A compression test is the most fundamental mechanical test used to determine a material’s compressive strength. This test measures the amount of stress a material can withstand when it is compressed in the axial direction.
Compression testing is widely used in engineering, construction, and research. It is applied to materials such as concrete cubes, steel, bricks, rubber, plastics, wood, and soil.
What is Compression Test?
Compression Test is a standardized laboratory method in which a material sample is gradually compressed and its maximum load carrying capacity is recorded.
- Main Purpose: To measure compressive strength, yield point and failure characteristics.
- Machine Used: Universal Testing Machine (UTM) or Compression Testing Machine (CTM).
- Common Materials Tested: Concrete, cement, metals, composites, polymers.
This test defines the mechanical properties of materials, which is important in construction quality control and industrial design standards.
Compression Test Formula
The simple formula to calculate Compressive Strength is:
Compressive Strength (σc) = Maximum Load (P) / Cross-sectional Area (A)
Example:
If a concrete cube specimen is subjected to a maximum load of 750 kN and its cross-sectional area is 22500 mm²:
σc = 750000 / 22500 = 33.33N/mm2
Procedure of Compression Test
The standard step-by-step procedure for performing a compression test is:
- Specimen Preparation – Standard cube (150 mm × 150 mm) or cylinder (150 mm diameter × 300 mm height).
- Machine Setup – The sample is placed in the Compression Testing Machine.
- Load Application – A uniformly increasing load is applied to the specimen.
- Observation – Failure load and deformation are recorded.
- Calculation – The compressive strength is calculated using a formula.
Types of Compression Tests
- Uniaxial Compression Test – A single axial load is applied.
- Confined Compression Test – The material is compressed by providing lateral support.
- Unconfined Compression Test (UCC) – Used in soil strength analysis.
- Flexural Compression Test – For concrete beams and slabs.
Applications of Compression Test
- Civil Engineering – Verifying the strength of concrete cubes and bricks.
- Mechanical Engineering – Measuring load bearing capacity of metals and alloys.
- Aerospace & Automotive – Safety analysis of composite materials.
- Plastic and Rubber Industry – Deformation capacity of flexible materials.
- Research & Development – Understanding the behavior of new materials.
Standards for Compression Test
Compression testing is standardized in different countries:
- IS 516:1959 (India) – Methods of Tests for Strength of Concrete (cube specimens, 150 mm).
- ASTM C39/C39M (USA) – Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens (150 × 300 mm cylinders).
- EN 12390-3 (Europe) – Testing hardened concrete – Compressive strength of test specimens.
- BS 1881 (UK) – Testing Concrete (replaced by EN 12390).
- IS 4031 (Part 6) (India) – Compressive strength of hydraulic cement (mortar cubes 70.6 mm).
- ASTM C109/C109M (USA) – Compressive Strength of Hydraulic Cement Mortars (50 mm cubes).
- ISO 679 (Europe/International) – Cement test methods – Determination of strength.
- IS 2720 (Part 10) (India) – Methods of Test for Soils – Determination of Unconfined Compressive Strength.
- ASTM D2166 (USA) – Standard Test Method for Unconfined Compressive Strength of Cohesive Soil.
- BS 1377 (UK) – Methods of Test for Soils for Civil Engineering Purposes.
- ASTM E9 (USA) – Standard Test Methods of Compression Testing of Metallic Materials.
- ISO 6892 (International) – Metallic materials – Tensile/compression testing (Part 1 covers general method).
- IS 1608 (India) – Mechanical Testing of Metals – Tensile Testing (compression indirectly follows similar procedure).
- ASTM D695 (USA) – Compressive Properties of Rigid Plastics.
- ISO 604 (International) – Plastics – Determination of Compressive Properties.
- BS 2782 (UK) – Methods of testing plastics.
- ASTM D575 (USA) – Rubber Properties in Compression.
- ASTM D1229 (USA) – Rubber Property – Compression Set at Low Temperatures.
- ISO 7743 (International) – Rubber, vulcanized or thermoplastic – Compression stress-strain properties.
- ASTM D3574 (USA) – Flexible Cellular Materials – Slab, Bonded, and Molded Urethane Foams.
- ISO 3386 (International) – Flexible cellular polymeric materials – Determination of stress-strain characteristics in compression.
- IS 3495 (India) – Methods of Tests of Burnt Clay Building Bricks – Part 1: Compressive Strength.
- ASTM C67 (USA) – Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile.
- EN 772-1 (Europe) – Methods of test for masonry units – Determination of compressive strength.
Advantages of Compression Test
- Simple and cost-effective method.
- Useful in material quality control.
- Directly measures load-bearing strength.
- Valid technical proof in construction disputes.
Limitations of Compression Test
- It only indicates compressive strength, not tensile properties.
- Specimen preparation errors can affect results.
- Lab and field conditions differ.
Importance of Compression Test
- Helpful in verifying the safety of concrete structures.
- Fundamental role in industrial product design.
- Used for quality assurance and standards compliance checks.
- Widely adopted method in research and academics.
Conclusion
Compression testing is the most reliable way to determine the compressive strength and deformation properties of any material. This test is very important not only in the construction industry but also in the mechanical, aerospace, plastics, and research fields.
If you are an engineer, researcher or quality control professional, it is important to have good knowledge of Compression Test procedure, formula, standards and applications.