LTPP Lessons Learned: Delaware SPS-2

1. LTPP Lessons Learned:Delaware SPS-2 Wednesday April 9, 2014 SPS-2 Tech Day, Dover, DE Gabe Cimini Project Manager, LTPP North Atlantic Regional Support Contractor (NARSC)

2. Delaware SPS-2 Lessons Learned Overview • How are the Sections Performing? • Construction Related Performance Issues • Overview of Performance • What Lies Ahead?

3. Delaware SPS-2 Lessons Learned Overview • SPS-2 experiments examine effects of climatic region, subgrade soil and Traffic rate on doweled jointed plain concrete pavement • Structural factors include drainage, concrete thickness, base type, concrete flexural strength and lane width • Requires that all test sections be constructed with perpendicular joints at 4.9 m spacing and stipulates a traffic load level in the lane in excess of 200,000 ESALs per year • The Climate for this SPS-2 project is considered to be a wet-freeze environment by LTPP definitions • Construction completed and section opened to traffic - May1996

4. Delaware SPS-2 Layout

5. How are the Section Performing? Overview of Maintenance/Rehabilitation Treatments

6. Longitudinal Cracking

7. Longitudinal Cracking 100207

8. Transverse Cracking

9. Transverse Cracking 100205

10. Roughness

11. Roughness 100208 100206

12. Pavement Deflections

13. Pavement Deflections 100201 100212

14. Construction Related Performance Issues • Subgrade • Eight of the 12 test sections contained partial shallow cuts that did not meet the specifications. Sections were excavated and received 12 inches of Type A borrow • DGAB • Bases did not extend the full width of the shoulder

15. Construction Related Performance Issues (cont.) • LCB • During paving of the LCB layer, depressions in the subgrade occurred during stoppage of the paver. Transverse shrinkage cracks developed in the LCB layer prior to PCC paving, and some of these shrinkage cracks developed in the depression areas • PCC • 7 sections have PCC slab thickness that exceed the allowable tolerance of ± ½ inch

16. Construction Related Performance Issues (cont.) • Both Flexural Strength values (14 day MPa) are over by more than 10% of design averages • 550 PSI (Actual averages = 657 PSI)(Type B Mix – 650PSI) • 900 PSI (Actual averages = 757 PSI) • No. 57 Stone was used as the edge drain backfill instead of PATB • No joint sealant was used between the mainline concrete pavement and the asphalt shoulder

17. Construction Related Performance Issues (cont.) • Sections 100205, 100201, 100209 received new PCC to replace original that showed early shrinkage cracks (Type B mix - 3000PSI Compressive Strength) • Sections 100206 and 100202 were also replaced (900PSI Flexural strength) • Before removing concrete coring of transverse and longitudinal shrinkage cracks showed cracks extended either entirely or partially through the PCC but not into the underlying LCB. No bond was found to occur between the PCC and the underlying LCB

18. Overview of Performance • More maintenance/rehabilitation treatments were required for sections with No Drainage • Sections with Drainage reported less cracking and lower maximum wheel path faulting as well as lower initial deflections with more sections performing better over time. Sections 100209, 100210, 100211, 100212, 100259, 100260) • Maintenance/rehabilitation treatments were effective at reducing cracking and faulting

19. What Lies Ahead? • LTPP monitoring to continue • SPS-2 Pavement Preservation Pooled Fund Study (2013 to 2016) – Partners - AZ, CA, CO, GA, KS, NC, WA • More Data Analysis and data insights • Data and reports available on LTPP InfoPave™

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