Cast
Date Test
Max Load (kN)
Compressive Strength (MPa)
Average CS (kN)
3 24-Oct 27-Oct 19.1 7.67
7.59
3 24-Oct 27-Oct 22.2 8.81
3 24-Oct 27-Oct 15.6 6.29
7 24-Oct 31-Oct 35.2 14.06
11.96
7 24-Oct 31-Oct 29.8 11.91
7 24-Oct 31-Oct 24.8 9.92
14 24-Oct 7-Nov 37.6 15.02
14.17
14 24-Oct 7-Nov 36.7 14.67
14 24-Oct 7-Nov 32.1 12.84
28 24-Oct 21-Nov 49.18 19.65
18.43 28 24-Oct 21-Nov 42.01 16.87
28 24-Oct 21-Nov 46.93 18.77
Figure 14 : Compressive Strength at 15% Replacement- Oven dried Seaweed Granules
7.59
11.96
14.17
18.43
0 2 4 6 8 10 12 14 16 18 20
0 7 14 21 28
Compressive Strength (MPa)
Curing (Day)
15% Replacement- Oven dried Seaweed Granules
41
Table 21 : Compressive Strength at 15% Replacement- Seaweed Ashes WATER CEMENT RATIO : 0.45 (15 % replacement) E-series
Curing (day)
Date Cured
Date Test
Max Load (kN)
Compressive Strength (MPa)
Average CS (kN)
3 2-Nov 5-Nov 22.08 8.85
9.94
3 2-Nov 5-Nov 22.78 9.12
3 2-Nov 5-Nov 29.63 11.85
7 2-Nov 9-Nov 41.1 16.45
15.67
7 2-Nov 9-Nov 39 15.62
7 2-Nov 9-Nov 37.32 14.95
14 2-Nov 16-Nov 69.4 27.77
27.62
14 2-Nov 16-Nov 67.4 26.98
14 2-Nov 16-Nov 70.3 28.12
28 2-Nov 30-Nov 72.8 29.12
29.9
28 2-Nov 30-Nov 74.6 29.82
28 2-Nov 30-Nov 76.9 30.76
Figure 15 : Compressive Strength at 15% Replacement- Seaweed Ashes 9.94
15.67
27.62
29.9
0 5 10 15 20 25 30 35
0 7 14 21 28
Compressive Strength (MPa)
Curing (Day)
15% Replacement- Seaweed Ashes
42 Abbreviations
OG = Oven Dried Seaweed Granules SG = Sun Dried Seaweed Granules SA = Seaweed Ash
15 = Replacement level of 15%
Figure 16 : Compressive Strength vs Mortar Sample (Mpa) at 7 days
All of the samples which incorporated with seaweed, either in granule or ash form are using the water cement ratio of 0.45. Hence all the comparions will be made with regard to the mix control of 0.45 which also known as C.45 ; At 7th days, none of our sample can surpass the compressive strength of control mortar. However, the highest compressive strength generated at 7th day among our sample would be the mortar incorporated with 5% (17.19 Mpa) of seaweed ash followed by 15% (15.67 Mpa).
43
Figure 17 : Compressive Strength vs Mortar Sample (Mpa) at 14 days
At 14th day, the sample which incorporated with 15% of seaweed ash has the closest compressive strength (27.62 Mpa) to the mix control (27.78 Mpa) at the same water cement ratio of 0.45.
44
Figure 18 : Compressive Strength vs Mortar Sample (Mpa) at 28 days
At 28 days, the modified mortar with 15% of seaweed ash has the highest compressive strength (29.9 Mpa) compared with the control mortar at a water cement ratio of 0.45.
The 5% seaweed ash sample has slightly lower compressive strength than the mortar at 29.6 Mpa.
45
Figure 19 : Full Cycle Compressive Strength of All Samples (15%)
After the curing period was completed, the strength of mortar obtained from an average of triplicate data. At 15% replacement of cement by seaweed ash, the compressive strength generated at 28th days is 29.9 Mpa which is slightly higher than the conventional concrete at 29.6 Mpa. It shows that the seaweed ash sample has considerably high strength compared to control. Polymer modified mortar has good binding properties and adhession to aggregates and it is beneficial in repairing and furnishing [56]. When used together with cement, polymer will fill the spongy parts and enhance cement property. Gracilaria Sp. and Eucheuma Cottonii have similar properties in gelling and thickening. They contain agarans and carrageenans that enhance the cement hydration phase [57].
5 10 15 20 25 30
3th 7th 14th 28th
Compressive strength (Mpa)
Curing (days)
Oven dried Sun dried Ash Control
reference compressive strength at 28 days : 26 Mpa
46
Figure 20 : Full Cycle Compressive Strength of All Samples (5%)
It is noticed that the sample with 5% of seaweed ash produce the compressive strength closest to the control mix at 28.79 Mpa. Its performance at 7th and 14th days are lower than the control mix. It might be due to the hydration that was partially complete. Undoubtedly, at 5% of replacement , the mortar which incorporated with seaweed in ash form outperform the sample in granules form in term of compressive strength.
47
Figure 21 : Combine Graph for Compressive Strength ( 5% & 15%)
No reading was took at the 3rd day of curing for the sample of 5% replacement due to the insufficient raw material of seaweed. It is worth mentioning that all of the samples display weaker than the control compressive strength at 14th days except for the sample which contain 15% of seaweed ash. The closest compressive strength to the control would be the mortar modified with 15% and 5%. However, the 15%
modified mortar manage to surpass the compressive strength of control mix whereas the performance of 5% modified mortar is slightly lower than the control mix at a difference of 0.81 Mpa.
48