Download - Concrete by Adesh
![Page 1: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/1.jpg)
CONCRETE
![Page 2: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/2.jpg)
What is Concrete?• Concrete is one of the most commonly used
building materials.• Concrete is a composite material made from
several readily available constituents (aggregates, sand, cement, water).
• Concrete is a versatile material that can easily be mixed to meet a variety of special needs and formed to virtually any shape.
![Page 3: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/3.jpg)
The word concrete comes from the Latin word "concretus"
(meaning compact or condensed).
The first major concrete users were the Egyptians in around
2,500 BC and the Romans from 300 BC
• OPUS CAEMENTICIUM• LAYING BARE ON TOMB
• ROMAN PANTHENON
Opus caementicium laying bare on a tomb near Rome. In contrast to modern concrete structures, the concrete walls of Roman buildings were covered, usually with brick or stone.`
Outer view of the Roman Pantheon, still the largest unreinforced solid concrete dome to this day.
![Page 4: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/4.jpg)
• There are various types of concrete for different applications that are created by changing the proportions of the main ingredients.
• The mix design depends on the type of structure being built, how the concrete will be mixed and delivered, and how it will be placed to form the structure.
Examples include:
• Regular concrete• Pre-Mixed concrete• High-strength concrete• Stamped concrete• High-Performance concrete• UHPC (Ultra-High Performance Concrete)
TYPES OF CONCRETE
![Page 5: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/5.jpg)
• Self-consolidating concretes• Vacuum concretes• Shotcrete• Cellular concrete• Roller-compacted concrete• Glass concrete• Asphalt concrete• Rapid strength concrete• Rubberized concrete• Polymer concrete• Geopolymer or Green concrete• Limecrete• Gypsum concrete• Light-Transmitting Concrete
![Page 6: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/6.jpg)
EXAMPLES OF CONCRETE TYPE
![Page 7: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/7.jpg)
Basic Composition for Main Concretes• Regular Concrete
– Cement, Aggregate, and water
• Geopolymer (Green concrete)– Fly Ash and Regular– Concrete
• High Strength Concrete ~<0.35%– Silica Fume– Strong Aggregates
• Ultra High Performance Concrete (UHPC) – Cement– Coarse/Fine Aggregate– Air– Silica Fume– Polypropylene Fibers
![Page 8: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/8.jpg)
Admixtures and Properties
![Page 9: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/9.jpg)
Chemical Admixtures• Dispersing Agents
– Water Reducers• Accelerators• Retarders
![Page 10: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/10.jpg)
Water Reducers• DEFINITION: Water Reducers are used for the
purpose of reducing the quantity of mixing water required to produce a concrete of given consistency.
![Page 11: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/11.jpg)
Accelerators• DEFINITION: Accelerating admixtures are added to
concrete for the purpose of shortening set time and accelerating early strength development.
![Page 12: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/12.jpg)
Retarders
• DEFINITION: Retarding, and Water-reducing and retarding admixtures are used to offset acceleration and unwanted effects of high temperature and keep concrete workable during placement and consolidation.
![Page 13: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/13.jpg)
Shrinkage Reducing Admixtures• DEFINITION: Shrinkage Reducing Admixtures are used to
minimize drying shrinkage cracking in concrete .
![Page 14: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/14.jpg)
Corrosion Inhibitors
• DEFINITION: Corrosion Inhibitors are used to mitigate corrosion of reinforcing steel in concrete.
![Page 15: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/15.jpg)
ASR Inhibitors
• DEFINITION: ASR Inhibitors (primarily Lithium) are used to mitigate alkali-silica reactivity in concrete.
![Page 16: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/16.jpg)
Concrete Materials
• Aggregate is the second most influential ingredient in concrete.
• Aggregate–Occupies 60-75 % of volume–Fine Aggregate is typically 35-45 % of
total aggregate–Mortar (Air, water, cement, fly ash,
sand) is typically 50 - 65 % of total volume of a mixture
![Page 17: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/17.jpg)
Aggregates in Concrete
• Fine: Sand or Crushed Stone (< 5mm)• Coarse: Gravel or Crushed Stone (5-50 mm) • Aggregate must be washed in many areas
– Granite & other crushed stone– Recycled concrete
• All must satisfy ASTM C33
![Page 18: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/18.jpg)
Concrete Construction
• Significance of aggregate grading– smooth grading curve
• (sieve size vs. % passing)– more voids will lead to more cement.– undersanded mixes tend to be harsh– large sizes have less surface area
![Page 19: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/19.jpg)
Desired Properties of Fresh Concrete
WorkabilityConsistencySegregationBleedingSetting TimeUnit WeightUniformity
![Page 20: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/20.jpg)
Concrete - Workability
• cement: too fine of material – stickiness – increased water demand
• water: too much water– segregation– bleeding
• water: too little water– harshness– compaction problems
• fly ash: increases flow– ball bearing effect– ionic effect– reduced water demand
• aggregate– rounded particles flow more
easily– Too much sand “stickiness”– Poor gradation - harsh
![Page 21: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/21.jpg)
Compressive Strength
Compressive Strength Uses of Concrete
41 MPa Highways and Structures
17-24 MPa Sidewalks and Driveways
> 55 MPa Prestressed Concrete
> 90 MPa High Strength Columnsand Beams
![Page 22: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/22.jpg)
Concrete Mixture Pre-Design
• Engineer
• Architect
• Contractor
• Concrete Supplier
• Define strength, congestion and durability properties
• Defines color, texture,• Defines workability,
setting time, ..• Defines aggregates,
cement, fly ash, admixtures....
![Page 23: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/23.jpg)
MIXING OF CONCRETE
Ready-Mix concrete: In this type ingredients are introduced into a mixer truck and mixed during transportation to the site.
• Wet – Water added before transportation• Dry – Water added at site
Mixing at the site• Hand mixed• Mixer mixed
![Page 24: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/24.jpg)
Ready Mix Concrete
![Page 25: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/25.jpg)
Hot Weather Concrete• Rapid hydration early setting rapid loss of
workability• Extra problems due to
– Low humidity– Wind, excessive evaporation– Direct sunlight
Solutions– Windbreaks– Cooled Concrete Ingredients– Water ponding (cooling due to evaporation)– Reflective coatings/coverings
![Page 26: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/26.jpg)
Cold Weather Concrete• Keep concrete temperature above 5 °C to
minimize danger of freezing
Solutions– Heated enclosures, insulation– Rely on heat of hydration for larger sections– Heated ingredients --- concrete hot when placed– High early strength cement
![Page 27: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/27.jpg)
Structure of “un-damaged” Concrete
Macrostructurem Microstructure
![Page 28: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/28.jpg)
VIBRATION OF CONCRETE The process of compacting concrete consists
essentially of the elimination of entrapped air. This can be achieved by:
– Tamping or rodding the concrete– Use of vibrators
![Page 29: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/29.jpg)
Internal Vibration
d
R
1½ R
Vibrator
Internal vibrator: The poker is immersed into concrete to compact it. The poker is easily removed from point to point.
![Page 30: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/30.jpg)
EXTERNAL VIBRATORSExternal vibrators: External vibrators clamp direct to the formwork requiring strong, rigid forms.
![Page 31: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/31.jpg)
Advantages
• Ability to be cast• Economical• Durable• Fire resistant• Energy efficient• On-site fabrication
![Page 32: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/32.jpg)
Disadvantages• Low tensile strength• Low ductility• Volume instability• Low strength to weight ratio
![Page 33: Concrete by Adesh](https://reader031.vdocument.in/reader031/viewer/2022022203/5870534e1a28aba2118b4be7/html5/thumbnails/33.jpg)
hT A n
YoUK
Submitted ByAdesh GuptaB.Arch