Core TradesCâu 167 / 700
Air-entraining admixtures are added to concrete PRIMARILY to improve resistance to:
a.Chemical attack from sulfates in soil
b.Cracking caused by drying shrinkage
c.Abrasion from vehicle traffic
d.Damage from repeated freezing and thawing
Giải thích
Entrained air creates microscopic bubbles that give freezing water room to expand, which is why air entrainment mainly protects against freeze-thaw damage. Sulfate resistance comes from cement type, shrinkage cracking from mix and curing control, and abrasion resistance from strength and finishing, not from entrained air.
Trích dẫn luật: 2025 CA Building Code, Chapter 19 (Concrete)Luyện miễn phí toàn bộ 700 câu hỏi — không cần đăng ký.
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