Assertion (A): The addition of shredded plastic waste in bituminous mixes improves the rutting resistance of the pavement. Reason (R): Plastic modified bitumen has a higher Marshall Stability value and better viscoelastic properties at high service temperatures. Choose the correct option: (A) Both (A) and (R) are correct and (R) is the correct explanation of
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)Correct
- BBoth (A) and (R) are correct, but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is incorrect
- D(A) is incorrect but (R) is correct
Solution
Concept
Plastic Modified Bitumen in Bituminous Mixes
Formula
N/A
Step-by-step solution
1. Evaluate Assertion (A): Shredded plastic waste improves the rutting resistance of bituminous pavement. 2. Evaluate Reason (R): Plastic-modified bitumen has higher Marshall Stability and better viscoelastic properties at high temperatures, which prevents rutting. 3. Conclude that both (A) and (R) are correct and (R) is the correct explanation of (A), selecting Option (a).
Explanation
Option (A) is correct because adding shredded plastic to bitumen makes the road binder stronger, stiffer, and more flexible under hot weather (better viscoelastic properties and higher Marshall Stability). This increased strength and stiffness directly prevents the road from forming permanent grooves or depressions (rutting) under heavy traffic. Therefore, both statements are true, and Reason (R) perfectly explains Assertion (A).
Shortcut
To remember the benefit of adding plastic to bitumen, use the mnemonic "Plastic Prevents Pits (PPP)": - Plastic: Bitumen + Shredded Plastic = Plastic Modified Bitumen. - Properties: Higher Marshall Stability & better viscoelasticity (stronger and more elastic at high temperatures). - Pavement Rutting Prevention: Higher strength and elasticity directly prevent grooves and rutting under heavy loads.
Common mistake
A common mistake is selecting Option B by assuming that while both statements are true, the reason does not explain the assertion. Students often fail to connect how higher Marshall stability and improved viscoelastic properties directly enhance deformation resistance, which directly prevents rutting under heavy loads.
Correct answer: A) Both (A) and (R) are correct and (R) is the correct explanation of (A)