Ce 197 Le 2

Front 1

Concrete

Back 1

A mixture of cement, water and air binding together fillers.

Main material present in rigid pavements.

*Other cementitious and chemical admixtures are also added to this mixture.

Front 2

Paste and Mortar

Back 2

Paste = Water + Cement

Mortar = Paste + Fine Aggregates

Front 3

Portland Cement

Back 3

It is a type of hydraulic cement which is a cementitious material.

Front 4

ASTM C 150

AASHTO M 85

Portland Cements (Type I-V)

Back 4

Specification based on

Chemistry-physical properties

Type I - Normal resistance

II - Moderate sulfate resistance

III - High early strength

IV - Low heat of hydration

V - High sulfate resistance

Front 5

ASTM C 1157

Portland Cements (Type GU, MS, HE, MH, LH)

Back 5

Specification based on

Performance

Type GU - General use

MS - Moderate sulfate resistance

HE - High early strength

MH - Moderate heat of hydration

LH - Low heat of hydration

Front 6

ASTM C 595

AASHTO M 240

Portland Cement (Type IS, IP and P, I (PM), S, I (SM))

Back 6

Classification of

Blended cements in terms of major constituents.

Type IS - Portland blast-furnace slag cement

IP and P - Portland-pozzolan cement

I (PM) - Pozzolan-modified portland cement

S - Slag cement

I (SM) - Slag-modified portland cement

Front 7

Hydration

4 (5) Stages

Back 7

Reaction of cement and water leading to hardening of the paste.

It is an exothermic process (generates heat)

4(5) Stages:

Mixing stage

Dormancy

Hardening

Cooling

Densification

Front 8

Major Compounds of Portland Cement

Back 8

Aluminates

Silicates

Sulfates

Front 9

Aluminates: C3A, C4AF

Which can cause premature stiffening?

Back 9

C3A

Front 10

Silicates: C3S, C2S

Which contributes to early and long-term strength, respectively?

Back 10

C3S

C2S

Front 11

Sulfates: CSH2, CSH1/2, CS

Which reduces the chances of premature stiffening?

Back 11

Gypsum

Bassanite

Gypsum

Front 12

Admixtures (ASTM C 260)

Back 12

Materials added to concrete mixtures to modify their properties (e.g. air content, water requirement, setting time etc.)

Used to create small air bubbles in the paste and

improve concrete resistance to freezing-thawing cycles.

Front 13

ASTM C 494

AASHTO M 194

Back 13

Water-reducing admixtures

Admixtures to decrease or increase rate of hydration.

Front 14

Thermal Analysis

Back 14

Used to identify cement composition and its interaction with other paste and concrete compounds.

Front 15

Thermogravimetric Analysis (TGA)

Back 15

Measures the change in mass of a sample under a change in temperature. This information is used to identify the presence of a particular chemical compound.

Front 16

Differential Scanning Calorimetry (DSC)

Back 16

Measures heat releases or absorbed to identify the presence of a compound. Useful to identify compounds present at different stages of hydration.

Front 17

Workability

Back 17

Consistency, mobility and compactability of fresh concrete.

Front 18

Workability depends on:

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1. Physical Characteristics of aggregates and cement

2. Proportioning of concrete components

3. Water content

4. Equipment used

5. Construction conditions

Front 19

ASTM C 143

AASHTO T 119

Slump Test

Back 19

Measures consistency

Front 20

Bleeding

Back 20

Presence of water at the pavement surface

Causes the generation of a weak layer on the surface (fine cement particles) that is susceptible to scaling.

Cause: Settlement of cement and aggregates

Migration of water to the top

Front 21

Strength

Back 21

Highly influenced by the paste strength more than aggregate strength.

Front 22

Maximum Strength

Back 22

Mixture with just sufficient water for hydration.

Front 23

Concrete Physical Properties Test

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Compression

Flexure

Shear

Bond

Modulus of Elasticity

Front 24

Concrete Stretching Modes

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1. Direct Tension

2. Flexure

3. Split Cylinder

4. Compression Cylinder

Front 25

How will you fix it all?

Back 25

I'll learn it as I go, step by step through experience.

Front 26

Why is it important to determine the tensile strength?

Back 26

To determine the resistance to cracking under shrinkage and temperature changes and loads in plain concrete.

Front 27

Stress-strain relationship

Back 27

It is used to compute the modulus of elasticity and poisson's ratio of a rigid pavement

Front 28

Poisson's Ratio

Back 28

Ratio of the lateral strain to the axial strain measured in a uniaxial test of concrete.

Front 29

Maturity Curve

Back 29

Relationship between concrete properties (strength and modulus of elasticity) to time and temperature.

Front 30

Shrinkage

Back 30

Caused by the loss of water from concrete that causes a reduction in volume.

Front 31

Shrinkage Cracks

Back 31

Develop on the surface of rigid pavements due to restrain in reduction of volume by friction between the concrete pavement and the supporting layer.

Caused by concrete contrqction under cooling temperatures

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Plastic Shrinkage Cracking

Back 32

1. Bleed water appears on concrete surface

2. Rate of evaporation exceeds bleed rate

3. Concrete surface dries

4. Concrete surface tries to shrink

5. Moist concrete resists shrinkage

6. Stress develops in soft "plastic" concrete

7. "Plastic" shrinkage cracks form

Front 33

Ultimate Shrinkage

Back 33

1/8 to 1/4 inch in 20 ft

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Autogenoshrinkage

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Caused because some hydration products of cement occupy less space than the original materials (significant when w/c < 0.4l

Front 35

Creep

Back 35

Time-dependent deformation under load.

Occurs mostly in the paste of hardened concrete.

Front 36

Creep recovery

Back 36

The time needed by creep strain to recover

Front 37

Durability

Back 37

Concrete resistance to environmental and chemical exposure

Front 38

Concrete durability is affected by

Back 38

1. Permeability

2. Freezing and thawing cycles

3. Temp variation

4. Influence of chemicals

5. Chemical reactions

Front 39

Examples of durability

Water penetration

Salt movement

Penetration of sulfates

Flow oxygen, moisture and chlorides

Back 39

Freezing-related cracking

Scaling at the surface

Sulfate attacks

Steel corrosion

Front 40

Permeabikity

Back 40

Property that quantifies transport og fluids in concrete.

Front 41

Durability : Scaling

Back 41

Caused by chemical reaction of deicers with concrete

Front 42

Durability: Alkali (in cement) - silica (in aggregates) reaction

Back 42

Caused by the presence of moisture

Causes swelling by aggregates and cracks

Can be controlled by avoiding aggregates with soluble silica

Front 43

Durability; Corrosion of steel in reinforced concrete pavements

Back 43

Electrochemical reaction caused by the presence of water with high salinity or deicing salts

Cements with high C3A helps to minimize this

Front 44

Durability: sulfate attacks

Back 44

Increase in volume and cracks

Caused by reaction of sulfates from soil and seawater with free calcium hydroxide and aluminates in cement

Front 45

Durability: Curling and Warping

Back 45

Caused by the variation in temp or moisture wuth depth

Causes loss of support under concrete slabs which increased the stresses developed under applied traffic loads

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Homogeneous (Inhomogeneous)

Back 46

The pressure is same in all directions

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Isotropic (Anisotropic)

Back 47

The pressure is the same in all directions

Front 48

Critical responses are dependent on

on

on

Back 48

Distress

Layer/ Material Type

Cross Section

Depth

Wheel load coordinates

Front 49

Pavement types

Back 49

Conventional deep strength full-depth semi-rigid