Python Notes for mca i year students osmania university.docx
High density concrete, high strength concrete and high performance concrete.
1.
2. 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
3. Main Components:
Cement
--- Provides limited strength
--- Not that useful in high density concrete
--- Used as binding material
Water
Aggregates
Admixtures
4. 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.
4.
3.
6. Admixture:
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
7. 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
8. Advantages:
High neutron and gamma ray attenuation
Good mechanical properties
Relatively low initial and maintenance cost
Easy to construct
Disadvantages:
Space
Weight
10. High Strength Concrete:
Using Type I Portland cement, gravel or crushed limestone coarse
aggregate, sand from a local deposit, and for some mixes a waterreducing 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.
11. 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.
12. 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.
16. 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
19. 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
20. 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.
Environment
Environment
Concrete
Impact
Resistance
Durable
Concrete
(HPC)
Deterioration
Concrete
21. 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 935011, 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.
