two-lift paving - txdot perspective
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 PavingTxDOT Perspective
Andy Naranjo, P.E.
• Use of Manufactured Sands• Use of Coarse Aggregates with High CoTEvalues
Use of Local Materials
Use of Manufactured Sands
Manufactured Sands
Natural River Sand Depletion
TxDOT Spec Limits
• Concrete subject to direct traffic requires the use of fine aggregates or blends to have a A.I. greater than 60%.
• Limits the use of Man. Sands
Use of High CoTE Concrete
High CoTEAggregates
CoTE Data
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
CoTE, m
icrostrain/F
Coarse Aggregate CoTE Values
25% above Limit
Acceptable for use in CRCP
Unacceptable for use in CRCP
San Antonio ACI June 27, 2012
Spalling in Concrete Pavement
Classification of TxDOT CRCP Distresses
0‐6274 Project Level Performance Database for Rigid Pavement in Texas, Phase II
San Antonio ACI June 27, 2012
Money Spent to Solve Problem
• Research– Over $2 million for the past 25 years
• Maintenance– The Houston District has spent:
• $41+ million to repair CRCP spalling• $400+ million to place bonded overlays
• Spalling virtually eliminated since the CoTErequirement began use in HOU ~10 years ago–Restricts the use of local aggregates
Lower CoTE ConcreteOr
Concrete with Natural Sands
Higher CoTEConcrete
OrConcrete with Man.
Sands
Questions