concrete pavement overlay design

Concrete PavementOverlay DesignJeffery Roesler, Ph.D., P.E. ProfessorDepartment of Civil & Env. Eng.University of Illinois Urbana-Champaign

25 June 2015ISCP Concrete Pavement SeminarIDOT District 1 (Schaumburg, IL)

Concrete Overlay Overview Overlay Design Objectives Overlay Design Guides Inputs & critical variables Bonded Concrete Overlays

Concrete-Asphalt

Unbonded Concrete Overlays Whitetopping & Composites

Performance of Illinois O/L References for O/L design Summary of Overlay Design

Concrete Overlay Design: Objectives Achieve desired concrete pavement overlay

service life given: Existing pavement condition Expected traffic Layer and material properties Interface condition Slab geometry Climatic conditions

SCinitial SCOverlay

SCeffective

SCfuture traffic

Load Applications

- 76

Guide on Existing Overlay Design Methods

Not a design procedure Background on

recommended overlay design methods 18 pages

Detailed design examples 35 pages

StreetPave12 released after this guide

http://www.cptechcenter.org/technical-library/documents/Overlays_Design_Guide_508.pdf

How to start design of concrete O/L? Roadway site evaluation Existing pavement structure New pavement performance objectives Select candidate Overlay Options Collect input data & choose design features

Support layers, Slab size, etc.

Use appropriate overlay design methods Optimize design Write construction specs to reflect design objectives

Concrete Overlays: General Types

Whitetopping (unbonded) Bonded Concrete Overlay Asphalt (BCOA)

Bonded Concrete to Concrete Unbonded Concrete w/ Separation Layer

Concrete Overlay Guide, Third EditionContents

Overview of Overlays Overlay types and uses Evaluations & Selections Six Overlay Summaries Design Section Misc. Design Details Overlay Materials Section Work Zones under Traffic Overlay Construction Accelerated Construction Specification

Considerations Repairs of Overlays

http://www.cptechcenter.org/technical-library/documents/Overlays_3rd_edition.pdf

Concrete Overlays Categories

Concrete Overlays

Bonded Concrete Resurfacing of Concrete Pavements

Bonded Concrete Resurfacing of Asphalt Pavements

Bonded Concrete Resurfacing of Composite Pavements

Bonded Overlay Group

UnbondedConcrete Resurfacing of Concrete Pavements

Unbonded Concrete Resurfacing of Asphalt Pavements

Unbonded Concrete Resurfacing of Composite Pavements

Unbonded Overlay Group

Thinner Thicker

Bond is integral to design Old pavement is base layer

Thinner Concrete Pavement Options

Bonded Concrete Resurfacing of Asphalt Pavements

Bonded Concrete Resurfacing of Composite Pavements

Bonded Overlay Systems

Unbonded Concrete Resurfacing of Concrete Pavements

Unbonded Concrete Resurfacing of Asphalt Pavements

Thinner Concrete Pavement or Short Slabs

Unbonded Systems

ACPA BCOA or BCOA MEh=3 to 6 in.L=4 to 6 ft

Thin Concrete

Inlay -Preservation

h=2 to 3.5 inchL=4 to 6 ftEmerging

Colorado Method6in. x 6ft x 6ft

Opti-Paveh=2.5 to 9 in.L=4 to 9 ft

Which Overlay Design Method(s)?Concrete Overlay Type Design MethodsUnbonded on Asphalt, Composite, or Concrete

AASHTO ME, ACPA StreetPave 12, AASHTO 93, OptiPave 2.0

Bonded on Asphalt or Composite

ACPA BCOA, ACPA StreetPave 12,BCOA ME, CO 6x6x6, IDOT Chpt 53

Bonded on Concrete AASHTO ME, ACPA StreetPave 12, AASHTO 93

• Slab thickness• Concrete Strength, CTE, Modulus, fibers (?)• Concrete-Asphalt Interface• Support layers (surface, base/subbase, soil) • Joint Spacing• Edge Support• Load Transfer• Subgrade Support • Traffic & Design Life• Climate

What are main Concrete Overlays Design Inputs?

Hamilton County, IL

Pre-overlay Repair & Reflective Crack Control Sub-drainage Structural vs Functional Overlays Recycling Existing Pavement (PCC & AC) Existing PCC Slab Durability PCC Overlay Reinforcement PCC Overlays Bonding / Separation Layers Overlay Design Reliability Level Pavement Widening Traffic Disruptions and User Delay Costs

Other Important Considerations in Overlay Design

BCOA vs. “Whitetopping” Whitetopping (h > 6 in.)

More conventional slab sizes (6ft to 15ft)

30+ years experience

Ignores interface bond (unbonded)

Bonded Concrete Overlay Asphalt (h ≤ 6 in.) 20+ years experience (1991)

Smaller slab sizes (≤ 6ft)

Concrete/AC bond is essential

Ultra-Thin Whitetopping (UTW)

Composite Behavior Mechanics

Unbonded“Whitetopping”

Neutral AxisPCC

Bit.

BondedBonded Concrete Overlay Asphalt

PCC

Bit.

Riley

Concrete Overlay Solutions:Rehabilitation and Maintenance

Site Visit: Existing Pavement Condition

Why use smaller slab sizes?

1.2m 1.2m1.2m>2m

•Interface bond assumption (BCOA)-Reduce de-bonding of concrete and asphalt at early ages

•Short slab sizes reduce bending and curling stresses

Thickness Design for Concrete Overlays Highways/Roads AASHTO Pavement ME (2011) or MEPDG StreetPave 12 (ACPA) ACPA (Whitetopping/UTW) – 1998

Illinois DOT (2009) – new fatigue eqn. & fibers Chapter 53-4.08

BCOA Calculator (2012) – add climate database

BCOA ME (2012) – Univ. of Pittsburg AASHTO (1993)

Airports: Federal Aviation Administration (FAARFIELD)

AASHTO Pavement MEor formerly known as MEPDG

AASHTO Pavement ME - INPUTS!

Many OUTPUTS to Synthesize

Bonded Concrete Overlay Options

Thinner overlays (3 to 6 in) Constructed over concrete,

asphalt, and composite sections.

Existing pavement condition fair to good

Interface Bond is Critical!

Bonded Concrete

Resurfacing of

Concrete Pavements

Bonded Concrete

Resurfacing of

Asphalt Pavements

Bonded Concrete

Resurfacing of

Composite Pavements

Bonded Overlay Options

Bonded Concrete Overlay of AsphaltAASHTO 1993 Not applicableAASHTO Pavement ME (2011) Thickness 6 in. Slab length 10ftACPA (2012);IDOT (2009);Pitt BCOA ME (2013)Ultra-Thin Whitetopping Thickness 6 in. Slab length 6ft

Unbonded ConcreteOverlay of HMA

http://apps.acpa.org/apps/bcoa.aspx

HMA

PCC

Base

40kN 40kN

EAC, AC

EPCCt

AC

Subgrade k-value

Bonded

hPCC

hAC

BCOA Critical Locations (Concrete and AC Layers)

t

Fibers Structural vs. non-structural (plastic shrinkage)

Structural Macro-Fibers

Micro-Fibers (non-structural)

012345

0 10 20 30 40CMOD (mm)

Load

(kN

)

IDOT Concrete Thickness Calculation

Variable

Design Traffic Factor (BDE Manual, Figure 54-4C) TF 2.50

Modulus of Rupture (3-point bending, 14-day average) MOR 750 psi MORFRC Residual Strength Ratio 20%

Remaining Thickness of Asphalt h ac 3.0 in.Joint Spacing L 72 in. L

Elastic Modulus of Concrete E c 3,600,000 psi E c

Coefficient of Thermal Expansion CTE 5.50E-06 in./in./°F CTEElastic Modulus of Asphalt E AC 350,000 psi

Modulus of Subgrade Reaction k 100 pci

k

Thickness of Concrete h c 5.48in.

Solved

Note 1: The design MOR is the mean design strength, not the minimum 550 psi flexural strength (center-point loading) specified for opening to traffic. Also note that as MOR increases the risk of debonding increases and the effectiveness of synthetic fibers decreases.

PCC Inlay / Overlay Design Sheet, Required Thickness of PCC

5.50 x 10-6 in./in./°F

E AC

100,000 psi (poor)

350,000 psi (moderate)

3,600,000 psi

0% (w/o fiber reinforcement)

20% (w/ fiber reinforcement)

600,000 psi (good)

100 pci

Default InputsDefault Value

750 psi (Note 1)

48 in. or 72 in.

150150R

Compute Concrete Thickness

Help

150150R

http://www.dot.state.il.us/desenv/pdp.html

IDOT Chapter 53-4.08 Tables

Asphalt Modulus (Eac)

0

1

2

3

4

5

6

1E+04 1E+05 1E+06 1E+07

ESALs

Conc

rete

Thi

ckne

ss h

c (in

)

Eac = 100,000psiEac = 350,000psiEac = 600,000psi

k = 100 pci

MOR = 650 psi

R150 = 0%

hac = 3 in

L = 4 ft

ΔT/h = -0.65 °F/in

35 % time

Effect of Asphalt thickness

0

1

2

3

4

5

6

1E+04 1E+05 1E+06 1E+07

ESALs

Conc

rete

Thi

ckne

ss h

c (in

)

hac = 3 inhac = 4 inhac = 5 inhac = 6in

k = 100 pci

MOR = 650 psi

R150 = 0%

Eac = 350,000 psi

L = 4 ft

ΔT/h = -0.65 °F/in

35 % time

R150= Residual Strength Ratio Concept

0

1

2

3

4

5

6

1E+04 1E+05 1E+06 1E+07

ESALs

Conc

rete

Thi

ckne

ss h

c (in

)

R150,3 = 0%R150,3 = 15%R150,3 = 20%R150,3 = 25%

k = 100 pci

MOR = 650 psi

Eac = 350,000 psi

hac = 3 in

L = 4 ft

ΔT/h = -0.65 °F/in

35 % time

Effect of Slab Size (L)

0

1

2

3

4

5

6

7

8

1E+04 1E+05 1E+06 1E+07

ESALs

Conc

rete

Thi

ckne

ss h

c (in

)

L = 12 ftL = 6 ftL = 4 ft

k = 100 pci

MOR = 650 psi

R150 = 0%

Eac = 350,000 psi

hac = 3 in

ΔT/h = -0.65 °F/in

35 % time

ACPA Bonded O/L of Asphalt

http://apps.acpa.org/applibrary/BCOA/ (2012)

BCOA ME failure modes5 to 7 ft

Long. & DiagCrack

Positive ΔT Negative ΔT

< 4.5 ftCorner Break

Positive ΔT

10 x 12 ft12 x 12 ft12 x 15 ft

Trans. Crack

Vandenbossche (2013)

Surface Preparation Milling AC surface.

Remove rutting Restore profile Enhance bond

Minimum AC thickness remaining after milling: 6.5 cm

Surface cleaning Waterblast - preferred Sweeping

Guide to Concrete Overlays of Asphalt Parking Lots (2012)

www.rmc-foundation.org/images/Concrete_Overlay_Guide_11-14-12.pdf

Contents: Parking Lot Features Existing Pavement

Condition Concrete Overlay

Design Jointing Parking lot details Materials Construction Fibers

PERFORMANCE OF UTW SECTIONS

Illinois Projects Visited (20)

UTW Projects in Illinois (USA)

Intersection

Farm / Rural Road

State Highway

Parking Lot

Decatur, IL: Intersection of US 36 and Oakland Avenue (1998)

Major distresses Longitudinal, transverse or corner cracking in

33.8% of slabs Faulting throughout the project in joints and

cracks Three to five instances of partial slab blowups

due to slab migration

Slab migration Inside five rows of slabs had migrated into the

intersection from 2.5 to almost 15cm at the end of the project

Use of structural fibers likely could have locked the panels in and prevented this movement

2012

Kane County, IL: North Lorang Road (2004) 11cm thick concrete overlay of 7.5-9cm of HMA over

aggregate base 2.4 kg/m3 synthetic macro-fibers Square 1.5m x 1.5m panels Project built to serve a quarry: average of 30 trucks/day (peak

of 280/day)

2012

Mundelein, IL: Schank Avenue (2005) 10cm. concrete overlay of a composite pavement (5.7-16.5cm

HMA over 12-23.5cm PCC) Square 1.2m x 1.2m panels 2.4 kg/m3 synthetic macro-fibers High truck traffic volume (no data available, but comparable

to Lorang Road and more general traffic)

2012

Hamilton County, IL (Sept. 16, 2014)FRC UTW (4 in.)

Existing Asphalt Concrete (3 in.)

Cement Treated Soil (8 in)Natural Soil

Built in 2013

Built in 9/2014

Built in 9/2014

Overall Summary for BCOA Parking lots = 4ft x 4ft panels are fine w/ fibers Maintain 5.5 ft or 6 ft panel sizes w/ fibers More cracking/faulting on skewed joints Thinner saw blades No sealing except when joint in wheel path

No faulting or cracking on 4x4 ft or 6x6ft slab sizes with macrofibers (>2006)

FRC needs minimum revolutions at high torque in mixer

Bonded Concrete Overlay

Concrete Overlay hol

Existing Concrete Pavement

he

Excellent Interface Bond

Bonded Concrete O/L Design Methods

AASHTO Pavement ME (2011) Slab thickness based on following: Slab geometry, climate, structure, concrete

material and layer properties Complete interface bond hol = hf - heff

AASHTO 1993 Dol = Df - Deff

Unbonded Concrete Overlay Options Thicker concrete overlays

than bonded.

Constructed on existing concrete, asphalt, or composite pavements.

Bond is NOT considered in the design.

Slab sizes vary depending on type of design

Unbonded Concrete Resurfacing of Concrete Pavements

Unbonded Concrete Resurfacing of Asphalt Pavements

Unbonded Concrete Resurfacing of Composite Pavements

Unbonded Overlay Option

“Whitetopping”

Pavement evaluation establishes whether existing concrete and subbase can provide uniform support and, if not, what actions are necessary to obtain that uniformity.

Look for movement in the slab. Profile is a good check.

Unbonded Concrete Overlays of Existing Concrete Pavements

Unbonded Concrete O/L Design Methods

AASHTO Pavement ME (2011) or MEPDG Slab geometry, climatic factors, concrete

material and layer Assumes unbonded interface without friction

AASHTO (1993) D2

0L = D2f - (Deff)2

StreetPave 12

Separation Layer Good Performance.

Isolate overlay from existing pavement: Prevent reflection cracking. Prevent bonding/mechanical

interlocking. Provide level surface for overlay

construction. Interlayer material:

2.5 to 5cm dense-graded HMA. GEOTEXTILE (Missouri 2008)

I-57/I-64 Alternatives (2010-2013)

HMA overlay of existing CRCP Rubblization with HMA JPCP and CRCP options

MEPDG & IDOT designs Milling options vs. rubblization Interlayer type Thickness options

Poor Section I-57/I-64 NB

MEPDG CRCP Overlay: Inputs 20-year design life Mattoon-Charleston, IL Climate

ESALs 80x106

A-7-6 soil type k=200 psi/in

Tied concrete shoulder 40 to 80% LTE

CRCP Steel properties 3.5 inch depth; #6 bar; 0.7% steel content

MEPDG CRCP Design: Results New CRCP = 11 inches HMA base unbonded = 4inches

Unbonded CRCP = 9 inches AC base interlayer = 2 inches CRCP (existing) = 8 inches

Unbonded CRCP = 10.5 inches HMA interlayer = 1 to 2 inches CRCP (rubblized) = 8 inches

I-57 / I-64 Mt. Vernon (2011-2013) Mill existing HMA overlay Rubblize existing 8-inch CRCP Place 3-inch HMA interlayer 10.5-in. CRCP overlay w/ 0.7% steel

2012 Unbonded CRCP Overlay (I-57)

Unbonded Concrete O/L of Asphalt Concrete

Dol = Df

Df = new concrete slab thickness

Existing Asphalt

Dol = Df

Subgrade

Base

Unbonded Bonded Concrete O/L of Asphalt

AASHTO Pavement ME (2011)-whitetopping Thickness > 6 inches Slab length > 10ftOptiPave 2.0 (2012) - TCPavements Short jointed slab systems Slab sizes < 10ft & thickness 2 in.AASHTO 1993 Existing asphalt treated as base layer

(Thin) Unbonded Concrete O/L

Interlayer or thicker slab required relative to BCOA

Empirical designs to date in U.S.

TCPavements, Inc. (2007) – Chile, S.A. OptiPave 2.0 (2012) Only current design method for short jointed

unbonded concrete overlay

Final Day PavingOak Park, July 2001

• 10 cm “Fast-Track” Unbonded, Steel-Fiber Reinforced Concrete Inlay

• Mirafi 500N Woven Geotextile

Pavement Depth

Oak Park, IL: Marion Street (2001)

10 cm concrete over original concrete layer UNBONDED- woven geotextile placed between the layers at the time

of casting

2.0m x 1.5m panels 24 kg/m3 crimped steel fibers

2012

I-72 Unbonded Overlay (2015)

6-inch PCC Asphalt

interlayer 8” CRCP 6ft x 6ft

panel sizes Fibers

What is Flowable Fibrous Concrete (FFC)?

187

Flowable Fibrous Concrete

Ultra-Thin Whitetopping

Fiber-Reinforced

Concrete

Self-Consolidated Concrete

High Toughness/ Reduced Cracking

Ease of Placement

Cost-Effective Thin Pavement

HPFRSCC(ECC)

ConventionalPavingMixture

Flowable Fibrous Concrete (FFC) for Thin Pavement Preservation Inlays

Lower speed applications Slab thickness < 8 cm 10-year service life Concrete wearing surface (Preservation) Asphalt-concrete bond essential Loads transmitted to substrate layers

Other sustainability enhancements: Reflectivity, skid, air pollutant reducer

Bordelon & Roesler (2010)

FFC Field Project (ATREL) Ensure Good Bond with Underlying HMA

Milled and cleaned surface Measured the FFC inlay bond with 10 cm diameter core, sheared off at greater

than 500 Nm torque (HMA overlays typically ~400 Nm)

Check Workability & Constructability of FFC Placed 5 cm thick inlay directly from truck Vibrated with screed and bull float finish

Joint Cracking Monitored Slabs sawcut at spacing 1.1 to 3.4 m (4 to 11 ft) Crack widths average from 0.4 to 1 mm wide after 20 days

Field Demonstration 2in (5 cm)

Concrete Overlay: Summary Existing pavement condition assessment Select new concrete pavement type Define interface assumption

Available structural design methods AASHTO Pavement ME (2011) IDOT BCOA (Chapter 53-4.08) ACPA (BCOA Calculator & StreetPave12) Pitt BCOA ME FAARFIELD- airfield

Construction details essential!!

Questions?

141 fibers 131 fibersBordelon (2011)

Acknowledgements Illinois Department of Transportation

Illinois Center for Transportation www.ict.illinois.edu

Randell RileyIL-ACPA

Amanda Bordelon Asst. Prof. @ University of Utah

National Concrete Pavement Technology Center Dale Harrington

American Concrete Pavement Association (ACPA) Rob Rodden

Daniel King (2012-2015) Research Assistant, UIUC

Dr. Julie Vandenbossche University of Pittsburg

Annotated Bibliography Harrington, D. et al. (2012), Guidance for the Design of Concrete Overlays

Using Existing Methodologies, National Concrete Pavement Technology Center, Iowa State University, Ames, IA.

Roesler, J. R., Bordelon, A., Ioannides, A. M., Beyer, M., and Wang, D. (2008), Design and Concrete Material Requirements for Ultra-Thin Whitetopping, Final Report, Illinois Center for Transportation Series No. 08-016, University of Illinois, Urbana, IL, 181 pp.

Rasmussen, R., Rogers, R., Ferragut, T. (2009), Continuously Reinforced Concrete Pavements Design and Construction Guidelines, FHWA-CRSI.

Harrington, D. et al. (2014), Guide to Concrete Overlays Sustainable Solutions for Resurfacing and Rehabilitating Existing Pavements, National Concrete Pavement Technology Center, Iowa State University, Ames, IA.

Smith, K.D., H. Yu, D. Peshkin, (2002), Portland Cement Concrete Overlays: State of the Technology Synthesis, Federal Highway Administration, Washington, DC.

Vandenbossche (2011) Development of a Design Guide for Thin and Ultrathin Concrete Overlays of Existing Asphalt Pavements, TPF-5(165)