ARB PART 3

MORTARS AND PLASTERS

MORTARS AND PLASTERS

a proportioned mixture of siliceous materials (sand, crushed stone)

and cement (lime, Portland) which, after being prepared in a plastic

state with water, hardens into a stonelike mass.

Mortar

is cement mix used to glue masonry units to each other, or

other surface finishing materials like tiles, bricks, stones to a

receiving structure like a wall or floor.

Plaster

is mortar applied to wall surfaces as a preparation or a hard

finish coat.

CEMENT MORTAR

is a proportioned mixture of cement, fine aggregate and water.

For first-class mortars 1 part of cement should be added to not more

than 3 parts of sand.

Replacing 10 or 15 percent of the cement by volume with hydrated

lime gives greater workability and increases the strength of the mortar.

For rubble stonework, 1 : 4 will be much stronger than lime mortar.

For the top surface of floors and walks, use 1 : 1 to 1-1/2.

Mortar made with fine sand requires a much larger quantity of cement

to obtain a given strength than mortar made with coarse sand.

Fiber or Hair

___is sometimes added to the mixture to give increased

strength as when used for the first coat.

Scratch Coat

First binding coat

Brown coat

A second straightening coat

Finish coat

final coat

Lime Plaster

Lime putty (hydrated lime and water), mixed on the job with sand

and gypsum plaster, used for two and three-coat finish surfaces

for interior walls and ceilings.

Gypsum Plaster

Plaster of Paris mixed with clay, lime and

other materials in combinations covered by trademarks or

patents. Mixed on the job with water, sand, lime putty, hair or

fiber for two or three-coat finish surfaces for interior walls and

ceilings; or used dry as ingredient for hard or sand float finish

with lime plaster

High-strength gypsum plaster.

Same as gypsum plaster but

mixed to meet established standards. Mixed on the job with

water, sand, lime putty, hair or fiber for two and three-coat finish

surfaces for both exteriors and interiors.

Fibered gypsum plaster.

Gypsum plaster premixed with

fibers. Mixed on the job with water and sand for scratch coat for

three-coat plastering job

Prepared gypsum plaster.

Gypsum plaster mixed with fine

white sand. Used for two and three-coat finish surfaces for

interior walls and ceilings

Bonding plaster.

Gypsum plaster mixed with ingredients

develop more adhesive strength in combinations covered by

trademarks or patents. Used for interior finish for smooth

concrete walls or ceilings. Mix and apply as per manufacturer’s

directions

Lightweight gypsum plaster, fire-resistant plaster.

Gypsum plaster mixed on the job with water, perlite, vermiculite or other

suitable mineral aggregate. Lightweight gypsum plaster is used

when weight is important, and for fire-proofing other materials

such as steel. Applied on lath. For interior use only

Keene’s cement.

Plaster of Paris mixed with alum or borax or

other materials and burned (calcined) at 932°F. Mixed on the

job with water, lime putty and fine white sand as hard finish for

two and three-coat gypsum plaster. For interior use only

Plaster of Paris.

For ornamental plaster work and castings.

Molding plaster.

For ornamental plaster work and castings. Mix

with water as per manufacturer’s directions.

Acoustics plaster.

For acoustic treatment of interior walls and

ceilings. Applied on gypsum plaster base coats. Mix with water as

per manufacturer’s directions.

Portland Cement Plaster

Mixed with water, sand and lime putty. Used for two and

three-coat finish surfaces for exterior and interior walls and

ceilings

“Sgraffito”

is highly decorative type of plaster work developed in Italy during

the Renaissance. This type of technique consists of applying two or

three thin coats of plaster different colors and then cutting away

certain areas of one or two coats to produce a three-dimensional

colored design.

Masonry

is a built-up construction or combination of building

materials as clay, concrete, or stone set in mortar; or

plain concrete.

Bed

The horizontal surfaces on which the

stones or bricks of walls lie in the courses.

Course

A continuous layer of bricks, stones,

or other masonry units

Wythe or Tier

– Each continuous, vertical

section of the wall, one masonry unit thick.

Bond

That connection between bricks, stones

or other masonry units formed by lapping them

one upon another carrying up the work, so as to

form an inseparable mass of building, by

preventing the vertical joints falling over each

other (also called a breaking joint).

Stretcher

A brick or block masonry laid

lengthwise of a wall

Header

– A brick or block masonry extending

over the thickness of the wall

Heading course

– A course in which the bricks

or other masonry units are all headers.

Soldier

A unit laid on its end with its face

perpendicular to the face of the wall.

Quoins

The corner stones at the angles of

buildings, usually rusticated so as to project

from the normal surface of the wall.

Bond Stones

Stones running through the

thickness of the wall at right angles to its face,

in order to bind it together.

Blocking or Blocking Course

– A course of stones placed on top of cornice crowning the walls

STONE

together with wood and clay, are the basic building materialof man. The history of architecture until as late as 1900 was largely the history of stone in architecture,

was the structural material, the exterior and interior finishing material, the flooring material and in many cases the roofing material. It was also used for all types of sculpture, statuary, and decorative and ornamental applications.

Rubble Stone.

Stone delivered from the quarries, rough and irregular shape.

Dimension Stone.

Stone cut into specific size, squared to dimensions, and to a specific thickness

STONEWORK:

are based on the shape and the surface treatment of finish of the stone :

Rubble work.

Masonry of rough, undressed stones.

Scabbled Rubble

When only the roughest

irregularities are knocked off,

Range Rubble

when the stones in each course are rudely dressed to a nearly uniform height,

Random work.

Stones fitted together at random without any attempt to lay them in course.

Ashlar.

Squared stones in regular courses, in contradistinction to

rubble work .

Ranged work or coursed ashlar

Uniform courses with stones uniform in size.

Broken range ashlar

Course laid with the horizontal joints uninterrupted but the width of the courses and the length of the stones are varied to produce a wall with a less regular pattern.

Random course

their rectangular shape and are laid on horizontal beds but no effort is made to continue the horizontal beds through in an uninterrupted manner. Large stones combine with small ones in a convenient and, if possible, an interesting manner.

Rustic or Rock work -

Courses of stone face which is jagged, so as to present a rough surface.

Rustication

occurs when heavier

stones or areas of stone project

from the normal face of the

surrounding wall or of the joint

themselves.

BRICKS

are structural units of clay or shale formed while plastic and

subsequently fired. The manufacture of brick consists essentially of screening,

grinding, or working the clay to the desired consistency for

moulding, whether by hand or machine.

Common or building brick.

Used for all

purposes, including facing.

Facing brick

Specially processed to give certain

specific surface characteristics. Used for

exposed masonry surfaces.

Glazed brick.

These have a smooth outer

surface with a dull satin or high gloss finish. They

are load bearing, fire resisting, and impervious.

They are usually formed with vertical hollow

cores through the body with scoring on the back.

Fire (refractory) brick.

These are ordinarily

made from a mixture of flint clay and plastic clay,

and are used for the lining of furnaces, fireplaces,

and chimneys.

Common Bond.

Consists of five

stretcher courses and then a

header course. It is generally

begun with a row of headers at

the bottom course

English Bond.

Consists of alternate courses of stretchers and headers

Flemish Bond

Consists ofalternate headers and stretchers in each course .

Herringbone.

The bricks are laid diagonally to form a herring-bone pattern.