Master Degree in StructuresMaster Degree in Structures

Seminar InSeminar In

High Performance &High Performance &Self Compacted Self Compacted

ConcreteConcretePrepared By: Prepared By: Eng. Albushra Abdel-Bagi &Taha Elnour Eng. Albushra Abdel-Bagi &Taha Elnour IsshageIsshage

Supervised By: Dr. Nadir M. HassanainSupervised By: Dr. Nadir M. Hassanain

July 2010July 2010

Tricalcium silicate 3CaO.SiO2 C3SDicalcium silicate 2CaO.SiO2 C2STricalcium aluminate 3CaO.Al2O3 C3ATetracalcium aluminoferrite

4CaO.Al2O3.Fe2O3 C4AF C3S and C2S

are responsible for the strength of hydrated cement paste

C3A is undesirableC3A is undesirableis present in small quantities. Reacts very rapidly with water (flash setting)

• gypsum retards this • provides early strength• prone to sulphate attack

C4AFC4AF dark in color with little cementing valueforms due to iron oxide, a useful flux during the burning process..

Regular concrete High-strength concrete Stamped concrete High-performance concrete Self-consolidating concretes Vacuum concretes Shotcrete Pervious concrete Cellular concrete, Cork-cement composites Roller-compacted concrete

Glass concrete Asphalt concrete Rapid strength concrete Rubberized concrete Polymer concrete Geopolymer or green concrete Limecrete Refractory Cement Concrete cloth Innovative mixtures Gypsum concrete

It is also known as Reactive Powder Concrete (RPC)

It is a high strength, ductile material formulated by combining portland cement, silica fume, quartz flour, fine silica sand, high-range water reducer, water, and steel or organic fibers

Concrete may be regarded as high performance for several different reasons:

high strength, high workability high durability – and perhaps also improved

visual appearance.

How to recognize concrete structure with KALMATRON® How to recognize concrete structure with KALMATRON® KF-A?KF-A?

Wash the surface with water and see the differenceWash the surface with water and see the difference

Intact surface of concrete with loweredshrinkage development.

Typical shrinkage cracks as a result ofretarded structure forming process.

High strength concrete (HSC) might be regarded as concrete with a strength in excess of 70MPa and such concrete can be produced as relatively normal concrete with a higher cement content and a normal water-reducing admixture.

However ultra high performance concrete (UHPC) will more usually contain cement replacement materials and a high-range water-reducer (HRWR) or superplasticiser(SP) (different names for the same thing).

How High? Strengths of 150-200MPa were

reported in several papers at a recent symposium

How is it done? Using only fine sand as an aggregate,

a high content of cement and silica fume, a high dosage of HRWR admixture plus steel fibres

In what kind of structures? Thin shell roofing (2cm thick) and

“bulb” double and single tees were reported

Both insitu and precast applications Flexural and tensile strengths also

high, allowing omission of secondary reinforcement.

Concrete in tees was generally self- compacting

High early strength High strength High modulus of elasticity High abrasion resistance High durability and long life

in severe environments Low permeability and

diffusion Resistance to chemical attack

High resistance to frost and deicer scaling damage

Toughness and impact resistance

Volume stability Ease of placement Compaction without

segregation Inhibition of bacterial and

mold growth

MaterialMaterial Primary Contribution/Desired Primary Contribution/Desired PropertyProperty

Portland cementPortland cement Cementing material / DurabilityCementing material / Durability

Blended cementBlended cement

Cementing material / Cementing material /

Durability / Durability /

High strengthHigh strength

Fly ash / Slag / Silica fumeFly ash / Slag / Silica fume

Calcined clay/ MetakaolinCalcined clay/ Metakaolin

Calcined shaleCalcined shale

SuperplasticizersSuperplasticizers FlowabilityFlowability

High-range water reducersHigh-range water reducers Reduce water-cement ratioReduce water-cement ratio

Hydration control admix.Hydration control admix. Control settingControl setting

MaterialMaterial Primary contribution/Desired Primary contribution/Desired propertyproperty

RetardersRetarders Control settingControl setting

AcceleratorsAccelerators Accelerate settingAccelerate setting

Corrosion inhibitorsCorrosion inhibitors Control steel corrosionControl steel corrosion

Water reducersWater reducers Reduce cement and water contentReduce cement and water content

Shrinkage reducersShrinkage reducers Reduce shrinkageReduce shrinkage

ASR inhibitorsASR inhibitors Control alkali-silica activityControl alkali-silica activity

Optimal graded Aggr.Optimal graded Aggr. Improve workability/reduce pasteImprove workability/reduce paste

Polymer/latex modifiersPolymer/latex modifiers DurabilityDurability

PropertyProperty Test MethodTest Method Criteria that may be Criteria that may be specifiedspecified

High StrengthHigh Strength ASTM C 39ASTM C 39 70-140 MPa @ 28 to 91 days70-140 MPa @ 28 to 91 days

Comp. StrengthComp. Strength ASTM C 39ASTM C 39 20-30 MPa @ 3-12 hrs or 1-3 days20-30 MPa @ 3-12 hrs or 1-3 days

Flex. StrengthFlex. Strength ASTM C 78ASTM C 78 2-4 MPa @ 3-12 hrs or 1-3 days2-4 MPa @ 3-12 hrs or 1-3 days

Abrasion ResistanceAbrasion Resistance ASTM C 944ASTM C 944 0-1 mm depth of wear0-1 mm depth of wear

Low PermeabilityLow Permeability ASTM C 1202ASTM C 1202 500 to 2000 coulombs500 to 2000 coulombs

Chloride PenetrationChloride PenetrationAASHTO T AASHTO T 259/260 259/260 Less than 0.07% Cl at 6 monthsLess than 0.07% Cl at 6 months

High Mode of Elsti.High Mode of Elsti.

Low Absorption ASTM C 642 2% to 5%2% to 5%ASTM C 469 More than 40 GPa

Type III or HE high-early-strength cement High cement content 400 to 600 kg/m3

(675 to 1000 lb/yd3) Low water-cementing materials ratio (0.20

to 0.45 by mass) Higher freshly mixed concrete temperature Higher curing temperature

May be achieved by —

Chemical admixtures Silica fume (or other SCM) Steam or autoclave curing Insulation to retain heat of

hydration Special rapid hardening cements

May be achieved by —

90% of ready-mix concrete

20 MPa - 40 MPa (3000 – 6000 psi) @ 28-d (most 30 MPa – 35 MPa)

High-strength concrete by definition —

28 day – compr. strength

70 MPa (10,000 psi)

9.5 - 12.5 mm (3/8 - 1/2 in.) nominal maximum size gives optimum strength

Combining single sizes for required grading allows for closer control and reduced variability in concrete

For 70 MPa and greater, the FM of the sand should be 2.8 – 3.2. (lower may give lower strengths and sticky mixes)

Aggregates —

Fly ash, silica fume, or slag often mandatory

Dosage rate 5% to 20% or higher by mass of cementing material.

Supplementary Cementing Materials —

Use of water reducers, retarders, HRWRs, or superplasticizers — mandatory in high-strength concrete

Air-entraining admixtures not necessary or desirable in protected high-strength concrete. Air is mandatory, where durability in a freeze-thaw

environment is required (i.e.. bridges, piers, parking structures)

Recent studies: w/cm ≥ 0.30—air required w/cm < 0.25—no air needed

Admixtures —

Delays in delivery and placing must be eliminated

Consolidation very important to achieve strength

Slump generally 180 to 220 mm (7 to 9 in.) Little if any bleeding—fog or evaporation

retarders have to be applied immediately after strike off to minimize plastic shrinkage and crusting

7 days moist curing

Placing, Consolidation, and Curing

1970s and 1980s focus on — High-Strength HPC

Today focus on concretes with high durability in severe environments resulting in structures with long life —

High-Durability HPC

Abrasion Resistance Blast Resistance Permeability Carbonation Freeze-Thaw Resistance Chemical Attack Alkali-Silica Reactivity Corrosion rates of rebar

Durability Issues That HPC Can Address

Properties of UHPC Compressive strengths up to

200 Mpa Flexural Strengths up to 50 Mpa Modulus of Elasticity 45 to 50

GPa Ductile strong Durable High bending tensile strength Low capillary porosity (high

endurance) High resistance to deicing salt Greatly reduced permeability to

moisture, chlorides and chemical attack

Increased resistance to abrasion, erosion and corrosion

Speedy construction

Properties of Concrete Compressive

Strength 25 to 35 Mpa

Relatively Weak Extremely Brittle Almost no tensile

strength High thermal

expansion and contraction with temperature fluctuations

Cement: 398 kg/m3 (671 lb/yd3) Fly ash: 45 kg/m3 (76 lb/yd3) Silica fume: 32 kg/m3 (72 lb/yd3) w/c: 0.30 Water Red.: 1.7 L/m3 (47 oz/yd3) HRWR: 15.7 L/m3 (83 oz/yd3) Air: 5-8% 91d strength: 60 MPa (8700 psi)

Confederation Bridge, Confederation Bridge, Northumberland Strait, Prince Northumberland Strait, Prince

Edward Island/New Brunswick, 1997Edward Island/New Brunswick, 1997

Scraper paths in treatment plants

Architecture Bridges Narrow supports Filigree beams Thin or slab-like

components Buttresses for

high pressures

developed in 1980s — Japan Increased amount of

Fine material (i.e. fly ash or limestone filler)

HRWR/Superplasticizers

Strength and durability same as conventional concrete

Self-consolidating concrete (SCC) also known as self-compacting concrete —flows and consolidates on its own

Never pre-mix admixtures before adding them to the concrete

The order and timing of admixture addition can be critical

When properties cannot be made by varying the composition of basic material

To produce desired effects more economically

Unlikely to make a poor concrete better Not a substitute for good concrete practice Required dose must be carefully

determined and administered

Check job specification Use the correct admixture

never use one from an unmarked container. keep containers closed to avoid accidental contamination.

Add the correct dosage. avoid adding 'a little bit extra' use a dispenser

wash thoroughly at the end the day Best if added to the mixing water Manufacturer's recommended dosage is usually

adequate Trial mixes are important to determine most effective

dosage

Self-compactability Avoidance of bleeding and

segregation Low shrinkage Low permeability Strength as needed

Less dependent on skill on site Safer, quieter sites (no

vibration) Better appearance Better durability Strength as needed

Segregation resistance from mortar viscosity, not aggregate grading

Workability through admixtures, not water content

Higher cost – especially if high strength not needed

Plant control has to be better

My guess is that 50% of concrete will be self-compacting within 10 years

In USA a very large proportion of precast concrete is already SCC

Paste Viscosity! Attained by one of three means:

High cement content High content of Fly Ash, Silica

Fume etc Use of Viscosity Modifying

Admixture Plus low water content using

HRWR

Reduces the total mass of the structures. Ability to have more additional floors. Less sections dimensions. Long Spans can be adopted in buildings. Less deflection can be achieved. High rise building high resistance to earth

quake. Overcoming hot weather concreting

problems.

Cost of HSC may be almost Doubled compared to Ordinary Strength Concrete.

This High cost is offset by high building performance and less durability problems.

For High rise building this extra cost accumulates to less than 20% of the skeleton cost.

Cost of Quality control inceases to 50% than the usual concrete works.

Measuring spread rather than height plus:

Speed of flow outwards Ability to pass through J-ring Observation of edge during flowInteresting to note that it works better

with the cone upside down!

Portland cement (Type I) 297 kg/m3 (500 lb/yd3)

Slag cement 128 kg/m3 (215 lb/yd3)

Coarse aggregate 675 kg/m3 (1,137 lb/yd3)

Fine aggregate 1,026 kg/m3 (1,729 lb/yd3)

Water 170 kg/m3 (286 lb/yd3)

Superplasticizer ASTM C 494, Type F (Polycarboxylate-based) 1.3 L/m3 (35 oz/yd3)

AE admixture as needed for 6% ± 1.5% air content

Properties: High strength — 200 MPa

(can be produced to 810 MPa)

Very low porosity Properties are achieved by: Max. particle size 300 m Optimized particle packing Low water content Steel fibers Heat-treatment

PropertyProperty UnitUnit 80 MPa80 MPa RPCRPC

Compressive strengthCompressive strength MPa (psi)MPa (psi) 80 (11,600)80 (11,600) 200 (29,000)200 (29,000)

Flexural strengthFlexural strength MPa (psi)MPa (psi) 7 (1000)7 (1000) 40 (5800)40 (5800)

Tensile strengthTensile strength MPa (psi)MPa (psi) 8 (1160)8 (1160)

Modulus of ElasticityModulus of Elasticity GPa (psi)GPa (psi) 40 (5.8 x 1040 (5.8 x 1066)) 60 (8.7 x 1060 (8.7 x 1066))

Fracture ToughnessFracture Toughness 103 J/m103 J/m22 <1<1 3030

Freeze-thawFreeze-thaw RDFRDF 9090 100100

Carbonation Carbonation mmmm 22 00

AbrasionAbrasion 1010-12-12 m m22/s/s 275275 1.21.2

Cement Sand Silica quartz Silica fume Micro-Fibres - metallic or poly-vinyl acetate Mineral fillers - Nano-fibres Superplasticizer Water

Raw Material Raw Material ComponentsComponents

Raw Material Raw Material ComponentsComponents

uctal

What is the typical Ductal® mix ?

230 kg/m3

710 kg/m3

210 kg/m3

40 - 160 kg/m3

13 kg/m3

140 kg/m3

1020 kg/m3

Cement

Silica fume

Crushed Quartz

Sand

Fibres

Superplasticizer

Total water

No aggregates !

uctal

What is the typical Ductal® mix ?

9 – 10%

28 - 30%

8.5 – 9%

1.7 – 6.5%0.6%

5.5 – 6%

42 –43%

Cement

Silica fume

Crushed Quartz

Sand

Fibres

Superplasticizer

Total water

No aggregates !

uctal

w/c = 0.20

Use concrete materials and proportions with satisfactory records in hot weather

Use cool concrete Use a concrete consistency that permits

rapid placement and effective consolidation Transport, place, consolidate, and finish

with least delay Protect concrete against moisture loss at all

times, during placement and curing period

Portland cement (Type I) 450 kg/m3

Slag cement 0.00 kg/m3

Coarse aggregate 1050 kg/m3

Fine aggregate 760 kg/m3

Water 160 kg/m3

Superplasticizer ASTM C 494, Type F (Polycarboxylate-based) 6.0 L/m3

AE admixture as needed for 6% ± 1.5% air content

W/C = 0.36

Special Mixes in KhartoumAl-Riyadh – Almashtel and Burri Durrat Alneel

Concrete Strength = 56N/mm2

Higher w/c = higher slump, workability