What Is Mortar?
Mortar is an intimate mixture of binding material, fine aggregate, and water. When water is added into the dry mixture of binding material and the inert material, binding material develops the property that binds not only the inert material but also the surrounding bricks and stones.
If the cement is the binding material, then the mortar is called cement mortar. Other mortars commonly used are lime mortar and mud mortar. The inert material used is sand.
Test on Mortar
The following tests are conducted on the prepared mortars to ensure their quality:
1. Crushing Test.
2. Tensile Strength Test.
3. Adhesive Test.
1. Crushing Test
This test is carried out on a brick-work using the mortar. This brick-work is crushed in a compression testing machine, and the load is noted down. Then the crushing strength is obtained as load divided by cross-sectional.
Determination of Compressive Strength of Mortar
To find the compressive strength of cement standard sand mortar cubes, the following would be the procedure and apparatus on the test.
Apparatus
Mortar Cube Size 7.06 cm x 7.06 cm x 7.06 cm
Mortar Cube Size
Apparatus for Gauging and Mixing Mortar
Apparatus for GaugingÂ
Vibrator for Morta Cube
Vibrator
Compression Testing Machine
Compression Testing Machine
Process for Compressive Strength of Mortar.
• Take 200gm of cement and 600gm of sand in the mix ratio 1:3 by weight in a pan.
• The standard sand will be of walnut, of light, gray or whitish variety and will be free of silt.
• The sand grains will soon be angular, the shape of grains approximating into the spherical form, elongated and flattened grains being present only in very small quantities.
• Standard sand will pass through 2 mm IS sieve and will be retained on 90 microns IS sieve using the following particle size distribution.
• Mix the cement and sand in dry condition using a trowel to get one minute and then add water.
• The quantity of water will be (p/4+3)% of the combined weight of cement and sand, where p is the % of the water required to produce a paste of standard consistency determined earlier.
• Add water and mix it until the mixture is of uniform color.
• The time of mixing shall not be < 3 minutes & not > 4 minutes.
• Immediately after mixing the mortar, then place the mortar at the cube mold and prod with the help of the rod.
• The mortar will be prodded 20 times in about 8 sec to ensure the elimination of entrained air.
• If the vibrator is used, the period of vibration will be two minutes in the specified speed of 12000±400 vibrations /minutes.
• Then place the cube molds in temp. of 27±2o C and 90% relative humidity for 24 hours.
• After 24 hours, remove the cubes in the mould and immediately submerge in clean water till testing.
• Take out the cubes from the water just before testing. Testing needs to be done on their sides without any packing.
• The rate of loading needs to be 350 kg/cm2/minute and uniform.
• A test ought to be conducted for 3 cubes and report the average value as the test result for both 7day and 28-day compressive strength.
Result of Mortar Cube Test
Compressive strength at 7 days =……….N/mm2
Compressive strength at 28 days =……….N/mm2
2. Tensile Strength Test.
The mortar prepared is placed in a mould of bracket that has a central cross-sectional area as 38 mm × 38 mm. After curing, the briquette (above fig) is pulled under the grips of the tensile testing machine. The ultimate load noted. Then the tensile strength of mortar is load divided from the central cross-sectional area.
3. Adhesive Test:
Two bricks are joined together with mortar to be tested as shown in above Fig. The upper brick is suspended from an overhead support. A board is hung from the lower brick. Then weights are added to the board till the bricks separate. The adhesive strength is the load divided by the area of contact.
FAQs about Mortar
What is mortar?
Mortar is a mixture of binding material (such as cement, lime, or mud), fine aggregate (usually sand), and water. It is used to bind bricks, stones, or other materials in construction.
What are the different types of mortar?
There are several types of mortar commonly used:
- Cement mortar: Uses cement as the binding material.
- Lime mortar: Uses lime as the binding material.
- Mud mortar: Uses mud as the binding material, commonly found in traditional construction.
What tests are conducted on mortar to ensure quality?
The following tests are typically performed:
- Crushing Test: Measures the compressive strength of mortar by crushing a brick-work sample.
- Tensile Strength Test: Determines the ability of mortar to resist tensile forces.
- Adhesive Test: Evaluates the adhesive strength of mortar by testing how well it bonds two bricks together.
How is compressive strength of mortar determined?
The compressive strength is determined by testing mortar cubes in a compression testing machine. Results are typically reported at 7 days and 28 days after curing.
What factors affect the quality of mortar?
Factors such as the type and quality of binding material, proportion of sand to binding material, water-cement ratio, curing conditions, and mixing techniques all influence the quality and strength of mortar.
Why is mortar testing important in construction?
Mortar testing ensures that the mortar used in construction meets specified standards for strength, durability, and bonding properties. It helps in ensuring the structural integrity and longevity of buildings and structures.
How should mortar be mixed for optimal results?
Mortar should be mixed thoroughly to achieve a uniform consistency. The mixing time, water content, and use of vibrators (for compacting) are critical factors to ensure that the mortar has adequate strength and workability.
What are the applications of mortar in construction?
Mortar is used for laying bricks, stones, and blocks in walls, for plastering and rendering surfaces, and for various repair works in construction projects.
How does curing affect mortar strength?
Proper curing (moisture and temperature control) is crucial for mortar to achieve its full strength potential. It allows the binding material to hydrate and develop optimal bonding properties over time.
Can mortar be customized for specific applications?
Yes, mortar can be customized by varying the type of binding material, aggregate size, additives (such as plasticizers or air-entraining agents), and curing regimes to suit specific construction requirements and environmental conditions.
