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.

THANK YOU.