Free Swell Index (FSI) Test — NABL Certified | Jancy Labs
NABL Accredited Laboratory (Certificate No. TC-12176) as per ISO/IEC 17025:2017
Laying a road on expansive soil without knowing the FSI? That's a slab failure waiting to happen. Jancy Labs provides accurate free swell index testing as per IS 2720 Part 40 — with NABL-certified reports ready for NHAI, PWD, and PMGSY submissions.
Jancy Labs provides accurate free swell index testing as per IS 2720 Part 40 — with NABL-certified reports ready for NHAI, PWD, and PMGSY submissions.
Our FSI test is conducted on calibrated apparatus by a qualified Materials Engineer. Your report carries NABL stamp TC-12176 — accepted at every site approval desk. Get your Free Swell Index test done today →
What Is a Free Swell Index (FSI) Test?
The Free Swell Index test tells you how much your soil expands when saturated — critical for designing safe foundations and subgrades on black cotton or clay-rich ground.
You collect a dry soil sample, allow it to swell freely in water, and measure the volume increase. This FSI value directly classifies your soil's swelling potential per IS 2720 Part 40.
Miss this test on an expansive soil site and you risk pavement heave, cracked slabs, and costly post-construction repairs that no project budget can absorb.
FSI Classification of Expansive Soil
Your FSI result places the soil into a recognised swelling-potential class used for foundation and pavement design decisions:
| Free Swell Index (%) | Swelling Potential | Design Implication |
|---|---|---|
| Below 20 | Low | Non-expansive — standard subgrade and foundation design applies |
| 20 – 35 | Moderate | Monitor moisture variation; consider improved sub-base thickness |
| 35 – 50 | High | Stabilisation typically required before pavement or footing construction |
| Above 50 | Very High | Lime/cement stabilisation, soil replacement, or deep foundation design needed |
Classification bands as per IS 2720 (Part 40): 1977 and standard Indian geotechnical practice. Your certified report states both the measured FSI value and the resulting classification.
Applicable Standards
IS 2720 (Part 40): 1977
The governing standard for this test in India — Methods of Test for Soils, Determination of Free Swell Index. This standard covers the test procedure, apparatus calibration, and result interpretation, ensuring your FSI report is defensible at any approval authority. Reference the standard at the Bureau of Indian Standards (BIS) →
Strict Compliance — No Omissions
At Jancy Labs, every Free Swell Index test is conducted strictly as per IS 2720 (Part 40): 1977 — no shortcuts, no omissions. Our scope and calibration status are verifiable on the NABL India portal → under Certificate TC-12176.
Why the Free Swell Index Test Matters
- NHAI / PWD Road Projects: Subgrade soil with FSI > 50% requires stabilisation before pavement. Your DPR cannot proceed without this data.
- PMGSY Rural Roads: Free swell index is a mandatory parameter in PMGSY soil investigation reports for black cotton soil zones.
- Foundation Design: A high FSI value (>100%) signals very high expansion risk. Structural engineers need this before finalising foundation depth and type.
- Soil Stabilisation Decisions: Lime or cement stabilisation dosage is directly derived from FSI classification. Guessing wastes project budget.
- Monsoon Resilience: Tamil Nadu's red and black soil belts see seasonal swell-shrink cycles. FSI data protects your long-term asset.
- Project Compliance: NHAI, PWD, and PMGSY field engineers routinely request NABL-certified FSI reports before issuing work commencement clearances.
⚠️ Skipping the FSI test on expansive soil is the single most avoidable cause of premature pavement failure in Tamil Nadu's black cotton soil regions. View all Soil Testing Services →
Why Choose Jancy Labs for Free Swell Index (FSI) Testing?
When your road project's DPR depends on soil swell data, one wrong result costs you a rejected submission — and weeks of delay.
- Calibrated graduated cylinders and kerosene + distilled water apparatus — dedicated to IS 2720 Part 40 FSI procedure.
- Free Swell Index test conducted strictly as per IS 2720 (Part 40): 1977 — every observation recorded, no shortcuts.
- FSI test reports signed by a qualified Materials Engineer — not a technician.
- NABL accredited laboratory — Certificate TC-12176 | ISO/IEC 17025:2017.
- Reports accepted by NHAI, Tamil Nadu PWD, and PMGSY field offices.
- Trusted for Free Swell Index testing by highway and infrastructure project engineers across Tamil Nadu.
Jancy Labs has been built on one principle: every result you receive must hold up at a site inspection, a DPR review, or a client audit. Our NABL accreditation guarantees that. See our NABL accreditation → · Talk to our team today →
How to Get Your Free Swell Index Test Done
Send Your Sample
Courier, transport, or drop in your soil sample with a test request letter. Pack oven-dry soil (minimum 200 g) in a sealed airtight container or zip-lock bag.
We Test It
Your sample is tested as per IS 2720 Part 40 by our Materials Engineer — including the mandatory 24-hour swell period in both kerosene and distilled water cylinders.
Certified Report Delivery
Receive your NABL-stamped FSI report by email or collect directly — with the measured FSI value, classification, and IS 2720 Part 40 reference.
Our Free Swell Index Process — as per IS 2720 (Part 40): 1977
- Oven-dry the soil sample at 105°C ± 2°C to constant mass.
- Pulverise the dried soil and sieve through 425 micron IS sieve.
- Take 10 g of sieved oven-dry soil for each test cylinder.
- Pour 10 g slowly into a 100 ml graduated cylinder containing kerosene. Record settled volume (Vk).
- A second 10 g portion goes into another 100 ml graduated cylinder containing distilled water.
- Leave undisturbed for 24 hours to allow the soil to swell fully.
- After 24 hours, record the final volume of soil in distilled water (Vd).
- Calculate FSI and classify as per IS 2720 criteria.
Frequently Asked Questions
How long does a Free Swell Index test take at Jancy Labs?
Can I send soil samples by courier to Jancy Labs for FSI testing?
Is your Free Swell Index report accepted by NHAI and PWD?
Do you conduct testing for both disturbed and undisturbed soil samples for FSI?
How much soil sample do I need to send for a Free Swell Index test?
Get Your Free Swell Index (FSI) Test Today
Your Free Swell Index report is the foundation of every sound decision on expansive soil — don't let missing test data delay your project approval. Submit your sample today and receive a NABL-certified FSI report that NHAI, PWD, and PMGSY will accept, first time.
| Contact Method | Details |
|---|---|
| 📞 Phone | +91-8680049004 / +91-9994421275 |
| +91-8680049004 | |
| ✉️ Email | jancylabsmdu@gmail.com |
| 📍 Address | No.6, Ganesh Nagar 3rd Street, Surya Nagar, Alagar Kovil Main Road, K.Pudur, Madurai — 625007 |
| 🕐 Working Hours | Monday to Saturday (10 AM to 6 PM) |
Request Your FSI Test
Leave your details and our team will call you back to confirm sample dispatch and turnaround.
Standards & Reference Sources
- Bureau of Indian Standards (BIS) — official publisher of IS 2720 (Part 40): 1977, Methods of Test for Soils: Determination of Free Swell Index.
- National Accreditation Board for Testing and Calibration Laboratories (NABL) — verify Jancy Labs' accreditation scope under Certificate TC-12176.
- Indian Roads Congress (IRC) — IRC:37 flexible pavement design guidelines referencing subgrade soil classification and swell behaviour.
- Ministry of Road Transport & Highways (MoRTH) — Specifications for Road and Bridge Works governing subgrade acceptance criteria.
- PMGSY — Pradhan Mantri Gram Sadak Yojana — rural road quality control requirements including soil investigation parameters.