07/03/2026
In pile construction, specifically for bored cast-in-situ piles, Bentonite is used to create a "drilling mud" or slurry. Its primary purpose is to maintain the stability of the borehole in loose or water-logged soil conditions where the walls would otherwise collapse.
The Role of Bentonite (Why it’s used)
Bentonite is a type of clay that exhibits thixotropic properties. This means it behaves like a liquid when stirred or pumped but forms a gel-like structure when left standing.
Borehole Stability: The slurry is heavier than water. It exerts outward hydrostatic pressure against the walls of the hole, counteracting the inward pressure of the soil and groundwater.
The "Filter Cake" Effect: The clay particles pe*****te the soil pores on the borehole wall, creating a thin, impermeable layer called a "cake." This seals the wall and prevents the slurry from leaking into the ground.
Suspending Cuttings: As the drill bit breaks up the soil, the bentonite slurry holds these particles in suspension, preventing them from settling at the bottom of the pile before they can be removed.
Lubrication: it cools and lubricates the cutting tools, increasing the efficiency of the drilling process.
