Concrete and Concrete Pavements Research Group

Meet the research team…

3 PhD Students

4 MS Students

1 Undergrad

What do I do……

Components of concrete

Fine Aggregate

Coarse Aggregate

WaterCement & SCM’s

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)

Characterization of material properties through laboratory testing

Pavements 101

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

Temp. or Moist.

+

_

Positive gradient

+

_

Negative gradient

Stress: Combined load and Gradients

Construction Gradient

Moisture and Heat

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

Currently Funded Projects

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)

.