Transcript CONCRETE MATERIALS Technology of Material II TKS 4012 Prepared by [email protected] Overview       What is concrete made of? Why do we use concrete? How do we use concrete? Where.

CONCRETE MATERIALS
Technology of Material II
TKS 4012
Prepared by [email protected]
Overview
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What is concrete made of?
Why do we use concrete?
How do we use concrete?
Where is concrete used?
Why is concrete often reinforced?
Why do we use solid waste as an
aggregate in concrete?
Constituent Materials
 Cement
 Water
 Coarse aggregate
 Fine aggregate
 Admixtures
Cement
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Cement is a building material made
by grinding calcined limestone and
clay into a fine powder.
When mixed with water, it will
harden as it undergoes chemical
changes.
Cement (cont’d)
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Portland Cement: limestone, shale,
and clay.
Chemical Composition:
 CaO (lime)
 Al2O3 (Alumina)
 SO3 (Sulfite)
Water
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We all know what water is …!
In general, consumable water can be
used in concrete making.
Coarse aggregate
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This is an aggregate that is
usually close to ¼ inch (5 mm) in
diameter or larger.
Fine aggregate
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This is an aggregate that is
usually very small/fine, such as
sand (< 5 mm).
Admixtures
ASTM C 494 Descriptions of Admixtures Types:
 A
: water reducing admixtures
 B
: retarding admixtures
 C
: accelerating admixtures
 D
: water reducing & retarding admixtures
 E
: water reducing & accelerating admixtures
 F
: water reducing, high range & accelerating admixtures
 G
: water reducing, high range & retarding admixtures
Concrete
A mixture of two components:
 Paste (25-40%)
 Aggregates (60-75%) and
Air
Paste
Comprises of:
 a binder (cement)
 Water
 Entrapped
air or
purposely entrained
air
Mortar
Comprises of:
 a binder (cement)
 Fine aggregate
 Water
Chemical reaction
The chemical reaction of paste:
2(3CaO.SiO2) + 6H2O
3CaO.2SiO2.3H2O + 3Ca(OH)2
2(3CaO.SiO2) + 6H2O
3CaO.2SiO2.3H2O + 3Ca(OH)2
Where:
CaO.SiO2
: calsium silicate
H20
: water
CaO.SiO2.H2O : tobermorite (hard)
Ca(OH)2
: calsium hydroxide (free)
Aggregates
Comprises of :
 Sand (fine aggregates)
 Gravel or crushed stone (coarse
aggregates)
Volume distribution
Percentage volume distribution of
materials in concrete:
Mixing
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The main concern is characteristic
compressive strength based on specific
design codes.
Manual or Machine?
Placing
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Considering about the height of fall to
avoid segregation (pumping and vertical
bucket).
Compacting by using a vibrator or
manual? Internal or external?
Curing
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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.
Forms
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A form is the mold for setting concrete
into a desired shape.
Why is concrete used?
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Economics
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Inexpensive, readily available
Material Properties
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Long Lasting
Molded into a desired shape
Great insulator
Hard
Great Compressive Strength
Waste aggregates
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Why is it important to use solid waste
as an aggregate in concrete?
Waste aggregates
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(cont’d)
Environmental Preservation
New Material Properties
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Recycled tires (crumb rubber)
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Broken Bricks
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Fire resistant
Plastic
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Insensitive to water
Greater resistance to freeze-thaw cycles
Glass, PVC, Wood Chips and several others
Fresh Concrete
Properties of Fresh Concrete:
 Workability
 Hydration
 Setting time
 Hardening
 Segregation
 Bleeding
Workability
Hardened Concrete
Properties of hardened concrete:
 Strength (compressive & tensile)
 Unit Weight
 Resistance to freezing and thawing
 Permeability and water tightness
 Abrasion Resistance
 Volume Stability (creep & shrinkage)
 Control of cracking
Compressive strength
Influence factors
Influence factors on compressive strength
of concrete:
 Age
 Density
 w/c ratio
 Amount of cement
 Type of cement
 Type of aggregate
Types of concrete
Based on its compressive strength:
① Plain Concrete
② Ordinary/Normal Concrete
③ Prestressed Concrete
④ High Performance Concrete/HPC
⑤ Ultra High Performance Concrete/UHPC
(< 10MPa)
(10 – 30MPa)
(30 – 40MPa)
(40 – 80MPa)
(> 80MPa)
Types of Concrete (cont’d)
Based on its unit weight:
1. Ultra Lightweight Concrete
for non structural
2. Lightweight Concrete
for lightweight structure
3. Normal Concrete
for structural
4. Heavyweight Concrete
for radiation shield structure
(< 1.000 kg/m3)
(1.000 – 2.000 kg/m3)
(2.000 – 3.000 kg/m3)
(> 3.000 kg/m3)
Any Questions?
Thanks for your kind attention!