IS 4031 Part 6 : 1988Methods of Physical Tests for Hydraulic Cement - Part 6: Determination of specific gravity

IS 4031 Part 6:1988 is the method for determining the specific gravity of hydraulic cement (Le-Chatelier flask, with a non-reactive liquid such as kerosene). Specific gravity (~3.15 for OPC) is a small but foundational input: it is required by IS 10262 concrete mix design (absolute-volume method) and is an early indicator of cement condition.

It sits in the cement-testing stack:

• IS 4031 Part 1 — physical tests for hydraulic cement (this is the specific-gravity method) · IS 10262 — mix design (consumes SG)
• IS 4031 Part 11 — density · IS 269 — OPC · IS 456 — concrete

Specific gravity is the ratio of cement mass to the mass of an equal volume of water, measured by displacement of a non-reactive liquid in a Le-Chatelier flask:

• Mix-design input: the IS 10262 absolute-volume method needs the cement SG (~3.15 for fresh OPC) to convert cement mass to volume and proportion the mix correctly — a wrong SG skews the yield and proportions
• Condition indicator: a markedly low SG flags cement that has air-set / partially hydrated from moisture exposure (a degraded, lumpy cement reads lower) — an early, simple quality screen
• Kerosene, not water: water would hydrate the cement and corrupt the measurement — the non-reactive liquid is essential

The engineering point: SG is a humble number but it is *used*, in mix design and as a quick degradation check. Assuming a textbook 3.15 for a stored or suspect cement, or running the test with water, are the ways it goes wrong — and the error propagates quietly into the mix proportions.

Scenario: establishing inputs for an IS 10262 mix and screening a stored cement.

Step 1 — non-reactive liquid: use kerosene in the Le-Chatelier flask (never water — it would hydrate the cement).

Step 2 — measure displacement: record the liquid level, add a known cement mass, record the new level → volume displaced.

Step 3 — compute SG: SG = cement mass / (volume displaced × density of water); fresh OPC ≈ 3.15.

Step 4 — use in mix design: feed the measured SG into the IS 10262 absolute-volume calculation — don't just assume 3.15 for a stored/suspect cement.

Step 5 — read as a condition check: a notably low SG → likely moisture-degraded / air-set cement → investigate further (setting/strength) before use.

The number is small but it both proportions the concrete and screens the cement — measured, not assumed, for any cement whose freshness is in doubt.

1. Assuming a textbook 3.15. Fine for fresh OPC in rough work, but a stored/suspect cement should be measured — the SG feeds mix proportions.

2. Using water instead of kerosene. Water hydrates the cement and corrupts the result — a non-reactive liquid is mandatory.

3. Ignoring SG as a condition indicator. A low SG is an early flag of moisture-degraded cement — don't discard the signal.

4. Confusing specific gravity with bulk density. SG is the particle ratio (for absolute-volume mix design); bulk/unit density is a different property.

5. Sloppy flask reading / temperature. Displacement is small — careless reading biases the SG and the downstream mix.

• IS 4031 Part 1 — physical tests for hydraulic cement · IS 4031 Part 11 — density (different property)
• IS 10262 — concrete mix design (consumes SG in the absolute-volume method)
• IS 269 — OPC · IS 4034 — fineness (companion physical property)
• IS 456 — concrete · IS 3025 — water (the other mix input)

IS 4031 Part 6 is reaffirmed and produces one of the least-glamorous numbers in cement testing — yet it is actually used: the IS 10262 absolute-volume mix design needs the cement specific gravity, and a wrong SG quietly mis-proportions the concrete and its yield. The two practitioner habits: don't reflexively assume the textbook 3.15 for a stored or suspect cement (measure it — and read a low value as a degradation flag), and never run the test with water (kerosene only, or hydration corrupts it). It's a small measurement that does two useful jobs — proportioning the mix and screening the cement — and is best treated as a measured input, not a remembered constant, whenever cement freshness is in any doubt.