LTPP Lessons Learned:LTPP Lessons Learned:Delaware SPS-2Delaware SPS-2

Wednesday April 9, 2014

SPS-2 Tech Day, Dover, DE

Gabe CiminiProject Manager, LTPP North Atlantic Regional

Support Contractor (NARSC)

Delaware SPS-2 Delaware SPS-2 Lessons Learned OverviewLessons Learned Overview

How are the Sections Performing?

Construction Related Performance Issues

Overview of Performance

What Lies Ahead?

Delaware SPS-2 Delaware SPS-2 Lessons Learned OverviewLessons 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

Delaware SPS-2 LayoutDelaware SPS-2 Layout

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

Sequence Date Activity Section(s)

1April 1996

Full Depth Transverse Joint Repair Patch

100209

2May 1996

Full Depth Transverse Joint Repair Patch

100210

3June 2000

Grinding Surface

100201100204100205100208100209100210100212100259

4June 2002

Transverse Joint Sealing and Lane-Shoulder Longitudinal Joint Sealing

100210

5June 2006

Lane-Shoulder Longitudinal Joint Sealing

100207100208100211

6June 2008

Crack Sealing 100207

7March 2011

Crack Sealing 100207Partial Depth Patching of PCC Pavement Other Than at Joint

100207100211

Patch Pot Holes - Hand Spread, Compacted with Truck

100207

Patch Pot Holes - Hand Spread, Compacted with Truck

100208

8May 2012

Partial depth patching of PCC pavements at joints and Partial

Depth Patching of PCC Pavement Other Than at Joint

100208

Longitudinal CrackingLongitudinal Cracking

Longitudinal CrackingLongitudinal Cracking

100207

Transverse CrackingTransverse Cracking

Transverse CrackingTransverse Cracking

100205

RoughnessRoughness

RoughnessRoughness

100208

100206

Pavement DeflectionsPavement Deflections

Pavement DeflectionsPavement Deflections

100201

100212

Construction Related Construction Related Performance IssuesPerformance 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

Construction Related Construction Related Performance Issues (cont.)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

Construction Related Construction Related Performance Issues (cont.)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

Construction Related Construction Related Performance Issues (cont.)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

Overview of PerformanceOverview 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

What Lies Ahead?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

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