two-lift paving - agency viewpoints
DESCRIPTION
A Two-Lift concrete Paving (2LCP) workshop was organized as a part of the Texas Department of Transportation (TxDOT) project 0-6749: Feasibility Study of Two-Lift Concrete Paving (2LCP). This workshop was conducted at the J. J. Pickle Research Campus (PRC), The University of Texas at Austin, Austin, TX on May 23rd, 2013. Dr. Jiong Hu, Texas State University, Research Supervisor, and Dr. David Fowler, The University of Texas at Austin, Co-Research Supervisor, co-chaired the workshop. The workshop offered the option of attending in person or remotely through webinar. Fifty-one attendees were present remotely or in person; 28 in person and 23 persons remotely.TRANSCRIPT
Two Lift Concrete Composite Pavements
Shreenath Rao, Ph.D., P.E.
Two‐Lift Paving WorkshopAustin, TX – May 23, 2013
Two Lift Concrete Paving‐A Forgotten Practice
Popular back in the 50’s, 60’s and 70’s when the Tollway was originally built
Tollway Requires 100% Recycling of Concrete and Asphalt Pavements with Reconstruction
In Base Aggregates In New Asphalt Mixes
Plenty of Coarse FRAP to be Left for Concrete – How do we Reuse it?
Composite Pavement Field Trials Initiated in 2010
Asphalt‐over‐concrete composite ramps built
6.5 bag fly ash mix with 20 percent black rock placed
Compressive strengths > 3500 psi in three days
Flexural Strengths >650 psi in seven days
Black Rock Ternary Mixes Researched
Further processing of FRAP to remove agglomerated sand/asphalt particles was not necessary
A ternary concrete design with a cement factor of 6.2 obtained specified strength properties with up to 50% of the coarse aggregate replaced with FRAP
Durability of concrete will be adequate for composite pavement applications
Composite Pavement Research Performed
Further evaluated black rock concrete mixes for fresh, hardened and durability properties
Developed better predictive models of the field performance for 2‐lift composite concrete pavements using recycled materials
Why Go Back to the Old Paving Methods?
Making Concrete Greener and Ultimately Cheaper For Both Lifts
Optimize gradation and reduce cement content
Replace Virgin Aggregate with Recycled
Replace portlandcement with SCM’s
Bottom Lift Concrete Options / Requirements
As Currently Specified Optimized Gradations 15% to 50% Coarse FRAP
(Black Rock) 0% to 85% Coarse RCA Ternary Mixes Required Blended Cements Allowed
Being Researched Use of Coarse FRAP from
IDOT mix sources Use of Lower Quality Virgin
Aggregates Use of Aged / Oxidized
Steel Slag FRAP
Options to Improve Top Lift Performance
Reduced Permeability, Mitigate ASR Concerns, and Improve Durability with Optimized Ternary Mixes
Reduce Noise and Improve Surface Friction with Exposed Aggregate Finish
Better Control on SmoothnessPervious Concrete Possible for Future Permeable Pavements
Photocatalytic Cements Can Be Used
Specifications For Composite Pavements
MaterialsTop Lift Concrete Designs either Standard Class PV, or Optimized Ternary Performance Based Mixes with Virgin Aggregate.
Bottom Lift Concrete Designs only Optimized Ternary Performance Based Mixes with some Recycled Aggregate.
Construction Methods
Removal and Reprocessing of Old Pavements
RCA for reuse as PGE or coarse aggregate for concrete
RAP Millings for reuse as coarse aggregate for
concrete, FRAP for new asphalt mixes, or for capping
stone
Specifications For Composite Pavements
EquipmentAll in accordance with
IDOT Standards
Test Strips to be Constructed for All Types of Placements (single and double lane)
Single Lift Placements vs. Two Lift
Dowel Alignment Tolerances
Consolidation to be Monitored
Two Slip Form Pavers / Two Belt Placers
One Slip Form Paver / Two Belt Placers
Envelope Outside Edges of Bottom Lifts
Finishing / Curing / Opening to Traffic
Economic Benefits of Greener Concrete
’04 – ’09 JPCP Bid Prices
> 3,000,000 Sq. Yds. of JPCP Built System‐wide
11.25” JPCP ‐ $61.00/SY 12” JPCP ‐ $65.00/SY 13” JPCP ‐ $70.00/SY
’13 Composite Bid Prices
> 700,000 Sq. Yds. to be built on I‐90 in 2013
11.25”– $40.66/SY 12” ‐ $45.92/SY 13” ‐ $49.70/SY
23
Prime contractor: Applied Research Associates, Inc. Sub contractors: University of Minnesota
Minnesota Department of TransportationUniversity of California at DavisUniversity of Pittsburgh
Key Staff: Darter, Rao, Khazanovich, Von Quintus, Harvey, Signore, Wu, Worel, Clyne, Watson, Vandenbossche, Tompkins, Vancura
Duration: ~48 months
SHRP2 R21 Composite Pavement Systems SHRP2 R21 Composite Pavement Systems
Acknowledgements: FHWA MCL; Illinois Tollway, CS McCrossan
2007 2008 2009 2010 2011
Phase 1
2012
Phase 1 (completed May 2008)• State of the practice
Phase 2 (completed May 2009)• Identify failure mechanisms and other factors the influence
performance.• Develop draft performance models• Research plan to evaluate critical design parameters• European report
Phase 3 (completed April 2012)• Construct experimental sections• Refine and validate performance models• Develop design procedures, guidelines, and construction
specifications• Research plan for future validation an refinement of models• Training materials to aid in implementation
Phase 2 Phase 3
SHRP2 R21 Composite Pavement Systems SHRP2 R21 Composite Pavement Systems
PCC/PCC HMA/PCC
SHRP2 R21 Composite Pavement Systems SHRP2 R21 Composite Pavement Systems
http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=2173
Thank You
1st Paver: Lower JPCP Layer
2nd Paver: Upper PCC Layer