Page 111 - Masonry and Concrete

Understanding Masonry
110 CHAPTER FOUR

4.5.3 Selecting Stone
Stone for building construction is judged
on the basis of appearance, durability,
strength, economy, and ease of mainte-
nance. In terms of practicality and long-
term cost, durability is the most important
consideration in selecting building stone.
Suitability will depend not only on the
characteristics of the stone, but also on cli-
matic conditions. Repeated freezing and
thawing is the most active agent in the nat-
ural destruction of stone. In warm, dry cli-
mates, almost any stone may be used to
build with good results. Stones of the
same general type may vary greatly in
durability because of softness and poros-
ity. Soft, porous stones, which are more
liable to absorb water and then to flake or
fracture when frozen, may not be suitable
in cold, wet climates.
The costs of various stones will depend
FIGURE 4-20
on the proximity of the quarry to the
Flagstone walkway. building site, the abundance of the mater-
ial, and its workability. In general, stone
from a local source is less expensive than imported stone; that pro-
duced on a large scale is less expensive than scarce varieties; and stone
quarried and dressed easily is less expensive than those requiring
more time and labor.

4.6 Masonry Mortar and Grout

Masonry mortar is similar in composition to concrete but different in
properties and performance. Masonry mortar is a mix of cement, lime,
sand, and water used to bond masonry units or individual stones in
walls and other building elements. Masonry grout is a more fluid mix-
ture of similar ingredients used to fill hollow cores and cavities and
to embed reinforcing steel and accessories in masonry construction.
The most important physical property of concrete is compressive

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