IS 10080 : 1982Specification for vibration machine for standard cement mortar cubes

IS 10080:1982 is the specification for the vibration machine used to mould standard cement mortar cubes — the vibrating table that compacts the 70.6 mm mortar cubes for the cement compressive-strength test in IS 4031 Part 6. Cement strength *grade* (33/43/53) is defined by that cube test, so this machine is part of the chain that classifies cement.

It sits in the cement-testing stack:

• IS 4031 Part 1 (and Part 6) — physical tests / compressive strength of cement (the test this machine serves)
• IS 650 — standard sand for the mortar · IS 269 — OPC (the grade the cube result assigns)

Cement strength is reported on a *standardised mortar* compacted *one standardised way* — change the compaction and you change the 'strength' of the same cement. IS 10080 fixes:

• Vibration frequency ≈ 12,000 ± 400 vibrations per minute and a controlled amplitude (~0.06 mm class) — enough to fully compact the standard 1:3 cement:IS 650-sand mortar without segregating it
• A rigid table and clamp holding the cube mould (70.6 mm, giving 50 cm² faces) firmly so all the energy goes into the mortar
• A fixed vibration time (per IS 4031 Part 6, typically 2 min) so every lab applies the same compactive effort

The engineering point: the cube test only compares cements if the *moulding* is identical. A machine running off-frequency or with the mould loosely clamped under-compacts the mortar and reports a falsely low strength — failing good cement, or masking a real shortfall if it over-compacts.

Scenario: verify an OPC 53 consignment to IS 269 via 28-day strength.

Step 1 — mortar: 1 part cement : 3 parts IS 650 standard sand, water = (P/4 + 3.0)% per IS 4031 Part 6.

Step 2 — mould on machine: clamp the 70.6 mm mould + hopper on the IS 10080 table; confirm the frequency is in the 12,000 ± 400 vpm band.

Step 3 — vibrate: introduce the mortar and vibrate for the specified 2 min — fixed energy, fixed time, every batch.

Step 4 — cure & test: demould at 24 h, water-cure, crush at 3/7/28 d in a calibrated CTM. 53-grade requires ≥ 53 MPa at 28 d.

If the table is off-frequency or the mould rattles loose, the 'failing' cubes are a *machine* artefact — you'd reject conforming cement, or worse, accept weak cement when over-compaction flatters it.

1. Unverified frequency. A table drifting outside 12,000 ± 400 vpm changes compaction and the reported strength — periodic check is mandatory, not optional.

2. Loosely clamped mould. A mould that vibrates relative to the table absorbs energy and under-compacts the mortar → false low strength.

3. Wrong vibration time. Cutting or extending the fixed time changes density; the time is part of the standardisation.

4. Worn/uneven mould (not 70.6 mm true). Bad face area or non-planar faces skew the MPa calculation independent of the cement.

5. Non-standard sand or water. Using site sand instead of IS 650 sand makes the whole test non-comparable regardless of the machine.

• IS 4031 Part 1 — physical tests for hydraulic cement (Part 6 = compressive strength, uses this machine)
• IS 650 — standard sand for testing of cement
• IS 269 — OPC 33/43/53 (grades defined by this strength test)
• IS 10078 — jolting apparatus (alternative compaction route for cement cubes)
• IS 456 — concrete (cement grade feeds mix design)

IS 10080 is a lab-only apparatus standard, but it sits directly under the number that *defines cement grade*. When a 53-grade consignment 'fails' on cube strength, the dispute is expensive and the cause is often the moulding rig, not the clinker — a drifting frequency or a chattering mould. The discipline is unglamorous: verify the table frequency periodically, clamp the mould hard, hold the fixed vibration time, use true 70.6 mm moulds and genuine IS 650 sand. Get the machine right and the cube test is a fair referee between cements; let it drift and you are litigating an instrument error as if it were a material defect.