Masonry Magazine July 2006 Page. 36
GROUT
* The grout slump is maintained between 10 and
11 inches; and
* The wall contains no intermediate bond beams
between the top and bottom of the pour height.
For grout pours over five feet, cleanouts are also required.
Cleanouts allow for the grout space to be cleaned prior to
grouting and can be used to verify reinforcement placement.
Grout pours less than 12 inches can be consolidated by
mechanical vibration or puddling, whereas grout pours greater
than 12 inches have to be consolidated and reconsolidated by
mechanical vibration. (It's important to note that a grout pour is
composed of one or more lifts. So a grout pour is the total of all
lifts placed in one operation.) Grout pour heights are given in
Table 7 of the Specification and are based on grout type (fine or
coarse), grout pour height, cavity width and size of core (cell).
In Article 3.5 F, a change introduced in 2002 permits alternate
placement methods from those described here if they have been
proven to be effective via a grout demonstration panel.
In a special case of low-lift grouting, some researchers are eval-
uating alternative techniques. One application of this has been for
residential construction where builders construct an occasional
bond beam. As the lift height is only a single course of concrete
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CIRCLE 165 ON READER SERVICE CARD
REFERENCES
Building Code Requirements for Masonry Structures, Specification for
Masonry Structures, Commentary on Building Code Requirements for
Masonry Structures, and Commentary on Specification for Masonry
Structures, JACI 530-05/ASCE 5-05/TMS 402-05 and ACI 530.1-05/ASCE
6-05/TMS 602-05), jointly published by the American Concrete Institute,
American Society of Civil Engineers and The Masonry Society, Boulder,
Colorado, 2005, 228 pages. (Available from Portland Cement Association
as LT292.)
"Grout Goes Straight on Prison Project," and "Characteristics of Self
Consolidating Grout" Masonry Today Newsletter, PL386, Vol. 14, No. 2,
Winter 2004/2005, Portland Cement Association, Skokie, Illinois, 2005, 4
pages. Free download at:
http://www.cement.org/bookstore/profile.asp?store-&pagenum=1&pos
0&catID=&id=6176
Selecting and Specifying Mortar and Grout for Unit Masonry, IS275,
Portland Cement Association, Skokie, Illinois, 1998, 8 pages.
masonry, typically eight inches tall, the beam can be filled with
material by hand. The fill material is high-strength mortar that has
had water added to make it easier to place. Model building codes
for residential construction such as the International Residential
Code (IRC) have for years permitted the use of high-strength
mortar as grout, as long as the mortar met certain criteria when
mixed to a pouring consistency. Some have suggested that criteria
for using mortar as grout should be considered for some com
mercial construction. The current research deals with evaluating
the influence of mortar on its performance as grout in compari-
son to traditional low-lift grout placement materials and tech-
niques. Mortar characteristics being evaluated are properties of
the mixture itself, consistency and placement techniques.
Extended Set Grout
EXTENDED SET GROUTS have been available for quite
some time. Where they can be especially useful are in harder-to-
reach project locations where the truck may be hauling long dis-
tances to the site. While conventional grout must be placed with-
in 1-1/2 hours from the time of introduction of water into the
mix, extended set grouts incorporate chemical admixtures to
delay the onset of hydration. In every other respect, these grouts
are like conventional grouts once they are introduced into the
cores of the masonry.
Specifying Grout
ASTM C 476 is the "go-to" document for grout. Grout is
classified as either fine or coarse depending on the size of aggre-
gate used. Allowable aggregate size is based on dimensions of
the grout space to be filled and the height of space to be grout-
ed. Grouts can be specified by proportions (a recipe) or by
property. Proportion requirements are given in Table 1 of the
standard. Alternately, specifiers can call for a compressive
strength, using 2,000 psi as a minimum.
All grout types are specified by C 476. Because SCGs are rela-
tively new, they currently are not a formal part of any standard.