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← Back to Blog FIELD GUIDE · CUBE TESTING · 24 JUL 2026
Field Guide · Cube Testing

Cube Testing
Procedure as per
IS 516.

The single test that decides whether your concrete passed or failed. Sampling, casting, curing, testing, and what to do with the numbers — the complete site-engineer guide.

24 Jul 2026 | 20 min read | Last reviewed: 24 Jul 2026
COMPRESSION FRAME · 2000 kN 150 mm 315 kN/min fck 30 MPa target load 675 kN
Cube testing (IS 516) — 150 mm cube, capping plates, CTM with 14 MPa/min loading arrow A schematic compression testing machine shows a top platen, a top capping plate, a 150 mm concrete cube, a bottom capping plate and a bottom platen. An orange loading arrow with the label 14 MPa per minute indicates the IS 516 loading rate. CUBE TESTING (IS 516) — 150 mm cube · capping plates · 14 MPa/min loading CTM schematic top platen top capping plate 150 mm CONCRETE CUBE 22,500 mm² 150 mm bottom capping plate 14 MPa / min IS 516 loading rate CUBE TEST · KEY · 150 mm standard · capping ±0.05 mm · platen parallel · load 14 MPa/min · peak = failure · fc = P / A (MPa) · 7 / 28 day ages · 3 cubes per result IS 516 controlled copy governs
IS 516 cube strength is peak load divided by 22,500 mm², applied at 14 MPa per minute on a capped, parallel-faced 150 mm cube — every deviation is a deviation from the test.

Codes referenced

IS 516 (Part 1/Sec 1):2018*
Methods of Tests for Hardened Concrete — Part 1 Strength Tests, Sec 1 Compressive, Flexural & Split Tensile

Sampling, casting, curing, and compressive strength testing of cubes.

IS 456:2000
Plain & Reinforced Concrete — Code of Practice

Clause 15 (sampling), Clause 16 (acceptance criteria — Table 11).

IS 1199 (Part 1):2018*
Methods of Sampling & Analysis of Fresh Concrete — Part 1 Sampling of Fresh Concrete

Sampling at the point of delivery / placement.

IS 10086:1982
Moulds for Concrete Cubes

Cast-iron mould specifications, dimensional tolerances.

* Earlier editions were IS 516:1959 and IS 1199:1959 — both superseded by the 2018-part-wise revisions while keeping the same standard number. Confirm the latest published revision on the BIS catalogue before quoting on a project.

Sampling frequency

One sample = a set of 3 cubes (tested at 7 & 28 days — actually 6 cubes if testing both ages). Take samples at the point of placement, not at the plant outlet.

Quantity of concrete (m³)Minimum samples
1 – 51
6 – 152
16 – 303
31 – 504
51 & above4 + 1 per additional 50 m³ or part thereof

Reference: IS 456:2000 Clause 15.2

The procedure, step by step

1

Sampling

IS 1199 (Part 1):2018

  • · Collect concrete at the point of placement using a clean, non-absorbent container.
  • · Take the sample from the middle third of the discharge.
  • · Re-mix with a shovel or trowel to ensure uniformity before moulding.
  • · Slump/temperature record should be noted alongside the sample ID.
2

Casting

150 mm cubes · 3 layers · 35 strokes each

  • · Clean mould, apply release agent, assemble tightly.
  • · Fill in 3 equal layers. Compact each layer with 35 strokes of a 16 mm tamping rod.
  • · Distribute strokes uniformly across the cross-section.
  • · Tap mould sides gently to release trapped air.
  • · Strike off flush with a trowel. Label with sample ID, date, grade, location.
3

Curing

27 ± 2 °C · ≥ 95% RH

  • · Cover moulds to prevent moisture loss; keep at 27 ± 2 °C for the first 24 hours.
  • · Demould at 24 ± 0.5 hours from time of adding water to mix.
  • · Transfer cubes to clean, fresh water tank at 27 ± 2 °C until testing.
  • · Test at 7 days or 28 days. Mark the test age on the cube.
4

Testing

14 MPa/min loading rate

  • · Remove cube from water; surface-dry. Weigh and dimension (150 mm assumed).
  • · Place centrally in the testing machine between platens.
  • · Apply load uniformly at 14 MPa/min (≈ 315 kN/min for a 150 mm cube).
  • · Record max load, compute area, calculate strength (load / area).
  • · Note the failure pattern (see below).

Assumed σ when you don't have 30 samples

IS 456 Table 8 gives assumed standard deviation values to use when you don't have enough history:

GradeAssumed σ (MPa)
M10 – M153.5
M20 – M254.0
M30 – M555.0
M60 – M806.0

Worked example — M30 grade

fck = 30 MPa, σ assumed = 5.0 MPa.

Group average criterion (Table 11, Cl. 16.1)
  • Option A: fck + 0.825σ = 30 + 0.825 × 5 = 34.125 → 34.0 MPa (rounded to nearest 0.5)
  • Option B: fck + 3 = 30 + 3 = 33 MPa
  • Higher of the two → 34.0 MPa
Individual criterion
  • fck − 3 = 30 − 3 = 27 MPa
  • No single cube (28-day) should drop below this.

Reading the failure pattern

IS 516 specifies a normal conical failure as the qualifying mode. Anything else is a flag for your investigation.

✓ Normal Conical

Both ends intact, double cone forms in the middle. Specified pattern — use the result.

⚠ Columnar

Vertical cracks through cube. Platen restraint issue or capping problem. Retest a spare cube.

⚠ Shear

Diagonal failure along one plane. Possible weak interface or capping weakness. Investigate.

✗ Explosive

Cube shatters violently. Possibly due to impact loading or very brittle mix. Result may not be valid.

Frequently Asked Questions

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About the author

Amit Haridas

Founder & Proprietor, ConcreteInfo. 25+ years experience in construction QA/QC, concrete technology, and RMC plant operations. NRMCA Certified Trainer (USA) and ISO Lead Auditor.