GB/T 51025-2016 in English
VALIDTechnical Specification for Seamless Construction of Super Large Area Concrete
- Issued on:2016-06-20
- Implemented on:2017-02-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$1,106.00
Introduction
Core Technology Innovation and Engineering Application
| Technical Indicators | Traditional Technology | Seamless Construction Specification Requirements |
|---|---|---|
| Expansion joint spacing | ≤40m | Cancel expansion joints, jump compartment spacing ≤40m×40m |
| Temperature control standard | Inside and outside temperature difference ≤25℃ | Inside and outside temperature difference ≤30℃, cooling rate ≤3℃/d |
| Reinforcement ratio | Calculated according to structure | Add temperature reinforcement ≥0.10%, spacing ≤200mm |
Key control of materials and mix ratio
The specification requires the priority use of medium and low heat Portland cement, and the total amount of fly ash ≤40% and slag powder ≤50% of the total amount of cementitious materials, and the total amount ≤50% when double added. The typical mix ratio is as follows:
- Water-binder ratio 0.40-0.45, sand rate 38%-42%
- Water consumption ≤165kg/m³, slump 140±20mm
- 60d/90d strength as the basis for acceptance
Key points of construction technology of skip bin method
Determine the skip bin spacing [L] by the calculation formula in Appendix C:
$$[L]=1.5\sqrt{\frac{E(t)H}{C_{\mathrm{x}}}\mathrm{arch}\frac{|αΔT_2(t)|}{|αΔT_2(t)|-ε_p(t)}$$
In actual engineering, it is necessary to combine The concrete elastic modulus E(t), constraint stiffness Cx and ultimate tensile value εp(t) are calculated comprehensively, and the pouring interval between adjacent blocks shall be ≥7 days.
Temperature stress calculation system
Establish a complete temperature field calculation model in accordance with the specifications:
- Adiabatic temperature rise: $$T(t)=\frac{WQ}{Cρ}(1-\mathrm{e}^{-mt})$$
- Comprehensive temperature reduction difference: $$ΔT_2(t)=\frac{1}{6}[4T_m(t)+T_{bm}(t)+T_{dm}(t)]+T_y(t)-T_w(t)$$
- Shrinkage equivalent temperature: $$T_y(t)=ε_y(t)/α$$
Construction monitoring technical requirements
| Stage | Temperature measurement frequency | Control indicators |
|---|---|---|
| 1-3 days | ≥1 time every 4h | Inside and outside temperature difference ≤30℃ |
| 4-7 days | ≥1 time every 8h | Cooling rate ≤3℃/d |
| After 7 days | ≥1 time every 12h | Surface-atmosphere temperature difference ≤20℃ |
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