3.2 MORPHOLOGICAL ANALYSIS
SEM photographs of limestone, ordinary Portland cement, and silicon manganese slag aggregate concrete are seen in Figure 2 (a), (b), and (c) at 500x magnification (SMC). Figure 2 (a) depicts a limestone sample aggregate that was used in architecture, housing, paving, and road materials in Sarawak, Malaysia. According to the samples, the limestone is brittle mosaic in surface structures of inconsistent grain size, with some having small soft bit structures that vary in form and grove [45–48]. Many researchers [49] have stated that the brittle and inconsistently sized, shapes, groove surface structures, and poor hydration of limestone can cause weak adhesion at certain parts of the concrete and composites, particularly when bonded with polymer, bitumen, or cement. Initial cracks may occur before or after the limestone has been bonded, particularly when the materials are loaded [49]. When a load is added to the components, this results in a random breaking point at a certain region of the threshold [49].
The ordinary Portland cement without admixture is seen in Figure 2 (b). The hydration process was irregular, as there was a combination of un-hydrated and hydrated cement in some areas, resulting in a small size crack on the cement surface [50]. In contrast, Figure 2 (c) depicts a slight crack between the silicon manganese slag and ordinary Portland cement used by SMC. The smooth surface of silicon manganese slag slipped, transferred, or moved due to the load added to it during the compressive strength test, which was also a typical failure in many forms of concrete [50–52]. It is also worth noting that for SMC, the interaction between sand and other materials is correctly combined, resulting in better samples.
Figure 3 (a), (b), (c), and (d) reveal images of Neat-SiMn, NaOH-SiMn, HCl-SiMn, and H2SO4-SiMn slag at 500x magnification. The alkaline treatment results in a smoother surface with less grain, as seen in Figure 3 (b), while the acidic treatment results in porosity on the surface of the silicon manganese slag, as seen in Figure 3 (c) and Figure 3 (d). It was also discovered that different chemical compositions and concentrations on the surface of the silicon manganese slag produce different reactions. The acid concentration and composition in Figure 3 (d) appear to produce a special needle fascinated shape, resulting in a rougher and more readily absorbent surface [53]. When comparing Figures 3 (c) and 3 (d), it can be shown that the acidic concentration and composition appear to eliminate unwanted weak structures, resulting in a small amount of porous structure on the surface [53].
3.3 EDX/EDS Analysis
Table 1, Table 2 and Table 3 shows the EDS/EDX elemental analyses for limestone, ordinary Portland cement, and silicon manganese concrete (SMC). Figure 4, Figure 5, and Figure 6 depicted the graph continuum of Table 2, Table 3 and Table 4 correlation results, respectively. Carbon (C), oxygen (O), calcium (Ca), natrium (Na), and chlorine (Cl) were found in the samples, according to Table 2. Table 3 shows the presence of carbon (C), calcium (Ca), oxygen (O), silicon (Si), potassium (K), natrium (Na), chlorine (Cl), and aluminium (Al) throughout the samples. Figures 4 and 5 and Tables 2 and 3 indicate that oxygen has the largest mass percentage, followed by calcium and carbon, while other elements have low mass percentages. This shows that limestone contained mostly CaCO3, CaO, Na2O, and slight amount of NaCl [54]. While ordinary Portland cement contained mostly CaCO3, CaO, SiO2, Al2O3, Na2O, K2O, and slight amount of NaCl [55–57]. The present of CaCO3 and CaO helps strengthen and increase the durability of the limestone and ordinary Portland cement, which also accelerate the effect of hydration reactivity rate [58]. However, the present of slight NaCl may promote corrosion towards steel in concrete, which make it weaker in long period [59–60]
In silicon manganese concrete, as shown in Table 4, the present element in the samples were calcium (Ca), oxygen (O), silicon (Si), carbon (C), aluminium (Al), manganese (Mn), barium (Ba), magnesium, (Mg), natrium (Na), and potassium (K). From Figure 6 and Table 4, it showed that oxygen had the highest content mass percentage, followed by calcium and silicon, while the other elements mass percentage remain low. This shows that silicon manganese concrete contained mostly CaCO3, CaO, Na2O, SiO2, Al2O3, Na2O, K2O, BaO, BaCO3, MgO, SiMn, MnO [4, 32]. The present of CaCO3 and CaO helps strengthen concrete, and accelerate the effect of hydration rate, while BaO, and BaCO3 increase the dense of the concrete [58, 32]. However, the absence of NaCl, especially chlorine, reduced corrosion effects towards steel in concrete, which could retain its strength in long period [4, 61, 62]
Table 2
EDS element composition for limestone
Element
|
Atomic No.
|
Mass Normal (%)
|
Atom (%)
|
Absolute Error (%) (1 sigma)
|
Relative Error (%) (1 sigma)
|
O
|
8
|
47.05
|
54.89
|
6.78
|
12.52
|
Ca
|
20
|
33.59
|
15.64
|
1.18
|
3.05
|
C
|
6
|
18.62
|
28.94
|
2.83
|
13.22
|
Na
|
11
|
0.50
|
0.41
|
0.07
|
12.07
|
Cl
|
17
|
0.24
|
0.12
|
0.04
|
14.15
|
Total
|
|
100
|
100
|
|
|
Table 3
EDS element composition for ordinary Portland cement
Element
|
Atomic No.
|
Mass Normal (%)
|
Atom (%)
|
Absolute Error (%) (1 sigma)
|
Relative Error (%) (1 sigma)
|
O
|
8
|
41.72
|
48.86
|
5.72
|
12.82
|
Ca
|
20
|
32.51
|
15.20
|
1.07
|
3.06
|
C
|
6
|
21.15
|
33.00
|
3.01
|
13.31
|
Si
|
14
|
1.97
|
1.31
|
0.12
|
5.57
|
K
|
19
|
1.01
|
0.48
|
0.06
|
5.91
|
Na
|
11
|
0.79
|
0.64
|
0.09
|
10.19
|
Cl
|
17
|
0.51
|
0.27
|
0.05
|
8.69
|
Al
|
13
|
0.34
|
0.24
|
0.05
|
12.74
|
Total
|
|
100
|
100
|
|
|
Table 4
EDS element composition for silicon manganese cement (SMC).
Element
|
Atomic No.
|
Mass Normal (%)
|
Atom (%)
|
Absolute Error (%) (1 sigma)
|
Relative Error (%) (1 sigma)
|
O
|
8
|
46.33
|
63.38
|
4.29
|
12.67
|
Ca
|
20
|
29.35
|
16.03
|
0.67
|
3.12
|
Si
|
14
|
10.63
|
8.28
|
0.35
|
4.53
|
C
|
6
|
3.65
|
6.60
|
0.58
|
22.04
|
Al
|
13
|
3.36
|
2.73
|
0.14
|
5.85
|
Mn
|
25
|
2.93
|
1.17
|
0.10
|
4.85
|
Ba
|
56
|
1.75
|
0.28
|
0.08
|
5.89
|
Mg
|
12
|
1.07
|
0.97
|
0.07
|
9.18
|
K
|
19
|
0.70
|
0.39
|
0.05
|
8.91
|
Na
|
11
|
0.25
|
0.17
|
0.03
|
19.09
|
Total
|
|
100
|
100
|
|
|
The EDS/EDX elemental analysis for Neat-SiMn, NaOH-SiMn, HCl-SiMn and H2SO4-SiMn slag are shown in Table 5, Table 6, Table 7, and Table 8. While Figure 7, Figure 8, Figure 9 and Figure 10 showed the graph spectrum correlation with data in Table 5, Table 6, Table 7, and Table 8, respectively. Based on Table 5, Table 6, Table 7 and Table 8, similar present element in all the samples were calcium (Ca), oxygen (O), silicon (Si), carbon (C), potassium (K), barium (Ba), and aluminium (Al). It is also noted that in the Neat-SiMn, NaOH-SiMn, and HCl-SiMn, there is a present of manganese (Mn), magnesium (Mg), and natrium (Na), even though it is not present in H2SO4-SiMn. NaOH treatment cause the present of nitrogen (N) in NaOH-SiMn, while HCl cause the present of chlorine (Cl) and lead (Pb), and H2SO4-SiMn cause the present of sulphur (S). From Figure 7, Figure 8, Figure 9 and Figure 10, and Table 5, Table 6, Table 7 and Table 8, it showed that the highest content was oxygen mass percentage, while other elements mass percentage remain low. This shows that Neat-SiMn slag contained mostly CaCO3, CaO, Na2O, SiMn, Al2O3, BaO, BaCO3, Na2O, K2O, SiO, SiO2, and MgO [4, 32, 63–65]. While BaO, and BaCO3 increase the density, CaCO3 and CaO helps to strengthen by increasing the durability of silicon manganese slag, by accelerating the hydration reactivity rate [58, 32]. The present of SiO and SiO2 created mixture of crystalline and amorphous structure, depending on the chemical reaction towards the chemical treatments, which was reflected in SEM result in Figure 3.
Table 5
EDS element composition for Neat-SiMn
Element
|
Atomic No.
|
Mass Normal (%)
|
Atom (%)
|
Absolute Error (%) (1 sigma)
|
Relative Error (%) (1 sigma)
|
O
|
8
|
44.63
|
55.73
|
6.36
|
12.18
|
Si
|
14
|
13.18
|
9.37
|
0.67
|
4.36
|
C
|
6
|
11.70
|
19.47
|
2.25
|
16.40
|
Ca
|
20
|
10.81
|
5.39
|
0.41
|
3.25
|
Al
|
13
|
6.77
|
5.01
|
0.40
|
5.04
|
Ba
|
56
|
5.18
|
0.75
|
0.22
|
3.63
|
Mn
|
25
|
4.03
|
1.47
|
0.18
|
3.91
|
Mg
|
12
|
2.34
|
1.92
|
0.18
|
6.52
|
K
|
19
|
0.82
|
0.42
|
0.06
|
6.48
|
Na
|
11
|
0.53
|
0.46
|
0.07
|
11.80
|
Total
|
|
100
|
100
|
|
|
Table 6
EDS element composition for NaOH-SiMn
Element
|
Atomic No.
|
Mass Normal (%)
|
Atom (%)
|
Absolute Error (%) (1 sigma)
|
Relative Error (%) (1 sigma)
|
O
|
8
|
47.05
|
57.21
|
7.26
|
12.07
|
Si
|
14
|
13.51
|
9.36
|
0.75
|
4.34
|
C
|
6
|
10.13
|
16.41
|
2.17
|
16.77
|
Ca
|
20
|
10.09
|
4.90
|
0.42
|
3.25
|
Al
|
13
|
5.99
|
4.32
|
0.39
|
5.06
|
Mn
|
25
|
4.15
|
1.47
|
0.20
|
3.83
|
Ba
|
56
|
2.81
|
0.40
|
0.15
|
4.14
|
Mg
|
12
|
2.49
|
1.99
|
0.20
|
6.36
|
N
|
7
|
1.93
|
2.68
|
0.68
|
27.66
|
Na
|
11
|
0.99
|
0.84
|
0.11
|
9.09
|
K
|
19
|
0.87
|
0.43
|
0.07
|
6.06
|
Total
|
|
100
|
100
|
|
|
Table 7
EDS element composition for HCl-SiMn
Element
|
Atomic No.
|
Mass Normal (%)
|
Atom (%)
|
Absolute Error (%) (1 sigma)
|
Relative Error (%) (1 sigma)
|
O
|
8
|
42.09
|
58.62
|
4.13
|
12.36
|
Si
|
14
|
13.39
|
10.62
|
0.47
|
4.44
|
Ca
|
20
|
11.27
|
6.27
|
0.30
|
3.35
|
Ba
|
56
|
10.90
|
1.77
|
0.29
|
3.36
|
Al
|
13
|
7.62
|
6.29
|
0.31
|
5.14
|
C
|
6
|
6.21
|
11.52
|
0.98
|
19.94
|
Mn
|
25
|
4.49
|
1.82
|
0.15
|
4.16
|
Mg
|
12
|
1.44
|
1.32
|
0.09
|
8.05
|
Cl
|
17
|
1.01
|
0.64
|
0.06
|
7.12
|
K
|
19
|
1.00
|
0.57
|
0.06
|
6.99
|
Na
|
11
|
0.58
|
0.56
|
0.06
|
13.25
|
Pb
|
82
|
0.00
|
0.00
|
0.00
|
1.51
|
Total
|
|
100
|
100
|
|
|
Table 8
EDS element composition for H2SO4-SiMn
Element
|
Atomic No.
|
Mass Normal (%)
|
Atom (%)
|
Absolute Error (%) (1 sigma)
|
Relative Error (%) (1 sigma)
|
O
|
8
|
56.54
|
71.56
|
7.53
|
11.96
|
Ca
|
20
|
14.88
|
7.52
|
0.53
|
3.19
|
S
|
16
|
11.08
|
6.99
|
0.47
|
3.78
|
Ba
|
56
|
7.30
|
1.08
|
0.28
|
3.44
|
C
|
6
|
5.75
|
9.69
|
1.25
|
19.46
|
Si
|
14
|
2.19
|
1.58
|
0.13
|
5.43
|
Al
|
13
|
1.79
|
1.34
|
0.12
|
6.23
|
K
|
19
|
0.48
|
0.25
|
0.05
|
9.10
|
Total
|
|
100
|
100
|
|
|
From the analysis it is noted that there are few possible chemical reactions happened during the treatments. Equation (1) to (6) shows the possibilities of the chemical reactions.
Mn + 2HCl → MnCl2+H2 (1)
Si + 2HCl → SiCl2 +H2 (2)
Mn + H2SO4 → MnSO4 +H2 (3)
Si + H2S04 → SiO2 + H2O2 (4)
Mn + 2NaOH → Mn(OH)2 +2Na (5)
Si + 2NaOH + H2O → Na2SiO3 + 2H2 (6)
3.4 FTIR ANALYSIS
Figure 11, Figure 12, and Figure 13 shows the FTIR images forlimestone, ordinary Portland cement and silicon manganese concrete. According to Figure 13, the broad band intensity of 3500 cm-1-3000 cm-1 designated to the water molecules, which is due to stretching of-OH and vibrations of H-0-H. The small sharp peaks in Figure 11 at 3940 cm-1, 3817 cm-1, 3745 cm-1and Figure 12 at 3739 cm-1 was due to the free hydroxyl groups. This free hydroxyl group tend to react during hydraulic hydration process. The reaction caused the surface materials entrapped in cavities or void in the polymeric framework. In Figure 11, Figure 12, and Figure 13, few small sharp peaks spotted throughout the 2520 to 1037 cm-1,2453 to 866 cm-1, 2520 to 690 cm-1, absorption band was designated to the calcium in the form of calcite (CaCO3) [66-68]. Whereas most CO32-having asymmetric stretching, in-plane and out-of-plane bending [69]. In Figure 13, at 1425 and 999 cm−1, the peak was designated for asymmetric stretching and vibration of Si-O-Al and/or Si-O-Si, respectively [70, 71].
Figure 14, Figure 15, Figure 16 and 17 shows the FTIR images for Neat-SiMn, NaOH-SiMn, HCl-SiMn, and H2SO4-SiMn. It is noted that multiple peaks at 2000-2500 cm-1 was due to stretching vibration of Si-O and Si-Mn, which occurred in and out of phase for SiOfor silicon manganese slag [70-72]. The alkaline treatment causes the peak almost diminished which shows the Si-Mn and Si-O structure were in plane, while acid caused the bending of Si-O and Si-Mn which at the end created rougher needle structure of silicon manganese slag [70-72]. In Figure 15, the peak at 977 to 1176 cm-1 was due to asymmetric and symmetric tetrahedral of SiO or stretch vibration of Al2O3, whereas 977 cm-1 was due to vibration bending of Si-O-Si [71]. It also noted that H2SO4 had eliminated Na and Mg as shown by EDS/EDX and FTIR in Figure 10, Figure, 17 and Table 8, which created the rough needle surface as shown in Figure 3(d).