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Properties of Properties of Concrete” Concrete” Introduction Introduction

“Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

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Page 1: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

““Properties of Concrete”Properties of Concrete”

IntroductionIntroduction

““Properties of Concrete”Properties of Concrete”

IntroductionIntroduction

Page 2: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Overview• What is concrete made of?

• What Is Concrete Used For?

• Why Is Concrete Used?

• Why Do We Reinforce Concrete?

• Curing of concrete

Page 3: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

What is concrete made of?What is concrete made of?What is concrete made of?What is concrete made of?

Page 4: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

What is concrete made of?

• Concrete is basically a mixture of two components:– Paste – Aggregates

• Paste (Portland cement, water, and air) • Aggregates (sand, gravel, crushed

stone)

Page 5: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

CEMENT• Cement (Dry powder of very fine particles) is a

building material made by grinding calcined

limestone and clay into a fine powder• Portland Cement chemical composition

– Limestone, shale and clay• CaO (lime)

• Al2O3 (Alumina)

• SO3 (Sulfite)

Page 6: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

CEMENT

• When mixed with water, forms a paste• it undergoes chemical changes

(chemical reaction-Hydration)• Glue paste coats all the aggregates

together• hardens and forms a solid mass

Page 7: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

WATER

• Water good for drinking is good for

concrete……

Page 8: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

WATER• needed for two purposes:

– chemical reaction with cement– workability

• only 1/3 of the water is needed for chemical reaction

• extra water remains in pores and holes• results in porosity• Good for preventing plastic shrinkage

cracking and workability• Bad for permeability, strength,

durability.

Page 9: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

AGGREGATES

• cheap fillers• hard material• provide for volume stability• reduce volume changes• provide abrasion resistance

Page 10: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

AGGREGATE• Aggregate are divided into two groups:

– Fine - AASHTO M-6 or ASTM C-33 – Coarse - AASHTO M-80 or ASTM C-33

• Fine aggregate consist of natural or manufactured sand with particle size up to 3/8 inch

• Coarse aggregate particles are retained on the #4 sieve and range up to 6 inches

Page 11: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

COARSE AGGREGATE

Page 12: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

FINE AGGREGATE

Page 13: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

CONSTITUENTS

• paste 25 to 40%– portland cement 7% to 15% by Vol.– water 14% to 21% by Vol.

• Aggregates 60% to 75%– coarse aggregates– Fine aggregates

• Admixtures

Page 14: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

CONSTITUENTSCement Water Air Fine Aggregate Coarse Aggregate

Cement paste constitutes about 25% to 40% volume of concrete

Page 15: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

AIR ENTRAINED CONCRETE

• Why the difference between line #1 and line #2?

• Line 1, small size CA, increased H2O and cement

• Line 2, larger CA, less H20, air, cement

Page 16: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

NON-AIR ENTRAINED CONCRETE

• Similar to Air Entrained Concrete slide• See how aggregate size impacts water

demand and amount of “paste” in the mix

Cement Water Air Fine Aggregate Coarse Aggregate

Page 17: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

ADMIXTURES

• increase set time• decrease set time• increase workability• adjust other

concrete properties

• reduce water demand

• entrain air• inhibit corrosion

•Plastic and hardened properties of concrete may be changed by adding admixtures•Admixtures are commonly used to:

Page 18: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

ADMIXTURES• chemical

– retarders– accelerators– water reducing– air entraining

• mineral– fly ash– silica fume– slags

Page 19: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

QUALITY OF CONCRETE• Quality of concrete

depends on quality of paste and quality of aggregates

• each particle of aggregate is completely coated with paste

• All spaces between aggregate is filled with paste

Page 20: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

QUALITY OF CONCRETEIs determined by:• W/C Ratio – • Advantage of reducing water

– Increased compressive and flexural strength– lower permeability– increased resistance to weathering– reduced shrinkage cracking tendencies

• The less water used, the better quality of concrete, provided it can be consolidated properly.

Page 21: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Ten cement-paste cylinders with water-cementratios from 0.25 to 0.70. The band indicates that eachcylinder contains the same amount of cement. Increasedwater dilutes the effect of the cement paste, increasingvolume, reducing density, and lowering strength.

Page 22: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

FORMS

• A form is the mold for setting concrete into a desired shape

Page 23: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

What Is Concrete Used What Is Concrete Used For?For?

What Is Concrete Used What Is Concrete Used For?For?

Page 24: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

What Is Concrete Used For?

• Construction Material

Art Work

Page 25: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Picture of Bench

Page 26: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Why Is Concrete Used?Why Is Concrete Used?Why Is Concrete Used?Why Is Concrete Used?

Page 27: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Why Is Concrete Used?

• Economics– Inexpensive, readily available

• Material Properties– Long Lasting– Molded into a desired shape– Great insulator– Hard

Page 28: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Material Properties (cont.)

• Great Compressive Strength (up to 8000 psi and even more than that)

• Poor Tensile Strength (almost 0)– Reinforcement methods ($)

Page 29: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Why Do We Reinforce Why Do We Reinforce Concrete?Concrete?

Why Do We Reinforce Why Do We Reinforce Concrete?Concrete?

Page 30: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Why Do We Reinforce Concrete?

• Prevent cracking due to tension forces

Page 31: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Question

• What is the difference between tension and compression?

Page 32: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?
Page 33: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Question

• Why would concrete never be used in tension?

Page 34: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

How Do We Reinforce Concrete?

• Steel rebar– Excellent in tension, poor in

compression

Page 35: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

CURING OF CONCRETECURING OF CONCRETECURING OF CONCRETECURING OF CONCRETE

Page 36: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

CURING OF CONCRETE

• Over time concrete will cure, which is a

hardening process.

• Concrete has a 28 day curing time, this

is the amount of time it takes to be

considered completely cured

Page 37: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

• Critical to durable concrete• Increases strength• Decreases permeability• Increases durability

Curing

Page 38: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Curing Concrete• How concrete is cured:

– Ponding or Immersion– Spraying or Fogging– Wet Coverings– Impervious Paper– Plastic Sheets– Membrane-Forming Curing

Compounds

Page 39: “Properties of Concrete” Introduction. Overview What is concrete made of? What Is Concrete Used For? Why Is Concrete Used? Why Do We Reinforce Concrete?

Questions?

• Remember:– Use Common Sense– Temperature

effects on your body have very similar effects on concrete

– If you are not sure, ASK!!!