masonry cement and mortar
TRANSCRIPT
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 1/31
1
Lecture #18
Masonry Cement and Mortar
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 2/31
MORTAR
• binder = mortar
• Masonry = mortar + masonry units
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 3/31
MORTAR
• definitions
• differences w/ other cementitious
mixtures
• classes
• components
• types
• properties
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 4/31
MORTAR
• cementitious
materials
– lime – portland cement
• sand
• water
• used with individual
masonry units
– bonding – bedding / seating
– leveling
– sealing irregularities
– providing strength
– providing aesthetic qualities
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 5/31
MORTAR
• weak link in masonry
construction
• thin layer stronger
(compression) than thick
layer
• lime added
– workability
– adhesive properties – extensibility
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 6/31
GROUT• cement
• fine and coarseaggregate
• sand
• water
• high slump
• no segregation
• used to bond two masonry
wythes together (walls one unitthick)
– filling cores and voids
– binding reinforcing steel and
wythes
– providing load carrying capability
• ASTM C476
• fine and coarse grouts f’C - lessin non-absorbent molds
– match with masonry f’C
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 7/31
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
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 8/31
8
Differences w/ other cementitious
mixtures• structural performance
– PCC is structural material, resists mainly compressive
stresses
– mortar, grout are binders, develop strong & durablebond 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
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 9/31
9
Classes• lime mortar
– lime, sand, water
– slow strength gain
– calcium carbonate
formation – seldom used in
permanent construction
• cement/cement-lime mortar
– cement, lime, sand, water
– most common
• masonry cement mortar – proprietary ingredients
– workable
– low bond strength, not
durable - most commonly
used but least desirable
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 10/31
10
Components• portland cement
– 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
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 11/31
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
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 12/31
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
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 13/31
13
Components• aggregates
– natural or manufactured – gradation (ASTM C144)
Amounts Finer than Each Laboratory sieve (Square Openings),
Weight %
Fine Aggregate Coarse Aggregate
Mortar or Grout
Sieve size
Grout Natural Manufactured
Size No. 8 Size No. 89
½ -in (12.5-mm)
3/8-in (9.5-mm)
No. 4 (4.75-mm) No. 8 (2.36-mm)
No. 16 (1.18-mm)
No. 30 (600-m)
No. 50 (300-m)
No. 100 (150-m)
No. 200 75- m
…
100
95 to 10080 to 100
50 to 85
25 to 60
10 to 30
2 to 10
…
…
…
10095 to 100
70 to 100
40 to 75
10 to 35
2 to 15
…
…
…
10095 to 100
70 to 100
40 to 75
20 to 40
10 to 25
0 to 10
100
85 to 100
10 to 300 to 10
0 to 5…
…
…
…
100
90 to 100
20 to 555 to 30
0 to 10
0 to 5…
…
…
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 14/31
14
Components
• water – clean
– potable
– free of deleterious
materials
• acids
• alkalies
• organic materials
• admixtures – color
– workability
– reduced water
penetration
– accelerated curing
– use w/ caution – air-entraining
– chlorides
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 15/31
15
Types (MASONWORK)• ASTM C270
– 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
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 16/31
16
Types (MASONWORK)
• Type S (structural masonry, reinforced brick) – high strength
– reinforced masonry
– areas subject to high wind
• Type N (normal, common)
– high strength
– general use
– below grade OR in contact w/ ground
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 17/31
17
Types (MASONWORK)
• Type O (interior) – low strength
– non-bearing applications
– not subject to severe weathering
• Type K (restoration)
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 18/31
18
Types (MASONWORK)• Proportion Specifications
Proportion by Volume (Cementitious Materials)
Masonry CementMortar Type
Portland
Cement or Blended
CementM S N
Hydrated Limeor Lime Putty
Aggregate Ratio
(Measured inDamp, Loose
Condition)
Cement-Lime M 1… … …
¼
S 1 … … … Over ¼ to ½
N 1 … … … Over ½ to 1 ¼
O 1 … … … Over 1¼ to 2 ½
Masonry Cement M 1 … … 1 …
M … 1 … … …
S ½ … … 1 …
S … … 1 … …
N … … … 1 …
O… … …
1…
Not less than
2¼ and notmore than 3
times the sum
of the separate
volumes of Cementitious
materials.
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 19/31
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)
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 20/31
20
Types (MASONWORK)• Property Specificationsa
Mortar Type
Average
Compressive
Strength at 28 Days,
Min. psi (MPa)
Water Retention,
min, %
Air Content,
max, %
Aggregate Ratio
(Measured in
Damp, Loose
Condition)
Cement-Lime M 2500 (17.2) 75 12
S 1800 (12.4) 75 12 N 750 (5.2) 75 14
b
O 350 (2.4) 75 14 b
Masonry Cement M 2500 (17.2) 75 …
c
S 1800 (12.4) 75 …
c
N 750 (5.2) 75 …
c
O 350 (2.4) 75…
c
Not less than 2¼
and not more
than 3½ times the
sum of the
separate volumes
of cementitious
materials
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%.
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 21/31
21
Selecting Mortar Types• considerations
– structural
requirements
– exposure
– wall type
– workability
• no single type for all
purposes
• DO NOT change mortar
types within samestructure
– uneconomical
• NEVER use mortar
stronger in compression
than required
– shrinkage, debonding
– uneconomical
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 22/31
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
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 23/31
23
Properties• plastic 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
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 24/31
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
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 25/31
25
Flow (ASTM C109)• cone formed on flow table
• raised & dropped 25 times in 15 seconds
• flow = ratio of increase in diameter
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 27/31
27
Bond Strength• most important physical property
• difficult to measure directly, simulate construction
Bond Strength
Max Bond
• cement: lime
1:1 to 1:1/4•Type S mortar
Suction (IRA)
Air Content
Elapsed Time
Mortar Flow
Brick Texture rough Retempering
Pressure
Movement after set
Water Retentivity
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 29/31
29
Other Hardened Properties
• durability
– not significant if
properly prepared
– no air-entraining
components
• extensibility
– max et at rupture
– elongation beforecracking
– lime contributes
7/28/2019 Masonry Cement and Mortar
http://slidepdf.com/reader/full/masonry-cement-and-mortar 30/31
30
Other Hardened Properties• compressive strength
– f (cement content, w/c)
– cubes (ASTM C109)
– cylinders, briquettes
Proportion f’c
Cement
Lime
Water
Flow