1. Masonry Cement and Mortar
Lecture #18
Masonry Cement and Mortar

2. MORTAR
binder = mortar
Masonry = mortar + masonry units

3. MORTAR definitions differences w/ other cementitious mixtures classes
components
types
properties

4. MORTAR cementitious materials sand water
lime
portland cement
sand
water
used with individual masonry units
bonding
bedding / seating
leveling
sealing irregularities
providing strength
providing aesthetic qualities

5. MORTAR lime added weak link in masonry construction
workability
adhesive properties
extensibility
weak link in masonry construction
thin layer stronger (compression) than thick layer

6. GROUT cement fine and coarse aggregate sand water high slump
no segregation
used to bond two masonry wythes together (walls one unit thick)
filling cores and voids
binding reinforcing steel and wythes
providing load carrying capability
ASTM C476
fine and coarse grouts f’C - less in non-absorbent molds
match with masonry f’C

7. Differences w/ other cementitious mixtures
component materials
mortar
cement, lime, water, fine aggregate
grout
cement, water, fine aggregate, small-sized coarse aggregate
portland cement concrete
cement, water, fine aggregate, coarse aggregate
proportions

8. Differences w/ other cementitious mixtures
structural performance
PCC is structural material, resists mainly compressive stresses
mortar, grout are binders, develop strong & durable bond w/ masonry unit
workability & placement methods
PCC placed in non-absorbent forms, minimum water, w/c ratio very important to performance
mortar, grout placed in absorptive forms, much more water, w/c ratio less important

9. Classes cement/cement-lime mortar lime mortar masonry cement mortar
cement, lime, sand, water
most common
masonry cement mortar
proprietary ingredients
workable
low bond strength, not durable - most commonly used but least desirable
lime mortar
lime, sand, water
slow strength gain
calcium carbonate formation
seldom used in permanent construction

10. Components portland cement sand lime water admixtures durability
high early strength
high compressive strength
bond strength
sand
filler
strength
lime
workability
water retentivity
elasticity
bond strength
extensibility
water
flow
required for hydration
admixtures

11. Components portland cement
Type I - general use when special properties not required
Type II - when moderate sulfate resistance or moderate heat of hydration required
Type III - when high early strength required
Air entrained portland cements tend to reduce bond strengths

12. Components hydrated lime [Ca(OH)2]
chalk or limestone (CaCO3) burned at 900 0C in kiln to produce quicklime (CaO)
water added to quicklime
Types (ASTM C207)
N - normal, unhydrated oxides & plasticity not controlled
S - special, commonly used
NA - normal air-entraining, not recommended
SA - special air-entraining, not recommended

13. Components
aggregates
natural or manufactured
gradation (ASTM C144)

14. Components water admixtures clean potable
free of deleterious materials
acids
alkalies
organic materials
admixtures
color
workability
reduced water penetration
accelerated curing
use w/ caution
air-entraining
chlorides

15. Types (MASONWORK) ASTM C270 Type M (paving brick)
proportion specifications - RECOMMENDED
property specifications
established with laboratory testing, trial & error
same letter designations, but
Type N (proportion) = Type N (property)
(proportion - higher compressive strength)
Type M (paving brick)
high strength
general use
below grade OR in contact w/ ground

16. Types (MASONWORK) Type S (structural masonry, reinforced brick)
high strength
reinforced masonry
areas subject to high wind
Type N (normal, common)
general use
below grade OR in contact w/ ground

17. Types (MASONWORK) Type O (interior) Type K (restoration) low strength
non-bearing applications
not subject to severe weathering
Type K (restoration)

18. Types (MASONWORK)
Proportion Specifications

19. Determine quantities and absolute volumes for an N Type Mortar
Vsand = 1.0 ft3
Vlime= 0.5 to 1.25 Vc
Vsand=2.25 to 3 (Vc+Vl)
1 ft3 of damp loose sand will yield 1 ft3 of mortar. (due to bulking of wet sand)

20. Types (MASONWORK) Property Specificationsa
a Laboratory prepared mortar only
b When structural reinforcement is incorporated in cement-lime mortar,
the maximum air content shall be 12%
c When structural reinforcement is incorporated in masonry cement mortar,
the maximum air content shall be 18%.

21. Selecting Mortar Types
considerations
structural requirements
exposure
wall type
workability
no single type for all purposes
DO NOT change mortar types within same structure
uneconomical
NEVER use mortar stronger in compression than required
shrinkage, debonding

22. Laboratory vs. Field Mortar
CANNOT COMPARE
field mortar
more water required (lost in evaporation or to masonry unit)
laboratory mortar
less water, lower initial flow
different curing conditions

23. Properties plastic properties hardened properties other properties
influence hardened properties
workability
initial flow
flow after suction
water retentivity
hardened properties
determine performance
bond strength
durability
extensibilty
compressive strength
other properties
color

24. Workability easily spread adhere to vertical surface
difficult to measure directly
no standard test or quantitative measure
indicators include flow, water retentivity, resistance to segregation
affected by properties of components

25. Flow (ASTM C109) cone formed on flow table
raised & dropped 25 times in 15 seconds
flow = ratio of increase in diameter

26. Water Retentivity (ASTM C91)
ability to resist loss of water to absorbent masonry unit
flow after suction (vacuum for 1 min)/ initial flow
low retentivity will bleed moisture unless brick has high suction (IRA)
high retentivity will create dry surface
low bond strength for low or high retentivity paired with average masonry unit

27. Bond Strength most important physical property
difficult to measure directly, simulate construction
Bond Strength
Suction (IRA)  
Air Content  
Elapsed Time  
Mortar Flow  
Brick Texture rough 
Retempering 
Pressure  
Movement after set 
Water Retentivity  
Max Bond
cement: lime
1:1 to 1:1/4
Type S mortar

28. Bond Strength

29. Other Hardened Properties
durability
not significant if properly prepared
no air-entraining components
extensibility
max et at rupture
elongation before cracking
lime contributes

30. Other Hardened Properties
compressive strength
f (cement content, w/c)
cubes (ASTM C109)
cylinders, briquettes
Proportion f’c
Cement  
Lime  
Water  
Flow  

31. Other Properties
color
colored aggregates - PREFERRED
colored pigment