Paver Segregation Tim Aschenbrener Colorado DOT North Central - - PowerPoint PPT Presentation

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Paver Segregation Tim Aschenbrener Colorado DOT North Central - - PowerPoint PPT Presentation

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Paver Segregation Tim Aschenbrener Colorado DOT North Central Asphalt User Producer Group St. Louis, MO January 12, 2006 Presentation Overview I-25 Forensic Investigation 2003 Top-Down Cracking Study CDOTs 2004 Direction

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SLIDE 1

Paver Segregation

Tim Aschenbrener Colorado DOT

North Central Asphalt User Producer Group

  • St. Louis, MO

January 12, 2006

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SLIDE 2

Presentation Overview

  • I-25 Forensic Investigation
  • 2003 Top-Down Cracking Study
  • CDOT’s 2004 Direction
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SLIDE 3

I-25 Distresses

Pavement Surface

44 inches 81 inches 117 inches

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SLIDE 4

Paving Width Top-Down Longitudinal Cracking and /or Segregation were found at these locations. Slat Conveyors

Longitudinal Construction Joint

Longitudinal Construction Joint Direction

  • f Paving

37” 36”

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SLIDE 5

I-25 Forensic Study Conclusions

Cracking was:

  • Predominantly top-down
  • Segregation related
  • Induced by paver
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SLIDE 6

Presentation Overview

  • I-25 Forensic Investigation
  • 2003 Top-Down Cracking Study
  • CDOT’s 2004 Direction
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SLIDE 7

2003 Top-Down Cracking Study

  • Identify extent and cause

65” 31”

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SLIDE 8
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SLIDE 9

First Question

Reflective Crack or Top-Down Crack?

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SLIDE 10

6” exploratory core 10” Control core sampled @ 18 inches from crack (Uncracked area) 10” core sample of top down cracking Longitudinal Cracking

18”center to center

Shoulder Stripe

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SLIDE 11

Top- Down or Reflective?

Distress Percent of 25 Sites Reflective Cracking 28% Top-Down Cracking (Segregation) 48% Top-Down Cracking (No Segregation) 24%

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SLIDE 12

Measuring Distance from the Joint to the Crack

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SLIDE 13

Distance from longitudinal Construction Joint Site No. Paver Manufacturer/ Model First Longitudinal crack Second Longitudinal crack Third Longitudinal crack

3 1/A 38” 73” No crack 6 1/B 18” No crack 102” 13 2/E 37” No crack 97” 17 1/C 46” No crack 109” 19 1/D 69” No crack 128” 20 3/* 58” 87” No crack 23 2/* 41” 70” 99”

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SLIDE 14

Paving Width Top-Down Longitudinal Cracking and /or Segregation were found at these locations. Slat Conveyors

Longitudinal Construction Joint

Longitudinal Construction Joint Direction

  • f Paving

37” 36”

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SLIDE 15

2003 Top-Down Study Conclusions

  • CDOT Research Report CDOT-DTD-R-

2003-7

  • Need to Core
  • Segregation not always apparent during

construction

  • More than one paver manufacturer/model
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SLIDE 16

Presentation Overview

  • I-25 Forensic Investigation
  • 2003 Top-Down Cracking Study
  • CDOT’s 2004 Direction
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SLIDE 17

D G A F E E F C C B

Spillage Out of Hopper Onto Grade Center Rear of the Hopper Rear Outside Edges of Both Hoppers Outside Edges of Both Conveyors Outside Edges

  • f the Screed

Outer Auger Bearing Pedestal Center Auger Conveyor Drive Box Outside of the Conveyor Chains

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SLIDE 18

Paver Modifications – Man. 1

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SLIDE 19

Paver Modifications – Man. 1

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SLIDE 20

Paver Modifications – Man. 2

1 2 1 2

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SLIDE 21

CDOT’s 2004 Direction

  • Peer Review Meeting
  • Method Specification Issued
  • Pursuing End-Result
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SLIDE 22

Peer Review Meeting

  • Jim Scherocman moderated
  • Caterpillar
  • Cedarapids / Terex
  • Ingersoll-Rand / Blaw-Knox
  • Roadtec
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SLIDE 23

Method Specification

  • Method Specification

Standard Specification 401.10

  • Construction Bulletin

Dated March 22, 2004

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SLIDE 24

Follow-Up Research

  • End Result Specification
  • Research Report CDOT-DTD-R-2005-16

Density Profiling Thermal Camera

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SLIDE 25

Presentation Overview

  • I-25 Forensic Investigation
  • 2003 Top-Down Cracking Study
  • CDOT’s 2004 Direction
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SLIDE 26

Questions?