Page 107 - Design of Reinforced Masonry Structures

CHAPTER 3
MATERIALS OF

MASONRY CONSTRUCTION

3.1 INTRODUCTION

A reinforced masonry member is built from four different components, viz., masonry
units (concrete or clay), mortar, reinforcement, and grout. A typical construction sequence
involves placing masonry units by hand in such a manner that both horizontal and vertical
reinforcement can be positioned as required by design, place mortar (by hand) over and in
∗
between the bedded units, and pour grout in designated cells as called for in the design
(in only the cells having reinforcement or in all cells of the masonry units). Both clay and
concrete masonry units were discussed in Chap. 2. Properties of mortar, grout, compressive
strength and masonry, and steel reinforcement are discussed in this chapter.
Historically, mortars have been in use since 2690 B.C. when burned gypsum and sand
mortars were used in Egypt. Later, in ancient Greece and Rome, mortars were produced
from various materials such as burned lime, volcanic tuff, and sand. The development of
modern mortar began with the advent of portland cement. The common use of portland
cement began in the early part of the twentieth century and led to greatly strengthened
mortar either when portland cement was used alone or in combination with lime [3.1].
Discussion of various materials in this chapter is based on the information provided in the
MSJC-08 Code [3.2] and Commentary [3.3], MSJC-08 Specification [3.4] and Commentary
[3.5], and 2009 IBC [3.6]. Constituents, testing, proportioning, and properties of various
materials are governed by applicable ASTM Standards; Ref. 3.4 (Section 1.3) provides a list
of ASTM Standards applicable to masonry construction.

3.2 MORTAR

3.2.1 Functions of Mortar
Masonry mortar is a versatile material capable of satisfying a variety of diverse require-
ments. It is one of the main constituents of a constructed masonry structure. Mortar is
required to lay masonry units. As such, it must facilitate the placement of units, contribute
to the serviceability of masonry structure, provide structural performance, and exhibit the
desired appearance.

*All specified/required reinforcement must be placed and properly secured against displacement by wire posi-
tioners or other suitable devices prior to grouting; loss of bond and misalignment of reinforcement can occur if it is
not placed and properly secured prior to grouting.

3.1