Selecting Aggregates
The paste (cement, supplementary cementitious materials,
ultra-fine aggregate, water, and pigments, if any) coats
the aggregate particles, giving the predominant color to
concrete, especially for smooth finishes. Light-colored or white
aggregates are recommended for light-colored or white concrete
because dark aggregates can shadow through the thin layer of
surface paste and produce a darker or spotted appearance.
Aggregates account for
the largest volume of the
concrete, so the overall
color and appearance can
be influenced by the color
of the fine and/or coarse
aggregates (depending
on the depth of exposure)
(see Fig. 4). Pigments of
similar color can be used
to tint the cement paste
and enhance the basic
concrete color established
by the aggregates.
Alternatively, purposely choosing aggregates and pigment with
dramatic color differences can create striking appearances, such
as a salt-and-pepper appearance achieved by a white paste with
white sand and black or very dark medium and/or large aggregate
(see Fig. 5).
Concrete mixes can be formulated with either natural (sand)
or manufactured fine aggregates which are made by crushing
larger stone, or a blend of the two can be used for colored
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