Page 15 - Masonry and Concrete

Understanding Concrete
14 CHAPTER TWO

There are many natural and manufactured cements, some of which
date back to Roman builders of the first centuries A.D. Since its devel-
opment in England in the early 1800s, though, portland cement has
become the most widely used cement in the world. Portland cement
got its name because the cured concrete it produced was the same
color as a gray stone quarried in nearby Portland, England. There are
five types of portland cement, each with different characteristics.
■ Type I is a general-purpose cement and is by far the most com-
monly used, especially in residential work. Type I portland
cement is suitable whenever the special characteristics of other
types are not required.
■ Type II cement has moderate resistance to sulfates, which are
found in some soil and groundwater, and generates less heat
during hydration than Type I. This reduced curing temperature
can be particularly helpful in large structures such as piers and
heavy retaining walls, especially when the concrete is placed in
warm weather.
■ Type III is a “high early strength” cement. High early strength
does not mean higher strength—only that strength develops at a
faster rate. This can be an advantage during winter construction
because it reduces the time during which fresh concrete must be
protected from the cold. Early strength gain can also permit
removal of forms and shoring more quickly.
■ Type IV cement produces less heat during hydration than Type
I or Type II and is used only in massive civil engineering struc-
tures such as dams, large highway pilings, or heavy bridge abut-
ments. Its strength development and curing rates, though, are
much slower than Type I.

■ Type V cement is used in concrete exposed to soil or groundwa-
ter that has high sulfate concentrations. This type of cement is
usually available only in areas where it is likely to be needed. In
the United States, Type V cement is common only in the south-
western states.

Types I, II, and III portland cement can also be made with a foam-
ing agent that produces millions of evenly distributed microscopic air

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