Why does the stress-strain curve of concrete exhibit a non-linear response even at low stress levels?
- ADue to microcracking in the cement pasteCorrect
- BDue to plastic deformation of aggregates
- CDue to perfect elasticity of concrete
- DDue to strain hardening behavior
Solution
Concept
Non-linearity of concrete
Step-by-step solution
1. Microcracks at the aggregate–paste interface and in the paste form even at low stress. 2. Their growth makes the curve non-linear.
Explanation
Concrete is a heterogeneous material whose bond cracks start early, so its stress-strain curve is curved from the start.
Why the other options are wrong
Concrete is not perfectly elastic and does not strain-harden.
Shortcut
Non-linear because of microcracks.
Correct answer: A) Due to microcracking in the cement paste