high performance concrete seminar report

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:

Space

Weight

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 strength

concrete

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 Concrete

Material

Primary contribution/Desired property

Portland cement

Cementing material/durability

Blended cement

Cementing material/durability/high strength

Fly ash


Slag


Silica fume


Calcined clay


Metakaolin


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

Concrete Environment Deterioration

Impact

Resistance Concrete Environment

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.

high performance concrete seminar report

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