Masonry

1/12/2001 Author: Tomas U. Ganiron Jr 1

Masonry
The term masonry refers to a construction material formed
by combining masonry units such as stone and brick with a
binding material called mortar. Masonry is used to build
masonry wall, which is a vertical structure , thin in
proportion to its length and height, that serves to enclose
or divide a space and/or support other elements. Masonry
is one of the oldest materials of construction; examples can
be found in all parts of the world such as the pyramids of
Egypt, the Great Wall of China, several Roman and Greek
ruins, the arches and vaults of Syria, and the great
cathedrals of Europe.


Masonry Walls can be divided into two types
based on their location:

 Exterior type
Load Bearing Wall - are those exposed to the exterior environment on
at least one side

 Interior type
Non-load Bearing Wall - as in a wall that divides two adjacent rooms,
have both sides exposed to the interior or environment.


Based on structural requirements, walls can be divided into two
types:
Load bearing - are also called structural walls, are those designed to carry loads
from other members.

Non Load bearing - carry the self weight only. For example, a partition wall that
does not support floor or roof loads is a non-load bearing
interior wall.

Based on the method of construction, walls can be divided into
two types:

Solid Wall - are masonry walls (stone ,brick or block)

Framed Wall - refer to timber or metal wall.


Each of the above two types of walls (solid and
hollow, and framed ) has different characteristics,
that satisfy the functional requirements of the
wall.

One type may have good resistance to fire but
may possess poor insulating properties against
heat (transfer of heat).

One may have poor resistance to rain
penetration but good insulation against heat
transfer.

Modular Planning
Concrete masonry walls should be laid out to make maximum use of full- and half-
length units, thus minimizing cutting and fitting of units on the job. Length and
height of walls, width and height of openings, and wall areas between doors,
windows, and corners should be planned to use full-size and half-size units, which
are usually available . This procedure assumes that window frames and doorframes
are of modular dimensions that fit modular full- and half-size units. Then, all
horizontal dimensions should be in multiples of nominal full-length masonry units,
and both horizontal and vertical dimensions should be designed to be in multiples
of 8 in. When units 8 by 4 by 16 are used, the horizontal dimension should be
planned in multiples of 8 in. (half-length units), and the vertical dimensions, in
multiples of 4 in. If the thickness of the wall is greater or less than the length of a
half unit, a special length unit is required at each corner in each course.

STRUCTURAL CLAY TILE MASONRY
Hollow masonry units made of burned clay or shale are called, variously, structural
tiles,


MASONRY UNITS
Masonry walls are built using various types of masonry units, solid or
hollow, and mortar. A masonry unit is brick, tile, stone, glass block, or
concrete block, conforming to certain product standards of ASTM.

A hollow masonry unit - is a masonry unit whose net cross-sectional
area m every plane, parallel to the bearing surface is less than 75% of
the gross cross-sectional area in the same plane.

A solid masonry unit - is a masonry unit whose net cross-sectional
area in every plane parallel to the bearing surface is 75% or more of the
gross cross-sectional area in the same plane. Generally, a clay unit is a
solid masonry unit and a concrete unit is a hollow masonry unit.


CLAY BRICKS AND STRUCTURAL CLAY TILES

A clay brick - is a small solid block, usually rectangular,
of burned clay. Note that a solid block of concrete and
sand-time (calcium-silicate) is also called a brick.

Structural clay tile - is a hollow clay unit, larger than
the brick, and developed for use where light weight
masonry, as in filter panels and partition walls, is
required.


MANUFACTURE OF BRICKS

Clays for brick making differ widely in composition from place to place,
even in the same field, clay deposits from one part or depth may differ
significantly from those from another part or depth. Clays are composed
mainly of silica (grains of sand) and alumna.

Alumna is the soft plastic part of the clay, which readily absorb water.
Makes the clay plastic, and melts when burned. Present in all clays in
addition to these two compounds are lime, manganese, sulfur, and
phosphates.

The proportion between these compounds varies from place to place.
Iron is useful in improving the hardness and strength of bricks. Lime
present in clays will decompose during burning and promote shrinkage
and disintegration when left in bricks.


Types of Clay

Surface clays- are found near the surface of the earth. They are
unconsolidated and un-stratified material. They have high oxide content,
about 10 to 25%.

Shales- it is also clay in its natural state, but as a result of heavy
compression due to heavy soil above is quite firm and had compressed
flaking characteristics. Most shales are not soluble in water except in
ground, becoming plastic with the addition of water. They are costlier to
remove from ground and contain large amount of fluxes.

Fire clays- it is a material that occurs at greater depths than either surface
clays or shale. It has more uniform physical characteristics and chemical
composition, and is able to withstand high temperatures. Fire clays contain
less oxide (2 to 10%) which raises their softening point much higher than
that of surface clays or shales. This gives refractory qualities for bricks
manufactured with fire clays and ability to withstand higher temperatures.

Three methods of manufacturing: Brick and Tiles

The Stiff-mud process - also called the wire-cut process, clay containing
a minimum amount of water, generally 12 to15% by weight, is forced
through a die. The die molds the mass into desired shapes and sizes for
bricks, tiles, and other products. The continued band of clay that is forced
out is later cut into bricks by a wire frame.

The Soft-mud Process - is well suited to clays containing too much water
in their natural state, ground clay is hydraulically pressed in steel molds.

The Dry Press Process - is suited for clay processing low plasticity,
consist of dropping the moist clay (mixed with about 7 to 10% water) into
dry press forming machines, where the bricks are molded under low
operating pressures.

Grades and Types Of Bricks
Bricks may be classified into different types, according to their uses such
as building brick (also called as common brick). Facing Brick, Floor Brick,
and Paving Brick. Building Brick is a brick for construction, not produced
especially for appearance (texture and color), and used as a structural
material where strength and durability are the most important requirements.

Facing Brick – The term face brick originates from the fact that the brick
is used in the front or face side of a wall. The material used and the
burning of the brick must meet controlled specifications if the brick are to
be used as face brick. All face brick must meet standards for absorption,
uniformity, and strength. The color and texture must meet the
specifications established for the variety of brick being made.

Floor Brick – is a smooth, dense brick, highly resistant to abrasion,
used on finished floor surfaces.

Paving Brick – is a low abrasion, generally furnished with spacing lugs
and produced in smooth or wire cut surface finishes. They are used for
roads, sidewalk, patios, driveways, and interior floors.

Building bricks are manufactured in three grades (durability Grades)

•Grade SW – Highest min. compressive strength requirements and lowest
maximum water absorption.

•Grade MW– Moderate compressive strength requirement

•Grade NW– Has the lowest min. compressive strength requirement and
no limit on the water absorption.

Grading is based on physical requirements (Minimum compressive
strength, maximum water absorption, and maximum saturation coefficient)
and is directly related to durability and resistance to weathering.

Sizes of Bricks
Like concrete blocks, bricks and tiles are designated by their
nominal dimensions.

The most widely used specification for building brick is ASTM
C62.

Building brick: available standard sizes and shapes

Properties Of Bricks

The physical properties of clay bricks and structural clay tiles are:

•Color – Depends on the composition of raw materials for presence of
metallic oxide and the degree of burning

•Texture – Surface appearance ranges from flat to smooth and irregular.

•Size – Varies, depends on what is needed

•Density – Depends on the specific gravity of the green clay, the method
of manufacture, and the degree of burning. The Specific Gravity of clays
and shales ranges from 2.6 to 2.8. The density of the burned material
exceeds100pcf (1600 kg/m³), averaging125pcf (2000 kg/m³)


The engineering or mechanical properties are:

Compressive Strength

Modulus of Rupture

Modulus of Elasticity

Tensile Strength

Absorption

Thermal Conductivity

Fire Resistance

ABSORPTION

Water absorption greatly affects the durability of bricks,
measured by it’s resistance to frost action. Very soft under
burned bricks may absorb less than 10% of water.

The smaller the amount of absorption, the greater is its
durability.


Weight of water absorbed

After 2 hrs in cold water
Absorption = ___________________________ X 100
Dry weight of unit

Absorption after 2 hrs in cold water
Sat. coefficient = ______________________________ X 100
Total absorption after boiling for 5 hrs

W2 - W1
= _____________ X 100
W3 - W1

Where W 1 is the dry weight of unit. W 2 the saturated weight of unit
after 24 hrs of submersion in water, and W 3 the saturated weight of
unit after 5 hrs submersion in boiling water.


(Weight of brick after 1 min. in ¼ in.
water – dry weight of unit)
Initial rate of absorption = ___________________________ X 30
Length of unit x width of unit

W2 - W1 X 30
= _______________________
LxB

Where W 1 is the dry weight of unit. W 2 the weight of unit after partial
submersion for 1 min, L the length of unit, and B the width of unit.


STRENGTH – The compressive strength of clay units depends on:

• Composition of the Clay

• Method of Manufacturing

• Degree of Burning
Failure Load
Comp. strength = ____________________
Net cross sectional area

1.5 Pl
MOR = _______
2
Bt

Where P is the failure load. l the span of length, and t the unit height


Concrete Masonry Units – also called cinder blocks, hollow blocks, and
concrete blocks, are masonry units, solid or hollow, made from concrete.

There are 2 types of masonry units:

•Concrete Building Bricks – is a solid masonry unit made from Portland
cement, water, and suitable lightweight or normal-weight aggregates with
or without the inclusion of other materials.

•Load-bearing concrete Masonry Units– is a solid or hollow masonry
units made from cement, water, and mineral aggregates with or without
the inclusion of other materials.


Both types of units—load-bearing concrete masonry unit and
concrete building brick—are manufactured in 3 weight
classifications:

•Normal weight units - are those weighing over 125pcf
(2000 kg/m³)

•Medium weight units - those in the weight range of 105
and 125pcf (1680 to 2000 kg/m³)

•Lightweight units - have weights between 85 and 105pcf
(1360 and 1680 kg/m³)

Types and Grades Of Concrete Masonry Units

Load-bearing concrete masonry units are manufactured in 2
types:

•Type I: moisture-controlled units – based on the moisture
content in the units as delivered to job site. This means that
these units should be protected from rain or other moisture at
the job site before they are placed in the wall.

•Type II: non-moisture-controlled units – are manufactured
without special consideration given to controlling moisture
content are used extensively in construction. These units
should not be so moist as to cause excessive shrinkage
cracks.

Concrete building bricks are manufactured in 2 grades and 2
types based on strength and absorption requirements:

•Grade N (types I & II) – is suitable as architectural veneer or
facing unit in exterior walls and for use where high strength
and resistance to moisture penetration and severe frost action
are required. The average maximum compressive strength of
grade N bricks, when tested flat wise, should be equal to or
higher than 3500 psi (24.1 Mpa).

•Grade S (types I & II) – are for general use where moderate
strength and resistance to frost action and moisture
penetration are required. Their average maximum
compressive strength should be at least 2500 psi (17.3 Mpa.)

water absorption in a unit = saturated weight – oven dry-weight

Gross area = actual width x actual length

The net area can be calculated as:

Net area = gross area x percentage of solid

% of solid = net vol. / gross vol. x 100


Types Of concrete Blocks and Bricks


Notes: Dimensions are actual block sizes a 7 5/8” x 7 5/8” x 15 5/8”
block is an 8” x 8” x 16” nominal-size block.


Concrete blocks come in several different types.

Stretcher - A stretcher block is the most commonly used block in
construction. It is laid with its length parallel to the face of the wall.

Corner - A corner block is used for corners at simple window and door
openings.

Double Corner or Pier - A double-corner or pier block is used for
constructing piers pilasters or for any other purpose where both ends of
the block would be visible.

Bull Nose - A bull-nose block serves the same purpose as a corner block,
but it is used where round corners are desired.

Jamb - A wood-sash jamb block is used with a stretcher and a corner
block around elaborate window openings. The recess in the block allows
room for the various casing members, as in a double hung window.

The most common concrete block is the hollow, load-bearing
stretcher
block, which is 8 by 8 by 16 inches nominal size, but 7 5/8 by 7 5/8 by
15 5/8 inches actual size. The
heavyweight load-bearing stretcher block weighs from 40 to 50 pounds.

the cores taper toward the top of the block, providing a
wider face shell.

Always lay this block with the wider face up to allow for a
greater area on which to lay a bed of

Hollow load-bearing stretcher block

Nominal height of concrete-block walls


Nominal length of concrete-block walls


Mortar, Grout, and Plaster

Mortar – is a mixture of cement, lime, sand and water. When
mortar is made with lime, sand, and water it is called lime
mortar. With the addition of cement to lime mortar, it becomes
cement-lime mortar or simply cement mortar. In general,
mortar is a term applied to material used for bedding, jointing,
and rendering brickwork, stonework, and concrete blockwork.


Masonry Construction


FIRST COURSE OF CONCRETE BLOCKS

Before mixing mortar and laying blocks, you should follow
these steps:

• Locate the corners of the wall.

• Use a chalk line to mark the footing for aligning the first
course of blocks.

• Check the wall layout by placing the blocks along the wall
without mortar. Remember to leave a 3/8-inch gap between
each block for the mortar. This will tell you if any cutting is
necessary.

Laying out block without mortar


Spreading the Mortar Bed. Spread a full bed of mortar, and
furrow it with a trowel. This will ensure that plenty of mortar is on
the bottom of the blocks for the first course.

Spreading and furrowing the mortar bed

Lay the corner block first and carefully position it. Be sure
to lay all blocks with the thicker side of the face shell up to
provide a larger mortar bedding area.

Positioning the corner block

Making Vertical Joints. Apply mortar to the ends of the blocks for vertical
joints. You can save time by placing several blocks on the ends and
applying mortar to the vertical faces in one operation. Then place each
block over its final position and push downward into the mortar bed and
against the previously laid block to obtain a well-filled vertical joint.

Applying mortar for vertical joints Positioning the block

Aligning, Leveling, and Plumbing. Lay the first course of blocks with great
care to ensure that they are properly aligned, leveled, and plumbed. This
will make the next course of blocks and the wall itself straight and true.

After you have laid three or four blocks, use the mason's level as a
straightedge to ensure correct alignment of the blocks. Check the first
course of blocks carefully with the level, bringing them to the proper grade.
Plumb the blocks by tapping them with the trowel handle

1/12/2001 Author: Tomas and plumbing
Leveling U. Ganiron Jr the blocks 42

CONTROL JOINTS
Control joints are continuous vertical joints that are built into concrete-blocks
walls to control cracking from unusual stress. They are usually spaced at 20 to
25 foot intervals in long walls and extend to the top course. A wall shorter than
20 feet does not normally require a control joint.

Using Full- and Half-length Blocks. Use full- and half-length blocks to form a
continuous vertical joint which will permit slight wall movement without cracking.
You should lay control joints up in mortar just like any other joint.

A control joint using full- and
half-length blocks

Using Paper and Felt.
You can make another type of control joint by inserting building paper or
roofing felt in the end core of the block and extending it the full length of the
control joint.

Cut the paper or felt to convenient lengths. Make sure it is wide enough to
extend across the joint to prevent the mortar from bonding on one side of the
joint.

Control joints using paper or felt

Caulking.
If the control joints are exposed to the weather or to view, you should caulk them.
When the mortar in the control joint is stiff, rake it out to a depth of 3/4 inch to
provide a recess for the caulking materials. Use a thin, flat caulking trowel to force
the caulking compound into the joint.

Raking mortar from the joints

LAYING UP THE CORNERS

After the first course of blocks are laid, build up the corners of the wall
next, usually four or five courses higher than the first course. As you lay
up the corners, cut each course back one-half block.

Applying Mortar. For the horizontal joints, apply mortar only to the tops of
the blocks already laid. You may apply mortar for the vertical joints to the
vertical end of the block to be laid, to the vertical end of the block
previously laid, or to both.

Using a Level. As you lay each course at the corner, check it with a
mason's level for alignment. Make sure that the corner is level and plumb.
Check each block carefully, making certain that the faces of the blocks are
all on the same plane. This will ensure true and straight walls.


Aligning, leveling, and plumbing


Using a Story Pole.
Use a story or course pole (a board with markings 8 inches apart) to
determine the height of the wall for each course.

1/12/2001 Author: Tomas U. Ganiron Jror
Using a story course pole 48

LAYING CONCRETE BLOCKS BETWEEN CORNERS
To ensure a good bond, do not spread mortar too far ahead of the actual
laying of the block. When mortar is allowed to sit, it will stiffen and lose
its plasticity. As each block is laid, cut off excess mortar with your trowel
and work it back into the fresh mortar.

1/12/2001 Author: Tomas U. Ganiron excess
Cutting off Jr mortar 49

Using a Mason's Line.
As you fill in the wall between the corners, stretch a mason's line from
corner to corner for each course. Lay the top outside edge of each
block to his line. Tip the block slightly toward you so you can see the
edge of the course below, making sure that the lower edge of the block
is directly over the course below.

1/12/2001 Laying the top outside Ganiron Jr the block to the line
Author: Tomas U. edge of 50

Making Adjustments.
You must make all adjustments to the final position of the block while
the mortar is flexible. If you try to make adjustments after the mortar has
stiffened, it will break the mortar bond and allow water to penetrate.
Level and align each block to the mason's line by tapping it lightly with
the trowel handle.

Installing the Closure Block.
The last block to be installed in every course is called the closure
block. When you install the closure block butter all edges of the opening
in the wall and all four vertical edges of the closure block with mortar.
Carefully lower the block into place. If any mortar falls out and leaves an
opening in the joint, remove the block and repeat the procedures.


Installing the closure block


TOOLING THE JOINTS
Proper tooling of mortar joints helps produce a weather tight, neat, and durable
concrete-block wall. For exterior concrete, the mortar joints you make should be
concave or V-joints. Tool the vertical jointer first, followed by the horizontal joints
with a longer jointer.

Mortar joints


Jointers.
To finish mortar joints, you will use a jointer, also called a finishing tool.

Jointers


Sled Runner. Use a sled-runner jointer to tool horizontal joint

Tooling horizontal joints


S-Shaped.
Use the S-shaped jointer to tool vertical joints. This is called
striking.

Striking vertical joints

Burrs.
You can reduce burring by finishing the horizontal mortar joints before you finish the
vertical joints. If mortar burrs remain on the wall after you have finished tooling, you
should remove them. This will prevent small amounts of water from being lodged in
the mortar joint.

INTERSECTING WALLS
Depending on the type of wall, intersecting walls are tied together with tie
bars or meal laths.

Bearing Walls.
Bearing walls or blocks in intersecting load-bearing walls should not be
interlocked in a bond. Instead, terminate one wall at the face of the other
with a control joint at the point where they intersect.
Placing Tie Bars. Tie bearing walls together with a tie bar that has a right
angle bend on each end. Place a metal lath over the core in the outside
wall to support the concrete or mortar for the next course.


A tie bar and metal lath

Spacing Tie Bars.
Space tie bars no more than 4 feet apart vertically. Fill the core of the block with
mortar or concrete and embed the right angle bend of the tie bar in the core.

Filling the core with mortar

Nonbearing Walls.
To tie nonbearing walls to other walls, place metal-lath strips across the
joints in alternate courses between the two walls. If one wall is constructed
first, build the metal laths into the first wall. Later, tie the metal laths into the
mortar joints of the second wall and construct control joints where the two
walls meet.

1/12/2001
Metal lath spanningAuthor:joint U. Ganiron Jr
the Tomas 60
Metal lath built into the first wall

Masonry

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