Concrete testing: Cube test vs Cylinder test

October 12, 2023

Compressive strength is a vital measure in assessing the durability and integrity of concrete structures. This article aims to compare two prevalent methods of testing concrete's compressive strength: the cube test and the cylinder test.

Read more: We explain three methods for measuring concrete maturity and make comparisons between using sensors and cube testing.

concrete cube and cylinder test ready in the lab

What is Compressive Strength?

Compressive strength refers to the capacity of any material, specifically concrete, to withstand loads tending to reduce size. Given its significance in determining the durability and stability of constructed structures, it's crucial to understand this property. 

The measure of compressive strength is expressed in force per unit area, typically in Mega Pascals (MPa). Structures made of concrete need to have ample compressive strength to sustain the weight placed on them. Hence, the cube and cylinder strength of concrete are frequently tested to ascertain this critical attribute.

The Cube Test

The cube test, commonly performed in countries following British standards, uses concrete cubes for the procedure.

  1. The test involves casting concrete in a cubic mould with dimensions 150mm x 150mm x 150mm.
  2. After 24 hours, the cubes are demoulded and cured in water until the testing age.
  3. The cubes are then placed under a compression testing machine, which applies a gradually increasing load.
  4. The maximum load at which the cube cracks or fails is recorded, giving the cube's compressive strength.

This test is cost-effective and less time-consuming, making it popular among engineers and architects. However, it may not accurately represent in-situ concrete strengths due to its idealistic, uniform shape.

The Cylinder Test

The cylinder test, widely adopted in countries following American standards, uses cylindrical moulds.

  1. The concrete is cast into a cylindrical mould with a standard size of 150mm diameter and 300mm height.
  2. Like the cube test, the cylinders are demoulded after 24 hours and then water-cured until the test age.
  3. The cylinders are then subjected to a compression testing machine to record the failure load.

The cylinder test provides a better approximation of the in-situ concrete strength due to the shape resemblance with structural elements.

Read more: We explain the Maturity Method and how sensors improve the measurement of concrete maturity.

Cube Test vs Cylinder Test

Both methods have their merits and demerits, and the choice depends on the standard being followed and the specific project requirements.

  1. Cube test vs cylinder test offers a compelling debate for engineers worldwide.
  2. The cube test often gives a higher compressive strength value due to the smaller area subjected to loading.
  3. The cylinder test, on the other hand, might yield a lower strength value but more accurately represents the in-situ strength.
  4. In general, the cube's strength is approximately 1.25 times the strength of the cylindrical specimen.

Therefore, it's essential to use these tests wisely, keeping in mind the purpose and the characteristics of the structure being built.

Things to keep in mind

Understanding the compressive strength of concrete is fundamental for ensuring the durability of any structure. The cube and cylinder tests provide useful methods to determine this vital property. 

The choice between cube test vs cylinder test largely depends on the standards followed and the specific requirements of the project. Regardless of the chosen method, these tests provide invaluable information in designing safe and durable structures.

Read more: Can you trust the maturity method and we explain AI and concrete maturity sensors.

Frequently asked questions

Are the cube and cylinder tests the only ways to determine compressive strength?

While cube and cylinder tests are the most common, other methods, like the split tensile test and flexural strength test, are also used. The choice of method often depends on the application and the standards followed in a specific region.

Are compressive strength tests necessary in construction?

Compressive strength tests are essential for determining the load capacity a concrete structure can bear without deformity. These tests help engineers ensure the structure's safety and durability, significantly reducing the risk of structural failure.

What is the advantage of concrete cube test?

The advantage of a concrete cube test is that it will give you the necessary information required to see if the concrete has reached its compressive strength. If the concrete has not reached the expectations then the quality and durability can not be guaranteed.

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