Download - 6-2 Hp Concrete
-
8/6/2019 6-2 Hp Concrete
1/28
Tony Kojundic
Silica Fume Associationc/o Elkem Materials Inc.PO Box 266
Pittsburgh, PA 15230(412)299-7229
Synopsis:
This presentation will provide a fundamental look into the definition of high-performanceconcretes (HPC) of today, and the technology behind silica-fume to produce HPC for bridgeapplications. The presentation will highlight key structural and durability properties of HPCand the life-cycle cost savings from implementing HPC into our nations transportationinfrastructure. Included are HPC bridge applications from around the country and the latestevolving HPC designs employing the lessons learned from 20 years of bridge experiences.One such lesson is a universally accepted construction technique and curing practice to bestutilize the properties HPC brings to the project. The presentation also highlights many
resources for information on HPC technology, application, and practice, provided by industryand the FHWA.
About the Presenter:
Tony Kojundic is a founding Board member of the Silica Fume Association, and BusinessManager for Elkem Materials in Pittsburgh, PA. The Silica Fume Association operates under aco-operative agreement with the FHWA to help provide technology transfer on High-performance Concrete(HPC) to state and local transportation departments. He is active on
numerous committees of the American Concrete Institute(ACI), the Transportation ResearchBoard, the American Society of Testing and Materials, the National Concrete Bridge Council,and the Society of Petroleum Engineers. His ACI duties include secretary of the Silica-fumeConcrete Subcommittee, and chapter author to the High-strength Concrete, ParkingStructures, and Concrete Proportioning Committees. Through his employment at Elkem hesbeen directly involved with silica-fume concrete research and implementation into projectapplications for the past 20 years A 1975 graduate engineer from West Virginia University
SESSION 6.2
Silica Fume High-performance Concretein Bridge Applications
-
8/6/2019 6-2 Hp Concrete
2/28
Eleventh StateEleventh State--wide Conference on Local Bridgeswide Conference on Local Bridges
Silica Fume HighSilica Fume High--performance Concreteperformance Concretein Bridge Applicationsin Bridge Applications
October 28, 2004October 28, 2004
-
8/6/2019 6-2 Hp Concrete
3/28
What is highWhat is high--performance concrete?performance concrete?
HPC is a concrete in which certain characteristicsHPC is a concrete in which certain characteristics
are developed for a particular application andare developed for a particular application and
environmentenvironment -- FHWA,FHWA, BridgeViewsBridgeViews, Issue, #1., Issue, #1.
-
8/6/2019 6-2 Hp Concrete
4/28
Examples of HPC
Ease of placement.Ease of placement.
Compaction without segregation.Compaction without segregation.
EarlyEarly--age strength.age strength.LongLong--term properties.term properties.
PermeabilityPermeability
DensityDensityHeat of hydration.Heat of hydration.
ToughnessToughness
Volume stability.Volume stability.
LongLong--life.life.
http://www.fhwa.dot.gov/bridge/hpcwhat.htmhttp://www.fhwa.dot.gov/bridge/hpcwhat.htm
-
8/6/2019 6-2 Hp Concrete
5/28
1999 National Bridge1999 National Bridge
InventoryInventory
585,000 US bridges,585,000 US bridges,+210,000 are deficient.+210,000 are deficient.
7,623 (48.9%) of NY7,623 (48.9%) of NY
bridges.bridges. #1 repair area#1 repair area -- bridgebridge
decks.decks.
$5 B/yr. dedicated for$5 B/yr. dedicated forbridges.bridges.
-
8/6/2019 6-2 Hp Concrete
6/28
Service Life Estimate
Initiation period,ti Propa gation period,tp
End of service life
D
amage
Time
Cl , CO2 penetration
O2 diffusion,
resistivity
Figure 4.1 Two-Stage Service Life Model Proposed by Tuutti (1982)
-
8/6/2019 6-2 Hp Concrete
7/28
-
8/6/2019 6-2 Hp Concrete
8/28
Ceramic: Particle Packing TheoryCeramic: Particle Packing Theory
100% packing100% packing
= 0% voids.= 0% voids.
-
8/6/2019 6-2 Hp Concrete
9/28
Concrete without silica fume with silica fumeConcrete without silica fume with silica fume
-
8/6/2019 6-2 Hp Concrete
10/28
-
8/6/2019 6-2 Hp Concrete
11/28
-
8/6/2019 6-2 Hp Concrete
12/28
Bridge Deck HPC PhilosophyBridge Deck HPC Philosophy
Implies using the leastImplies using the least
amount of cement possible!amount of cement possible!
Judicious use of pozzolans.Judicious use of pozzolans.Particle packing / reducedParticle packing / reduced
permeability.permeability.
ASR control.ASR control.Less water / lessLess water / less
shrinkage.shrinkage.
Reduced heat of hydration.Reduced heat of hydration.Reduced cracking.Reduced cracking.
-
8/6/2019 6-2 Hp Concrete
13/28
Typical HPC ProportionsTypical HPC Proportions -- Piles, Piers, Caps.Piles, Piers, Caps.
High Strength, HPC.High Strength, HPC.
CementCement 624 pcy624 pcy
Fly ashFly ash 120 cy (15%)120 cy (15%)SFSF 56 pcy (7%)56 pcy (7%)
w/cmw/cm 0.340.34
1d1d 5000 psi5000 psi28d28d 9000 psi9000 psi
-
8/6/2019 6-2 Hp Concrete
14/28
Hoover Dam Bypass - Box Girder Arch, 12,000psi HPC.Hoover Dam Bypass - Box Girder Arch, 12,000psi HPC.
www.hooverdambypass.comwww.hooverdambypass.com
-
8/6/2019 6-2 Hp Concrete
15/28
Deck Concrete Performance GoalDeck Concrete Performance Goal
Extended service life.Extended service life.
Reduce mortar permeability.Reduce mortar permeability.
Reduce shrinkage or tendency to crack.Reduce shrinkage or tendency to crack.
-
8/6/2019 6-2 Hp Concrete
16/28
Extended Service LifeExtended Service Life
Reduce permeability.Reduce permeability.
Particle packing and pozzolanic chemistry.Particle packing and pozzolanic chemistry.
Reduced shrinkage and/or tendency to crack.Reduced shrinkage and/or tendency to crack.
Less water per volume (cubic yard) ofLess water per volume (cubic yard) of
concrete.concrete.
Lower cement content.Lower cement content.
Greatest amount of aggregate.Greatest amount of aggregate.
Least amount of mortar.Least amount of mortar.Control evaporation.Control evaporation.
-
8/6/2019 6-2 Hp Concrete
17/28
Typical HPC ProportionsTypical HPC Proportions -- Bridge Decks.Bridge Decks. Low permeable, lowLow permeable, low
cracking.cracking.
CementCement 500 pcy500 pcyFly ash 135 pcyFly ash 135 pcy (20%)(20%)
SFSF 40 pcy40 pcy (6%)(6%)
w/cmw/cm 0.400.40
28d28d 5000 psi5000 psi
Perm.Perm.
-
8/6/2019 6-2 Hp Concrete
18/28
Bridge Deck Concrete Comparison HPCHPC volvol DOT AAA mix.DOT AAA mix.
Cement, pcyCement, pcy 470470 2.392.39 665665 3.393.39
Fly ash, pcyFly ash, pcy 100100 0.640.64 117117 0.750.75
Silica fume, pcySilica fume, pcy 4040 0.290.29 ------
Water, galWater, gal 29.829.8 3.973.97 36.836.8 4.914.91
Total volumeTotal volume (
-
8/6/2019 6-2 Hp Concrete
19/28
Cohesive silica-fume concrete-- OK to increase slump
-
8/6/2019 6-2 Hp Concrete
20/28
Evaporation
Bleeding
If Evaporation > Bleeding Plastic Shrinkage Cracking
Problem: Concrete Surface Drying
ConstructionConstruction
-
8/6/2019 6-2 Hp Concrete
21/28
What is Plastic Shrinkage Cracking?What is Plastic Shrinkage Cracking?Cracking that occurs in the surface of fresh concrete
soon after it is placed and while it is still plastic.
-- ACI 116RPlastic shrinkagecracking
-
8/6/2019 6-2 Hp Concrete
22/28
Test Pours for NeverTest Pours for Never-- evers.evers.
Makes slump appear less.Makes slump appear less.
SilicaSilica--fume concrete doesfume concrete does
not bleed.not bleed. Susceptible to plasticSusceptible to plastic
shrinkage cracking.shrinkage cracking.
Requires immediateRequires immediateevaporation protection.evaporation protection.
No delay in final finishing.No delay in final finishing.
Key to fastKey to fast--track finishingtrack finishing.
Document finishing plan.Document finishing plan.
-
8/6/2019 6-2 Hp Concrete
23/28
Machine FoggingMachine Fogging
-
8/6/2019 6-2 Hp Concrete
24/28
OneOne--Pass FinishingPass Finishing
Under finish, over cure.Under finish, over cure.
Excessive hand finishingExcessive hand finishing
gains no advantage, andgains no advantage, and
harms surface durability.harms surface durability.
Avoid tools thatAvoid tools that stick to thestick to the
HPC surface.HPC surface.
Photos of placement
-
8/6/2019 6-2 Hp Concrete
25/28
OneOne--Pass Finishing.Pass Finishing.
Steel bull floats andSteel bull floats and
FresnosFresnoswork well.work well.
Curing requirements.Curing requirements.
Wet cure begins 10Wet cure begins 10--1515
min. after placementmin. after placement
for a minimum 7d.for a minimum 7d.
Membrane cure afterMembrane cure after
wet cure and texturingwet cure and texturingExpedite placing, finishing, texturing
and use immediate curing
-
8/6/2019 6-2 Hp Concrete
26/28
Cracking Performance of HPC Bridge DecksCracking Performance of HPC Bridge Decks -- NY DOTNY DOT
-- TRB Paper No. 5B0121TRB Paper No. 5B0121
SurveySurvey -- 84 bridges84 bridges
constructed between 95constructed between 95and 98.and 98.
Class E concrete decksClass E concrete decks
(95(95--96).96).60% transverse60% transverse
cracking.cracking.
58% longitudinal58% longitudinalcracking.cracking.
Class HP concrete decks 97Class HP concrete decks 97--
98.98.
39% transverse cracking.39% transverse cracking.
33% longitudinal cracking.33% longitudinal cracking.
The 98 decksThe 98 decks -- 33% and 25%33% and 25%respective cracking.respective cracking.
55% of cracks appeared55% of cracks appeared
between 0between 0 --14 days.14 days. No difference steel andNo difference steel and
concrete bridge structuresconcrete bridge structures..
-
8/6/2019 6-2 Hp Concrete
27/28
FHWAFHWA -- HPC Technology Delivery Program.HPC Technology Delivery Program.
Innovative Bridge Research ProgramInnovative Bridge Research Program
http://ibrc.fhwa.dot.gov/http://ibrc.fhwa.dot.gov/
240 projects, 61 HPC.240 projects, 61 HPC.
HPCHPC -- Technology Delivery TeamTechnology Delivery Team
http://www.fhwa.dot.gov/bridge/hpc.htmhttp://www.fhwa.dot.gov/bridge/hpc.htmhttp://knowledge.fhwa.dot.gov/cops/hpcx.nsf/homehttp://knowledge.fhwa.dot.gov/cops/hpcx.nsf/home
Silica Fume Association.Silica Fume Association.
www.silicafume.orgwww.silicafume.org
-
8/6/2019 6-2 Hp Concrete
28/28