Concrete Mixture Designs for OHare Modernization Plan

1
Concrete Mixture Designs for OHare Modernization
Plan
University of Illinois (Urbana-Champaign) Departm
ent of Civil and Environmental Engineering
Chicago OHare January 12, 2006
2
Project Goal

• Investigate cost-effective concrete properties
  and pavement design features required to achieve
  long-term rigid pavement performance at Chicago
  OHare International.

3
Project Team

• Principal Investigators
• Prof. Jeff Roesler
• Prof. David Lange
• Students
• Cristian Gaedicke
• Sal Villalobos
• Zach Grasley
• Rob Rodden

4
Project Objectives

• Develop concrete material constituents and
  proportions for airfield concrete mixes
• Strength
• volume stability
• fracture properties
• Develop / improve models to predict concrete
  material behavior
• Crack width and shrinkage
• Evaluate material properties and structural
  design interactions
• joint type joint spacing (curling and load
  transfer)
• Saw-cut timing

5
Project Objectives
Material constituents and mix design
Analysis of existing concrete mix designs
Long-term perfor-mance at ORD
Concrete properties
Laboratory tests
Modeling
Test for material properties
Optimal joint types and spacing.
6
FY2005 Accomplishments

• Tech Notes (TN) -
• TN2 PCC Mix Design
• TN3 Fiber Reinforced Concrete for Airfield Rigid
  Pavements
• TN4 Feasibility of Shrinkage Reducing Admixtures
  for Concrete Runway Pavements
• TN11 Measurement of Water Content in Fresh
  Concrete Using the Microwave Method
• TN12 Guiding Principles for the Optimization of
  the OMP PCC Mix Design
• TN15 Evaluation, testing and comparison between
  crushed manufactured sand and natural sand
• TN16 Concrete Mix Design Specification
  Evaluation
• TN17 PCC Mix Design Phase 1

www.cee.uiuc.edu/research/ceat
7
TN2 PCC Mix Design
8
Survey of Existing Mixes
9
Tech Note 3

• Fiber Reinforced Concrete for Airfield Rigid
  Pavements

• Final cost reduction of 6 to an increase of
  11

10
Tech Note 4

• Feasibility of Shrinkage Reducing Admixtures for
  Concrete Runway Pavements
• Reduced Shrinkage and Cracking Potential 50
  reduction
• Cost limitations (?)

Figure 1. Unrestrained shrinkage of mortar bars,
w/c 0.5 (Brooks et al. 2000)
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Tech Note 11

• Measurement of Water Content in Fresh Concrete
  Using the Microwave Method
• Strengths quick, simple, and inexpensive
• Limitations need accurate information on
• cement content
• aggregate moisture and absorption capacity

12
TN 12 Guiding Principles for the Optimization
of the OMP PCC Mix Design

• 1st order
• Strength, workability
• 2nd Order
• Shrinkage, fracture properties
• LTE strength gain

13
Tech Note 15

• Evaluation, testing and comparison between
  crushed manufactured sand and natural sand
• Gradation
• physical properties

14
Manufactured vs Natural Sand

• Visual evaluation
• Material retained in the 8 sieve shows
  difference in the particle shape
• The Manufactured sand shows a rough surface and
  sharp edges due to the crushing action to which
  it was subjected.

Sieve No. 50
Sieve No. 8
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Tech Note 16

• Concrete Mix Design Specification Evaluation
• Preliminary P-501 evaluation
• Strength, shrinkage, and material constituent
  contents

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2005 Accomplishments

• Specification Assistance
• On-site meetings at OMP headquarters
• Brown bag seminars
• Continued specification assistance (2006)
• Material constituents (aggregate type and size,
  SCM, etc.)
• Modulus of rupture and fracture properties of
  concrete
• Shrinkage (cement content, w/c ratio limits,etc.)
• Saw-cut timing, spacing and depth
• Pavement design

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PCC Mix Evaluation Phase II

• Effect of aggregate size (0.75 vs. 1.5)
• Effect of 1.5 coarse aggregate
• Total cementitious content
• 688 lb/yd3, 571 lb/yd3, 555 lb/yd3 and 535 lb/yd3
  
• Water / cementitious ratio
• 0.38 versus 0.44
• Fly Ash / cementitious ratio
• 14.5 versus 0
• Effect of coarse aggregate cleaniness

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PCC Mix Evaluation Phase II

• Testing
• Fresh concrete properties
• Slump, Air Content, Unit Weight
• Mechanical Testing
• Compressive strength (fc) at 7 and 28 days
• Modulus of Elasticity (E) at 7 and 28 days
• Split tensile strength (fsp) at 7 and 28 days
• Modulus of Rupture (MOR) at 7 and 28 days
• Volume Stability Testing
• Drying and Autogenous Shrinkage trends for 28
  days
• Fracture tests
• Early-ages (lt48 hrs)
• Mature age (28 days)

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Mixture design nomenclature

• 9 mixes were prepared
• 555.44 555.44 st 688.38 688.38 st
• AAA.BB

max aggregate size st 0.75 Otherwise 1.5
Cementitious content (17FA) lbs/cy
w/cm
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Phase II Mix Design Results
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Strength Summary
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Shrinkage Results Phase II

• Total and Autogenous shrinkage

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Drying Shrinkage Phase II
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Fracture Energy Phase II

• GF cracking resistance of material
• GF joint surface roughness indicator

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WST Test

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Testing Plan 4 Mixtures

• Wedge splitting specimens (7)
• 6, 8, 10, 12 and 24 hours
• 7 and 28 days
• Cylinders for compression and split tensile
  strength for 1,7 and 28 days and E values for 7
  and 28 days
• MOR for 28 days

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Fracture Plots of PCC mixtures
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Fracture Energy Results-Phase II

• Age 28-days

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Concrete Brittleness

• Characteristic Length

Less brittle mixes w/ larger MSA
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GF vs Joint Performance

• Fracture Energy ? Shear Stiffness
• ? Joint Performance
• need crack width!

Chupanit Roesler (2005)
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PCC Mix Design Phase II

• Summary
• Larger aggregates reduce strength by 20
• 28-day GF similar ? similar cracking resistance
• Larger aggregates reduce concrete brittleness
• 1-day fracture energy ? with larger MSA
• ? greater joint stiffness / performance
• No significant shrinkage difference
• TNXX February 2006

Roesler, J., Gaedicke, C., Lange, Villalobos,
S., Rodden, R., and Grasley, Z. (2006),
Mechanical Properties of Concrete Pavement
Mixtures with Larger Size Coarse Aggregate,
accepted for publication in ASCE 2006 Airfield
and Highway Pavement Conference, Atlanta, GA.
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Saw-cut timing and depth

• Stress analysis of slab (temp shrink)
• Size Effect (fracture) Model
• Concrete Material Fracture Parameters
• Wedge Splitting Test _at_ early ages
• No method to obtain Critical Stress Intensity
  Factor (KIC) and Critical Crack Tip Opening
  Displacement (CTOCC) for WST

FEM MODEL FOR THE WST SPECIMEN
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Saw-cut timing and depth

• Fracture Parameters
• WST specimen

Notch detail


b
t
a
a a/b
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Saw-cut timing and depth

• FEM Model
• Special Mesh around crack tip
• Q8 elements
• Symmetry and BC consi-derations

200 mm
100 mm
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Saw-cut timing and depth

• FEM Model
• Stress around crack tip
• Calculation of KI

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FEM ANALISYS
FEM MODELING OF THE WST
Psmax peak splitting load KIC critical
SIF CTODc critical CTOD CMODc critical
CMOD f1(a) geometrical factor 1 f2(a)
geometrical factor 2 f3(a) geometrical factor
3 E modulus of elasticity Gf initial fracture
energy
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Evolution of GF vs Age
Large increase in GF between 8 and 24 hrs
(saw-cutting operations).
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Saw-Cut Timing Model

• Concrete E and fracture properties(cf ,KIC) at
  early ages.
• Using Bazants Size Effect Model to analyze
  finite size slabs.
• Develop curves of nominal strength vs notch depth
  for timing.

• After Soares (1997)

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Joint Type Analysis

• How can we rationally choose dowel vs. aggregate
  interlock joint type joint spacing?
• Need to predict crack width LTE
• Shrinkage, zero-stress temperature, creep
• Aggregate size and type (GF)
• Slab length base friction

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Reduced aggregate interlock with small max. size
CA
Dowels deemed necessary
Crack width, w
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Larger max. size CA
Larger aggregate top size increases aggregate
interlock and improves load transfer
Crack width, w
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Crack Width Model Approach
after DG2002
Crack spacing Drying shrinkage Temperature
drop Restraints
Base friction Curling (thermal and
moisture) Steel reinforcement
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Step 1 Predicting crack width opening, w
Average increase with age due to shrinkage
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Future Joint Analysis Questions

• What is an acceptable LTE?
• What is LTE when dowels are removed?
• Can joint spacing be increase from 18.75 to 25
  ft?
• How much can LTE be changed by concrete property
  changes?

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Project Tasks and Progress
Status

• Literature Review
• Survey of existing mix designs
• Review of mix design strategies
• Volume Stability Tests
• Drying and Autogenous shrinkage
• Optimization of concrete mixes to reduce
  volumetric changes
• Strength Testing
• Modulus of rupture, splitting and compressive
  strength
• Fracture energy and fracture surface roughness

Done, TN2, 3, 4, 15
Done, TN 12
Done Done, TN 12 and TN 17.
Done, TN 12, TN 17, conf. paper
Fracture Tests Done
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Project Tasks and Progress

• Joint Type Design
• Slab size and jointing plans productivity, cost,
  performance.
• Optimization of concrete aggregate interlock to
  ensure shear transfer.
• Joint (crack) width prediction model for concrete
  materials.

In progress, TN 3. Analysis pending, fracture and
shrinkage tests done.
In progress, TN 12. Fracture tests
In progress
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Project Tasks and Progress

• Saw-cut timing and depth
• Saw-cut timing criteria for the expected
  materials
• Analytical model / Validation
• Fiber Reinforced Concrete Materials
• Overview of structural fibers for rigid pavement

FEM model developed to obtain fracture results
from WST samples, currently applying results to
determine saw-cut timing and depth.
Literature Review done, TN 3.
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New Work for FY2006

• Functionally-layered concrete pavements
• Multi-functional rigid pavement
• Cost saving
• GREEN-CRETE
• Recycled concrete aggregate
• Effect of recycled aggregate on mechanical and
  volumetric properties of concrete

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Current workRecycled Concrete as Aggregates
(RCA) for new Concrete
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Recycled Concrete Aggregate
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Use of RCA for OMP

• RCA may lead to cost savings
• Disposal costs
• Trucking costs
• Natural aggregate costs
• RCA may increase shrinkage?
• RCA less stiff than natural aggregate
• RCA can shrink more than natural aggregate
• Shrinkage may be same or reduced if RCA is
  presoaked to provide internal curing

52
UIUC First Trial

• RCA from Champaign recycling plant
• Concrete came from pavements, parking garages,
  etc.
• Mix of materials with unknown properties
• Material washed, dried, and sieved to match
  natural fine aggregate
• Soaked for 24 hrs, surface dried, and then 100
  replacement of natural fine aggregate

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Saturated RCA vs Lab Aggregates

• Similar autogenous shrinkage curves

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RCA Summary to Date

• Optimization of RCA gradation may lead to
  reduction in overall shrinkage
• Other concerns
• Reduced concrete strength and modulus
• Potential for ASR from RCA?
• Source of chlorides to cause corrosion of dowels?
• Future work - use RCA with known properties
• Try different gradations
• Measure strength/fracture properties also

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Functionally Layered Concrete Pavement
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Functionally Layered Concrete Pavement

• Experimental Program

(a)
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Functionally Layered Concrete Pavement

• Structural Synthetic Fibers in Beams

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Functionally Layered Concrete Pavement

• Steel Fibers in Beams

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Functionally Layered Concrete Pavement

• Synthetic Fibers in WST Specimen

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Project Tasks and Progress

• Recycled Concrete Aggregate (RCA)
• Review of previous experiences with RCA
• Experimental program, and test to determine
  effect of RCA on relevant mix properties

In progress
In progress
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Project Tasks and Progress

• Functionally Layered Concrete Pavement
• Overview of structural fibers for rigid pavement
• Layered pavement systems- preliminary study
• Fracture resistance of two layer concrete
  pavement systems

Literature Review done, TN 3.
Done, preliminary results show potential
In progress
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2006 First Quarter Deliverables

• TN - Phase II concrete mix evaluation
• Large aggregate mixtures paper (ASCE)
• TN Fracture Properties of Concrete Mixtures
  (WST)

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(No Transcript)
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Saw-cut timing and depth

• FEM Model
• Determination of Fracture parameters

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Saw-cut timing and depth

• FEM Model
• Determination of Fracture parameters

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Recycled Concrete Aggregate

• Some findings from literature
• When used with a very low w/cm, RCAC compressive
  strength can exceed 9000psi at 28 d
• Autogenous shrinkage can be lowered by 60 by
  adding saturated RCA

While there are no reports in the literature, it
is likely that RCA increases tensile creep, which
would reduce propensity for shrinkage cracking or
curling
I. Maruyama, R. Sato, A trial of reducing
autogenous shrinkage by recycled aggregate, in
Proceedings of self-desiccation and its
importance in concrete technology, Gaithersburg,
MD, June 2005.