Steel fiber
1. Categories of steel fiber in terms of tensile strength
Tensile strength 380--600MPa Grade 380
Tensile strength 600--1000MPa Grade 600
Tensile strength 1000 MPa Grade 1,000
Since the general steel fiber reinforced concrete is normally damaged by pulling the fiber instead of the fiber being broken, as long as the tensile strength of the steel fiber is over 380MPa, the normal serving purposes can be satisfied.
2. Comparison of Steel fiber Reinforced Concrete and Ordinary Concrete
| Item | Ordinary concrete |
Steel fiber reinforced concrete | Enhancement rate |
| C30(RC) | C30(SFRC) | （,%,） | |
| Tensile strength | 3,5MPa | 5,39-7MPa | 54-100 |
| Compressive strength | 31,2MPa | 32,5-40MPa | 4,4-28,2 |
| Ultimate bending strength | 5,5MPa | 9,18-13,75MPa | 67-520 |
| First crack bending strength | 4,88MPa | 7-8Mpa | 43-100 |
| First crack strength | 8,85N,m | 23-53N,m | 160-500 |
| Impact and fatigue strength | 5,96/cm2 | 53,3-91/m2 | 8-15 times |
| Impermeability grade |
P4 | P6~p12 | 0,5 ~2,5 times |
3. Reference for using the steel fiber reinforced concrete
| Type of steel fiber reinforced concrete | length/mm | L/D |
| For general purpose | 20～60 | 30～80 |
| Jet concrete | 20～35 | 30～80 |
| Joints of seismic frame | 35～60 | 50～80 |
| Railway sleeper | 30～35 | 50～70 |
| Layered composite pavement | 30～120 | 60～100 |
4. Proportion of steel fiber and concrete
Proportion for general projects:
| Content of steel fiber | Sand percentage (%) |
Water cement ratio | Slump (cm) |
Unit amount (kg/m3) | ||||
| Steel fiber | Cement | Gravel | Sand | Water | ||||
| 1—1.2 | 40 | 0.45 | 3—5 | 78 | 400 | 1233 | 819 | 180 |
Proportion for important projects:
| Content of steel fiber | Sand percentage (%) |
Water cement ratio | Slump (cm) |
Unit amount (kg/m3) | ||||
| Steel fiber | Cement | Gravel | Sand | Water | ||||
| 1.5—1.8 | 48 | 0.45 | 3—5 | 120 | 450 | 1210 | 1035 | 200 |
5.Technical Standards for Operation
(1) The strength grading of the cement is no less than 425. The water cement ratio shall be no more than 0.5.
(2) The diameter length of the coarse aggregate shall be no more than 2/3 of the length of the steel fiber.
(3) The volume of the steel fiber shall be no less than 0.5% of the total steel fiber reinforced cement. Normally the ratio is 0.5-2%.
(4) Sea water and sea sand are not allowed to be used for the steel fiber reinforced cement. Chloride Salt is forbidden.
(5) In addition to the above rules, the other raw materials used for the steel fiber reinforced cement shall follow the current specifications for the steel fiber reinforced cement.
(6) The consistency of the steel fiber reinforced cement shall be decided by referring to the figure of general concrete required by similar projects. The slump value shall be 20mm lower than the general concrete while the Vebe consistency value is the same as the latter.
(7) When the expansion joint of the steel fiber reinforced concrete is of the flat type and the layer of the concrete has no dust to reinforced the foundation beneath, the following conditions shall be met: a) Prior to reduction, the total thickness of the bed course and top coat is no less than 130cm; b) The thickness of the reinforced foundation shall be higher than that of the bed course. The thickness may be multiplied by the reduction factor of 0.75 but shall no less than 50cm.
6. how to putting the steel fiber:
1） Put the steel fiber and coarse aggregate into the mixer for 30 second mixing to make sure the steel fiber is distributed in the coarse aggregate without any lump.
2） Then put sand, cement into the mixer for another 30-second mixing..
3）While the mixing is going on, add water and mix for 3 more minutes.
7.How to use the steel fiber ---- right stirring is the key
In using the steel fiber, right stirring is one of the critical step, which will decide all physics and chemistry performance of the steel fiber reinforced concrete. Therefore, scientific stirring is needed to ensure the best performance of the steel fiber reinforced concrete, so that the index will reach and exceed the desired standard.
Put appropriate steel fiber into the sand and gravels to mix them without any water (Remember, water is forbidden at this moment.) for one or two minutes. Then add some water to mix the concrete. Do not add too much water, otherwise the steel fiber may become a lump.