CE 3220 Lecture 1-2 page format.pdf

7/26/2019 CE 3220 Lecture 1-2 page format.pdf

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Lecture 1-2

Building Materials


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Objectives

Objectives include:

An appreciation for the impact of

selecting different materials and

different construction methods.

An understanding of the impact

materials and methods may have onoverall cost of the structure, as well

as its appearance and life expectancy.


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Building Materials

Concrete

Masonry

Wood

Reinforcing steel

Structural steel


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Concrete

History

Romans

Pozzolana

Modern (1824) Portland cement


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What is Concrete?

Cement (Portland)

Lime

Aggregate

Rock

Sand

Gravel

Water

Additives


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Uses of Concrete

Sidewalks

Foundations Building frames

Building walls

Highway pavements

Dams

Retaining walls Traffic barriers

Bridge decks


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Concrete

Water Ratio

The amount of water used inthe mix should not beexcessive because excess water

eventually evaporates, leavingsmall voids in the spaces itonce occupied


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Characteristics of Concrete

Concrete is characterized by:

good compressive strength but is relatively weak in

tension or shear


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Concrete Strength

Compressive strength of 20 to

50N/mm2 is common

Generally any concrete over 60

N/mm2 as high strength concrete


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Concrete Reinforcing - Rebar

For structures that require flexural

strength for resistance to bending

moments, reinforcing steelrebaris embedded in

the concrete.


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Concrete Reinforcing - Rebar

In some cases tensioned cables are

placed in the concrete to make pre-

stressed or post-tensioned concrete

The tension to resist the bending

moment comes from the reinforcingsteel or the stressed cables


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Concrete Formwork

Plastic

Lifted orPumped

Vibrated


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Reinforcing steel

The purpose of reinforcing steel, or

rebar, is to give the concrete flexural

strength. Without reinforcement, concrete

cracks very easily when placed

under tension or moment.

Reinforcing bars are placed in the

areas of greatest tension.


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Reinforcing steel


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Structural steel

During the 1800s,most iron products

were either wroughtiron or cast iron.

Steel is iron, plus a small amount ofcarbon, dissolved in its structure.


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Steel


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Steel Connections

Rivets

Welds

Bolts


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Wood

Wood is the oldest common building

material. It has a warm pleasant

appearance. It is used for framing,

floors, walls, paneling and even

ceilings. People enjoy the

appearance of high quality wood.


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Wood Beams

Wood beam used in

commercial construction.


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Wood Wood used in

residentalconstruction.


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Wood

Plywood

made up of

three or more

thin veneers of

wood


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Masonry

Sun baked clay bricks (6000-8000years).

The process of kiln or oven dryingbricks was developed around 2500years ago.

The art of masonry construction istherefore not a new constructionmethod.


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MasonryExamples

Eskimos developed the igloo - icemasonry

Some of the worlds greatestconstruction projects are masonryprojects:

Pyramids of Egypt, the Romanaqueducts, the Parthenon, theGreat Wall of China, and the Inca

cities of South America


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Masonry


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Masonry

Masonry buildingblocks are

Quarried stone

Brick

TileConcrete masonry

units (CMU)


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Masonry

Mortar

Used to provide the bondbetween the blocks

To ensure even contact in

spite of irregularities


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Mortar

Mortar is a mixture of:

CementLime

Sand

Water


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Masonry

Documents

CE 3220 Lecture 1-2 page format.pdf