Page 119 - Design of Reinforced Masonry Structures

MATERIALS OF MASONRY CONSTRUCTION 3.13

sampled and tested as specified in ASTM C67-05c: Test Methods for Sampling and Testing
Brick and Structural Clay Tile [3.19]:
1. ASTM C62-05: Specification for Building Brick (Solid Masonry Units Made from Clay
or Shale) [3.20].
2. ASTM C216-05a: Specification for Facing Brick (Solid Masonry Units Made from
Clay or Shale) [3.21].
3. ASTM C652-05a: Specification for Hollow Brick (Hollow Masonry Units Made from
Clay or Shale) [3.22].
Likewise, concrete masonry units should conform to the following ASTM specifica-
tions as applicable, and be sampled and tested in accordance with ASTM C55-03a or
ASTM C90-06.
ASTM C55-03: Specification for Concrete Brick [3.23].
ASTM C90-06: Specification for Load Bearing Concrete Masonry Units [3.24].

For grouted masonry, the grout for both clay and concrete masonry should conform
to ASTM C476 [3.16]; its compressive strength should equal or exceed the compressive
strength of masonry but should not be less than 2000 psi. The thickness of bed joints for
both types of masonry should not exceed / 8 in.
5
3.5.2.2 Prism Test Method The prism test method provides a means of verifying
that masonry materials used in construction result in masonry that meets the specified
compressive strength. Masonry prisms are assemblages of masonry units, mortar, and
grout (when applicable) that are prepared and tested for their compressive strength
according to the ASTM C1314-03b: Standard Test Method for Constructing and
Testing Masonry Prisms Used to Determine Compliance with Specified Compressive
Strength of Masonry [3.25]. This method covers procedures for constructing masonry
prisms, testing, and procedures for determining the compressive strength of masonry,
f , which is used to determine compliance with the specified compressive strength of
mt
masonry, f ′ .
m
The prisms are made from masonry units that are representative of those that are
to be used in the construction. The test method requires constructing a set of prisms
(i.e., at least three prisms) of the same material and testing them at the same age in
accordance with specified procedure. A prism should consist of at least two masonry
*
units. The aspect ratio (height-to-least lateral dimension ratio, h /t ) is required to
p
p
be between 1.3 and 5.0. All prisms should be constructed by laying the units in stack
bond in stretcher position (Fig. 3.4). The units should be oriented as in the correspond-
ing construction and prepared with full mortar beds (i.e., mortar all the webs and face

shells of hollow units). Both the mortar and the mortar joint thickness between the
units, and the method of positioning and aligning the units during the preparation of
the prisms should be representative of the construction. The prisms can be hollow or
solid, being representative of the corresponding construction—hollow or solid grouted.
If the corresponding construction is to be solidly grouted, the prisms are required to be
grouted not less than 24 nor more than 48 h following the construction of the prisms.
The grout, grout consolidation, and reconsolidation procedures should be representative
of the corresponding construction. In case where the masonry is to be partially grouted,
the test method requires constructing two sets of prisms: one set solidly grouted and
the other ungrouted.
*h p = prism height, t p = least actual lateral dimension of the prism.