high density concrete, high strength concrete and high performance concrete
DESCRIPTION
advanced concrete technologyTRANSCRIPT
HIGH DENSITY CONCRETE,HIGH STRENGTH CONCRETE, HIGH
PERFOMANCE CONCRETE.
By, Shebina. A
High Density Concrete
High Density=Heavyweight
Density should be more than 2600 kg/m3
Dens CRETE
Offers more strength
Can be used everywhere, in all construction practices Resistant to extreme weather
Main Components:
Cement --- Provides limited strength --- Not that useful in high density concrete --- Used as binding material
Water
Aggregates
Admixtures
Natural Aggregates•Aggregates are obtained from iron ores
•Large amount of iron content
•Varying densities so variety of high density concrete can be produced
Types:
1. 2. 3.
4.
Man-made (Synthetic) Aggregates:
Iron Shots
Lead Shots Chilcon
Fergran
Synthetic Aggregates
Water reducing admixture is used
Consists Lignosulfonic acid, carboxylic acids
Use of Water reducing admixture in high density concrete
–Increase workability
–Reduces water requirement
–Reduces cement content requirement
–High early strength
Admixture:
Application:
High density radiation shielding Precast blocks Mass concrete projects High density concrete applications columns Gravity seawall, coastal protection & breakwater
structures Bridge counterweights Ballast for ocean vessels Off shore platforms noise and vibration dampening
Advantages:
High neutron and gamma ray attenuation Good mechanical properties Relatively low initial and maintenance cost Easy to construct
Disadvantages:
SpaceWeight
Production:
High Strength Concrete: Using Type I Portland cement, gravel or crushed limestone coarse
aggregate, sand from a local deposit, and for some mixes a water-reducing retarding admixture.
Water-cement ratios ranged from 0.70 to 0.32
Concrete strength of 90-120 MPa
Uniaxial compressive strengths ranged from about 21 to 76 MPa.
Pertaining to compressive strength, strength gain with age, specimen
size effect, effects of drying, stress-strain curves, static modulus of elasticity, Poisson’s ratio, modulus of ruptuie, and split cylinder strength.
Has to take care about mix proportioning, shape of aggregates, use of
supplementary cementitious materials, silica fume and super plasticizers.
Special methods of making high strength concrete Seeding: This involves adding a small percentage of finely ground, fully
hydrated Portland cement to the fresh concrete mix.
This method may not hold much promise.
Revibration: Controlled revibration removes all the defects like bleeding, water accumulates , plastic shrinkage, continuous capillary channels and increases the strength of concrete.
High speed slurry mixing: This process involves the advance preparation of cement - water mixture which is then blended with aggregate to produce concrete.
Use of admixtures: Use of water reducing agents are known to produce increased compressive strength.
Inhibition of cracks: If the propagation of cracks is inhibited, the strength will be higher.
Concrete cubes made this way have yielded strength up to 105MPa.
Sulphur Impregnation: Satisfactory high strength concrete have been produced by impregnating low strength porous concrete by sulphur.
The sulphur infiltrated concrete has given strength up to 58MPa.
Use of Cementitious aggregates: Cement fondu is kind of clinker.
Using Alag as aggregate, strength up to 25MPa has been obtained with water cement ratio 0.32.
Fire resistance of High Strength Concrete:
Strength-weight ratio becomes comparable to steel:
0
5
10
15
20
25
30
35
40
45
Structural steel Concrete High strengthconcrete
Lightweight HSC
Strength-Weight Ratio
High-strength concrete is often used in bridges
HIGH PERFOMANCE CONCRETE: “A high performance concrete is a concrete in which certain characteristics are developed for a particular application and environments”:
Ease of placement Compaction without segregation Early-age strength Long term mechanical properties Permeability Durability Heat of hydration Toughness Volume stability Long life in severe environments High resistance to frost and deicer scaling damage Toughness and impact resistance Volume stability
High-performance concrete is often used in bridges and tall buildings
Materials Used in High-Performance ConcreteMaterial Primary contribution/Desired property
Portland cement Cementing material/durability
Blended cement Cementing material/durability/high strength
Fly ash Cementing material/durability/high strength
Slag Cementing material/durability/high strength
Silica fume Cementing material/durability/high strength
Calcined clay Cementing material/durability/high strength
Metakaolin Cementing material/durability/high strength
Calcined shale Cementing material/durability/high strength
Super plasticizers Flow ability
High-range water reducers Reduce water to cement ratio
Hydration control admixtures Control setting
Retarders Control setting
Accelerators Accelerate setting
Corrosion inhibitors Control steel corrosion
Water reducers Reduce cement and water content
Shrinkage reducers Reduce shrinkage
ASR inhibitors Control alkali-silica reactivity
Polymer/latex modifiers Durability
Optimally graded aggregate Improve workability and reduce paste demand
ConcreteEnvironment Deterioration
ImpactResistance
ConcreteEnvironment
Durable Concrete
(HPC)
The required durability characteristics are governed by the application of concrete and by conditions expected to be encountered at the time of placement. These characteristics should be listed.
REFERANCE: Publication:Journal Proceedings Author(s):Ramon L. Carrasquilio, Arthur H. Nilson,
and Floyd 0. Slate CSTR49: ‘Design guidance for high strength concrete’, Concrete Society Technical
Report No. 49, The Concrete Society, 1998 CEB-FIP Model code for concrete structures, 1990. Comité Euro-International du
Beton. Thomas Telford, London, 1993. Bulletin d’Information No. 213/214. 437 pp. BRITISH STANDARDS INSTITUTION. BS 8110 Structural use of concrete Part 3:
1985. Design charts for singly reinforced beams, doubly reinforced beams and rectangular columns. 112 pp.
BS EN 1992-1-1:2004 Eurocode 2. Design of concrete structures. General rules and rules for buildings
Aı tcin, P.-C., High-Performance Concrete, Modern Concrete Technology 5, E & FN Spon, London, 1998
ASCE, High-Performance Construction Materials and Systems, Technical Report 93-5011, American Society of Civil Engineers, New York, April 1993.
Farny, James A., and Panarese, William C., High-Strength Concrete,EB114, Portland Cement Association, 1994
Perry, V., “Industrialization of Ultra-High Performance Ductile Concrete,” Symposium on High-Strength/High-Performance Concrete, University of Calgary, Alberta, November 1998.
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