Which of the following is a primary characteristic of "Self-Healing Concrete"?
- AIt contains encapsulated bacteria that produce limestone to seal cracks when moisture enters.Correct
- BIt uses a high amount of plastic fibres to prevent any cracks.
- CIt is a type of concrete that never requires any reinforcement.
- DIt can only be used in underwater construction.
Solution
Concept
Self-Healing Concrete
Formula
N/A
Step-by-step solution
1. Understand the working mechanism of self-healing concrete. 2. Note that it utilizes encapsulated bacteria that produce limestone to fill and seal cracks upon contact with moisture. 3. Match this property with Option (a) as the correct answer.
Explanation
Option A is correct because self-healing concrete uses special bacteria packed inside tiny capsules. When cracks form and water gets in, the bacteria wake up, feed on nutrients, and produce limestone (calcium carbonate) that automatically fills and seals the cracks.
Shortcut
To remember the mechanism of Self-Healing Concrete, think "Bacteria + Water = Limestone Seal": - Bacteria: Encapsulated bacteria act as the healing agent. - Water: Moisture entering the crack activates the bacteria. - Limestone: Bacteria produce limestone (calcium carbonate) to seal the crack.
Common mistake
A common mistake is selecting option B by confusing self-healing concrete with fiber-reinforced concrete, assuming that added fibers heal or completely prevent cracking. Another frequent error is selecting option C by overestimating its capabilities and assuming self-healing properties eliminate the need for structural steel reinforcement.
Correct answer: A) It contains encapsulated bacteria that produce limestone to seal cracks when moisture enters.