1. Final Project - Materials - Masonry Flashcards
Mortar
mixture of cement, lime, sand, and water
- normally portland cement (harsh, doesn’t apply well). Cures by hydration (chemical reactions), NOT drying.
- lime is a plasticizer; helps retain water, improves workability
- Sand must be clean and screened to get out particles that are too coarse or fine
Makes up about 20% of the exposed surface of a brick wall
- Cushion the masonry units and allows them to bear fully against one another despite surface irregularity
- Seals between the units to keep water and wind from penetrating
- Adheres units to one another to bond them into a monolithic structural unit
90 minutes or less stiffening - can be retempered (not concrete)
Older than 2 1/2 hours must be discarded
grout
similar to mortar
- used to fill cavities between masonry units
- fine grout is used when dimensions of cavity is less than 2 in
- course grout includes no 4 aggregate
masonry cement
prepared mixture of portalnd cement and pulverized limestone
- not as strong of expensive as portland cement, but has greater plasticity
- suitable for lowrise building veneers and for interior, non loadbearing applications
mortar types
- *Types M or S**: for masonry that is load-bearing and/or exposed to the weather.
- *Types N and O**: lesser compressive strength required.
- each has a different porportion of cement, lime, and aggregate
- each has a different compressive strength
the slope of brick coping at top of a masonry wall is called
the wash
Efflorescence
Sometimes appears on the surface of a wall of brick, stone, or concrete masonry
• Consist of one or more water soluble salts that were originally present in the masonry unit or in the mortar
• Brought to the surface and deposited there by water that seeped into the masonry,
dissolved the salts, then migrated to the surface and evaporated
- Can be avoided by choosing masonry units that are lab tested and don’t contain water soluble salts
- Will eventually diminish and disappear with time as the salt is gradually leached out of the wall
WHich type of masonry cement mortar has the highest compressive strength?
type M
type N
type O
type S
type M
type M mosrtar has a minimum average 28 day compressive strength of 2500 psi
type O has the lowest strength (350 psi)
What is the compressive strength for the following types of concrete mortar?
M
S
N
O
M - 2500 psi
S - 1800 psi
N - 750 psi
O - 350 psi
for exterior walls what type of mosrtar is commonly used
type N
type S mortar is typically used for what type of applications
heavier loading on interior walls and
exterior walls at or below grade, such as foundation walls, retaining walls, pavements, and patios
when high strength mortar is required for heavy loads of for cases where the mortar will be exposed to severe saturated freezing, type ___mortar is used
S or M
Type ___ mortar is used only for light loads and where freezing is not expected.
O
What is a requirement for a door opening in a masonry partition?
a. bond beam
b. arch action
c. weep holes
d. flashing
a. bond beam
reglets
horizontal grooves cast into concrete that allow a piece of flashing to be slipped inside and then across the airspace and through the brick for proper drainage and moisture control
in order to achieve a workability equivalent to that of converntional cement-lime mortars,
masonry cement mortars are formulated with
air-entraining admixtures that result in higher workability
- results in higher air content in the cured mortar than cement lime mortar
- reduces bond strength between mortar and masonry to half
- masonry cement should not be used for wall that require high strength and low permeability
type N mortar
general purpose mortar
- balance of good bonding strength and workability
- recommended for exterior veneers, nonloadbearing exterior walls, parapets, chimneys, and interior load bearing walls
type S mortar
- higher flexural bond strneght than Type N mortar
- recommended for exterior reinforced masonry, exterior loadbearing masonry wall, and veneers and walls subject to high wind forces or high seismic loads
Type O mortar
low strength
-recommended mainly for interior nonloadbearing masonry and historic resotration work
type M mortar
high strength mortar with _less workabilit_y than S and N
-recommended for masonry constrction below grade, masonry subject to high lateral or compressive loads, masonry exposed to high frost action
Mortar are specified under
ASTM C270
mortar that was mixed less than ___ minutes prior to its stiffenings can be retermpered with water to make it workable again.
90 minutes
-mortar that is unused for more than 2.5 hours must be discarded as it has already begun to hydrate and can no longer be retermpered
what masonry unit is most resistant to fire
brick
What are the 2 most common modular block types for structural masonry walls?
1 - Bricks = heat hardened
2 - Blocks (concrete) = chemically hardened
Mortar is a mix of cement and/or lime w water and sand.
What makes each of these unique:
1 - Cement Mortar
2 - Lime Mortar
3 - Cement/Lime Mortar
4 - Masonry Cement
1 - Cement Mortar
• portland cement
• water
• sand
2 - Lime Mortar
rarely used
3 - Cement/Lime Mortar
•cement mortar + lime
= increased plasticity and water retention
4 - Masonry Cement
• proprietary mix of port.cement w lime and plasticizers
= rqr only the addition of sand and water
List the 5 types of mortar. (based on strength)
M - high strength
• use: reinforced masonry below grade or in contact w earth
S - med - high strength
• use:bond lat. strength more import than comp.
N - med strength
• use: above grade where high lat./comp. strength NOT rqrd
O - Low strength
• use: int. non-LB partitions
K - Very low strength
• use: int. non-LB partitions
Masonry: what is a brick?
Masonry unit made of clay, formed into a rectangular prism in a plastic state and hardened by heating in an oven or by drying.
Masonry: what is efflorescence? What to do to avoid it?
- White, powdery deposit that forms on the visible surface of masonry or concrete as a result of the filtration and crystallization of soluble salts from the material.
- The best protection against efflorescence lies in the reduction of water absorption.
Grades for Building and Facing Bricks
- Grade SW: Severe Weathering (Oregon, most of the Eastern half of US)
- Grade MW: Moderate weathering (Midwest, most of Washington)
- Grade NW: Negligible weathering (Along southern US border)
- ASTM testing procedures establish three grades of brick based on resistance to weathering and three types of facing bricks, bricks that will be exposed to view, based on the degree of uniformity in shape, dimension, texture, and color from one brick to the next
brick masonry
Produced by factories all with local clay and shale.
- After molding bricks are dried for 1-2 day in a low temp dryer kiln and then fired
- Entire process of firing takes about 40 - 150 hours
- There’s no truly standard brick size. The most common is 8” x 3 5/8” x 2 1/4”
- Use of larger bricks can lead to substantial economies in construction
- Brick shapes can be solid, cored, hollow, or frogged
- Reducing the volume of a brick reduces fabrication, transportation costs
Types of Facing Bricks
available in SW and MW grades
• Type FBX: High degree of perfection, narrow color range, slight size variation
- Type FBS: Wide range of color and greater size variation per unit
- Type FBA: Non uniformity in size, color, and texture per unit
Wythe
simplest wall, a vertical layer of masonry units one unit thick
Course:
a horizontal layer of bricks or other masonry units
Header:
a brick laid to bond two wythes together
Stretcher:
a brick laid with its face parallel to the wall and its long dimensions
horizontal
Solider:
brick laid on its end with its face (long skinny side) parallel to the wall
Sailor:
brick laid on its side with its end parallel to the wall
Rowlock:
brick laid on its face with its end (short skinny side) visible in the wall.
Often used for caps on walls and floor sloping sills under windows
Name Brick laying positions
Structural bonds for brickwork
- Running bond: entirely of stretchers
- English Bond: alternates course of headers and stretchers
- Common Bond: header course every sixth course, head joints are aligned between the header and stretcher courses
- Flemish Bond: alternates headers and stretchers in each course
in masonry walls, water is prevented from seeping back into the wall through capillary action by using
drips
Drips are extensions of through-wall flashing or projections below masonry units
Three courses of bull stretcher using standard brick and standard mortar joints equal
12 in
a bull stretcher is a brick laid on its face so that the width of at he brick is visible. With a width of 3 5/8 in and a mortar joint of 3/8, three courses would be 12 in .
Three standard stretcher courses equal 8 in.
Crack #1
1 : Expansion crack in masonry : temperature & moisture change. It has consistent width.
Sometimes stepped crack.
Not structurally significant but lets water inside the building. Filling the crack with a mastic or sealastic compound is recommended.
Crack #2
2 : Above openings in masonry : 4 possible causes:
- Removal of windows or doors with inadequate propping: reset the lintel and repoint or rebuild the brickwork above
- Inadequate bearings: Overhang (bearing) of the lintels above openings is 150mm (6 inches), replace lintel
- Loads applied directly over the opening: replace lintel
- No lintels: new lintels need to be installed and the cracks repaired
Crack #3
3 : Tie failure, rust
When the metal ties rust they expand causing the cracking normally seen every sixth course horizontally in the mortar joints.
Replacement wall ties are essential. The cracking is an early indication of failure. Without replacement, collapse of the wall could occur.
Crack #4
4 : Subsidence: worse
The foundations of the building are moving. Raking cracks (widest at the top) and can occur to corners of the building or from the top to the bottom of the walls. Underpinning of foundation required.
Crack #5
5 : Ground heave
Crack widest at the bottom of the wall. Clay soils expansion and foundations move upwards.
Remove as much of the clay as possible around foundations, or underpinning / deeper foundations.
common or american
english
enlgish cross or dutch
flemish
running bond
stack
a good rule of thumb for designing corbels is that the projection should not exceed…
1” per course; T/3 max overall corbel
Name the parts of an arch:
Jack arch
Horizontal soffit with voussoirs radiating from a center below
Skewback = 1/2” per 1’ of span
Tudor arch
Four centered arch having the inner pair of curves with radii much greater than that of the outer pair.
Drop arch
Pointed arch having 2 centers and radii less than the span
Roman arch
Semi-circular
Gothic arch
Pointed arch having 2 centers and equal radii
Lancet arch
Pointed arch having 2 centers and radii greater than the span
Segmental arch
Struck from a center below the springing line
Provide movement joints:
- every 100’@125’
1. Changes in wall height
2. At columns, pilasters, wall intersections
3. Near corners
4. On both sides of openings larger than 6’
5. On one side of openings smaller than 6’
name common mortar joints
