Civil Engineering MCQJE Level Civil Engineering
Air entraining agents (AEA) in concrete are primarily used to improve:
Building MaterialsBuilding MaterialsMEDIUM
Choose the correct answer
A
Compressive strength
B
Freeze-thaw durability by providing pressure-relief air voids
C
Bond strength to steel
D
Fire resistance
Correct Answer
B. Freeze-thaw durability by providing pressure-relief air voids
Why is this the answer?
AEA (vinsol resin, sulfonated hydrocarbons): create millions of tiny stable air bubbles (0.05–1.25 mm dia). Primary purpose: resistance to freeze-thaw cycles — air voids provide pressure relief when pore water freezes and expands. Also improves workability. 4–8% air content for severe frost exposure. Air reduces strength ~5% per 1% air.
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