Page 35 - Masonry and Concrete
P. 35
Understanding Concrete
34 CHAPTER TWO
FIGURE 2-19
Relationship between moist curing and concrete strength (from U.S. Army, Concrete and
Masonry. Technical Manual No. 5-742. U.S. Government Printing Office, Washington,
D.C.).
a Type-I general-purpose cement, but the Type III hardens and devel-
ops compressive strength more rapidly after it has set.
Concrete normally cures to its full design strength in 28 days. Cur-
ing is slower in cold weather, and at temperatures below 40°F, the con-
crete can be easily and permanently damaged if it is not properly
protected. Concrete must be kept moist for several days after it is
placed to allow the portland cement in the mix to cure and harden
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