Control of grout specific gravity in bored piles

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Control of mud specific gravity in bored piles: 1. Selection of mud specific gravity – The mud specific gravity should be maintained between 1.10 and 1.20 g/cm3 (the required values vary depending on the type of soil); the mud specific gravity is measured during the hole-drying process as well as once the drilling is complete. (The specific gravity of the mud can be determined based on the local construction experience of the specialized subcontractors; alternatively, 3 piles can be selected as test piles to conduct on-site experiments using different mud specific gravities.) 2. Mud preparation (GB51004-2015 \"Code for Construction of Building Foundation Works\"): The mud used is that which circulates back from within the piles during pile drilling and then settles in a sedimentation tank; bentonite and admixtures are added to enable this recycled mud to be used again. 3. Slurry specific gravity test: Measurement using a slurry specific gravity gauge – Fill the slurry cup with the slurry to be tested, cover it, and clean any slurry adhering to the outside of the cup. Place it on a stand, move the slider so that the lever is level (i.e., the bubble is in the center), and read the scale indicated on the left side of the slider; this value represents the relative density of the slurry. 4. Adjustment of mud specific gravity: Excessively high mud specific gravity can lead to excessive sediment accumulation at the bottom of the pile. The mud specific gravity is too low: the wall-protection effect is poor, and hole collapse is likely to occur. Determine whether it is caused by an unreasonable ratio; if it is due to an excessive amount of water added, the amount of water added needs to be reduced. If the specific gravity of the mud is too low due to soil conditions, bentonite must be added to prepare the mud.