Precautions for the Construction of CFA Piles
2022-05-16
A) Control the particle size of the coarse aggregate, the proportion of concrete and the slump to make it meet the requirements of the on-site slump test. It is recommended that the concrete slump should be controlled no less than 220mm.
B) During grouting, the bending of the pipeline should not be too big, and the grouting pipe must be thoroughly cleaned every time when it is disassembled.
C) When the outdoor temperature is higher than 30 ℃, it is advisable to cover the concrete delivery pump pipe with the thermal insulation material, and spray water to cool down at regular intervals.
Recommendations
(1) Adopt the combined application of the vibration tube + vibrator for lowering the rebar cage, to ensure the successful performance of Bi-direction Static Load Testing.
(2) When grouting, the lifting speed of the CFA auger should not be too fast. Otherwise, it will easily lead to the poor quality grouting, which will affect the quality of the pile shaft and the fluidity of the concrete, and increase the difficulty of lowering the rebar cage.
(3) Insert the rebar cage within 3 minutes after the grouting is completed (reduce the time difference to reduce the difficulty in lowering the rebar cage).
(4) Concrete slump: It shall be controlled at no less than 220mm.
(5) The rebar cage is hoisted by a truck at multiple points to ensure that the Super Cell shall not be damaged by the bending moment.
(6) The embedded position of the Super Cell shall be no less than 1m above pile toe, because the bottom of the rebar cage needs to be set with a cone head.
(7) The cone head at the bottom of the rebar cage needs to be welded firmly, otherwise it will easily spread out during the vibration, which may increase the difficulty in lowering the cage.
(8) Ensure the verticality of the rebar cage, otherwise it will affect the lowering of rebar cage.
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