The compressive strength test is one of the most important tests performed on concrete. This test gives a fair idea about the quality of the concrete that is being poured at the site. While conducting this test, the major question that emerges in front of a site engineer is - **How many Concrete Cubes to Cast?**

In this article, we will discuss how to determine the number of samples to cast as per IS 456 with examples.

## Concrete Cubes Sampling

The minimum frequency of sampling of concrete of each grade shall be in accordance with the following:

**Note:**

The number of samples mentioned in the table is for a 28 days compressive strength compliance requirement. Additional samples shall be cast to determine the strength of 7 days or at the time of striking the formwork as per the instruction of the engineer-in-charge.

*Example 1:*

**Quantity of Concrete: ****14 m**^{3}

The prescribed number of samples for 14 m^{3} of concrete as per the above table is 2 samples (6 cubes)

*Therefore, 2 samples (6 cubes) from each batch of 7 m ^{3} shall be cast for 28-day testing and an additional 1 sample (3 cubes) shall be cast for 7-day testing.*

*Example 2:*

*Example 2:*

**Quantity of Concrete: ****220 m**^{3}

The prescribed number of samples for 220 m^{3} of concrete as per the above table shall be:

**= 4 + 1 + 1 + 1 + 1 Samples** **= 8 Samples**

(4 samples up to 50 m^{3}, 1 sample for 50 - 100 m^{3}, 1 sample for 100 - 150 m^{3}, 1 sample for 150 - 200 m^{3} and 1 sample for 200 - 220 m^{3})

**Therefore, 8 samples (32 cubes) from each batch shall be cast for 28-day testing and an additional 2 samples (6 cubes) shall be cast for 7-day testing as per the engineer in-charge.**

**Read More**

**Compressive Strength of Concrete -Cube Test [PDF], Procedure, Results**

**Standard Deviation for Compressive Strength of Concrete with Example [PDF]**