properties of concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. ·...
TRANSCRIPT
![Page 1: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/1.jpg)
Properties of Concrete 1
Properties of Concrete
![Page 2: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/2.jpg)
CE-203PROPERTIES OF CONCRETE
• Introduction
• Batching, Mixing, transportation andplacing of concrete, Properties of fresh andhardened concrete, testing of concrete forvarious properties. Compaction and curingof concrete
10/9/2010 Properties of Concrete I 2
![Page 3: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/3.jpg)
Introduction to use of additives andadmixtures in concrete, strength evaluationof existing concrete structures, Qualitycontrol in concrete construction,industrialized construction, Rehabilitationand strengthening of existing structures.Design of Concrete mixes.
10/9/2010 Properties of Concrete I 3
![Page 4: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/4.jpg)
Properties of Concrete 4
What is Concrete?
• Is the second most commonly used
building material (after timber).
• Concrete is a composite material made from several readily available constituents.
• Concrete is a versatile material that can easily be mixed to meet a variety of special needs and formed to virtually any shape.
![Page 5: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/5.jpg)
Properties of Concrete 5
Advantages of Concrete
• Ability to be cast
• Economical
• Durable
• Fire resistant
• Energy efficient
• On-site fabrication
• Composite with other material
![Page 6: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/6.jpg)
Properties of Concrete 6
Disadvantages of Concrete
• Low tensile strength
• Low ductility
• Volume instability
• Low strength to weight ratio
![Page 7: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/7.jpg)
Properties of Concrete 7
Concrete Constituents
(1) Portland Cement
(2) Water
(3) Aggregates
(4) Air
(5) Admixtures
![Page 8: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/8.jpg)
Properties of Concrete 8
(1) Portland Cement
• Patented by Joseph Aspdin in 1824
• The name is the result of its similarity to limestone quarried in Portland, England.
• Prime ingredients are limestone and clay.
• Ingredients are crushed, ground, blended and burned.
Concrete Constituents: (1) Portland Cement
![Page 9: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/9.jpg)
10/9/2010 Properties of Concrete I 9
Manufacturing Process of Portland Cement
![Page 10: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/10.jpg)
Properties of Concrete 10
Typical Chemical Makeup- four main compounds
1. ~50% Tricalcium Silicate (3Ca0-Si02 or C3S). Fast reaction with water. Provides most of the early strength (first 3-4 weeks).
2. ~25% Dicalcium Silicate (2CaO-SiO2 or C2S).
3. ~12% Tricalcium Aluminate(3CaO-Al2O3 or C3A). Fast reaction with water.
4. ~8% Tetracalcium aluminoferrite (4CaO-Al2Fe2O3 or C4AF).
5. ~3.5% Calcium sulfate dihydrate (gypsum) (CaSO4-H20 or CSH2). Slows the reaction of C4AF.
![Page 11: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/11.jpg)
Properties of Concrete 11
Hydration Reaction of Cement
• Cement hardens as the result of a chemical surface reaction (hydration) with water.
• Tricalcium silicate hydration reaction:
3CaO.SiO2+H2O=2CaO.SiO2.x H2O+Ca(OH)2
hydrated calcium silicate
• Concrete does not “dry”, it “sets”.
• Hydration is an exothermic reaction.
Concrete Constituents: (1) Portland Cement
![Page 12: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/12.jpg)
Properties of Concrete 12
Types of Portland Cementas defined by ASTM C 150
• Type I - Normal
• Type II - Modified
• Type III - High Early Strength
• Type IV - Low Heat
• Type V - Sulfate Resistant
• Types with an “A” added to their number have an air entrainment additive included.
![Page 13: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/13.jpg)
Properties of Concrete 13
(2) Water
• Rule of Thumb:
“If you can drink it, you can make concrete with it.”
• Some soluble inorganic salts may retard the setting and curing.
• Dissolved organic material may retard hydration and entrain excessive amounts of air.
Concrete Constituents: (2) Water
![Page 14: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/14.jpg)
Properties of Concrete I 14
Quality of Water
• Suspended solids of clay or silt up to 2000 ppm.
• Acidic waters can be used to a pH around 3.0.
• Sea water lowers strength 10-20%, corrodes reinforcing steel and causes problems with efflorescence.
Concrete Constituents: (2) Water
![Page 15: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/15.jpg)
10/9/2010 Properties of Concrete I 15
Determine the Quantity of Water• The free or surface moisture of an aggregate
becomes a part of the mixing water, and must be taken into account in determining
the quantity of water.
• A dry aggregate absorbs some of
the mixing water.
• In the proportioning and batching
of concrete mixes, all calculations are based on the saturated surface-dry condition.
Concrete Constituents: (2) Water
![Page 16: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/16.jpg)
Properties of Concrete 16
Approximate Absorption Capacities of various Aggregates
Aggregate Absorption capacity
(% by mass)
Average concrete sand 0 to 2
Granitic-type rocks 0 to 0.5
Average gravel & crushed limestone 0.5 to 1
Sandstone 2 to 7
Lightweight porous materials Up to 25
Concrete Constituents: (2) Water
![Page 17: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/17.jpg)
10/9/2010 Properties of Concrete I 17
(3) Aggregates
• Occupies 70-80% of the volume
• Strength of concrete is generally independentof aggregate strength.
• Durability may be affected by aggregate strength
• Should be free from impurities
• More angular aggregates require more cement paste than rounded aggregates.
Concrete Constituents: (3) Aggregates
![Page 18: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/18.jpg)
Properties of Concrete 18
More about Aggregates
• Generally two size categories:
Fine and Coarse
• Gradation is important.
• Maximum size of aggregate is controlled by opening size between reinforcing bars and forms.
• The larger the aggregate size, the lower the volume of paste that is required.
Concrete Constituents: (3) Aggregates
![Page 19: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/19.jpg)
10/9/2010 Properties of Concrete I 19
(4) Air
• Generally 1-2% with out using an air entraining admixture.
• For good freeze-thaw durability the concrete should have between 4-7% entrained air.
• Increasing the air content improves workability.
Concrete Constituents: (4) Air
![Page 20: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/20.jpg)
10/9/2010 Properties of Concrete I 20
(5) Admixtures
• Admixtures are used to enhance a particular property such as strength, workability, freeze-thaw durability, time to set, etc…
• Two important admixtures:
(a) Air Entrainment
(b) Calcium Chloride (CaCl2)
Concrete Constituents: (5) Admixtures
![Page 21: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/21.jpg)
10/9/2010 Properties of Concrete I 21
(a) Air Entrainment
• Increases workability
• Decreases density
• Decreases strength
• Reduces bleeding
• Reduces segregation
• Increases durability (10 times or more)
• Allows reduction in sand (fine aggregate) content
• Allows reduction in water content.
• Increases resistance to surface scaling resulting from salt.
Concrete Constituents: (5) Admixtures
![Page 22: Properties of Concretescetcivil.weebly.com/uploads/5/3/9/5/5395830/lect1... · 2018. 10. 4. · Properties of Concrete 4 What is Concrete? • Is the second most commonly used building](https://reader036.vdocuments.us/reader036/viewer/2022062607/6055d6fb605969584847b843/html5/thumbnails/22.jpg)
10/9/2010 Properties of Concrete I 22
(b) Calcium Chloride
• Accelerates setting
• Increases strength up to a year.
• Reduces bleeding
• Lowers resistance to sulfate attack
• Increases dry shrinkage
• Increases expansion under moist curing
• Increases heat. Warning: Do not use as an antifreeze. It will not produce enough heat. ?
• Increases expansion of Alkali aggregates
• Corrodes reinforcing
Concrete Constituents: (5) Admixtures