Slide 1

Bricksand

Mortar

Slide 2 Mortar Cushions the masonry units (MUs) Gives the MUs full bearing against one

another despite surface irregularities Acts a seal to prevent wind and water

penetration Adheres MUs to one another to form a

monolithic structure Important to the appearance of the

finished masonry wall

Slide 3 Mortar Composition

Historic: hydraulic lime, sand, water Modern: Portland cement, pure lime,

sand, water Additions to mortar: Pigments for colors Larger aggregate particles for texture

Slide 4 Shells were the source of lime

-- Gathered from middens

-- Burned in ricks (layers of shells & wood), forming quicklime

Slide 5

1. Burning shells [CaCO3, calcium carbonate] makes quicklime [CaO, calcium oxide] .

2. When water is added (slaking), quicklime becomes hydrated (slaked) lime [Ca(OH)2, calcium hydroxide].

3. Over time, hydrated lime absorbs carbon dioxide (CO2) from the atmosphere, changing back to calcium carbonate => leads to increased durability.

Burning

Slide 6 Hydraulic vs. Non-Hydraulic Lime

Hydraulic lime sets when in contact with water or atmospheric moisture. It also sets by combining with atmospheric carbon dioxide to some degree. It sets faster than non-hydraulic lime. Non-hydraulic (pure) lime does not set in the

presence of water. It sets by combining with carbon dioxide in the atmosphere to turn back into chalk or limestone (i.e., it has to air dry).

Slide 7 Hydraulic Lime

Obtained from calcium carbonates (some limestones, shells) which contain impurities When burned in a rick to form

quicklime, the impurities plus the wood ash create the calcium silicates or aluminates that react with water, causing it to set

Slide 8 Non-hydraulic (Pure) Lime

Made from pure calcium carbonate (limestone or chalk) When burned in a kiln to form

quicklime, no calcium silicates or aluminates are formed; thus, it will notset in water This is the lime used in modern mortars

Slide 9 Hydrated Lime (Calcium Hydroxide)

Can be either hydraulic or non-hydraulic Produced when quicklime is slaked with a

minimal amount of water, producing a powder Add more water, and it becomes lime putty or

slurry Non-hydraulic lime putty can be stored Hydraulic lime putty sets up too quickly to be

stored

Slide 10 Portland Cement Mixture of oxides of calcium, silicon, alumina,

and iron (limestone, clay, sand)

Slide 11 How Portland Cement is Manufactured

Ingredients are crushed, ground, proportioned, blended, fired at 2600°-3000° F creates clinker After cooling, gypsum is added to retard curing Product is pulverized to powder finer than flour When water is added, it cures to a hard,

durable, impervious solid. Portland cement supplies hydraulicity to modern mortars.

Slide 12 History of Portland Cement 1824: Patented in Great Britain by Joseph

Aspdin, bricklayer Named after Portland limestone, quarried on

the Isle of Portland in Dorset, England

Slide 13 First Portland cement manufactured in the US

by David Saylor in 1872 in Coplay, PA Portland cement was imported from Great

Britain until 1885, when U.S.-manufactured quantities exceeded British imports Used primarily as an additive to shorten set

time through 1920s By 1930s, Portland cement was used in equal

parts with lime putty for mortar

Slide 14 Portland cement is today used as an

ingredient in mortar as well as concrete Manufacture of Portland cement requires

the burning of large quantities of fuel, typically coal, which along with impurities contained in the limestone can result in significant emissions of pollutants, i.e., it is NOT a GREEN substance!

Slide 15

Slide 16 The mortar should always be weaker than the masonry, so that if anything has to fail, it is the new mortar, which

is expendable.It is easier and less

expensive to replace the mortar than the masonry units.

Weaver, pp. 135-136

Slide 17 Advantages of Lime-based Mortar over

Cement-based Mortar

Is produced at lower temperatures than cement; therefore less energy is required to manufacture lime mortar, resulting in 20% less CO2 output. Lime putty absorbs CO2 in the curing

process. Non-hydraulic lime absorbs nearly its own weight in CO2; hydraulic lime, around 75% and lower.

Slide 18 Can be re-cycled, unlike cement Strong, flexible, permeable Bricks using lime mortar can be recycled

unlike the cement-bonded bricks which can only be used for hardcore — the pieces of broken stone, brick, etc. used to make the base under a floor, path, or road.

Slide 19 Traditional buildings built using lime

mortar move and absorb moisture because the lime mortar 'moves' with the structure and so prevents masonry from cracking. No expansion joints are needed. Cement mortar is rigid; may require

expansions joints to prevent cracking of the masonry.

Slide 20 Cement mortar is impervious, which

prevents it from absorbing water from the surrounding masonry. Lime mortar wicks up moisture from the

surrounding masonry, and allows it to evaporate. Lime mortar keeps the masonry dryer and lessens the risk of spalling.

Slide 21 Advantages of Cement-based Mortar over Lime-based Mortar

Stronger Sets quicker Good to use in areas of damp, or below

grade Good to use in areas that carry heavy

loads, e.g. arches

Slide 22 Lime-based vs. Portland-based mortars: Traditional vs. Modern

Huge variations in limestones – could be surprised with result Limes could be poorly mined, burned, and slaked;

Portland offers a predictable premix Making traditional mortars is like making biscuits or

cornbread – there are countless recipes, varieties of ingredients, and production conditions – it was not an industrialized and regulated process.

Slide 23 Mortar Joints

Vary in thickness from ¼” to ½”; most common are ⅜” and ½” Joints are tooled 1-2 hours after laying

the masonry units Gives neat appearance Some joint profiles can provide weather-

resistance

Slide 24

Common Joint

Profiles*

* = more weather resistant

*

Slide 25

http://www.endicott.com/pdf/endicottBrickDetails.pdf

Slide 26

St. John’s Lutheran Church Sanctuary, Atlanta, GA, Architects Barker & Cunningham, 1969

Beaded Mortar Joint

Mistakenly called

“grapevine”

Slide 27 Kew Palace, Surry, England, 1631

Adam ThoroughgoodHouse, Norfolk, VA, 1680s

Slide 28 Colored Mortar White Mortar

Colored mortars are generally weaker than white mortar!

Slide 29

Penciling

Mixture of chalk, glue, and water painted on top of the mortar joints to improve their appearance or strengthen the joints

Valley View, ca.1848, Cartersville, GA

Slide 30 Mortar Joints — the weakest link

Water accumulates in the joint Efflorescence of water-soluble salts Spalling, especially from freeze/thaw cycle Dissolves the lime out

Clay and other impurities can cause mortar to crumble

Slide 31 BRICK

Made of local clays and shale (historic brick usually 70% clay and 30% shale) 2007: began making bricks using fly-ash, a

by-product from coal-burning power plants Hand-size Less likely to crack during drying and firing Easier to manipulate

Slide 32 Additives to Brick Clays

Manganese and barium added to make the clay hold different shapes Barium carbonate added to improve

weather-resistance Flux (glass or sand containing colorants)

added to produce surface textures or colors

Slide 33 Changes to Brick Surface

Surface may be brushed, rolled, cut, scratched to roughen the surface Surface may be stamped to produce a

specific pattern Brick may be tumbled before or after

firing to produce “antique” finish Surface may be coated with ceramic

glazes to produce colors or a shiny surface

Slide 34 Making Bricks

1. Grinding the clay in a pug mill2. Forming the brick Soft mud process (oldest) — relatively moist clay

pressed by hand (later machine) into a mold, or extruded from a press Stiff mud process — clay passed through a vacuum

(to remove air), then extruded through a rectangular die and wire cut into bricks Dry press — small amount of water added to the

clay then pressed into steel mold under pressure (good for clays with low plasticity)

Slide 35 Making Bricks, cont.

3. Drying the formed bricks Dried for several days Turned Then dried for about two weeks

4. Firing Glazed first, then fired, may be re-fired]

5. Controlled cooling

Slide 36 Molding Bricks

Water struck (aka slop molding) —wood mold is soaked with water Sand struck — wood or metal mold is

wet with water, then coated with sand Or, the brick is roughly formed, coated

with sand, then put into the wet mold

Oiled — metal mold is coated with oil

Slide 37

Slide 38 Brick Technology

http://asslh.org.au/hummer/the-hummer-vol-9-no-1-2014/bricktechnology/

Slide 39

Handmade bricks

The brick (top left) is the famed Savannah Gray, and was made my slaves in the 1800s. The fingerprints are thought to be from a slave. http://www.alexbeephoto.com/trip-to-savannah/ Handmade bricks (bottom right) at the Salzburgers Jerusalem Lutheran Church in Ebenezer, GA, built in 1769. http://savannah.for91days.com/tag/lutherans/

Slide 40 Fired Brick Clinkers (closest to the fire) — overburned,

distorted, unsuitable as exposed brick Bricks near fire — burned but not distorted,

good exterior facing bricks, more weather-resistant Bricks further from fire or lower in the kiln —

softer, used on interior walls, good insulation, “salmon” bricks Bricks on perimeter — not fired sufficiently for

any use, discarded

Slide 41

Historic bricks were fired at lower temperatures (around 1500°-1800°F) compared to the much higher temperatures achieved in modern kilns (up to 2400°F) Salmon bricks fired at around 850°F

Firing Brick

http://www.colonialwilliamsburg.com/plan/calendar/firing-brick-kiln/ Colonial Williamsburg's "brick gang" hand-molds as many as 20,000 bricks each season. The bricks are used in construction projects throughout the town.

Slide 42

Incompletely fired brick with

“salmon” interior

Slide 43 Unevenly fired and burned bricks — used on an interior wall of the basement. Still structurally sound but not attractive for an exterior use.

Attic of Rebekah

Slide 44 Clinkers as design features

Brick wall with clinkers, http://www.flickr.com/photos/ottonomy/2637706217/ Clinker bricks are formed during the firing process when wet bricks are placed too close to the heat source. Originally, clinkers were discarded because of their dark, uneven color, and their odd shapes made them difficult to lay in even rows. Later, during the Arts and Crafts movement of the early 20th century, architects and builders were drawn to their interesting earthy texture and colors and often incorporated them into their designs. Clinkers—from the Dutch word “klinken” meaning “sound”—were so named because when tapped they make a distinctive clear sound. Anacortes, WA house, ca. 1910: http://museum.cityofanacortes.org/AHPB/documents/FindItClinkerBrick.pdf

Slide 45 Serpentine/ribbon/crinkle-crankle walls use 25% fewer bricks and their curved shape increases lateral stability so they can be built one wythe thick. Used for centuries in England, Thomas

Jefferson introduced them at the University of Virginia ca. 1820.

Slide 46

http://www.endicott.com/pdf/endicottBrickDetails.pdf

Slide 47 Brick Veneer Examples

Types of ties: http://www.advancedbuildingproducts.com/clientsuppliedcontent-forms/BIATechNoteTextPDFs/Tech%20Note%2028.pdf Veneer over backup walls: http://www.aecinfo.com/1/company/05/39/29/cadlist1051_1.html

Slide 48 Types of

ties / anchors

http://www.endicott.com/pdf/endicottBrickDetails.pdf Seismic anchor: http://www.pinehallbrick.com/userfiles/TN28B_000.pdf

Slide 49 Installing an accordion anchor

Hammering an accordion tie into place: http://www.diyadvice.com/diy/patios-walls/masonry/brick-veneer-house-wall/ Unit ties with mortar laid over: http://mymason.ca/chimney-repair-Ottawa.html

Slide 50 Brick veneer construction using metal ties

Slide 51

Diaper Pattern — surface decoration (carved, painted, or created by placement of

stones/bricks/tiles) generally square or diamond shape,

often containing other simple figures (e.g., flower, leaves). The pattern is repetitive and is usually based on a grid.

Alexander-Withrow Building, ca. 1789, Lexington, VA

Decorative Brick Patterns

Slide 52 Diaper patterned brick on GSU campus

1925 Kell Hall

Slide 53

Brick details from Server Hall, Harvard University, Boston,

MA.

Specially shaped bricks create voids

Herringbone brickwork —bricks laid diagonally, sloping in alternate directions

Slide 54 Brick Sculpture

http://media-cache-ec0.pinimg.com/736x/6c/4c/d1/6c4cd128618211b34578243dfbe2156b.jpg (left photo) The Brick Association of the Carolinas commissioned this sculpture honoring the AIA of both North and South Carolina. In keeping with the literary theme of The Green, sculpture garden, "Life Is An Open Book" by Brad Spencer shows brick children climbing an open brick book. This is only one of many unique and thought-provoking sculptures in the park that deserve exploring. In Charlotte, NC. Stone children climb on a giant brick book statue, one of the many public art offerings in Charlotte, North Carolina. The statue is located on The Green Uptown, a passive park (an urban wild area with a natural ecosystem found in a developed urban area) located atop an underground parking garage next to the Ratcliffe Condos in Center City Charlotte, NC. The Green, one of the many things to see and do in downtown Charlotte, includes fountains, landscaped walkways, motion-activated stone walls, chess boards built into stone tables and riddles on the ground. http://patrickschneider.photoshelter.com/image/I0000.WaMxyREJ4E (right photo)

Slide 55 Common Types of Brick

Cored Hollow Frogged

(Solid not pictured)

Slide 56 Once produced in large quantities to meet consumer demand, specially shaped bricks all but disappeared during the 1970s and 1980s as suburbia advanced in monotonous regularity. They are now beginning to make a welcome return.

http://asslh.org.au/wp-content/uploads/2014/07/3-Screen-shot-2013-03-06-at-4.20.11-PM.png http://asslh.org.au/hummer/the-hummer-vol-9-no-1-2014/bricktechnology/

Slide 57 Brick Size -There is no standard size

Historic: 8½” x 4” x 2½”; ½” mortar joint Length = 2 widths + 1 mortar joint Length = 3 heights + 2 mortar joints

Modern: 7½” x 3½” x 2¼”; ⅜” mortar joint Historic Roman: 16” x 16” x 4” Modern Roman: 12” x 4” x 2”

Slide 58 In general, historic brick is larger than modern brick

Slide 59

Robie House, Chicago,Frank Lloyd Wright, 1906

Faux Roman brick (11.5” x 4” x 1.5”) with limestone copings

Roman building, Ostia, 2nd century

Historic Roman: 16” x 16” x 4” Modern Roman: 12” x 4” x 2”

Slide 60 Gauged Brick—often used when forming arches or

circles

Mortar joint is uniform along its

length

Unassembled jack arch: http://www.pyromasse.ca/articles/images/connotes/1600px/PGF20.jpg

Slide 61 Round arch formed with ungauged blocks —mortar joints are not a uniform size

http://henninghouse.com/2012/06/building-the-entry-arch-to-the-pizza-oven/

Slide 62 Some Types of Masonry Arches

Slide 63 Corbelling

Slide 64 Brick colors depend on:

Composition and proportions of the clay and shale Temperature of fire in kiln Glazing

Slide 65 Victorian

Polychromy

Keble College, Oxford University, Oxford,

England Architect William

Butterfield, constructed 1867-1883

Slide 66

Townhouses in the Victorian District, Savannah, GA, late 1800s. Brick walls on second floor bays intersect at angles > 90°, creating surface voids. Victorian polychromy

Slide 67 Glazed Brick Trust Company

Bank, Atlanta, GA,

Architect Henri Jova, 1961-1962.

Slate gray brick with bright blue glazing; veneer laid in soldier

courses. Mortar is mix of light and dark

grays.

Slide 68 Savannah Gray Brick Lightweight, porous, oversized Manufacturing began in 1730s Often covered with stucco

Savannah gray brick in the Main Line Viaduct of the Central of Georgia Railroad, built ca. 1850s.

Slide 69

St. Simon’s Island (GA) lighthouse keeper’s dwelling built of

Savannah gray brick,

1872

Slide 70

Slide 71

Slide 72 Deterioration of Historic Brick

Underfired bricks crumble when exposed to moisture Improper pointing repairs with Portland

cement-based mortar Treatment with water repellant coatings

– Retains water within brickwork Improper cleaning (esp. sandblasting) Failure of ties or anchors

Slide 73

Prolonged contact with water Removes mortarWater-soluble salts form crystals, leading

to exfoliation or spalling Acid rain & pollution – dissolve mortars,

deposit salts, accumulation of dirt Freeze/thaw cycle Shatter bricks Buckle outer wythe

Deterioration of Historic Brick, cont.

Slide 74 Repairs to Brickwork

Re-tool mortar joint Re-attach using appropriate mortar Remove and replace brick — replace in

kind Dismantle and rebuild wall Do all work in accordance with the

Secretary’s standards

Slide 75 Mortar Repairs

Replacement mortar must match the historic mortar in composition (esp. type of sand), texture, color, and tooling (joint profile) Replacement mortar must have great vapor

permeability and be softer* than the MUs Replacement mortar must be as vapor

permeable and as soft or softer than the historic mortar *Softness measured in compressive strength

Slide 76 What’s wrong

and why?

John Deere Plow Company 326 Nelson Street, Atlanta5-story building, built in 1914, listed in National Register & in the Castleberry Hill Historic District; now 49 loft apartments

Slide 77

What’s wrong and why?

982 North Highland Avenue, Atlanta, 1914

Craftsman bungalow

Slide 78 PLASTER Generic term for cementitious substances applied to a

surface in paste form that harden to a solid material Prehistoric plaster — mud smeared over masonry

walls or over a mesh of woven sticks and vines (wattle & daub) Egyptians and Mesopotamians developed fine plasters

based on gypsum and lime Portland cement added in late 1800s Chosen wall surface until ca. World War II, replaced

by drywall (gypsum board)

Slide 79 Early Plaster

Clay and water Sand added to reduce shrinkage Straw, grass added as reinforcement

Slide 80 Lime Plaster

Composed of non-hydraulic lime, sand, fiber or hair, and water Can be applied directly to masonry or

over wood or metal lath More water resistant than early plaster Used in finish coats

Slide 81 Gypsum Plaster

More rigid than lime plaster Requires furring strips against masonry More vulnerable to water damage Has more sculptural potential than any

other architectural material

Slide 82

Sedimentary rock with low hardness Alabaster is a type of gypsum Uses: manufacture of wallboard,

cement, plaster of Paris, soil conditioning, and as a hardening retarder in Portland

Gypsum

http://geology.com/minerals/gypsum.shtml Gypsum mine in Albuquerque, NM: http://www.thelocationguide.com/blog/wp-content/gallery/location-focus-albuquerque-new-mexico/albuquerque-gypsum-mine.jpg

Slide 83

Quarried, crushed, dried, ground to fine powder, heated to 350° F to remove most of the moisture (calcining) Calcined gypsum ground to fine powder is

Plaster of Paris (discovered by Egyptians) When mixed with water, rehydrates and

recrystallizes rapidly, giving off heat as it hardens, and expands

Gypsum, cont.

Slide 84 Characteristics of Plaster

Major disadvantage — water soluble Durable Lightweight Somewhat soundproof Easy to work, wet or dry Fashioned into a variety of shapes and textures

Inexpensive Highly resistant to fire

Slide 85 Historically, plaster applied by hand using hawk and

trowel; now usually sprayed on

Slide 86 Plaster Application

Can be applied directly to masonry surface Most often applied to lathWood strips nailed to wood framing with small

spaces in between allowing keying of the plasterHand split (riven) lath Accordion lath Sawn lath

Metal lath, must be attached with furring strips

Slide 87 Accordion Lath, ca. 1800, Portsmouth, RI

Accordion lath, Almy-Cory House, ca. 1800, Portsmouth, RI: http://www.newportrestoration.org/writable/slideshows/full/almycory_july_2004_detail_16_slideshow_a27.jpg

Slide 88 Hand split (riven) Lath on left; Sawn Lath on right, 1867, Bristol, VA

Riven lath on left; sawn lath on right: http://ih.constantcontact.com/fs050/1105780001568/img/16.jpg?a=1107614948952 I. C. Fowler House, Bristol, VA, 1867

Slide 89

Sawn Lath, 1911, 491 Auburn Ave.,

Atlanta, GA

Slide 90 Three-coat application

SCRATCH BROWN

FINISH

1. 2.

3.

Slide 91 The scratch coat forms “keys” when it oozes between the lath. These help hold the plaster onto the wall.

http://www.gdiy.com/projects/removing-lath-and-plaster-walls/

Slide 92

Riven Lath and Plaster

Keys,Bulloch Hall, 1839-40,

Roswell, GA

Slide 93 Expandable Metal Lath, 1928, Swan

House, Atlanta, GA

http://archive.org/stream/No.639GeneralCatalogueOfBuildersPlumbersMaterials/TheIronMarbleCo.Ltd.Cca593511#page/n213/mode/2up The Iron and Marble Company, Ltd. (Bristol, UK), Catalogue 639, General Builder’s Ironmongery, etc. April, 1936.

Slide 94 Ornamental Cast Plaster Poured into molds “Running” with a template to make linear

ornaments

Slide 95 Kenmore Dining Room

Built by Fielding Lewis & wife, Betty, sister of George Washington,

1770s, Fredericksburg, VA

Kenmore, one of the most elegant colonial mansions in America, lies in the heart of historic Fredericksburg. Built in the 1770s by patriot Fielding Lewis and his wife, Betty (the sister of George Washington), the house contains some of the most elaborate plasterwork from colonial America. It was crafted by an unknown artist who also completed plasterwork at Mount Vernon. This house was originally part of a plantation of almost 1,300 acres just outside the village of Fredericksburg. Fielding Lewis lived in the house until December of 1781, when he died just weeks after Cornwallis surrendered to George Washington. Betty remained at Kenmore for another 14 years although the property was inherited by Fielding's oldest son, John, who was the last Lewis family member to own Kenmore. John sold the property in 1797. After 1797, the plantation was sold several times. The Gordon family purchased the property in 1819, later naming it "Kenmore" after their ancestral home in Scotland

(Kenmuir). The Gordons added the slate roof and stone portico that are still in existence today. They occupied the property until just before the Civil War. The house remained in private hands until the Kenmore Association saved the house from destruction or division into apartments in the early 1920s. In 1970, the National Park Service designated Kenmore as a National Historic Landmark.

Slide 96 Problems with Plaster It is rigid, will crack Structural movement, settling, vibrations Lath movement

Poor workmanship; e.g., too much sand crumbling Improper application Improper curing Lath set too closely, keys cannot form Water - softens plaster, rots wood lath,

corrodes nails, causes iron lath to rust

Slide 97 Solutions

Filling cracks Patching Re-plastering Veneer plaster replacement system

All fills, patches, replacements should be compatible with the original for

appearance and durability.

Slide 98 Preservation Briefs

#21: Repairing Historic Flat Plaster Walls and Ceilings #23: Preserving Historic Ornamental

Plaster