TM 5-809-3/NAVFAC DM-2.9/AFM 88-3, Chap. 3
CHAPTER 3
MATERIALS, PROPERTIES, STANDARD TESTS AND EFFLORESCENCE
3-1. Introduction. This chapter is an overview of
sequence are in the 2000-degree Fahrenheit range.
the nature, properties and standard tests of the
Solid clay units, as defined below, may also be
materials which are used for masonry construction.
manufactured by molding processes, for example,
The material presented in this chapter is primarily
the soft mud and dry press. Subsequent to molding,
concerned with the properties of clay and concrete
the units are dried and fired as in the wire-cut
masonry units which affect structural design. A
process.
c. Size and shape. Clay masonry units are avail-
discussion of the causes, methods of prevention
and methods of cleaning of efflorescence is also
able in a wide variety of shapes, sizes and coring
included.
patterns, several of which are illustrated in figure
3-1. Figures 3-la through 3-1e represent clay units
3-2. Clay masonry units.
defined as solid, that is, the net area is 75 percent
a. Ingredients. Clay masonry units primarily
or more of the gross area. Figure 3-1f illustrates a
consists of clay, shale or similar naturally occurring
hollow unit. The width, W, of solid clay units
earthy substances, water and additives. Most clays
normally ranges from 3 inches to 4 inches, the
are composed mainly of silica and alumina of
height, H, from 2 inches to 4 inches and the
extremely small particle size formed by decomposi-
length, L, from 7e inches to 11e inches, although
tion of rocks.
larger units have been produced. Hollow clay units
b. Manufacturing processes. The majority of the
whose net area is less than 75 percent of the gross
solid and hollow clay masonry units currently used
area, as shown in figures 3-1f have been produced
in the U.S. are produced by the "stiff-mud" pro-
in a relatively small number of sizes and core
cess, also known as the "wire-cut" process. The
configurations. The shape shown has a length equal
basic components of the process are-preparation of
to 11e inches and a height equal to 3e inches.
the clay or clays; mixing with water, and additives
Widths of 3e inches, 5e inches and 7e inches are
if any; extrusion through a die as a continuous
also available.
ribbon; cutting the clay ribbon into discrete units
d. Visual properties. The color of clay masonry
using steel wire; and controlled firing in which the
units by the chemical composition, surface treat-
units are heated to the early stage of incipient
ment, burning intensity, and methods of burning
vitrification. Vitrification occurs when a material
control. These factors also affect the strength of
changes to a glassy substance by heat and fusion.
units. The choice of color for aesthetic purposes
Peak temperatures attained during the firing
3-1
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