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





