Masonry
Construction
Masonry/General
A. Masonry
is an ancient art.
1. Masonry construction may be
of brick, concrete masonry units(CMU), stone, or structural tile
2. The materials may
be acquired right at the project site.
3. Masonry is durable. Some
buildings constructed from masonry may stand
4. Modern masonry structures
require steel reinforcing.
a. Cannot build tall
buildings because of dead loads
5. Masonry is the craft of the
"little guy".
a. The tools
required are simple and the skills may be learned by most
people.
b. All masonry is work relatively labor intensive.
B. Masonry
terms: Apply to brick and CMU masonry
1. Bond - pattern in which
masonry is laid - running bond or stack bond are most common for CMU's - Also
Flemish bond, common bond, English bond, Monk bond,
2. Wythe - number
of masonry units thick.
Single-wythe,
double-wythe
double wythe walls are sometimes
built as cavity walls.
3. Backing wythe - inner wall
4. Facing wythe - outer face wall
5. Course - horizontal rows of units .
6. Mortar joints -
a.
Bed joints,
horizontal joints, head joints, and
vertical joints
b. Finish style: Flush, veed, weathered (water runs out), struck (water runs in) or
raked (deep trough).
c. Mortar joints are tooled usually concave, but can be
7.
Stretcher - unit laying lengthwise
8.
Soldier - standing
up
9.
Header - across
double-wythe wall
10.
Rowlock - laid
across the top of double-wythe walls or at window
sills
C. Masonry Ties - Veneer is attached to structure by various means including
corrugated ties, adjustable ties, Z-ties,
D. Insulation
1. Insulating
of CMU's is usually accomplished in
2. Insulation may
be placed in cavity of composite walls.
Explain EIFS systems. Dryvit or Pleko.
3. Good for
retrofit of existing concrete or CMU buildings.
4. EIFS can be
used over any substrate wood, steel studs, etc.
E. Efflorescence
1. Staining caused by water soluble salts in the CMU’s or the mortar.
2. Cover masonry while under
construction to keep water out of the walls and cavities.
3. Efflorescence will leach through
paint.
4. Removed with an
acid wash.
F. Scaffolding
is a critical part of all masonry construction.
1. Scaffold must proceed up as
blocks are laid
2. Most commonly used scaffold
is framed type with wooden planks, and X bracing Some
is self-jacking or proprietary adjustable type.
3. Scaffold systems designed by structural engineers -
usually hired by Mason.
4. On
high buildings are usually specially designed by engineers with experience inscaffold systems.
5. In
a. eat usually natural gas or
propane heaters. Hot water in the grout trucks ready mix.
b. Adds
to construction costs.
c. Owner must decide if the
extra cost is necessary when they determine the project schedule.
G. Stone:
structural stone construction is very rare
1. Most stone is decorative veneer attached to
structures
2. Fascinating and
beautiful but not very practical in
3. Usually only a
facade.
H. Glazed
masonry - very expensive materials ($10 - 15 per unit)
1. Good for interior walls of
kitchens, bathrooms, etc.
I. Laying out walls - design considerations -
dimensioning considerations
Brick/General
A. Brick, stone, and structural
tile masonry is not often used for Alaskan masonry structures. B. Brick is not mad in AK.
C. Bricks made from clay in many different sizes, colors, types,
finishes, and shapes
1. Clay varies in color and
texture from locale to locale resulting in variations in the final brick
product.
2. Stiff mud process - clay
mixture is extruded through a die. Cut by wires into
uniform sizes.
a.
Specs usually call for all brick to come from the same source.
b.
Dried in a low-temperature kiln for one or two days.
c.
Fired in a high temperature kiln turns clay into ceramic material.
Brick/Product
A. Brick
Sizes-
1. Common - 3-3/8 x 2-1/4 x 7-5/8 (WxLxH)
2. Jumbos - 3-5/8"
thick x 3-5/8" high x 11-5/8" long
3. Romans - 3-5/8"
thick X 1-5/8" high x 11-5/8" long
4.
Face
finishes are smooth, textured, or raked vertically
5. Special shapes can be
manufactured for special uses, corners, window sills,
arches, openings, decorative courses, accent courses, etc.
B. Specifying
brick:
1. Size, shape, colour,
and finish
2. Three grades of brick based on
resistance to weathering ( SW - MW - NW)
C. Quality
of facing brick
1. Type FBX - excellent - very
uniform for color and size
2. Type FBS - greater variation
3. Type FBA - non-uniform
D. High
compressive strength
Brick Construction/Execution
A. Solid, single-wythe brick wall construction is virtually unreinforced, and is not used in
B. Composite or cavity walls
with a brick veneer attached to interior structural system (CMU) can be utilized.
1. Composite walls require secure
reinforcing between wythes.
2. Wire anchor ties, dovetailed
ties, corrugated tabs, galvanized mesh, and truss type wires, etc.
C. Reinforced brick walls,
double wythe, difficult
engineering to meet structural requirements, but are difficult to insulate and
expensive to build.
D. Weep
holes are required, allowing moisture to escape from between the wythes
E. Lintels
in brick walls/veneers are usually steel angles or precast
concrete.
F. Ledgers (steel angles) are used to support brick attached to steel and concrete
structural systems.
CMU/General
A. CMU's
- most widely used structural masonry material, very common in
1. Versatile in
design.
2. Highly resistant to damage
a. Good
earthquake resistance. Very stiff - lots of
reinforcement at grout.
3. Fire resistant
4. Easy to design - economical
compared to other masonry structures.
B. Manufacture
of CMU's
1. CMU's are made
from a relatively dry concrete mix with small aggregate.
a.
Color dyes may be added to the concrete mix for any
block.
3. Mix is
placed in metal forms that hold about a dozen blocks
a. Each type of block requires it's own mold. Metal molds are very expensive for block
manufacturers to purchase. Special blocks may require the manufacturer to
purchase special molds.
4. Wet blocks are
turned out on racks.
5. Racks are cured using steam
and controlled temperatures.
6. Blocks are allowed to dry to a specified moisture content
7. CMU’s are palletized and
stored.
CMU/Product
A. Grades
of blocks
1. Load bearing grades: 5 and N. 5 for above grade - non-weather exposed. N for
below grade and/or weather exposed.
B. Types
of blocks (ASTM C90)
1. Type I - moisture controlled
during manufacture to avoid shrinkage and size variation
2. Type II - Non-moisture
controlled. Final size can vary
C. Weight of blocks - corresponds to the weight of the concrete mix (ASTM C90)
1. Normal weight
2. Medium Weight
3. Light weight
D. Types of CMU finishes: split-faced, scored
face, striated face, fluted face, fluted split-faced. 1. CMU shapes have special construction purposes.
b. Most common 8 x 8 x 16 actual
size is 7-5/8” x 7-5/8” X 15-5/8” with 3/8" for mortar joint each way.
c. Blocks are
manufactured in 4", 6", 8", 10”, and 12” thicknesses.
12"
normal weight blocks are very heavy to handle.
Stretcher
blocks are all 8" high x 16" long.
d. Other block shapes include;
bond beam blocks or lintel blocks, corner blocks, half blocks, half-highs,
pilaster blocks, bull-nose corner blocks,
2. ASTM C90 - Hollow load bearing units'
3. Two grades, two types, and three
weights
a. Most common are: Grade N,
Normal weight,
b. The weight of the units is varied by using concrete aggregates than weight less or
more -pumice very light, cinder block, light, normal sand/aggregates. Between 100 to 150 Ibs. per cubic foot.
CMU Construction/Execution
A. CMU
walls are normally designed to use standard sized
units.
1. Less cutting of CMU's
translates into saved labor.
B. CMU
wall reinforcement
1. Vertical Rebars
2. Horizontal rebars
(bond beams)
3. Rebars
around openings
4. Bars are lapped a minimum of 30 -
40 diameters.
5. Lintel construction using
lintel blocks, precast concrete lintels, or built up
bond beams.
6. Grout is
placed in "lifts" in the hollow cores of the block. Pumped or
poured into place.
7. Wire joint reinforcing is often
required in the mortar joints.
C.
Pilasters are constructed from special blocks. H-blocks, C-blocks.
1. Pilasters - act like columns to
support roof or upper floor structures.
D.
Basic steps for laying up block
1) Corners first
2) Fill in wall
E. CMU
details:
1) interior
wall bearing footings
2) non-bearing
interior wall footing (thickened slab)
3) floor
joist bearing - (also bolted steel ledgers)
4) top
course details - solid grouted bond beams - embedded anchor bolts – treated wood
sills or steel bearing plates
F.
Insulation of masonry structures
1. Rigid insulation between wythes.
2. Interior non-bearing light
gage metal or wood framing with insulation batts and
vapor barrier.
3. Exterior
insulation and finish systems.
G. Wall Reinforcing
1. Standard grade deformed bars
are used, the same as concrete CMUs reinforced
vertically and horizontally and filled with grout
a. Vertical bars are stood up
inside the cells and grouted in 4' lifts
b. Single or double horizontal
bars are placed in the cells in bond beams
c. Bars are
lapped vertically and horizontally by 30 to 40 bar diameters.
2. Grout
- Concrete - made
with a small aggregate - usually 3/8" minus round rock
3. Pumped or poured into hollow
cells around the reinforcing.
a. Cells containing
rebar must be grouted
b. Solid
grout for great compressive or shear strength.
c. Solid grout specified
for shear walls in CMU structures.
H. Typical
reinforcing bars are placed in the concrete footing at
16" or 24” vertical dimensions. 1.
CMUs are placed over and laid. . .
2. Wire joint reinforcing (Dur-o-wal) is sometimes required usually in every other
course.
1.
Must have bearing on adjacent wall.
2. Vertical openings - doors,
windows- usually have extra reinforcing bars placed beside the openings.
3. Steel angles can
be imbedded in CMU, or in the brick to span openings.
4. Very labor intensive and
beautiful brick/stone arches, lintels, and corbels
5. Very expensive
because of the cost of labor in the
J. Pilasters
- structural built column
1. In
building corners and every structural grid along the walls.
2. 16” and 24” are most common - but
can be larger.
3. Reinforcing bars are placed in "cages” on the interior of pilasters,
filled with grout.
4. Pilasters are
constructed as bearing points for the roof or upper floor structure
5. Different shapes
Square pilaster, Hand C
shapes, bullnose on interior facing
pilaster blocks.
Joint/General
A. Control/Expansion
Joints
1. Allow for expansion and contraction due to temperature changes
2. Control joint blocks - create a
tongue and groove type joint in the wall.
3. Preformed tee joints - uses
special grooved blocks to accept one arm of the tee.
4. The structural engineer carefully
considers joint placement.
5. Joints are
filled with joint sealant and backer rod
Joint/Product
A.
Mortar - Portland cement, hydrated lime, and aggregate.
1. Often mixed with
"admixtures'! like plasticizers and air
entrainment mixture
2. Mixed on the
jobsite on an as-needed basis. Life of mortar is limited.
3. Types of mortars are specified in ASTM C270
a.
Four basic types Type M, S, N, O.
M is
high-strength 2500 PSI
0 is low-strength 350 PSI
Joint/Execution
A. Control
joints required at
1.
Changes in direction
2. Changes in height
3. Near/above
openings
4. Adjacent to pilasters
5. Wall
intersections.
B. Mortar Joint Deterioration
1. Weather water rain, especially
salt-water weather and spray, will cause mortar soften and deteriorate over
time.
2. Pointing is the process of
putting new mortar in existing joints.
a. Substantial job, but must be
done as often as necessary over the life of the building to preserve the
masonry.