The duct grouting

 Problems    |      2018-10-19
1. Mixing of cement slurry:
The water cement ratio is 0.40 ~ 0.45. The consistency is controlled between 14 ~ 18s, the bleeding rate is controlled within 3%, and the cement is no. 52.5 ordinary Portland cement. When the cement slurry is mixed, it is first put into water and then ashes. The mixing time shall not be less than 2min, and the interval between the mixing of the cement slurry and the pressure hole shall not exceed 40min.
2. Grouting process:
(1) the order of hole grouting is first down and then up. After the prestressed reinforcement is stretched, the hole should be pressed as soon as possible within 48 hours.
(2) electric piston type electric slurry pump is adopted. The pressure of the slurry is ensured to be solid in the grouting hole. The starting pressure should be small and gradually increased. At the outlet end of each hole, there is gas-free grout, and the consistency is the same as that of the pressure-injected slurry. The outlet hole is closed and the pump pressure of the grouting end rises above 0.7mpa. The maintenance time should not be less than 10min.
(3), when the temperature is below 5 ℃, the duct grouting should use hot water, and the beam body heat preservation measures must be taken within 48 hours after grouting, can the beam body with plastic sheeting all closed, at the same time in heat preservation heat preservation, fire because it is not cold. Ensure grouting back rest body,
(4) when the cement slurry was mixed, the standard test block was made, and 3 groups were made under the same condition, and 2 groups were made under the standard curing condition, as the 28d compressive strength of cement slurry. After the cement slurry strength reaches the design requirements (controlled by the specimen maintained with the beam), the maintenance is cancelled, and the displacement and hoisting are carried out.


(5) during the grouting, the special person shall fill in the construction record carefully.