Bentonite for piling, diaphragm walls and tunnelling
Soda-activated bentonite for support fluids in bored piles, diaphragm walls, cut-off walls and slurry tunnelling. Mixes quickly to a stable slurry inside the EN 1538 fresh-slurry window.
Slurry to EN 1538 · EN 1536
A support fluid has one job: hold the trench or the bore open until the concrete goes in. That means a slurry that builds a thin, tight filter cake, keeps sand in suspension, and stays inside the density and viscosity limits the project specification sets.
Our civil grade is tuned to that window rather than to drilling yield, so it costs less than OCMA grade while giving a contractor a slurry that passes site acceptance tests.
Every shipment carries a certificate of analysis from an independent NABL-accredited laboratory, with the slurry properties measured at 6% concentration.
Where it is used
Civil engineering and piling bentonite specification
Civil / piling grade
Slurry properties at 6% (60 kg/m³) in fresh water
| Property | Test method | Unit | EN 1538 fresh slurry | Our typical | Guaranteed range |
|---|---|---|---|---|---|
| Swell index | ASTM D5890 | mL/2 g | — | 22 | ≥ 20 |
| Marsh funnel viscosity | Marsh funnel, 946 mL | s | 32–50 | 38 | 35–45 |
| Density | Mud balance | g/cm³ | < 1.10 | 1.035 | 1.03–1.05 |
| Fluid loss, 30 min at 100 psi | API filter press | mL | < 30 | 17 | ≤ 22 |
| Filter cake thickness | API filter press | mm | < 3 | 1.6 | ≤ 2.5 |
| pH | pH meter | — | 7–11 | 9.5 | 9.0–10.5 |
| Residue greater than 75 µm | Wet sieve | % by mass | — | 2.8 | ≤ 4.0 |
| Moisture as shipped | Oven dry, 105 °C | % | — | 10.8 | ≤ 12.0 |
Typical mixing
40–60 kg per m³ of water (4–6%), mixed in a high-shear mixer and left to hydrate before use. Adjust concentration to the Marsh funnel and density the project specification asks for. Site acceptance values are set by the project, not by us.
Packing and shipping
25 kg laminated PP bags, sealed. Floor-loaded at 1,040 bags, 26.0 MT net per 20ft container, with desiccants fitted. Jumbo bags on request.
MOQ one 20ft FCL · CFR or CIF · Mundra Port
Frequently asked questions
What properties should a piling bentonite slurry meet?
EN 1538 sets typical limits for fresh slurry: density below 1.10 g/cm³, Marsh funnel viscosity of 32 to 50 seconds, fluid loss below 30 mL, pH between 7 and 11 and filter cake thinner than 3 mm. The project specification always governs.
How much bentonite do I need per cubic metre of slurry?
Usually 40 to 60 kg per cubic metre of water, a 4 to 6% slurry, adjusted to the target Marsh funnel viscosity and density. Let it hydrate before use.
Can I use drilling grade bentonite for piling?
Yes. OCMA grade works well and gives more viscosity per kilogram. Civil grade costs less and is tuned to the EN 1538 window, which is all most piling jobs need.
How is it packed?
25 kg laminated PP bags, floor-loaded at 1,040 bags and 26 tonnes per 20ft container. Jumbo bags can be quoted on request.
Other products: Drilling gradeFoundry gradePelletising gradePlastic white clay
Test it against what you buy today.
A 2.5 kg sample with its certificate of analysis, sent by DHL or FedEx. Tell us your current supplier's figures and we will tell you honestly how ours compare.