What is the primary objective of the tensile strength test on mortar?
- ATo determine the compressive strength of the mortar.
- BTo evaluate the mortar's ability to resist cracking.Correct
- CTo measure the setting time of mortar.
- DTo assess the workability of mortar.
Solution
Concept
Evaluation of tensile behavior and crack resistance of mortar.
Step-by-step solution
1. Understand the mechanical properties of masonry mortar. 2. Recognize that mortar joints are subjected to tensile stresses due to structural loads, temperature variations, and shrinkage. 3. Identify that tensile strength testing specifically measures the material's resistance to tensile failure and cracking.
Explanation
Mortar is inherently weak in tension, and shrinkage, thermal movements, or structural settlements induce tensile stresses that lead to cracking. The primary objective of conducting a tensile strength test on mortar (such as briquette tests or direct tension tests) is to evaluate its ability to resist these tensile forces and subsequent cracking.
Why the other options are wrong
A: Compressive strength is determined by cube or cylinder compression tests. C: Setting time is measured using Vicat apparatus. D: Workability is assessed using flow table or slump tests.
Shortcut
Remember: Mortar fails primarily in tension; tensile tests evaluate crack resistance.
Common mistake
Confusing tensile strength with compressive strength, which is the more commonly measured parameter for overall quality.
Correct answer: B) To evaluate the mortar's ability to resist cracking.