2016 SEAoG Fall Seminar-Wilsonseaog.org/Wayne Wilson's presentation.pdf · ASTM C270 Portland Cement-Lime, a blended cementitious proportion of ASTM C150, C595 or C1157 hydraulic

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Masonry and Mortar Basics

9/29/2016© 2016 Holcim Ltd

Learning Objectives

After today’s program you will be familiar with:

1. Mortar Basics: Purpose Mortar making materials Mortar plastic and hardened properties

2. ASTM standards related to masonry mortar

3. Basic masonry terminology and good construction practice

4. Some Common Masonry Troubleshooting Issues Complaints Causes How to avoid


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What makes a good masonry wall?

4 Critical Factors for good masonry wall performance:

Wall Design (The Masonry Society):

• Masonry Design Code: TMS 402 / ACI 530 / ASCE 5• Masonry Specifications: TMS 602 / ACI 530.1 /ASCE 6• Masonry Specifier’s Guide

Masonry Units:

• National Concrete Masonry Association• Brick Industry Association• ASTM

Mortar

• ASTM

Workmanship

• Mason Contractors Association of America• Local Masonry Associations


Mortar Basics

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What is Masonry Mortar?

A mixture of cementitious materials, aggregate and water (possibly admixtures) used with masonry units to construct masonry assemblies.

Masonry and Mortar Basics © 2016 Holcim Ltd

Purpose of Masonry Mortars:

• Bonds units together and holds them apart.

• Seals joints against air and water penetration.

• Compensates for unit size variations.

• Bonds with joint reinforcement to create integral structural wall performance.


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ASTM C270, Specification for Mortar for Unit Masonry

Historically classified as:

Type M, S, N, O, & K

MASON WORK

Masonry Mortar Types:

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ASTM C270

Type M, Generally used in load-bearing and below grade applications: The strongest mortar Minimum Compressive Strength @ 28 days = 2500 psi

Type S, Generally used in commercial construction or were seismic design applications are required: Minimum Compressive Strength @ 28 days = 1800 psi

Type N, Considered a general purpose mortar, generally used in non-load bearing applications: Most common mortar for facing brick and residential construction Minimum Compressive Strength @ 28 days = 750 psi

Type O, Generally used for tuck-pointing and/or historical restoration: The weakest commercial mortar, often used where brick strength is a concern Minimum Compressive Strength @ 28 days = 350 psi

Type K, Abandoned for most practical use today: A very weak mortar, for special historical applications Minimum Compressive Strength @ 28 days = 75 psi


Standard Specification for Mortar for Unit Masonry

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Cementitious Materials used in Mortar

Portland Cement (ASTM C150)

Hydraulic Cement (ASTM C1157)

Blended Hydraulic Cement (ASTM C595)

Hydrated Lime (ASTM C207)

Masonry Cement (ASTM C91)

Mortar Cement (ASTM C1329)


Common Cementitious Mortar Types

ASTM C270 Portland Cement-Lime, a blended cementitious proportion of ASTM C150, C595 or C1157 hydraulic cement and ASTM C207 hydrated lime or lime putty, proportioned on-site (at the mixer) by the mason or pre-blended in bags.

ASTM C1329 Mortar Cement, a manufactured hydraulic cement meeting fineness, autoclave expansion, time of setting, compressive strength, flexural bond, air content and water retention requirements for M, S or N Mortar Cements.

ASTM C91 Masonry Cement, a manufactured hydraulic cement meeting fineness, autoclave expansion, time of set, compressive strength, air content and water retention requirements for either M, S or N Masonry Cements.


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Sand makes up approximately 75% of a mortar’s volume; so, the quality of sand greatly effects all the plastic and hardened mortar properties, like: workability, board life, compressive strength, drying shrinkage and color.

Should meet ASTM C144 “Standard Specification for Aggregate for Masonry Mortar”.

Aggregate, masonry sand...


Standard Specification for Aggregate for Masonry Mortar

Gradation or Size Deleterious Substances1% Max. Friable Particles0.5% Max. Lightweight Particles

Organic Impurities

SoundnessNot greater than 10% mass loss in a Sodium Sulfate wash or 15% for Magnesium Sulfate

Aggregate requirements in ASTM C144


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Water

Acts as a lubricant in plastic mortar.

Required for chemical hydration of the cementitious material.

Should be clean and potable.

Dirty, Lightweight andOrganic Particles


Plastic Mortar Properties:

Workability

Mason’s evaluation of how a plastic mortar performs during wall construction.

Board Life

Length of time a mortar retains its workability.

Water Retention

Reduction in flow (fluidity) of a mortar sample subjected to suction in the laboratory. Simulates the effect of absorptive units on mortar in a wall.

Air Content

Percentage of mortar volume made up of small air bubbles. Increases workability and water retention.


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Hardened Mortar Properties:

Compressive Strength

The compressive strength of mortar is not as important as in concrete.

Used to differentiate between mortar types (M, S, N & O). Generally not a direct indication of wall strength.

Durability

Resistance to freeze-thaw deterioration: higher strength and air entrained mortars offer greater freeze-thaw resistance.

Resistance to sulfate attack. Absorption: measure of how much the hardened mortar

will absorb. Reduce absorption by increasing cement content or using air entrained mortar.


More Hardened Mortar Properties:

Volume Stability

Drying Shrinkage, How much a mortar shrinks as it hardens. Can be reduced by reducing the mortar’s water content. For example, using a well-graded mason’s sand.

Appearance

Selection of mortar materials for uniform color and consistency (sand, cement and clean water)

Hardened mortar joint surface texture greatly effects apparent joint color shade and hue. Mortar texture is influenced by:

- Sand gradation

- Time of joint tooling

- Type of joint tool used

- Cleaning solutions and/or procedures


ASTM Standards and Specifications

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ASTM C270 Mortar Specifications

Proportion Specification, prescribes mortar proportions for each mortar type as parts by volume for each ingredient.

Property Specification, prescribes performance requirements for each type of mortar as tested under laboratory conditions with job specific materials and proportions. The laboratory established mixture is then used for construction in the field.


Two Methods for Meeting the Specification:

If neither specification is specified the proportion specification governs

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Proportion Specification

Proportions by Volume (Cementitious Materials)Portland Cement Masonry Mortar Hydrated Lime Aggregate Ratio

or Cement Cement orBlended Cement M S N M S N Lime Putty

M 1 --- --- --- --- --- --- ¼Cement-Lime S 1 --- --- --- --- --- --- over ¼ to ½

N 1 --- --- --- --- --- --- over ½ ro 1¼O 1 --- --- --- --- --- --- over1¼ to 2½M 1 --- --- 1 --- --- --- ---M --- 1 --- --- --- --- --- ---

Masonry S ½ --- --- 1 --- --- --- ---Cement S --- --- 1 --- --- --- --- ---

N --- --- --- 1 --- --- --- ---O --- --- --- 1 --- --- --- ---M 1 --- --- --- --- --- 1 ---M --- --- --- --- 1 --- --- ---

Mortar S ½ --- --- --- --- --- 1 ---Cement S --- --- --- --- --- 1 --- ---

N --- --- --- --- --- --- 1 ---O --- --- --- --- --- --- 1 ---

(Measured in a damp loose

condition). Not less than 2 1/4 and

not more than 3 times the sum of

separate volumes of cementitious

materials


Property Specification

Average Compressive Water Retention Air Content Aggregate RatioStrength at 28 days: Min., psi Min., % Max., %

M 2500 75 12Cement-Lime S 1800 75 12

N 750 75 14*O 350 75 14*M 2500 75 12

Mortar Cement S 1800 75 12N 750 75 14*O 350 75 14*M 2500 75 18

Masonry Cement S 1800 75 18N 750 75 20**O 350 75 20**

(Measured in a damp loose

condition). Not less than 2 1/4 and

not more than 3 times the sum of

separate volumes of cementitious

materials


* When structural reinforcement is incorporated in cement-lime or mortar cement mortar, the maximum air content shall be 12%.** When structural reinforcement is incorporated in masonry cement mortar, the maximum air content shall be 18%.

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Section 3. Specification Limits 3.1 – “Specification C270 is not a specification to determine

mortar strengths through field testing.”

3.2 – “…The property specification of this standard appliesto mortar mixed to a specific flow in the laboratory.”

3.3 – “The compressive strength values resulting from fieldtested mortars do not represent the compressive strength ofmortar as tested in the laboratory nor that of the mortar inthe wall. Physical properties of field sampled mortar shallnot be used to determine compliance to this specificationand are not intended as criteria to determine the acceptanceor rejection of the mortar…”

Comments from ASTM C270 on mortar strength...


ASTM C780 “Standard Test Method for Preconstruction andConstruction Evaluation of Mortars for Plain and Reinforced UnitMasonry”

• Section 1 Scope: 1.2 – “Preconstruction Evaluation – This test method permits

comparisons of mortars made from different materials undersimulated field conditions. It is also used to establish baselinevalues for comparative evaluation of field mortar.”

1.3 – Construction Evaluation – Use of this method in the fieldprovides a means for quality assurance of field-mixed mortar. Itincludes methods for verifying the mortar mix proportions,comparing test results for field mortars to preconstruction testing,and determining batch-to-batch uniformity.”

1.4 – “The test results obtained under this method are not requiredto meet the minimum compressive values in accordance with theproperty specification in C270.”

Field testing of mortar for strength...


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The following test methods may be singly or collectivelyincorporated into the testing to establish mortar composition, andmortar plastic and hardened properties:

Annex A1 - Consistency by Cone Penetration

Annex A2 - Consistency Retention of Mortars for Unit Masonry

Annex A3 - Initial Consistency and Retention of Board Life ofMasonry Mortar using a Modified Concrete Penetrometer.

Annex A4 – Mortar Aggregate Ratio Test

Annex A5 – Mortar Air Content

Annex A6 – Compressive Strength of Molded Masonry MortarCylinders and Cubes

C780 Methods of Testing...


ASTM C91, Laboratory Cubes w/ a graded silica sand.

3330 psi

ASTM C270, Laboratory Cubes w/ a field mason sand.

2490 psi

ASTM C780, Field Cubes tested right out of the mixer.

1800 psiASTM C780, Field Cubes tested after resting on the surface of a masonry unit for approximately 15 minutes.

2230 psi

A Compressive Strength Experiment with a Type S Masonry Cement


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ASTM C1314, Compressive strength of a 3 brick prism laid up with the C780 mortar right out of the mixer.

3350 psi


What does this mean for wall strength?

Good Construction Practice

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Mortar Mixing Basics

Mortar should be machine mixed for a minimum of 3 minutes and no more than 5 minutes maximum.

If mortar is mixed for less than 3 minutes or greater than 5 minutes, the mortar may:

- Be non-uniform

- Have poor workability

- Have low water retention

- Have less than optimal air content

- Have lower strength and/or durable properties

Charge mixer to full capacity for optimal mixing action.

Empty full contents of mixer so as to not impair subsequent batches.


Steps Proper Mixing Procedure1 Add ¾ of required water to an empty, clean mixer and start the mixer2 Add ½ the amount of sand required to the mixer3 Add any coloring pigments to the mixer (if applicable)4 Add lime to the mixer (if applicable)5 Add cement to the mixer:

• Portland Cement, Masonry Cement, or Mortar Cement6 Add remaining sand to the mixer7 If necessary, add remaining water to the mixer until proper consistency is achieved8 Mix for 3-5 minutes minimum

Mortar Materials Batching Sequence


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Maintaining Mortar Consistency

• Fresh mortar should be prepared at the rate its needed.

• Control moisture loss on dry windy days by:

Keeping mortar boards moist.

Covering mortar tubs or wheelbarrows with plastic.

Keep mortar materials cool.

• Try to keep the same person in charge of mixing all the mortar.

• Keep mixing area clean and avoid material contamination.

• Keep sand pile covered to better control material moisture.

• Use a cubic foot sand box, or other uniform measuring container…


• A stiff non-workable mortar often times can be “restored” by adding a small amount water on the mortar board, this process is commonly refereed to as: re-tempering.

• Mortar older than 2 ½ hours should not be re-tempered.

• Thoroughly remix mortar after adding water.

• Small water additions will increase the mortar w/c ratio and slightly reduce mortar strength.

• Building walls with a workable, plastic mortar (instead of a dry, stiff mortar) will: Have better bond strength between the mortar

and masonry units. Be more resistant to water penetration. And will likely not prematurely dry out after

being laid in the wall

• Not recommended for colored mortar


Mortar Re-Tempering...

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Colored mortar should not normally be re-tempered as color is very sensitive towater content – any extra water tends tolighten the mortar color.

If absolutely necessary, re-temper with caution.

Better to plan accordingly so re-tempering is not required.

Mortar should be mixed only as needed to eliminate the need for re-tempering


Considerations for colored mortar

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Masonry Units

Concrete Masonry Units

Should be dry at time of wall construction.

Should never be wetted immediately before or during wall construction.

Units shrink when they dry - could cause drying shrinkage cracks in the masonry wall

Clay Masonry Units

Protect at job site to prevent uneven wetting and accumulation of dirt.

It may be desirable to wet high IRA (initial rate of absorption) units prior to laying them in the wall.


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Special pre-caution for plastic shrink wrap...

Use common sense and be observant when clay orconcrete units are delivered and/or stored with plasticshrink wrap…

If units were not manufactured and stored in a dryenvironment, removal of wrap once delivered toconstruction site may be required to promote drying.


• Hot weather reduces board-life of mortar and increases evaporation rate

• Cold weather threatens freezing of the mortar before adequate strength is obtained

• Wet weather can cause wet units and sand sacrificing strength in the mortar and the bond

• Cover new construction to protect the masonry assembly from the elements to promote better curing of the mortar.

• Cure mortar a minimum of seven days before cleaning.

• Take special precautions in either “cold” or “hot” weather

Pre-heat and/or cool mortar materials. Protect masonry units from extreme cold or hot

weather, i.e. ice or storage in direct sunlight… Protect new construction from extreme temperatures,

i.e. freezing or drying out due to heat…

Jobsite Protection & Weather


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• Tooling a mortar joint creates a neat finished appearance and helps to make the joint “water tight”.

• Different joints offer a wide range of architectural looks or appearance in a finished wall.

• Concave or Vee joints are best at resisting water penetration.

• Timing is critical for a uniform finish and appearance.

• Generally, tooling can be done when mortar is thumb-print hard.

• Do not tool at different time intervals after placement as this can cause inconsistent color and texture.


Finishing a Mortar Joint

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• Cure assembly 7 days before cleaning• Protect other parts of the structure• Use appropriate cleaning solution for

masonry unit and mortar.• Avoid using acids.• Pre-wet wall, apply cleaner and completely

rinse after cleaning.• Clean top down in small manageable

sections, don’t over reach!• Use plenty of water, 6-8 gallons per minute

and limit water pressure to 400 to 1000 psi.• Test section is always a good idea.

Cleaning Finished Masonry


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Troubleshooting Masonry Problems

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• With masonry construction, attention to ambient conditions and construction practices will produce beautiful and durable results.

• As with any form of construction; however, variations in weather or lack of attention to detail will affect the final product.

• Most common complaint usually involves an aesthetic issue related to appearance and/or COLOR.

• Strength issues related to field testing are second most common.

• The following slides illustrate some commons problems that we have seen in the field.

9/28/2016Masonry and Mortar Basics

Masonry Troubleshooting

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Non uniform brick moisture

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Joint surface texture, wet & dry tooling

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Joint Tooling with wet, normal & dry brick

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Rain infiltration & effloresence

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Wet constrution with effloresence

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Workmanship, mortar shading...

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Joint surface texture, pressure washed surface

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Joint surface texture, pressure washed surface

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Pressurer washer burn

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Cleaning, acid stains

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Cleaning, acid stain mortar & brick

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Cleaning, acid stain mortar & brick

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Cleaning, improper post-rinse

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Holcim Product Line

• ASTM C91 Masonry Cement, Types N, S & M

• ASTM C1329 Mortar Cement, Type S

• ASTM C270, Cement-Lime, Type O, N, S & M

• +/- 45 Stock Colors, 900+ Colors on File

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Strength. Performance. Passion.

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Holcim Rainbow Product LineHolly Hill, SC

2016-08-26 © 2016 Holcim Ltd

Rainbow Product Line(commercial kit)

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Rainbow Product Line (restoration kit)

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Rainbow Lab QC

• Wet Paste Samples

• Color Spectrophotometer

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Rainbow Lab Customer Support

• Custom Color Match

• Sample Channels

• Test Panel Samples

Thank you for your attention!

Comments, Questions?

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My Contact Information:

Wayne M Wilson, PE

Senior Technical Service Engineer

LafargeHolcim (US)

1000 Peachtree Industrial Blvd., Ste. 6, #281

Suwanee, GA 30024

(770) 789-3254

[email protected]

2016-08-26 61

Documents

2016 SEAoG Fall Seminar-Wilsonseaog.org/Wayne Wilson's presentation.pdf · ASTM C270 Portland Cement-Lime, a blended cementitious proportion of ASTM C150, C595 or C1157 hydraulic