# Compressive Strength of Brick - Compression Test on Bricks

## Compressive Strength of Various Bricks

Type of Brick | Min. Compressive Strength of Brick |
---|---|

First Class Brick | 10 N/mm² or 100 kgf/cm² |

Second Class Brick | 7.5 N/mm² or 75 kgf/cm² |

Third Class Brick | 3.5 N/mm² or 35 kgf/cm² |

Fourth Class or Un-Burned Brick | 1.5 N/mm² or 15 kgf/cm² |

Type-A Engineering Brick | 125 N/mm² |

Type-B Engineering Brick | 75 N/mm² |

Sand Lime Brick | 10 N/mm² (Approx) |

## Compressive Strength of Brick As Per IS Code 3495 Part -1

### Indian Standard Used

- IS: 5454 - 1978 [Method for Sampling of Clay Bricks]
- IS: 3495 (Part 1) - 1992 [Method of Test of Burnt Clay Building Bricks]
- IS: 1077 - 1992 [Common Burnt Clay Building Bricks- Specification]

### General Requirements

- The dimensions of the bricks shall be measured to the nearest 1 mm.
- All apparatus and testing equipment shall be calibrated at frequent intervals.
- The number of specimens for the test shall be selected as per IS: 5454 - 1978.

### Apparatus and Materials Required

- Compression Testing Machine [C.T.M.]
- Measuring Tape [Least Count 1 mm]
- Plywood or Plaster of Paris [3 mm Thick]
- Trowel [To Mix the Mortar & Fill the Frog]
- Grinder [To Make Smooth & Parallel Faces of Brick Beds]
- Sand [Graded 3 mm and down]

### Compressive Strength of Brick Formula

**Note:-**''Peak Load'' is also known as ''Maximum Breaking Load' or ''Maximum Load at Failure''.

### Preconditioning (**Only For Solid Bricks)**

**Step-1:** By grinding, Remove the unevenness observed in the bed faces (frog side and its opposite side) to
provide two smooth and parallel faces.

**Step-2:** Measure the bed faces with measuring tape and note its average.

**Step-3: **Immerse the specimens in water at room temperature for 21
hours.

**Step-4: **Remove all the specimens and drain out any
surplus moisture at room temperature.

**Step-5: **Prepare cement mortar of ratio (1 Cement : 3 Sand of grade 3 mm and down).

**Step-6: **Fill the
frog (where provided) and all voids in the bed
faces flush with the cement mortar.

**Step-7: **Store the Sample under the damp jute bags for 24 hours.

**Step-8: **Immerse in clean water for 3 days.

**Step-9: **After then, bring out from water and wipe out any traces of moisture.

## Test Procedure For Compressive Strength of Brick

**Step-10:** Place the specimen with flat faces horizontally, the mortar filled face upward.

**Step-11: **Place two
3-ply plywood sheets (each of 3 mm thick) and
carefully centered between plates of the compression testing
machine.

**Step-12: **Apply load axially at a uniform rate
of 14 N/mm² (or 140 kg/cm²) per minute till
failure occurs and note the maximum load at
failure. The load at failure shall be the maximum
load at which the specimen fails to produce any further increase in the indicator reading on the
testing machine. Repeat the ''**Step-10**'' for rest specimens.

**Note:-**In place of plywood sheets, plaster of Paris may be used to ensure a uniform surface for the application of load.

### Test Result of Brick

Compressive strength of bricks after filling frog and immersing in water for 5 days in different stages is calculated as:

Compressive Strength of Brick (N/mm²) = [Maximum Peak Load (N)/ Average Area of Bed Faces (mm²)]

## Compressive Strength of Brick Lab Report

Compressive strength of brick lab report is the average of results obtained from each specimen, it shall be reported as:

Compressive Strength of Brick As Per IS:3495 (Part-1) is = ...... N/mm².

### Requirements of Compressive Strength of Brick

As per IS: 1077 - 1992 [Common Burnt Clay Building Bricks- Specification], The brick test accordance with the procedure given in IS: 3495 (Part 1)- 1992, shall have a minimum average compressive strength given below separately for each and every classes of bricks.

The compressive strength of any individual brick tested shall not fall below the min. compressive strength specified for the corresponding class of brick. The lot shall be then checked for the next lower class of bricks.

## Reasons Behind Compressive Strength of Brick Test

**Comparing Different Types of Bricks:**

**Ensuring Durability:**

**Quality Control:**

The compressive strength test is used as a "quality control" measure to ensure that bricks produced by manufacturers meet the required standards. The bricks with low compressive strength may not be suitable for use in construction and can lead to structural failure.

**Design of Structures:**

## 👉FAQs

**What is the Minimum Compressive Strength of Brick?**

## Compressive Strength of First Class Brick?

**10 N/**

**mm²**or 100 kgf/cm².

## What is the Compressive Strength of Engineering Bricks?

## How Many Brick Samples are Taken For Compression Test?

## Standard Compressive Strength of Brick in N/mm2?

**²**for second class brick.

## What is Compressive Strength of Brick Formula?

## Compressive Strength of Brick in psi?

## Compressive Strength of Brick in MPa?

**7.5 MPa**for second class bricks.