The clay building brick is the most extensively used building material in the construction works. Its quality is of fundamental importance in ensuring the soundness of the buildings and structures. Masonry walls are built using these bricks, brick masonry walls can be load-bearing and non-load bearing (Framed structure) types depending on their structural functionality and thickness.
Bricks are critical construction material and their selection should be given due importance. Bricks used at the site are to be tested for quality to ensure their suitability for building construction.
There are 3 tests that can be done in a laboratory as Per IS Code-
Test-1 Determination of Compressive Strength.
Test-2 Determination of Water Absorption.
Test-3 Determination of Efflorescence.
Test-1 Determination of Compressive Strength
To test the compressive strength of brick a Compressive strength testing machine is used which applies an axial load over the sample. Also, before testing, there is certain preconditioning procedure that needs to be followed and are mentioned below.
Test for Solid Bricks
For solid bricks, the sample should not have any uneven faces and if there are any uneven faces then they must be removed by grinding. The brick is then placed in water for 24 hours and then removed to drain out any surplus moisture at room temperature.
The frog of the brick is filled with mortar and the sample is placed under damp condition using a jute bag followed by immersion of sample in 3 days.
Also, read Reasons not to use sea sand for Concrete and mortars
Procedure for Testing-
Place the sample flat-faced horizontally and the mortar-filled face up between two sheets of 3-ply plywood, each 3 mm thick and carefully centered between the sheets of the testing machine. Apply load axially at a uniform rate of 14 N / mm * (140 kgf / cm2) per minute until failure occurs and record the maximum load at failure. The load at the time of failure is the maximum load at which the sample does not cause a further increase in the indicator reading on the test machine.
The Compressive strength of brick is given by formula-
Compressive strength in N/mm2=
Test for Perforated Bricks
A similar procedure is followed for testing as of hollow bricks but here the bricks are not filled with mortar and they are placed under a testing machine with perforated faced between the plywood sheets. Also, for calculations, the net area of the perforated surface is considered.
Compressive strength values for bricks as per IS code are given below-
Test-2 Determination of Water Absorption
In this test, the Water absorption quantity is calculated.
Before testing all the apparatus that is being should be highly calibrated and can measure 0.1 percentage of mass. A ventilated oven is also required for drying the sample.
The first step is to dry the sample using a ventilated oven at a temperature of 105-115 ° C until it reaches a nearly constant mass. Cool the sample to room temperature and obtain the weight (M1).
The second step consists of immersing the completely dry sample in clean water at a temperature of 27 ° C for 24 hours, removing the sample and wiping the water with a damp cloth, and weighing the sample. Complete the weighing 3 minutes after removing the sample from the water (M2).
The water absorption of brick is given by formula-
Suggested water absorption value as per IS code-
After immersion in cold water for 24 hours, water absorption shall not be more than 20 percent by weight up to class 12.5 and 15 percent by weight for higher classes.
Articles you may also like –
- Understanding the Different Types of Bricks Used in Building
- Classification of bricks, Properties, and their use
- From Clay Bricks to Smart Concrete: The Fascinating Evolution of Civil Materials Engineering
Test-3 Determination of Efflorescence
The testing Consists of a flat bottom dish that can contain distilled water to completely saturate the sample brick. It can be of glass, porcelain, or glazed stoneware.
The sample brick is immersed 25 mm in the dish plate and then it is allowed for absorption at 20 to 30 degrees in a fully ventilated room. The specimen is covered with a cylinder glass so to avoid excessive heat evaporation from the dish. Once the brick looks dry and water is fully evaporated then the water of a similar amount should be added and left for drying as earlier. Once the second evaporation is done then the report is generated.
The liability to efflorescence shall be reported as ‘nil’, ‘slight’, ‘moderate’, ‘heavy’ or ‘serious’ in accordance with the following definitions:
Nil – When there is no observable efflorescence.
SIight: When no more than 10 percent of the exposed surface of the brick is covered with a thin deposit of salts.
Moderate: When there is a deposit that is heavier than a layer of “light” and covers up to 50 percent of the exposed area of the brick surface but is not accompanied by dust or flaking of the surface.
Heavy – When there is a heavy deposit of salts covering 50 percent or more of the exposed surface of the brick surface, but not accompanied by dust or flaking of the surface.
Severe: when there is a large deposit of salts associated with the formation of dust and/or scaling of the exposed surfaces.
Suggested efflorescence value as per IS code-
The rating of efflorescence shall not be more than ‘moderate’ up to class 12·5 and ‘slight’ for higher classes.
Join Our Whatsapp Group for the latest updates -Click Here
Join Our Telegram Channel for the latest updates -Click Here
Comments are closed.