Mining Tunneling
FULL THREADED RE BAR, ROCK BOLT, MINING TUNNEL APPLICATION
Rock bolts are widely used for rock reinforcement in mining and tunneling. Our heat-treated rebars have big advantage on yield strength, tensile strength and pre-stress, which could help to support underground tunnels, roof support.
Steel grade: 20MnSi
| Dia | Yield strength MPa | Tensile strength MPa | Elongation Rate % | Yielding Load KN | Tensile Load KN | Weight Kg/m |
| φ16 | ≧345 | ≧510 | ≧25 | ≧69 | ≧100 | 1.6 |
| φ18 | ≧345 | ≧510 | ≧25 | ≧87 | ≧126 | 2 |
| φ20 | ≧345 | ≧510 | ≧25 | ≧108 | ≧156 | 2.5 |
SCREW-THREAD RE BARS FOR PRE-STRESSING OF CONCRETE
The bar portion of rock bolt, is called as screw-thread steel bars, mostly applying for pre-stressing of concrete, which has dis-continuous threads with high strength, high precise, and can be anchored directly by nuts or internal threaded connectors/coupler. <br>
We divide the fully thread bars by the yield strength – Code PSB + minimum yield strength(eg: PSB830). P, S, B represent Prestressing, Screw-thread, bars, and 830 means this rebars’ standard yield strength is 830 MPa.
| Strength Class | Yield Strength, Rel/Mpa | Tensile Strength,(Rm/Mpa) | Elongation after fracture, A/% |
| PSB830 | 830 | 1030 | 7 |
| PSB930 | 930 | 1080 | 6 |
| PSB1080 | 1080 | 1230 | 6
|
TOLERANCES
Nominal diameter range : 18 ~50 mm
25mm, 32mm is the mostly common diameters.
Rebar lengths are often fixed according to orders. Length tolerance is 0~+50mm; Cutting length tolerance is 0~+20mm;
Curving degree shall be less than 0.4% rebar’s total length, and less than 4mm per meter.
top ends must be flat and smooth, to ensure nuts or connectors/coupers passing through.
| Nominal Diameter, mm | Nominal Cross Section Area, mm² | Theoretical Weight. kg/m |
| 6(6.5) | 28.27(33.18) | 0.222(0.260) |
| 18 | 254.5 | 2 |
| 20 | 314.2 | 2.47 |
| 22 | 380.1 | 2.98 |
| 25 | 490.9 | 3.85 |
| 28 | 615.8 | 4.83 |
| 32 | 804.2 | 6.31 |
| 36 | 1018 | 7.99 |
| 40 | 1257 | 9.87 |
| 50 | 1964 | 15.42 |
| Theoretical weight in this table is according to steel density 7.85g/cmm³. | ||