Compressive strength tests are conducted on bricks to assess their ability to bear loads under compression, using a compression testing machine. Bricks are commonly employed in the construction of load-bearing masonry walls, columns, and footings, which are subjected to compressive loads. Therefore, it is crucial to ascertain the compressive strength of bricks in order to determine their suitability for construction purposes. The apparatus, sampling technique, procedure, and calculations for determining the compressive strength of bricks are outlined below.
Compressive Strength Test on Bricks
Apparatus
The compression testing machine features a compression plate with a unique ball seating design. The ball seating is in the form of a portion of a sphere, and the center of this sphere coincides with the center of the plate. This innovative design allows for efficient and accurate compression testing, ensuring precise results. The spherical ball seating provides stability and evenly distributes the compression force, minimizing any potential impact on the testing process. This design also facilitates easy alignment and positioning of the test specimen, enhancing the overall performance and reliability of the compression testing machine.
Specimens
When collecting samples of whole bricks for measurement, it is important to select three bricks to ensure accuracy. These bricks should be chosen randomly from the sample set. To obtain precise measurements, the dimensions of the bricks should be measured using appropriate tools such as rulers or calipers. It is essential to record the measurements to the nearest 1mm to ensure consistency and reliability of the data. Taking three measurements will help account for any potential variations in brick size within the sample set, and measuring to the nearest 1mm will provide accurate and detailed information for analysis and reporting purposes.
Sampling of Bricks
To achieve smooth parallel faces on bricks, the unevenness observed on the bed faces can be removed through grinding. First, immerse the bricks in water at room temperature for 24 hours to ensure they are fully saturated. Afterward, remove the bricks from the water and allow any excess moisture to drain at room temperature.
Next, prepare a cement mortar mixture using a ratio of 1 part cement to 1 part clean coarse sand (graded 3mm and down). Fill the frog (indentation) and all voids in the bed faces of the bricks with the cement mortar, making sure it is flush with the surface.
Place the bricks under damp jute bags and store them for 24 hours. Then, immerse the bricks in clean water for 3 days. After the immersion period, remove the bricks from the water and wipe off any remaining moisture.
By following these steps, the bed faces of the bricks will be smoothed out and voids filled, resulting in two smooth parallel faces for a better-quality finish.
Procedure of Compressive Strength Test on Bricks
To conduct the test, position the specimen with the flat face horizontally, and ensure that the mortar-filled face is facing upwards. Place the specimen between the plates of the testing machine. Apply load axially at a uniform rate of 14 N/mm2 (140 kg/cm2) per minute until failure occurs. Keep track of the indicator reading on the testing machine throughout the test. The load at failure is the maximum load at which the specimen no longer produces any further increase in the indicator reading on the testing machine.
Calculation
The compressive strength of bricks is determined by dividing the maximum load at failure (in Newtons) by the average area of the bed face (in square millimeters). The resulting value is then reported as the average of multiple test results. To calculate the range, the maximum compressive strength, contact area, and maximum expected load must be considered. The range selected will depend on these factors, and it should be determined carefully to ensure accurate and reliable results.
Result
The context refers to the average compressive strength of bricks, expressed in units of N/mm2.
Specifications of Bricks
The speciation of common clay building bricks includes their dimensions, which are determined based on standard size requirements. Clay bricks are typically manufactured to specific dimensions to ensure consistency and compatibility in construction applications.
The standard size of clay bricks is defined based on certain specifications. These specifications outline the acceptable dimensions for clay bricks to be used in building construction. Standard size requirements for clay bricks may vary depending on regional or national building codes, as well as specific industry standards.
The dimensions of common clay bricks are carefully determined to ensure their usability and structural integrity. These dimensions typically include the length, width, and height of the brick. The length of clay bricks is usually measured from end to end, while the width refers to the side-to-side measurement, and the height is the measurement from top to bottom.
Manufacturers of clay bricks must adhere to these standard size requirements to ensure that the bricks can be properly used in construction projects. This helps to ensure consistency in brickwork, allowing for efficient and effective construction practices. Additionally, standard size requirements for clay bricks facilitate compatibility with other building materials and systems, ensuring that the bricks can be seamlessly integrated into various construction applications.
In conclusion, the speciation of common clay building bricks includes their dimensions, which are determined based on standard size requirements. Adhering to these specifications ensures consistency, usability, and compatibility of clay bricks in construction projects.
| Length (mm) | Width (mm) | Height (mm) |
| 190 | 90 | 90 |
| 190 | 90 | 40 |
Classification of Bricks based on Compressive Strength
The classification of common burnt clay is determined based on its average compressive strength, as outlined in the table.
| Bricks Class Designation | Average compressive strength of Bricks | |
| Not less than (N/mm2) | Less than (N/mm2) | |
| 350 | 35 | 40 |
| 300 | 30 | 35 |
| 250 | 25 | 30 |
| 200 | 20 | 25 |
| 175 | 17.5 | 20 |
| 150 | 15 | 17.5 |
| 125 | 12.5 | 15 |
| 100 | 10 | 12.5 |
| 75 | 7.5 | 10 |
| 50 | 5 | 7.5 |
| 35 | 3.5 | 5 |