properties of portland cement concrete handouts/14 - properties of pcc.pdfconcrete strength 1....

Properties ofPortland Cement Concrete

CIVL 3137 2

Concrete Ingredients

Gravel

Sand

Water

Cement

Air

40%

20%

5%10%

25%Pa

ste

Mor

tar

Concrete Strength

1. Aggregate

2. Cement/Aggregate Bond

3. Cement Paste

CIVL 3137 3

CIVL 3137 4

Water-Cement Ratio

0.2

Water-Cement Ratio

CIVL 3137 5

31 sack of cement 1ft bulk 94 lb

gallons of waterw/c gallons sacksacks of cement

1 gallon of water 8.34 lb

Water-Cement Ratio

CIVL 3137 6

mass of waterw/cm

mass of cement + SCMs

mass of waterw/c dimensionless

mass of cement

CIVL 3137 7

Water-Cement Ratio

0.2

TYPICALRANGE

0.25 = Full Hydration

CIVL 3137 8

Water-Cement Ratio

Rodded

Vibrated

CIVL 3137 9

Water-Cement Ratio

WaterCement

0% Hydration

100% Hydration

Hydration Products WaterAir

CIVL 3137 10

Cement Paste Strength

Air Content of Paste - percent

Freeze-Thaw Durability

CIVL 3137 11

Freeze-Thaw Durability

CIVL 3137 12

Air Entrainment

CIVL 3137 13

CIVL 3137 14

Air Entrainment

(data from tests on mortar cubes)

Air Requirements

CIVL 3137 16

Air Content

CIVL 3137 17

60%Mortar

40%Gravel

Concrete Air Content0.6 9% = 5.4%

Mortar Air ContentAssume 9%

3/4″NMAS

Air Content

CIVL 3137 18

50%Mortar

50%Gravel

Concrete Air Content0.5 9% = 4.5%

Mortar Air ContentAssume 9%

3″NMAS

Air Requirements

0

1

2

3

4

5

6

7

8

40 50 60 70 80

Tota

l Air

Con

tent

(%)

Mortar Content (%)

CIVL 3137 19

3"1½"

¾"

⅜"

Optimum Air Content = 9% of Mortar Volume

NMAS =

CIVL 3137 20

Properties Affected by Air Content

durability

consistency

strength

bleeding

CIVL 3137 21

Air Entrainment

CIVL 3137 22

Air Entrainment

CIVL 3137 23

Important Properties

workabilityharshness

compressive strengthtensile / flexural strength

stiffnessdurability

permeabilityshrinkage / creep

CIVL 3137 24




stiffnessdurability


CIVL 3137 25

Workability

workability (n.) the ease with which theconcrete ingredients (gravel, sand, cement,water) can be mixed, transported, placed,consolidated, and finished with minimumloss of homogeneity.

CIVL 3137 26

Workability

workability = consistency + cohesion

refers to the fluidity of the concrete and how easily it can be transported, placed, and

consolidated without inhomogeneity

refers to the stickiness of the concrete and how easily it can be placed and finished

without inhomogeneity

CIVL 3137 27

Inhomogeneity

segregation (n.) the tendency for the gravel particles to separate from the rest of the ingredients.

bleeding (n.) the tendency for the mixing water to separate from the rest of the ingredients.

CIVL 3137 28

Causes of Segregation

improper placement

too much mixing water

over-vibration

CIVL 3137 29

Causes of Bleeding

too little cement

too much water

over-vibration

over-working

CIVL 3137 30




stiffnessdurability


Harshness

CIVL 3137 31

CIVL 3137 32




stiffnessdurability


Strength Gain Over Time

CIVL 3137 34

w/c = 0.3

w/c = 0.4

w/c = 0.5w/c = 0.6w/c = 0.7

0 20 40 60 80 100Age (days)

90

80

70

60

50

40

30

20

10

0

Com

pres

sive

Str

engt

h (M

Pa)

CIVL 3137 38




stiffnessdurability


CIVL 3137 39

Tensile Strength

0.1t cf f

CIVL 3137 40

Tensile Strength

6.7t cf f cf in psi

CIVL 3137 41

Beam Flexure Test

3L

CIVL 3137 42

Modulus of Rupture

2

PLMORbd

CIVL 3137 43

Concrete Behavior

1

E

1

E

CIVL 3137 44

Beam Flexure Test

2

PLMORbd

ft

CIVL 3137 45

Flexural Strength

8.4 cMOR f cf in psi

6.7t cf f cf in psi

1.25 or 0.8t tMOR f f MOR

CIVL 3137 46

Flexural Strength

CIVL 3137 47




stiffnessdurability


CIVL 3137 48

Stiffness and Strength

1

E

CIVL 3137 49

Stiffness and StrengthSource: ACI Manual of Concrete Practice

1.5cE 33w f

2

3

2c

E elastic modulus in lb inw unit weight in lb ftf compressive strength in lb in

CIVL 3137 50

Stiffness and Strength

cE 57,000 f

Typical test data

CIVL 3137 52




stiffnessdurability


CIVL 3137 53

Durability

Sources ofDeterioration

Alkali-SilicaReaction

SulfateAttack

Freeze-ThawCycles

aggregate typecement type

air contentw/c ratio

cementtype

CIVL 3137 54




stiffnessdurability


CIVL 3137 55




stiffnessdurability


CIVL 3137 56

Shrinkage / Creep

Sources ofVolume Change

TemperatureChanges

CreepStrains

DryingShrinkage

CIVL 3137 57

Coefficient of Thermal Expansion

AggregateType

Coefficient(10-6 in/in/oF)

Quartz 6.6Sandstone 6.5

Gravel 6.0Granite 5.3Basalt 4.8

Limestone 3.8Average 5.5

Example

How much strain would develop in a graniticconcrete due to a 60°F temperature change?

CIVL 3137 58

6 46.0 10 in/in/°F 60 F 3.6 10 in/in

CIVL 3137 59

Example

1

E

43.6 10

CIVL 3137 60

Drying Shrinkage Coefficient

TensileStrength

(psi)

ShrinkageCoefficient

(in/in)300 or less 0.0008

400 0.0006500 0.00045600 0.0003

700 or more 0.0002Typical 0.0006

Example

How much will a typical 14-ft pavement slabshrink during curing if it is unrestrained?

CIVL 3137 61

46.0 10 in/in 14 ft 12 in/ft 0.10 in

Example

How much tensile stress will develop in theslab in the previous example if it is restrained?

CIVL 3137 62

6 4E 3.6 10 psi 6.0 10 in/in 2160 psi

CIVL 3137 63

properties of portland cement concrete handouts/14 - properties of pcc.pdfconcrete strength 1....

Documents