2. The Preparation of the Aligned Steel-Fiber-Reinforced Concrete
2.1. The Method of Aligning Steel Fibers by a Nonuniform Magnetic Field
2.2. Preparation of Aligned Steel-Fiber-Reinforced Concrete
3. Results of Aligning Steel Fibers in Cementitious Composites Using the Device of the Assembly of Magnetic Pieces
4. Flexural Properties of the ASFRC Prepared Using the Magnetic Field Generated by the Assembly of Magnet Pieces
4.1. Three-Point Bending Test
4.2. Flexural Property
4.3. Flexural Toughness
- When a number of small magnets are assembled and form a plate, the magnetic field near the surface of the plate has almost straight magnetic lines. The magnetic field can be used to align the steel fibers in cementitious composites, which was proven by experimental tests. After trials tests, a magnetic device was developed, which was the assembly of small magnetic pieces arranged in the same manner. The advantage of using the new device to prepare the ASFRC was that in the aligning process, the magnetic field device only treated the structures or members on one surface, and there was no limit on the size or shape of the structures or members.
- In the preparation of the ASFRC specimens, the fresh mixture of cementitious composites in the mold were treated using the device on one surface when compacted. Both the magnetic induction intensity of the device and the distance between the device and surface of the specimen significantly influenced the quality of the aligning of the steel fibers in the matrix. The appropriate parameters (magnetic field induction intensity and distance of magnetic treatment of the specimen using the device) were optimized experimentally. By using the developed device, aligned steel-fiber-reinforced cementitious composite (ASFRC) specimens were prepared, and the orientation effective coefficient of the steel fibers in the ASFRC specimens reached 0.9 or higher.
- Compared with a random steel-fiber-reinforced cementitious composite (SFRC), the flexural properties of the ASFRC prepared by the device were significantly improved, in which the flexural strength and flexural toughness of ASFEC were increased by 20–70% and 40–150%, respectively. On the other hand, the flexural properties of the specimen prepared by the device were comparable to that of the specimen prepared by the solenoid, which indicated that the device has excellent performance in aligning steel fibers.
Conflicts of Interest
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|Type of Specimen||Water |
|Water (kg/m3)||Cement (kg/m3)||Sand (kg/m3)||Water Reducer (kg/m3)||Steel Fiber (kg/m3)|
|Type of |
|Density (kg/m3)||Average Length (mm)||Equivalent Diameter (mm)||The Ratio of Length to |
|Elastic Modulus (GPa)||Tensile Strength (MPa)|
|Straight circular type /Hooked type||7800||30||0.5||60||210||1150|
|Type of Specimen||0 mm|
|0 T||Upper layer||51||0.54||52||0.53||47||0.50|
|0.1 T||Upper layer||50||0.95||48||0.92||37||0.88|
|0.2 T||Upper layer||61||0.93||52||0.94||51||0.91|
|0.3 T||Upper layer||72||0.94||62||0.94||54||0.93|
|Group||P600 (kN)||ƒ600 (MPa)||P150 (kN)||ƒ150 (MPa)||T150 (J)||Growth Rate|
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