Fig. 1
Appearance of Kuralon fibers
Table 1
Properties of Kuralon fibers
| Property | Testing value |
|---|---|
| Relative density | 1.30 |
| Tensile strength | 880–1,600 MPa |
| Elongation | 6% |
| Elastic modulus | 29.12 GPa |
Table 2
Mixture designs of concrete (kg/m3)
| Mix No. | Water | Cement | Coarse aggregates | Fine aggregates | Graphite powders | K fibers | Superplasticizer |
|---|---|---|---|---|---|---|---|
| NG0 | 236.46 | 535.0 | 929.8 | 612.96 | 0 | 0 | 2.67 |
| NG4 | 234.85 | 513.6 | 929.8 | 612.96 | 21.4 | 0 | 4.28 |
| NG8 | 233.54 | 492.2 | 929.8 | 612.96 | 42.8 | 0 | 5.59 |
| NG12 | 232.17 | 470.8 | 929.8 | 612.96 | 64.2 | 0 | 6.96 |
| NG16 | 231.64 | 449.4 | 929.8 | 612.96 | 85.6 | 0 | 7.49 |
| KG0 | 236.46 | 535.0 | 929.8 | 612.96 | 0 | 6.5 | 2.67 |
| KG4 | 234.85 | 513.6 | 929.8 | 612.96 | 21.4 | 6.5 | 4.28 |
| KG8 | 233.54 | 492.2 | 929.8 | 612.96 | 42.8 | 6.5 | 5.59 |
| KG12 | 232.17 | 470.8 | 929.8 | 612.96 | 64.2 | 6.5 | 6.66 |
| KG16 | 231.64 | 449.4 | 929.8 | 612.96 | 85.6 | 6.5 | 7.49 |
Table 3
Concrete tests
| Specimen | Properties | Detailed tests | Standard |
|---|---|---|---|
| Concrete | Hardened concrete properties | Compressive strength test | ASTM C39 |
| Elastic modulus test | ASTM C469 | ||
| Flexural strength test | ASTM C78 | ||
| Permeability | Saturated absorption test | ASTM C642 | |
| ISA test | BS 1881 | ||
| Microscopic properties | Scanning electron microscopy | ASTM C1723 | |
| Electrical properties | Four-electrode resistivity test | Wenner method | |
| DC loop resistance test | Designed method in Section 2.3 | ||
| Cyclic loading test |
[i] DC, direct current; ISA, initial surface absorption
Fig. 2
Schematics of resistance measurement
Fig. 3
Appearance of actual resistance measurement
Fig. 4
Compressive strength of normal and fiber concrete groups at 56 days
Fig. 5
Elastic modulus of concrete specimens at 56 days
Fig. 6
Regression curves of compressive strength with regard to the elastic modulus
Fig. 7
Modulus of rupture of concrete specimens at 56 days
Fig. 8
Regression curves of compressive strength with regard to the modulus of rupture
Fig. 9
Saturated water absorption rates of normal and fiber concrete specimens at 56 days
Table 4
Permeability of concrete [39]
| Time (min) | Permeability of concrete using ISA (ml/m2s) | ||
|---|---|---|---|
| Low | Average | High | |
| 10 | <0.25 | 0.25–0.50 | >0.50 |
| 30 | <0.17 | 0.17–0.35 | >0.35 |
| 60 | <0.07 | 0.10–0.20 | >0.20 |
[i] ISA, initial surface absorption
Fig. 10
Initial surface water absorptions rates of normal concrete specimens at 56 days
Fig. 11
Initial surface water absorptions rates of fiber concrete specimens at 56 days
Fig. 12
SEM image (3,000×). (A) NG0, (B) NG4, (C) NG8, and (D) NG12
Fig. 13
Resistivity coefficients using the four-electrode method. (A) Normal concrete specimens and (B) Fiber concrete specimens
Fig. 14
Resistivity coefficients using the DC loop resistance test. (A) Normal concrete specimens and (B) Fiber concrete specimens. DC, direct current
Fig. 15
Relationship between resistance variation, stress, and strain of the normal concrete group. (A) NG0, (B) NG4, (C) NG8, (D) NG12, and (E) NG16
Fig. 16
Relationship between resistance variation, stress, and strain of the fiber concrete group. (A) KG0, (B) KG4, (C) KG8, (D) KG12, and (E) KG16
Fig. 17
Resistance variations in the normal specimens under cyclic loading at 50% of ultimate load. (A) NG0 specimens at 50% of the ultimate load, (B) NG4 specimens at 50% of the ultimate load, (C) NG8 specimens at 50% of the ultimate load, and (D) NG16 specimens at 50% of the ultimate load
Fig. 18
Resistance variations in the fiber specimens under cyclic loading at 30% and 50% of ultimate load. (A) KG0 specimens at 50% of the ultimate load, (B) KG4 specimens at 50% of the ultimate load, (C) KG8 specimens at 50% of the ultimate load, and (D) KG16 specimens at 50% of the ultimate load