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
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