CHENG

LI MADE GREAT ACHIEVEMENTS IN THE FUTURE, 

AND DEVOTED HIMSELF TO PRAGMATIC INNOVATION

LI
Method of concrete pouring in inclined roofing
1. construction method
      1. The single template method: this method is more commonly used in slope roof concrete construction of simple and easy method, but many aspects affecting the quality of casting, such as the size of the roof pitch, smooth degree of the template and the influence of the slump.The concrete cannot be vibrated according to the conventional vibration, and the concrete is in the initial stage of solidified.At this time, the concrete's plasticity is reduced, and then the vibration is bound to cause internal injury and crack.For this reason, some measures should be adopted in the construction, such as the control of the concrete slump of 30-50mm, the use of the welded plate reinforcement for the anti-slip belt and the determination of the concrete flow and the section construction.In order to ensure the flatness of the plate, the cement mortar is finished with 1:2.5 cement mortar.
      2. Double-sided splint method.Things slope up to 75 °, double-sided splint method must be used to ensure construction quality.The construction needs to be used for the support of the short steel bar and the water stop film to control the thickness of the roof and the water stop and anti-seepage.In the center of the two templates, the size of 400x400mm concrete casting hole is set.
      From the comparison of two construction methods, the double-sided splint method of concrete is not easy to vibrate, but the concrete compaction of the concrete.Through the water test, the leakage is mostly in the reinforcing wire;There is no honeycomb or hole in the surface of single surface template method, but leakage is more common. It is difficult to find and repair difficulties.
2. analysis and suggestion
      1. Concrete on the single template Inclined roofing construction mainly rely on their own concrete coagulability, templates, the friction resistance and the limit of steel fabric tension resistance, to no longer after concrete hardening molding along the slope slide.If the template exceeds a certain Angle, the friction resistance of the template to the concrete will not be sufficient to counteract the sliding force of the concrete.Before concrete initial coagulation, such as slow displacement continuous occurrence, easy to cause concrete and internal injury leakage.Therefore suggested that when the roof slope is greater than 26 °, unfavorable use single template method.
      2. Double-sided template method can ensure that the concrete board meets the requirement of internal and external light.However, since the thickness of the plate is small (usually only 100mm), the intermediate clearance is less than 50mm, except for the reinforcement and protection layer. If the reinforcement is in error, it is more difficult to insert the tamping rod.Therefore, the construction must pay attention to prevent the reinforcement displacement and the concrete pouring not in place and the resulting honeycomb.Unable to observe the full strength of the concrete in the template, you can tap the sound check and use the adhesive vibrator at the bottom of the board to enrich the concrete.Vibrating, adopting Φ 33 small vibrators, sequential vibration, prevent leakage plugging.The external vibration of the dead corner can be combined with the artificial insertion.For the construction of this method, the slump degree of concrete shall be strictly controlled, and the concrete shall be controlled at 50-70mm according to the temperature of the construction.In order to guarantee the structural safety and waterproof effect of the plane, the slant roof of the slope should be preferred with double-sided splint.
      3. Since the template support system is subjected to the lateral thrust of the inclined roof, it must be set up.It is necessary to pour concrete on both sides to reduce lateral pressure and force the welding reinforcement.Preventing the concrete casting from the single side to cause the displacement of the stent, even collapse accident.
      4. The construction of inclined roofing concrete is affected by high work, slope size, shape change and groove, and it is difficult to mould and pour concrete.Due to the large surface area of the concrete slab, the water loss is fast and the people are not able to use the water.
      5. Inclined roofing construction cost higher than the roof cost greatly, so reduce the waterproof layer, improve the effect of waterproof, is one of the important measures to reduce the project cost, therefore, to ensure that the inclined roof boarding the compactness of concrete is very important.
      6. It is an effective way to facilitate the construction of inclined roofing with high performance concrete or self-compacted concrete.