concrete and concrete pavements research group. meet the research team… 3 phd students 4 ms...
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Materials: Multi-scale solutions
MicrostructureMixture Constituents
Material Propertieshttp://pittsburgh.about.com/library/pictures/bridges/uc_bridge-12.htm
Structures
Development and evaluation of engineered pcc materials Dimensional stability/compatibility (drying
shrinkage, thermal coefficient, creep…) Strength (split tensile, flexural, compressive) Stiffness (dynamic & static) Fracture toughness Surface texture Abrasion resistance Durability (chemical and freeze-thaw)
Stress: Uniform drops in temperature and moisture
Restraint Conditions
Thermal & Moisture Conditions
Moisture and Heat
Temp. or Moist.
+
_
Positive gradient
+
_
Negative gradient
Stress: Nonuniform changes in temperature and moisture
Zero Stress ConditionZero Stress Condition
Construction Gradients
Moisture and Heat
At set:
Slab Temperature = 105 F
Gradient = +0.5 F/in
Gradient = 0 F/in
Stress as a Result of Stress as a Result of the Construction the Construction
GradientGradient
Measuring Slab Response to Environmental and Applied Loads
Instrumentation - Useful in the calibration/validation of models.
Pavement Design
Bridge Design1. Define critical load and axle configuration
1. Accumulate damage of each vehicle load for each hour of the day of each mth of the year
Pavement Design
INPUTS•Layer thickness•Material properties•Environmental conditions•Axle loads and volumes
STRUCTURALMODEL
FATIGUEDAMAGEMODEL
nN
CALIBRATIONWITH FIELDDISTRESS
OUTPUTS•Cracking•Faulting•IRI
Traffic, moisture & temperature prediction models,material models
PROCESSED INPUTS
Models Consider Changing Conditions
Time, years
Traffic
No
Uni
ts
PCC Strength
Base Modulus
Subgrade Modulus
CTB
Time increment
2 8640
Current Design Approach:
INPUTS•Slab thickness•k-value•ESAL•PCC Mr
OUTPUTS•PSI
STATISTICALREGRESSION
MODEL
Concrete Mixture Properties: Modulus of rupture (28 day) Elastic Modulus (28 day)
New MEPDG Design Guide Inputs Concrete Mixture Properties:
Modulus of rupture (7, 14, 28 & 90 day, 28 day to 20 yr ratio) Elastic modulus (7, 14, 28 & 90 day, 28 day to 20 yr ratio) Poisson’s ratio Unit weight Thermal coefficient of expansion Drying Shrinkage Thermal conductivity Heat capacity
Mixture Design Information Cement type w/c ratio Aggregate type
Set Temperature Information Zero stress temperature Zero stress temperature profile
1. Project Title: Evaluation of the R1-37A Rigid Pavement Design Procedure
Sponsoring Agency: Federal Highway Administration
Pitt Expenditures/Duration: $100,000/1 year
Collaborators: ARA, AET
PI: J. Vandenbossche
INPUTS•Layer thickness•Material properties•Environmental Conditions•Axle Loads and Volumes
STRUCTURALMODEL
FATIGUEDAMAGEMODEL
nN
CALIBRATIONWITH FIELDDISTRESS
OUTPUTS•Cracking•Faulting•IRI
PROCESSSED
INPUTS Traffic, moisture & temperature prediction models,material models
2. Project Title: Investigate the Design and Construction of Composite Pavement Systems
Sponsoring Agency: SHRP 2/National Academy of Science
Pitt Expenditures/Duration: $102,000/4 year
Collaborators: ARA, U of Mn & UCDavis
PI: M. Darter
Objective: Focus on debonding, built-in curl and joint (crack) formation
Pitt’s Role
1. Instrumentation of test sections
2. Use of instrumentation data for model calibration/validation
(Bolander et. al. 2007)
A PCC surface placed over a just placed PCC layer (“wet on wet”).
3. Project Title: Using Falling Weight Deflectometer Data with Mechanistic-Empirical Design and Analysis Sponsoring Agency: Federal Highway Administration
Pitt Expenditures/Duration: $51,000/1.5 year
Collaborators: ApTech, MSU
PI: K. Smith
Rigid Pavements1. Backcalculate layer properties
2. Detect voids
3. Characterize joint performanceNDT Sensors
NDT Load
r
4. Project Title: The Development of a Design Procedure for Thin and Ultra-Thin Concrete Pavements
Sponsoring Agency: Federal Highway Administration
Pitt Expenditures/Duration: $330,000/3 year
PI: J. Vandenbossche
Primary Concerns
1. Characterize effects of fibers
2. Bond strength/degradation
Adapted from ACPA & Rosler
5. Project Title: Establish Inputs for the New Rigid Component of the Mechanistic-Empirical Pavement
Design Guide Sponsoring Agency: PennDOT
Pitt Expenditures/Duration: $509,000/3 year
PI: J. Vandenbossche
Primary Efforts
1. Material characterization
2. Pavement instrumentationMoisture and Heat
6. Project Title: Premature Deterioration of Jointed Plain Concrete Pavements
Sponsoring Agency: PennDOT
Pitt Expenditures/Duration: $257,000/1.5 year
PI: J. Vandenbossche
Material Characterization•Strength development•Fracture toughness•Thermal coefficient•Drying shrinkage•Environmental loads•Axle loads and volumes
Structural Model
-100
-50
0
50
100
150
200
250
300
350
400
0 12 24 36 48 60 72
Time (hrs)
Ten
sile
Str
ess
and
Stre
ngth
(p
si)
.
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