4.2
Construction Science 253 with Segner at Texas A&M University
About this deck
By: Daniel Gandy
Created: 2011-12-11
Size: 90 flashcards
Views: 20
Created: 2011-12-11
Size: 90 flashcards
Views: 20
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Mortar definition
One or more cementitious materials
Clean, well graded agg
Enough water for workability
Grout definition
Used to fill voids in reinforced and unreinforced masonry
Same ingredients as mortar, just in a pourable consistency
Second type: tile-setting grout used in filling joints in unit masonry or stone/floor paving
What does mortar do?
Provides level setting bed for units
Seals spaces between units
Compensates for size variations in units
Provides esthetic qualities w/ color effects and shadow lines
Grip metal ties and reinforcement
What does grout do?
Produce solid filled and reinforced masonry walls
Where is grout poured?
Between masonry unit wythes
Into the cores in hollow masonry units
Grip metal ties and reinforcement
When is mortar workable?
Particles in mix don't segregate
Spreads easily
Holds unit weights
Makes alignment easy
Clings to vertical surfaces of units
Easily extrudes from joints w/o dropping or smearing
What affects mortar workability?
Water retention
Flow
Resistance to segregation
NO STANDARDS FOR WORKABILITY
Water retention
Prevents rapid loss of water/plasticity when mortar or grout contacts unit w/ high absorption rate
Prevents bleeding
Bleeding
Process in which water leaves mortar and is deposited in a thin layer between the unit and the mortar
Float
When water is between a masonry unit and mortar
Reduces bond
Flow
Ratio of plastic characteristics after mixing and characteristics after suction
More water = more flow
Initial flow
Flow immediately after mixing
Measuring initial flow
Truncated cone of mortar 4" in diam. is placed on flow table
Flow table raised and dropped 25 times in 15 seconds w/ height of 1/2"
Mortar flows outward
Ratio of final diameter to beginning diameter as %
What must initial flow be?
110%, plus or minus 5% for water retention/compressive strength
ASTM C270
Flow after suction test
Used to predict theoretical flow of a mortar units after it has lost water to absorption
Sample of mortar for first test is placed over absorbent filter in metal dish mounted over vacuum device
Vacuum removes some moisture
Tested for flow in same way
What is the laboratory value of water retention?
Ratio of flow after suction to initial flow
Answer multiplied by 100 then expressed as %
(A/B) x 100
What is required water retention for flow after suction test?
No less than 75%
ASTM C270
Properties that affect bond strength
Type and Amt. of cementitious mats.
Workmanship
Units mortar contacts
Amt. of water in mix
Water retention
Air entrained content
Compressive strength
Air temp. and humidity during curing period
Mortar's tensile bond strength function
Mechanical, not chemical
Bond strength ______ as mortar flow ________
Increases, increases
Wetter mortar flows better into pores
Masonry unit characteristics than can affect bond
Suction
Surface texture
MC
How does workmanship affect bond?
If unit is moved after it's laid
Water on surface of clay masonry
Delay in laying masonry after placement of mortar
How is durability of mortar measured?
In ability to resist water penetration
What will repeated freeze/thaw cycles do to surface?
Spalling
Efflorescence
When water enters unit and dissolves salts that crystallize on exterior face of a wall
Unsightly but do no harm
Cryptoflorescence
When crystallization occurs within a wall
AKA subfloresnce
Causes damage
Causes spalling after many wetting/drying periods
Affects on mortar durability regarding entrained air
Increases durability but decreases bond strength and other props.
Okay on masonry cement
Not recommended on PC-lime mortar
Properties that affect compressive strength
Amt. of PC in mix
Flow
What kind of mortar strength should be used in normal construction
No higher than moderate
What is more important than compressive strength in mortar?
Bond strength
Workability
Water retention
How extensive is mortar shrinkage?
You can't even see it if properly tooled joint is used w/ good mortar
Where are cracks in masonry normally found?
Between the mortar and unit
Especially in vertical joints
What is rate of hardening? (mortar/grout)
Speed at which mortar/grout develops resistance to indentation and crushing
If done correctly, allows mason to tool joints at same hardness and obtain uniform joint color
Factors other than materials used that can affect uniformity of color
Atmospheric conditions
MC of units
Admixtures used
Control exercised over mixture
Timing of tooling joints
Sand-Lime Mortars
Hardly used except for renovation work
Not suitable for grout
Harden at slow, variable rate
Low compressive strength
Poor durability in freeze/thaw cycles
High workability
High water retention
Cracks healed in hardening process
Portland Cement Mortars and Grouts ingredients and characteristics
PC, Sand, Water
Harden quickly
High compressive strength
Good durability
Workability and water retention low
Grouts in installation of ceramic veneer in architectural terra cotta
Not permitted in engineered unit masonry walls
Portland Cement-Lime Mortars and Grouts ingredients and characteristics
PC, lime, sand, water
Widely used
Combines advantages of PC and lime and gets rid of disadvantages
Produces most predictable mortars and grouts
Ready-mixed PC-lime mortars available
What does PC contribute in PC-lime mortars & grouts?
Durability
High early strength
Consistent rate of hardening
High compressive strength
Bond strength
What does lime add to PC-lime mortars and grouts?
Workability
Water retention
Plasticity
Bond strength
Water in PC-lime mortars and grouts
Mixing vehicle
Creates plastic workability
Initiates cementing action
Sand in PC-lime mortars and grouts
Filler
Makes mix economical
Strength
Masonry Cement Mortar
Uses masonry cement
Sold in one bag w/ all ingredients inside
Masonry Cement Mortar advantages
Readily available
Convenient to mix
Produces mortar w/ good workability
Masonry cement mortar disadvantages
No standard on ingredients and proportions w/ ASTM C91
Unpredictable reliabilty
Not recommended for reinforced masonry or masonry subjected to heavy loads
Masonry cement
ASTM C91
Available w/ color pigments added at factory
Makes uniformity a lot easier
Often selected for architectural projects for that reason
Air content can't exceed 22%
Should be limited to 12%
Quicklime
ASTM C5
CaO
Slaked to consistency of putty
Stored for 2 weeks
Only used in preservation work
Hydrated lime
ASTM C207
Quicklime that's been slaked before packaging
Calcium hydroxide or CA(OH)
Mixed and used without delay
Types S and N
Air entraining available, but not suitable for mortars and grout
Aggregates
Aggs in masonry MUST comply w/ ASTM C144
Aggs in grout MUST meet ASTM C404
Characteristics of masonry aggregates
Clean
Sound
Well graded
Manufactured aggs
Ground stone
Agg affect on mortar/grout
BIG effect on workability and durability
Agg mortar sizes
Up to 1/4"
Large particles in mortar agg
Aggs w/ less than 5% very fine particles have low workability
Aggs w/o some large particles result in weaker mortars
Aggs for joints narrower than 1/4" wide
95% pass through No. 16 sieve
100% pass through No. 8 sieve
Agg gradation for stone joint-pointing mortar
Very fine
Nothing retained in No. 16 sieve
Agg gradation for grout
Determined by size of grout space and height of pour
Divided by ASTM C476 into two separate categories
Aggs controlled by ASTM C404
Agg in ceramic veneer
Pea gravel
Agg that is uniformly graded 1/4" and below that will pass through no. 8 sieve
ASTM C404
Water in mortar/grout
No acids, alkalis, and organic mats.
Potable
In what ways is mortar colored?
Controlling ingredients (preferred)
Adding pigments
Colored agg mortar
White or gray PC
Aggs are ground stone
Limit on colors
Colored Pigmented mortar
Pigments must be added in field
Minimum quantity of pigment produces best results
Organic pigment avoided
Premixed with PC in large controlled quatities
Pigment mats.
Metallic oxides like
Iron
Manganese
Chromium oxides
Carbon black
Ultramarine blue
Limits on mineral oxides pigment
10% in PC-lime
5% in masonry cement
2% carbon black in PC-mortar
1% carbon black in masonry mortar
ASC 530.1/ASCE 6/ TMS 602
Admixtures in masonry/grout
Color pigments
Air-entraining agents
Water-repellant agents
Accelerators
Retarders
Antifreeze compounds
Admixtures limitations
Chlorides not allowed in both (ASC 530.1/ASCE 6/ TMS 602)
No antifreeze compounds in grout (ASTM C476)
Additives will discolor/harm stone so they shouldn't be used. Latex and pigments
Type M Mortar
HIgh-strength
Recommended for unit masonry and stone
Also used in reinforced masonry and where large load will be applied
Also used for walks, sewers, and manholes in paving installations
Type S Mortar
Medium-high strength
Recommended where bond and lateral strength are more important than compressive
Recommeded in reinforced masonry and unreinforced where max. flexural strength req.
Setting beds for granite, marble, and slate in other than paving installations
Type N mortar
Medium-high-strength
Recommended for general use in exposed masonry above grade where comp. and lateral strength aren't factors
Used for chimneys, parapet walls, and ext. walls subject to severe exposure
Used to set limestone except for paving
Type O Mortar
Low-strength mortar
Only suitable for interior use in non load bearing masonry and tuck pointing
Never used in freezing conditions
Basic rule for selecting mortar
Never select mortar that is stronger in compression than necessary
Basis for selection of mortar type for each unit masonry
Masonry type
Location
Additional info about selection of mortar types
BIA's Technical Notes on Brick Construction
Technical notes No. 8 "Mortars for brick masonry"
8A "Standards Specifications for Portland Cement-lime mortar for Brick Masonry, BIA Designation M1-88"
"Mortar for Brick Masonry - selections and controls"
Mortars for cavity walls
If wind will exceed 80 mph, Type S
Either can be used in lower velocities
Mortars for facing tile
Aggs must pass through No. 16 sieve (1/16")
Facing tile often laid w/ 1/4" thick joints
Additions to masonry mortar for medium dirt resistance
Aluminum tristerate
Calcium Stearate
Ammonium stearate
Limited to 3% weight of mix if no code
Additions to masonry mortar for maximum dirt resistance
Mortar raked to 3/8"
Joints pointed w/ 1 part pc, 1/8 pt lime, and 2 pts. finely graded sand
Aluminum tristerate, Calcium Stearate, Ammonium stearate added to 2% weight of mix
Tuck-Pointing
Refilling of an existing joint from which some of the mortar has been removed
Must be pre hydrated
Same ingredients as original mortar
Use N if type unknown
Pre hydration process
Ingredients thoroughly mixed w/o water
Mixed again and adding enough water to make unworkable compound
After 1-2 hrs., enough water is added to make it workable
Used immediately
How to place 2 different mortars in same joint
Lay unit masonry like normal
Then rake back the joints about 1/2" and point them w/ new mortar
Proportion for adhesion-type ceramic veneer
1 part PC
1/2 part lime putty or hydrated lime
4 parts sand
Grout Proportions
1 part PC
1/10 part hydrated lime or lime putty
Damp, loose, fine aggs between 2-1/4 and 3 times the volume of cementitious mats.
Grout in anchored type ceramic veneer should have
1 part PC
1 part sand
5 parts pea gravel
Water in mortar/grout mixing
Mortar should be mixed w/ max. amt. of water possible
As long as its not soupy
Grout Mixing
Enough water for 8-11" slump
Retempering shouldn't be nec.
Used 1.5 hrs after mixing
Terms of ingredients
Ingredients can be added by volume or weight
ASTM does it by weights per cubic foot of mortar ingredients
Oversanding of mortar
Happens when sand measured by shovel
Harsh and unworkable, weak bond, erodes
Measurements for sand based on BIA "Mortar for Brick Masonry - Selection and Controls"
Machine Mixing
Mortar mostly machine mixed unless it's small project
Grout always machine mixed
Water added slowly until proper consistency reached
After all ingredients added, let is mix for min. 3 to max. 5 minutes
Empty drum before next load
Hand mixing
Sand first spread in box
Cementitious mats. on top of sand
Ingredients mixed w/ hoe from both ends of box
3/4 of water added until mix is uniform
Water added in mall amounts and mixing continues until workability reached
Batch allowed to sit for 5 min then remix w. hoe
Cold Weather Mixing
Temp of mortar grout at placement should be 70-120 when outside temp is below 40
Mixing water not above 160
Flash set can occur
Sand heated slowly and carefully to prevent scorching
Don't use antifreeze units
Retempering
Not allowed in deep south
Reduces bond comp. strength, but no retempering causes lower bond strength
Replace evaporation water
You can't place mortar 2-1/2 hrs after initial mixing regardless of retempering or not
No mortar used after its set
Change in time between spread and placement of masonry
Affects flow
Especially w/ high suction
Lowest time is optimal
Varying this time limit along a wall will vary bond strengths
About this deck
By: Daniel Gandy
Created: 2011-12-11
Size: 90 flashcards
Views: 20
Created: 2011-12-11
Size: 90 flashcards
Views: 20
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“Simply amazing. The flash cards are smooth, there are many different types of studying tools, and there is a great search engine. I praise you on the awesomeness.”
Dennis
Dennis