Promising Practices for Construction, Repair, and Rehabilitation of Continuously Reinforced Concrete Pavement Sponsored by TRB Committees: Rigid Pavement Design (AFD50) Pavement Rehabilitation (AFD70) Portland Cement Concrete Pavement Construction (AFH50) January 28, 2016

Webinar Background • This webinar is Part 3 of the series of webinars on CRCP

started last year

– Part 1 (March 2015) - Considerations for the Selection of Continuously Reinforced Concrete Pavement (CRCP) for Projects

http://onlinepubs.trb.org/Onlinepubs/webinars/150330.pdf

– Part 2 (June 2015) - Mechanistic-Empirical Design and Details for Continuously Reinforced Concrete Pavement (CRCP)

http://onlinepubs.trb.org/Onlinepubs/webinars/150603.pdf

Today’s Presenters • Moderator

Roger Schmitt, Consultant

• US Construction Practices & Case Studies Shiraz Tayabji, Applied Research Associates, Inc.

• European Construction Practices Sam Tyson, Federal Highway Administration

• Patching and Overlays for Repair & Rehabilitation Jeff Roesler, University of Illinois at Urbana-Champaign

• Illinois Tollway Initiatives for Implementation of CRCP Steve Gillen, Illinois Tollway

• Innovative Methods for Construction Shiraz Tayabji, Applied Research Associates, Inc.

NCHRP is...

A state-driven national program

• The state DOTs, through AASHTO’s Standing Committee on Research... – Are core sponsors of NCHRP

– Suggest research topics and select final projects

– Help select investigators and guide their work through oversight panels

NCHRP delivers...

Practical, ready-to-use results • Applied research aimed at state

DOT practitioners • Often become AASHTO

standards, specifications, guides, manuals

• Can be directly applied across the spectrum of highway concerns: planning, design, construction, operation, maintenance, safety

NCHRP uses...

A range of research approaches • Traditional NCHRP research reports • Syntheses of highway practice • Innovations Deserving Exploratory Analysis

program studies • Domestic scans of innovative practices • Quick-response research for AASHTO committees • Research for AASHTO and state DOT leadership • Long-range strategic studies

NCHRP Webinar Series • Part of TRB’s webinar program • Opportunity to interact with experts

and learn about challenges, opportunities and updates

• Complementary to other products that spread results and foster implementation

– Reports and Syntheses – Research Results Digests – Legal Research Digests – Web-Only Documents and CD-ROMs

Today’s First Presenter

• US Construction Practices & Case Studies Shiraz Tayabji, Applied Research Associates, Inc.

Shiraz Tayabji, Ph.D., PE Applied Research Associates, Inc.

stayabji@gmail.com

Transportation Research Board Webinar on Continuously Reinforced Concrete Pavement (CRCP) – Part 3: Promising

Practices for Construction, Repair and Rehabilitation of CRCP January 28, 2016

US CRCP Construction Best Practices

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What is CRCP? CRCP differs from other concrete pavements

• No transverse joints • Continuous longitudinal reinforcement interacts with

concrete to produce tight cracks at about 3 to 6 ft spacing & then holds the cracks tight

• Cracks MUST be tight for a high crack load transfer effectiveness (need >90%)

• CRCP can extend, joint-free, for many miles with breaks provided only at structures

• Considered to be a true long-life concrete pavement

Background

First introduced in the US in1921 Production use in US during 1940s Widely used in the US since 1960s Over 30,000 lane miles constructed in the U.S. Large portions of Interstate (freeway) system in Illinois,

Texas, Oregon; used in other states too Several US States use CRCP as pavement of choice for

highways with heavy truck traffic • California (a new comer) has constructed >300 miles

recently & several hundred miles are in design, 11 to 13 in. thick, 0.7 to 0.8% steel

California 60 year old CRCP

Original PCC surface service life – 40+ years Pavement will not exhibit premature failures and

materials related distress Pavement failure=> Result of traffic loading and

accounting for environmental loading Pavement will have reduced potential for

punchouts (less than 15/mile after 30 to 40 years) Pavement will maintain desirable ride and surface

texture characteristics with minimal intervention activities to correct for ride & texture, and minor repairs

CRCP Long-Life Expectations

4

Presentation Focus

Construction practices unique to CRCP Base requirements Longitudinal steel placement Concrete requirements for CRCP Concrete placement Transverse construction joints End treatments

6

Critical Factors for CRC Paving A good concrete mixture A good grade & trackline (pad) for paving Stringline management Steel placement & proper lapping Continuous supply of concrete to slipform paver Consistent concrete workability Well maintained paving equipment Proper operation of paving equipment Controlled density of concrete – just the right

vibration/consolidation & finishing Most requirements for construction of jointed concrete pavements apply to CRCP construction

Bases for Long-Life CRCP A key requirement

• Some friction necessary at the slab/base interface to help induce cracking & minimize end (terminal) movements; use of geo-fabric at interface not recommended

Base types • Granular base • Stabilized bases (for high volume truck traffic)

• AC base (preferred) • CTB (need to use bond-breaker at the interface) o AC interlayer (preferred by many) o Two coats of wax-based curing compound o AC emulsion

Permeable bases not recommended for CRCP

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Concrete Mixture Requirements - A workable mix to minimize risk of honeycombing

Dense, low permeability concrete matrix Minimum 28-day strength: Flexural/Compressive: ~ 600/4,000 psi

Maximum w/cm ratio: 0.42 to 0.45 Slump (measure of consistency, not workability)

1 to 2 in. for slipform paving Some agencies limit Concrete Coef. Of Thermal

Expansion to < 6.0 * 10-6 in/in/F Design concrete strength & steel amount are balanced by design Shooting for higher strength concrete

during construction is not recommended

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CRCP Longitudinal Steel

Use of US Grade 60 bars (ASTM A615/AASHTO M31)

Longitudinal bar length is 60 ft Black steel or epoxy-coated bars Steel percent – 0.65 to 0.80% Steel percent determines crack

spacing and crack width (< 0.02 in. recommended) Bars placed at about ~1/3T from

the surface (minimum concrete cover > 2.5 in.)

12-in. thick slab with #6 bars at 5 in. cc

= 28 bars/lane = 0.73% steel

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Longitudinal Steel Placement Transverse bars used to support longitudinal bars

• Bars placed manually on bar supports prior to concrete placement, also bar splicing done

• Common work-rate = 1000 lbs of bars/man-hour Work in progress to develop improved tube feeders

to reduce field labor & allow concrete placement in front of paver

New tube feeder system developed in Korea (discussed later)

Pre-Paving Rebar Inspection

Inspect: • Depth to steel & minimum

cover (important) • Horizontal placement • Lap lengths & splice pattern • Tying of bars • Bar supports integrity • Bar support settlement,

especially into AC base during warm weather

12

Concrete Placement (side discharge necessary for CRCP)

•

Different techniques for concrete distribution in front of the paver, over the steel

13

Concrete Placement Issues Concrete uniformity behind paver very important

to develop uniform crack spacing Proper concrete vibration important to ensure

good steel-concrete bond Concrete strength needs to be balanced with

steel content • Higher strength than design strength or thicker

concrete than design thickness can lead to longer crack spacing & wider cracks

14

Concrete Curing

Concrete curing and concrete temperature management is very important as it can affect the initial crack pattern

Specifications typically limit concrete temperature to 50 to 90 oF

Also, asphalt base and steel need to be wetted during hot days

Cracks form within 24 to 72 hours (~60%) and gradually for up to a year (100%)

Transverse Construction Joints Placed at end of day's work

or whenever paving operations interrupted for more than 30 minutes

Weak spot with no natural aggregate interlock, current practice relies solely on longitudinal bars for load transfer

Manual concreting: concern related to adequate consolidation

16

Transverse Construction Joints (at the end of the day)

What are some of the concerns? Poor consolidation – double amount of rebar NEED better load transfer at the header joints –

consider using deformed dowel bars, 1-1/4 in. diameter

Over-finishing by hand – brings up paste to the surface

17

CRCP End Treatments (At Bridges) Need to manage the large end

movements due to daily and seasonal temperature variations • Studies indicate only end ~150 ft active in

daily/seasonal expansion & contraction Past practice – series of anchor lugs

• Restrains end movement • More effort to construct

Current preferred practice (allow end movement) • Wide-flange expansion joint • Simple doweled expansion joints

Shoulders for CRCP Tied-Shoulders (minimal maintenance)

• Continuously reinforced concrete (preferred) oSame section as mainline

• Jointed plain concrete oMust be paved after CRCP mainline reaches

satisfactory strength oApply bond breaker to vertical face of CRCP in the

vicinity of planned shoulder transverse joints oMust keep tie bars within middle third of JPC panel,

away from transverse joints in the shoulder Shoulders not tied with or without widened lane

• Asphalt • Roller-compacted concrete

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Summary CRC pavements in the US have provided good long-

term performance when designed and constructed well

The LCCA typically shows CRCP to be very cost-effective considering very little M&R is needed for the first 20 to 25 years of service

CRCP requires minimal maintenance and repair & causes minimal disruption to traffic once constructed

Built smooth; CRCP stays smooth longer Efforts continue to improve design and construction

features (some discussed in the last presentation)

Thank You! stayabji@gmail.com

Samuel Tyson, P.E. Concrete Pavement Engineer

Office of Asset Management, Pavements & Construction Federal Highway Administration

January 28, 2016

European Construction Practices

TRB Webinar: Promising Practices for Construction, Repair and Rehabilitation of Continuously Reinforced Concrete

Pavement (CRCP)

Countries with significant miles of exposed CRCP: Belgium France Australia South Africa

Countries with significant miles of composite CRCP: Netherlands England Italy Germany

Brief History of CRCP in Other Countries (Thanks to

Michael Darter, Ph.D., P.E.)

CRCP in Belgium 1970 to 1977 t = 20 cm (8 in); Steel 0.85%

1977 to 1991 (after US visit ) t = 20 cm (8 in); Steel 0.67%

1992 to 1995 t = 23 cm (9 in); Steel 0.72%

Since 1995 t = 23 cm (9 in); Steel 0.76%

CRCP – 23 cm

AC – 6 cm Lean Concrete

20 cm

Subgrade

Catalog Designs EX: Class B1

Design life 30 years

Brussels E-40 CRCP 1970-2010

•8-in. CRCP, 0.85% steel, placed 2.5 in. from surface. •Concrete 10,000 psi at 90 days (674 lb./cy cement). •3- to 8-in. lean concrete over granular materials. •2.5-in. bituminous base course. •Over 60 miles constructed with excellent performance.

Antwerp Ring Road R1 Design practice based on experience

and practice seen in Belgium Slab: t = 23 cm (9 in.); Steel 0.74% Base: Cement treated rubble from

existing AC pavement with AC interlayer

Transverse steel placed on diagonal (60-degree angle)

CRCP in The Netherlands

Antwerp Ring Road R1, 2005 325 million trucks over 40-year design life

AADT = 200,000, 10 Lanes AADTT = 50,000

9-in CRCP, Asphalt Base

A73 in The Netherlands 2007

Transverse steel placed at 60-degree angle

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A12 Motorway – CRCP Principal Route Between

The Netherlands and Germany

A12 Motorway The Netherlands Porous Asphalt on CRCP

Composite Pavement Porous asphalt surfacing in 1998 40-year design with 100,000 AADT 5 cm (2 in) Porous Asphalt (Friction course)

25 cm (10 in) CRCP; 0.7% steel 6 cm (2.5 in) Dense AC base 25 cm (10 in) Cement-stabilized

recycled asphalt subbase 2.2 km (1.3 mile) length, 4-lane width Crack spacing: 0.8 to 3.0 m (3 to 12 ft)

A12 Motorway The Netherlands No transverse cracks in porous asphalt overlay after 10 years

CRCP Use by US Highway Agencies

Full understanding of and commitment to CRCP. Considering the use of CRCP. Constructed CRCP in the past but have since discontinued. Have not constructed CRCP or have no current experience.

DC

PR

• Longitudinal reinforcement • Joints only at transitions (bridge

structures; existing pavement; end-of-day)

• Predictable crack spacing • Cracks narrow and restrained

Long-Life Strategy for CRCP

Thank You

Sam Tyson, P.E. Federal Highway Administration

Phone: 202-366-1326 E-mail: sam.tyson@dot.gov

Professor Jeffery Roesler, P.E. Dept. of Civil & Environmental Engineering University of Illinois at Urbana-Champaign

TRB Webinar Continuously Reinforced Concrete Pavement - Part 3: Practices for Construction, Repair, and Rehabilitation

January 28, 2016 2:00-3:30 PM

MAINTENANCE, REPAIR, AND REHABILITATION OF CRCP

PRESENTATION OVERVIEW

CRCP Performance Benefits Maintenance Options Full-Depth Repair of CRCP Overlays with and for CRCP Rehabilitation Case Study

CRCP BENEFITS

Long-life pavement option* Lower life cycle cost Lower life cycle assessment

High traffic volumes w/ heavy trucks Maintain smooth ride over time Longer service life (>40 years)

Minimal maintenance! Favorable for HMA overlays CRCP overlays for renewal

REVIEW CRCP DISTRESSES

Punchouts

Roughness

Spalling Durability: D-cracking

Delamination

CRCP MAINTENANCE

Longitudinal joint sealing Lane-Shoulder tied construction

joint Lane-Lane tied construction or

contraction joint

Transverse construction joint Edge drains - cleanout Diamond grinding

Restore Friction/texture

↑ Smoothness & ↓ Noise Depth to steel

MAINTENANCE − PREVENTIVE

Longitudinal joint seal every 15 to 20 years Construction & contraction

Transverse joints: none = NO joint sealing

CRC JPC

CRCP REPAIR − RESTORATIVE

1. Determine distress type, extent and severity 2. Repair SEVERE localized distress to preserve pavement

Full-depth repair (FDR) – punchout or spalls Partial-depth repair (PDR) – shallow spall repairs

3. Prevent reoccurrence by delaying and/or stopping deterioration (durability, moisture) Repair asphalt or tied shoulders Retrofit with edge drains Overlays

4. Restore ride quality by surface restoration Diamond grind AC overlay

REPAIR OF CRCP PUNCHOUT FACTS

Full-depth asphalt patches not recommended as permanent repairs Temporary repair

Plain concrete full-depth patches unreinforced not commonly used South Carolina DOT has positive experience

Best performing are continuously reinforced concrete (CRC) patches

GUIDELINES FOR FULL-DEPTH REPAIR

Minimum repair length 6 ft if rebar is tied/lap spliced 4 ft if rebar is mechanically spliced or welded

Transverse cut should be perpendicular to centerline Cracks tend to cross skewed cuts If not possible, cut along crack

Repairs should not be closer than 18 in. Full width patches recommended

Minimum repair width 6 ft

Replace as a single area

DEFINING A CRCP PATCH AREA

NHI (2001)

EXAMPLE FULL-DEPTH CRCP REPAIR (1)

CRCP

CRCP

Min. Repair Length = 6ft ACPT (2011)

EXAMPLE FULL-DEPTH REPAIR

Full-depth and partial-depth (2-3 in) sawcuts Jackhammer limited to 25 lb or less

Full-depth sawcut Partial-depth sawcut

EXAMPLE FULL-DEPTH CRCP REPAIR (2)

-Min. Repair Length = 6ft -Base will likely need repair

ACPT (2011)

FULL-DEPTH REPAIR: STEEL DETAILS

Match existing rebar sizes Connect to existing rebar (25db to 30db)

Tied lap splice, mechanical or welded splice Drilling & grouting rebar into existing concrete has been

used to maintain continuity (e.g., Texas)

Provide support (chairs) to prevent bar bending Provide minimum 2.5 in. concrete cover Provide supplemental transverse rebars

REINFORCING STEEL PLACEMENT

FULL-DEPTH CRCP PATCH

POOR PERFORMANCE OF CRC FULL-DEPTH REPAR (FDR)

ACPT (2011)

TEXAS FDR OF CRC W/ TIE BARS

ACPT (2011)

REPAIR OF CRCP PUNCHOUT: JPCP PATCH

South Carolina

Dept of Transport. Method

Don’t use JPCP repair full roadway width of CRCP ACPT (2011)

REHABILITATING EXISTING CRCP OR WITH CRCP

Unbonded CRCP over existing CRCP Unbonded CRCP over existing asphalt concrete (AC)

or composite pavement AC overlay of existing CRCP

2 to 4 inch of AC

CRCP Overlay hol

Existing Concrete Pavement

he Separator layer (AC)

UNBONDED CRCP OVERLAYS ABRIDGED HISTORY

• 600 miles of CRCP Overlays (6 to 9-inches) since 1959 (CRSI 1988) Waco, TX first CRCP overlay (CRSI 1973) IN, MD, MS, TX, OR, IL, PA, ND, IA, CT (PCA 1976)

Oregon DOT (e.g., 1970 to 1975) 4 projects (29.6 miles)

TxDOT (e.g., 1972- present) > 10 projects Illinois DOT (1967- present) - 7 projects

UNBONDED CRCP OVERLAYS ISSUES

1. Assessing existing pavement conditions Failures / mile Deflection or PSIt

Drainage condition Interlayer or subbase erosion

2. Interlayer type and thickness 3. Overlay structural design (AASHTO Pav’t ME) 4. Pre-overlay repairs (?) 5. Construction specifications and details

IDOT CRCP UNBONDED OVERLAYS HISTORY

Constructed Unbonded overlays since 1967 I-55 and I-70 (3 sections) – 1967,1970, 1974

Unbonded CRCP overlay of JRCP

I-74 Knox County - 1995 I-88 Whiteside County – 2000-01 I-70 Clark County (Marshall) – 2002 I-80 Morris - 2003 I-57/I-64 Mt. Vernon – 2011-2013

I-70 CRCP Overlay

I-57/I-64 CRCP PAV’T REHAB (2010-2013)

9.4 centerline miles ADT = 40,000 with 33% trucks (2011) 3 - 12 ft lanes each direction 10 ft & 12 ft shoulders

HMA overlay of existing 8-in. CRCP Rubblization with HMA O/L HMA, JPCP, and CRCP O/L options

MEPDG & IDOT designs Interlayer type (HMA or GT) Thickness options

POOR SECTION I-57/I-64 NB

CRCP UNBONDED OVERLAY AASHTO PAVEMENT ME INPUTS

20-year design life Charleston-Mattoon, IL Climate

ESALs 80x106 approx. (AADTT=17,400)

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

Tied concrete shoulder 40% LTE

CRCP Steel properties 3.5-inch depth, #6, 0.70%

MEPDG CRCP DESIGN RESULTS

New CRCP = 11 in. HMA base unbonded = 4 in.

Unbonded CRCP = 9 in.

AC base interlayer = 2 in. CRCP (existing) = 8 inches

Unbonded CRCP = 10.5 in.

HMA interlayer = 1 to 2 in. CRCP (rubblized) = 8 in.

CRCP = ? Asphalt Separation – 2”

Existing CRCP – 8”

A-7-6

Existing 4” Granular

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

10.5-inch JPCP tied shoulders

I-57/I-64 STRUCTURAL SECTIONS

Mill 3.5” existing HMA & rubblize existing CRCP (56,000 yd2) 10.5-in CRCP overlay (#7 @ 0.7%)

3” HMA interlayer

10.5-inch JPCP shoulders (20ft joints)

Remove and replace 12-in CRCP on 4-in HMA base & 12-in. lime modified

soil 12-in JPCP shoulders

2011-2013 CRCP OVERLAY CONSTRUCTION

SUMMARY: MAINTENANCE, REPAIR, & REHABILITATION OF CRCP

Minimal maintenance Sealing of construction joints; long. contraction joints Diamond grinding – ride, friction, noise reduction

Repair of CRCP Full-depth repair for punchouts and severe spalls Partial-depth repair for shallow spalls only

Overlays with and for CRCP Unbonded CRCP for long-life AC overlay for extending life

Reconstruction w/ CRCP always an option!

ACKNOWLEDGMENTS

CRSI / FHWA Mr. Mike Plei Illinois DOT

Key resources for further reference: FHWA/CRSI (March 2016), CRCP Design, Construction, Maintenance, and Rehabilitation Guidelines.

Gulden, W. (2013), Continuously Reinforced Concrete Pavement: Extending Service Life of Existing Pavements, FHWA/CRSI, FHWA-HIF-13-024, 65 pp.

ACPT, Jointed Full-Depth Repair of Continuously Reinforced Concrete Pavements, TechBrief, FHWA-HIF-12-007, 8 pp.

Steve Gillen Tollway Deputy Program Manager

Materials / Pavement Management

TRB Webinar – CRCP Part 3 January 28, 2016

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Illinois Tollway Initiatives for Implementation of CRCP

Illinois Tollway Being Rebuilt/Expanded with 18 Billion Dollar Capital Program

286-mile system comprised of four corridors – Tri-State (I-94/I-294/I-80) – Jane Addams Memorial (I-90) – Reagan Memorial (I-88) – Veterans Memorial (I-355)

Opened in 1958 as a bypass around Chicago to connect Indiana and Wisconsin

Carries more than 1.4 million vehicles per day

User-fee system – no state or federal gas tax dollars used

2

0 5 10 15 20 25 30 35 40 45 50

CRC is low a low maintenance pavement

3

Continuously Reinforced Concrete

0 5 10 15 20 25 30 35 40 45 50

Jointed Plain Concrete

0 5 10 15 20 25 30 35 40 45 50

Full Depth Asphalt

CRC Pavements Are Too Costly Upfront For the Tollway Based on Current Standards

4

Construction Cost Life Cycle Cost JPCP $219.2 $273 - $304 CRCP $231.0 $265 - $281 HMA $170.4 $259 - $304 HMA-JPCP $184.4 $259 - $293 HMA-CRCP $223.5 $270 - $320

Re-engineer CRC Pavements to Reduce Initial Costs

Nine 3 lane test sections to be constructed on the Elgin O’Hare under 3 contracts in year 2016 Contract I-13-4629 (2000 ft.) Contract I-13-4642 (1000 ft.) Contract I-13-4644 (1000 ft.)

Research to be conducted by University of Illinois (Prof. J. Roesler), Oregon State University (Prof. W.J. Weiss), and Texas A&M (Prof. D. Zollinger).

5

CRCP (University) Research Objectives Innovative Structural and Material Design for

Continuously Reinforced Concrete Pavement (CRCP) Collaboration between University of Illinois, Oregon State,

and Texas A&M w/ Tollway 3-year

Multi-year study with following components: laboratory concrete material experiments Innovative structural design Construction process improvements Field test section monitoring and evaluation

Additional partners – CMC, Inc. (steel industry) & ESCSI, inc. (lightweight fines industry)

6

Laboratory Concrete Materials Research

Development of optimized CRCP crack spacing and widths using internally cured concrete with saturated lightweight aggregates (LWA’s)

Impact of black steel vs. epoxy-coated steel on CRCP service life especially with chloride salts

Concrete mixture improvements Combined PLC + SCM Mixture proportioning adjustments Evaluate freeze-thaw damage potential

Effects of IC on curling and warping of concrete

7

UIUC ATREL Outdoor Beam Tests

8

Evaluate crack spacing/width: • IC vs. virgin aggregate • Reinforcement ratio • Macro-fiber or none • Induced vs. natural cracking • Curing process • Slab-base friction

Innovative Structural Design Thinner CRCP slab thickness from internal curing Minimize crack width Use of reduced steel content

Non-erodible support layers Asphalt Concrete vs. Cement Treated Base Designing erosion resistant layers from recycled materials Hamburg Wheel Load Tracking – performance tests

Transverse post-tensioning system for reducing thickness Transverse bars (#4) used to post-tension concrete Matching funds will build test section in Texas

9

Construction Process Improvements

Steel placement Reduce labor costs of steel placement Two-lift placement without transverse bars and same

mixture Re-assess tube feeding technology (Texas A&M)

Curing Management Active curing monitoring and management plan Minimize undesirable cracking patterns

Induced cracking at regular intervals Active cracking through early-age sawcutting or dynamic

fracturing Terminal and header joint construction efficiency

and performance

10

Field Test Section Objectives Field test sections in 2016 will provide data to connect

lab results to field observation and final design suggestions for the upcoming reconstruction of the Tri-State Tollway (I-294)

Sensors and Measurements: Crack spacing and width over time IRI and friction over time Temperature and relative humidity FWD for slab-base friction, crack LTE, deflection variability, and

support properties GPR – layer thicknesses and steel location verification Surface runoff and drainage of sections

11

Numerous Variables to be Studied

Standard Class TL concrete vs. internally cured concrete Black bar reinforcement content low (0.60%) vs. high (0.80%) Strengthened bases Non-drainable base - 2” AC interlayer over 4” cement treated base

(CTB) over 4” dense graded aggregate base Non-drainable base - thin AC interlayer over 6” cement treated

base (CTB) over 4” dense graded aggregate base Drained base – 3” AC stabilized subbase over 6” open graded

aggregate over stabilized subgrade soils/embankment Drained base – 3” AC stabilized subbase over 3” rap cap over 6”

PGE over triaxial geogrid/filter fabric

12

Numerous Variables to be Studied

Stabilized sub-base types (asphalt vs. CTB) Chair rebar placement vs. possible tube placement Single lift placements vs. two lift placements of concrete

all placements to be of one concrete class

CRCP with and without macro-fibers Natural cracking vs. sawed induced cracking Lug systems replaced with special end treatment

designs incorporating expansion joints

13

Re-engineering CRCP is important

Need to reduce initial construction costs No impact on out year maintenance

Project is being watched and may have major input

to future national standards

CRCP is an important tool to have available for critical infrastructure, especially metropolitan expressways

14

THANK YOU

15

Shiraz Tayabji, Ph.D., PE Applied Research Associates, Inc.

stayabji@gmail.com

Transportation Research Board Webinar on Continuously Reinforced Concrete Pavement (CRCP) – Part 3: Promising

Practices for Construction, Repair and Rehabilitation of CRCP January 28, 2015

CRCP Innovative Practices

Original PCC surface service life – 40+ years Pavement will not exhibit premature failures and

materials related distress Pavement failure=> Result of traffic loading, but

accounting for environmental loading Pavement will have reduced potential for punchouts

(less than 12/mile after 30 to 40 years) Pavement will maintain desirable ride and surface

texture characteristics with minimal intervention activities to correct for ride & texture, and minor repairs

CRCP Long-Life Expectations

2 Are we there yet?

Or, rather, can we attain above consistently?

How does innovations help CRCP technology? Reduce initial cost – even though CRCP has better

life cycle costs, many agencies still make decisions on basis of initial costs • But, any cost reduction must be made without sacrificing

performance Improve performance

• Optimize CRCP design features Improve construction efficiencies Continue to make CRCP more sustainable – A long-

life CRCP is sustainable over its life cycle – less need for repairs/rehab, less congestion, less lane closures

Need for Innovations? (That is the nature of human endeavors)

Current Efforts to Optimize CRCP Pavement design optimization (reduce cost &

improve performance) • Optimizing slab thickness, steel content &

concrete strength & support improvement • End treatment improvement

Concrete mixture optimization (improve perf.) • Internal curing • Dense concrete matrix

Reinforcement related (reduce cost) • Black steel vs. epoxy-coated steel

Construction efficiencies - bar placement • Korea-developed tube feeder system • Use of steel rolls (Bamtec system)

Punchout repairs – using jointed full-depth repairs (durable repairs) 4

Presentation Topics

Steel placement innovations • Korea developed tube feeder – allows

CRCP construction in tight construction zones

• Rolled steel – Bamtech (reduces cost & setup time on site)

CRCP Roundabouts (new application) Jointed full-depth repairs for punchouts

5

A CRCP Limitation – Side Discharge of Concrete

Need additional space for side discharge equipment Makes CRCP impractical to construct in areas with

limited side clearances Solution – SAMWOOIMC (Korea) developed MRCP

(Mechanically-Reinforced Concrete Pavement) – allowing concrete placement directly in front of paver

MRCP (Mechanically-Placed Concrete Pavement)

MRCP can be used for tight spaces,

especially in urban areas)

MRCP is CRCP constructed using

Tube feeding machine – tension keeps steel

bars at proper alignment

Components of MRCP Equipment

Concrete supplier

Features of MRCP No transverse reinforcing bars Simultaneous placement of reinforcing bars

and concrete pavement using the tube feeding machine

(Active discussions to implement MRCP in US)

Rolled Steel Placement (Bamtec®) A patented rolllout steel bar carpet system

developed in Denmark for floor applications & used for CRCP in Australia using OK Steelex jig (NSW Pacific Highway Boneville Upgrade)

Includes rolled transverse & longitudinal bar carpets Reduces field labor and improves field production

rate (~2,000 ft steel placement/day)

Bamtec® CRCP Application - Australia

CRCP Roundabouts

Used in Europe and use being considered in the US

For long-term durability and performance • Eliminates AC rutting and

shoving • Provides smooth ride & so

is less distracting to users & so is safer to traverse

FM-1375 ROUNDABOUTS, WALKER COUNTY Reinforcing steel placement - radial

• Inside Radius: 51’-6” (9” CRCP with #6 bar at 6” spa. = 0.61%)

• Intermediate Radius at Apron: 65’-6” (7” CRCP with #5 bar at 6.5” spa. = 0.68%)

• Outside Radius: 89’-6” (7” CRCP with #5 bar)

Belgium CRCP roundabout The country has built more than a

dozen CRCP roundabouts

Jointed Full-Depth Repairs for CRCP Based on technique developed by SCDOT

• Cast-in-place jointed full-depth repairs • Precast concrete jointed full-depth repairs

South Carolina Full-Depth Repair - Good performance

Conventional – Steel continuity maintained

Jointed FDR – doweled joints

16

Summary CRC pavements in the US have provided

good long-term performance when designed and constructed well And, efforts continue to improve design

and construction features to make CRCP more cost-effective (some discussed in this presentation)

Thank You! stayabji@gmail.com

FHWA/CRSI Workshop on CRCP Federal Highway Administration (FHWA) and the

Concrete Reinforcing Steel Institute (CRSI) have developed a one-day workshop on CRCP to present the latest information on design, construction and performance of CRCP and to allow the highway agency to determine when CRCP can be a viable pavement option and how to assure that it performs in accordance with desired performance goals.

Highway agencies can request the workshop by contacting: Sam Tyson, FHWA, sam.tyson@dot.gov