Development of Performance Curves for Whitetoppings in Minnesota - Research Update

April 19th, 2016 Tom Burnham, Tim Andersen

Safer, Smarter, Sustainable Pavements through Innovative Research

Agenda

• Objectives

• Study tasks and timeline

• Field condition survey results

• Preliminary performance curves

• Associated research

Acknowledgements

• Chago Heurta – Student worker

• American Engineering Testing

• MnDOT, Q3, and County Traffic Control Forces

• MnDOT Concrete Office

• Tim Andersen - Technical Liaison

Objective: Development of Performance Curves

for Whitetoppings in Minnesota

• Review performance in Minnesota • Develop performance curves for MnDOT Pavement

Management System • Identify best practices for design and timing of

maintenance • Improve project selection (CPTech Center study)

Study Tasks and Timeline • Task 1 - Literature search and project database (Aug 2015)

– Task 1 report available for review • Task 2 - Field condition survey – Part 1A and 1B (Mar 2016)

– Task 2 report available for review • Task 3 - Data Analysis – Part 1 (Jun 2016) • Task 4 - Interim Report (July 2016) • Task 5 - Field condition survey - Part 2 (Dec 2016) • Task 6 - Data Analysis – Part 2 (Feb 2017) • Task 7 - Draft final report (Mar 2017) • Task 8 - Final report (May 2017)

Task 1 Literature Search • Very limited performance curves available

– Louisiana DOT, 13.5 years, 4’x4’panels, 4” PCC

Xingwei Chen (2015)

Task 1 Project Database • Breakdown

– 5 MnDOT projects • TH30 (1993) • TH212 (2009) • I-35 (2009) • TH56 (2010) • TH24 (2014)

– 21 MnROAD sections

– 20 County projects (oldest built in 2009)

Task 1 Conclusion

Developing performance curves will be challenging due to lack of older projects in Minnesota

(MnROAD data will help!)

Task 2 Field Condition Surveys

• Data collected on 21 statewide projects – GPR for thickness variation – Profiled for IRI [9 projects revisited in Nov 2015] – Initial visual distress survey – 3 core samples

• Assess bond quality • GPR thickness calibration • HMA assessment

Task 2 Field Observations • Most projects are good to very good condition

– Most are still “young” – Some longitudinal cracking – A few buckled panels (McLeod County)

• Transverse reflective cracking not prevalent

– I-35 project: early cracks remain tight – Matching PCC joints to HMA cracks not necessary

Task 2 Field Observations • Undoweled transverse joints can developing faulting

when subject to heavy truck volumes/loads – Noticeable faulting on TH22 Olmsted County project

• 4 years old, 6.5” thick, 12’x12’ panels, undoweled joints • Very heavy truck volumes • No cracked panels

– Attempts to match overlay joints to underlying HMA cracks seems to lead to early faulting

• Full-depth vertical movement – With smaller joint spacings, not all joints appear to deploy

• Leads to 12’ effective panel lengths

• Little to no maintenance on most projects

Task 2 MnROAD Observations Faulting of joints

6’ x 6’ doweled vs undoweled 10’ x 12’ faulted (and cracked)

Faulting Mechanism NCHRP 338 (Rasmussen and Rozycki), 2004

– Hypothesis for joint faulting = permanent deformation of HMA

Current TPF 5-269 UBOL design pooled fund (Vandenbossche), 2014

– Observed permanent deformation in HMA interlayers in lab

Task 2 MnROAD Observations Potential design option?

12’ x 6’ do not crack transversely (Cell 614, plate dowels)

Task 2 Field Observations GPR testing revealed typical variations in concrete overlay and asphalt thickness

Task 2 Field Observations Core samples revealed various PCC/Asphalt

bonding conditions

Task 3 Data Analysis - Part 1 Population by age (includes MnROAD)

Task 3 Data Analysis - Part 1 Population by thickness (includes MnROAD)

Task 3 Data Analysis - Part 1 Population by panel size

Task 3 Data Analysis - Part 1 • Other population details

– Remaining asphalt thicknesses from 3” to 14” – 20.5/46 projects with unsealed joints – No major projects with structural fibers

• MnROAD Cells 160, 162 (built in 2013)

Interstate traffic

Next steps

• Further breakdown and analysis to determine variability of RQI

• Surface rating will be determined for each project • Preliminary performance curves will be generated and

published in Interim Report • One or more profile measurements and distress

surveys will be done on projects during summer/fall of 2016

12 millions CESALS in 2010

500,000 CESALS

Associated Research

Thin Whitetopping Selection Procedures

Research Team: Dale Harrington, Julie Vandenbossche, Gary Fick

working under Peter Taylor, CPTech Center

Questions and Discussion