Table 1
Properties of used aggregates.
Property
|
Sand
|
Gravel
|
COBCB
|
Specific gravity
|
2.5
|
2.5
|
1.35
|
Unite weight (t/m³)
|
Loose
|
1.44
|
1.56
|
0.98
|
Compact
|
1.6
|
1.67
|
1.03
|
Shape Factor
|
1.18
|
1.13
|
1.16
|
Maximum nominal size (mm)
|
---
|
40
|
40
|
Fineness modulus
|
2.45
|
7.11
|
7.7
|
Specific surface area (cm²/gm)
|
56.24
|
2.06
|
2.03
|
% Water Absorption (By Weight)
|
1.2
|
0.64
|
13.25
|
% of Chloride ions
|
0.04
|
0.008
|
0.018
|
% of Sulphates ions
|
0.129
|
0.012
|
0.04
|
Power of Hydrogen (PH)
|
8.5
|
8
|
10.5
|
% of Clay and Other Fine Materials Content
|
2.5
|
0.7
|
0.8
|
Table 2
Mechanical properties of the used steel.
Diameter (mm.)
|
Yield Stress (MPa)
|
Ultimate Stress (MPa)
|
Elongation (%)
|
8
|
362
|
491
|
29.03
|
10
|
420
|
622
|
18.0
|
12
|
450
|
654
|
20.54
|
Table 3
Details of the tested beams.
Group
|
Beam
|
Silica fume content (% by weight of cement)
|
Reinforcement
|
Group I
|
N0-3
|
0%
|
3Φ12
|
N0-5
|
5Φ12
|
N0-7
|
7Φ12
|
Group II
|
L0-3
|
0%
|
3Φ12
|
L0-5
|
5Φ12
|
L0-7
|
7Φ12
|
Group II
|
L10-3
|
10%
|
3Φ12
|
L10-5
|
5Φ12
|
L10-7
|
7Φ12
|
Group IV
|
L15-3
|
15%
|
3Φ12
|
L15-5
|
5Φ12
|
L15-7
|
7Φ12
|
Group V
|
L20-3
|
20%
|
3Φ12
|
L20-5
|
5Φ12
|
L20-7
|
7Φ12
|
Table 4
Mix proportion of concrete constituents for 1 .
Concrete Mix
|
Cement (kg)
|
Silica fume content (kg)
|
Fine aggregate (kg)
|
Coarse aggregate (kg)
|
Water (L)
|
Superplasticizer (L)
|
N0
|
350
|
0
|
779
|
Gravel
|
1066
|
168
|
7
|
L0
|
0
|
458
|
COBCB
|
635
|
168+84.14*
|
L10
|
35
|
L15
|
52.5
|
L20
|
70
|
* Amount of water absorbed by COBCB.
Table 5
Density, compressive strength for all concrete mixes.
Concrete mix
|
Density of concrete (kg/m3)
|
Compressive strength, fcu, MPa
|
N0
|
2,587
|
32.78
|
L0
|
1,910
|
27.51
|
L10
|
1,937
|
33.82
|
L15
|
1,956
|
39.76
|
L20
|
1,984
|
45.59
|
Table 6
Experimental and predicted cracking and ultimate moments.
|
Beam
|
Cracking Load (kN)
|
Mcr,exp. (kN.m)
|
Ultimate Load (kN)
|
Mu,exp. (kN.m)
|
ACI 318-14
|
CSA-A23.3-14
|
|
|
|
|
Group I
|
N0-3
|
20.15
|
9.0
|
87.32
|
39.29
|
1.90
|
1.16
|
1.96
|
1.17
|
N0-5
|
12.36
|
5.4
|
129.34
|
58.19
|
1.14
|
1.11
|
1.18
|
1.12
|
N0-7
|
22.69
|
9.9
|
162.19
|
72.95
|
2.09
|
1.07
|
2.16
|
1.09
|
Group II
|
L0-3
|
16.2
|
9.9
|
75.93
|
34.16
|
1.74
|
1.05
|
2.12
|
1.03
|
L0-5
|
10.08
|
11.7
|
92.37
|
41.54
|
1.05
|
0.85
|
1.27
|
0.83
|
L0-7
|
18.48
|
8.6
|
126.65
|
56.97
|
1.91
|
0.94
|
2.33
|
0.89
|
Group III
|
L10-3
|
24.45
|
10.8
|
88.57
|
39.83
|
2.25
|
1.19
|
2.73
|
1.18
|
L10-5
|
21.72
|
9
|
107.42
|
48.15
|
1.97
|
0.94
|
2.39
|
0.92
|
L10-7
|
25.61
|
7.2
|
153.87
|
69.21
|
2.34
|
1.05
|
2.84
|
1.02
|
Group IV
|
L15-3
|
22.79
|
8.1
|
107.39
|
48.29
|
1.90
|
1.42
|
2.31
|
1.41
|
L15-5
|
26.37
|
11.7
|
135.14
|
60.80
|
2.25
|
1.15
|
2.73
|
1.13
|
L15-7
|
20.14
|
4.5
|
172.63
|
77.67
|
1.73
|
1.13
|
2.10
|
1.10
|
Group V
|
L20-3
|
25.42
|
8.1
|
121.41
|
54.45
|
2.02
|
1.58
|
2.45
|
1.57
|
L20-5
|
30.19
|
13.5
|
151.37
|
68.09
|
2.42
|
1.26
|
2.94
|
1.24
|
L20-7
|
26.43
|
11.7
|
182.35
|
82.04
|
2.10
|
1.15
|
2.55
|
1.13
|
Average Standard deviation Coefficient of variation (%)
|
1.92
|
1.13
|
2.27
|
1.08
|
0.36
|
0.04
|
0.40
|
0.05
|
18.52
|
3.73
|
17.48
|
4.68
|
Table 7
Deflection, ductility index and maximum strains.
Group No.
|
Beam
|
Mid-span deflection
|
Ductility, µ
|
Max. Steel Strain, με
|
Max. concrete Strain, με
|
∆y (mm)
|
Δu,exp. (mm)
|
|
|
Group I
|
N0-3
|
8.84
|
18.85
|
2.44
|
2.33
|
2.13
|
11475
|
-2775
|
N0-5
|
8.11
|
14.35
|
1.41
|
1.34
|
1.77
|
5400
|
-2685
|
N0-7
|
9.29
|
12.90
|
1.18
|
1.12
|
1.39
|
5178
|
-2946
|
Group II
|
L0-3
|
5.76
|
22.07
|
3.26
|
3.12
|
2.83
|
16000
|
-3134
|
L0-5
|
6.34
|
14.13
|
1.87
|
1.78
|
2.23
|
11375
|
-1840
|
L0-7
|
7.81
|
12.25
|
1.36
|
1.29
|
2.17
|
9600
|
-2866
|
Group III
|
L10-3
|
7.51
|
19.24
|
2.44
|
2.34
|
2.56
|
13988
|
-2978
|
L10-5
|
7.33
|
16.04
|
1.94
|
1.85
|
2.19
|
10386
|
-2823
|
L10-7
|
8.86
|
12.77
|
1.18
|
1.12
|
1.92
|
8497
|
-1365
|
Group IV
|
L15-3
|
6.81
|
17.83
|
1.74
|
1.66
|
2.47
|
9200
|
-2932
|
L15-5
|
7.89
|
15.92
|
1.52
|
1.45
|
2.02
|
7362
|
-2514
|
L15-7
|
8.91
|
13.14
|
1.09
|
1.03
|
1.47
|
6119
|
-1325
|
Group V
|
L20-3
|
2.26
|
15.74
|
1.32
|
1.26
|
1.84
|
4960
|
-3011
|
L20-5
|
4.24
|
13.15
|
1.07
|
1.02
|
1.91
|
5700
|
-2667
|
L20-7
|
4.35
|
9.12
|
1.29
|
1.23
|
1.88
|
3692
|
-2262
|
Average Standard deviation Coefficient of variation (%)
|
1.67
|
1.60
|
|
0.3
|
0.80
|
49.81
|
50.24
|