Page 124 - Masonry and Concrete

Understanding Masonry
123
UNDERSTANDING MASONRY

For outdoor work that is above grade,
use a Type N or Type O mix. For below- Proportions by Volume
grade construction and for paving pro- Mortar Type Portland Cement Lime Sand
jects, use a Type S or Type M mix. The 1 1
M 1 ⁄4 3 ⁄2
proportions used to produce the various 1 1
S 1 ⁄2 4 ⁄2
mortar types are shown in Figures 4-23
N 1 1 6
and 4-24. Bags of masonry cement and
O 1 2 9
mortar cement are marked as Type M,
K 1 3 12
Type S, or Type N and should be mixed
with sand in a 1:3 proportion, 1 part FIGURE 4-23
cement mix to 3 parts sand. For most resi-
Portland cement and lime mortar mixes. (from ASTM
dential masonry veneers, a Type N mortar C270 Standard Specification for Mortars for Unit
is the best choice for overall structural Masonry, American Society for Testing and Materials,
West Conshohocken, PA).
and functional performance. The unnec-
essary use of a Type M or Type S mortar
when the higher compressive strength is
not needed will not only cost more Proportions by Volume
because of the higher cement content, but Masonry Cement
it will reduce workability in the fresh or
mortar and elasticity in the hardened Mortar Cement
mortar and ultimately be detrimental
Mortar Type M S N Sand
rather than beneficial. For foundation and
basement wall construction, a Type M or M 1 3
Type S mortar may be required by some S 1 3
N 1 3
building codes.
Grout mixes should be made from port-
FIGURE 4-24
land cement and lime because most build-
Masonry cement and mortar cement mixes. (from
ing codes do not permit the use of
ASTM C270 Standard Specification for Mortar for Unit
masonry cement for grout. Masonry grouts masonry, American Society for Testing and materials,
are classified as fine or coarse according to West Conshohocken, PA).
the size of aggregate used. If the maximum
3
aggregate size is less than 8 inches, the
3
grout is classified as fine. If the aggregate contains particles 8 inches
or larger, the grout is classified as coarse. Standard mix proportions
are shown in Figure 4-25. Use of a fine grout or coarse grout is deter-
mined by the size of the grout spaces and the pour height as shown in
Figure 4-26.

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