intelligent compaction

Understanding the Technology

INTELLIGENT COMPACTION

Jimmy Si, Ph.D., P.E. Austin, TX, April 3, 2014

Table of Contents

6-9

10-11

12

13

3-5Why Use Intelligent Compaction

TXDOT IC Projects

Benefits and Challenges

Future Plans

Summary

1

2

3

4

5

2

Ordinary Compaction

Density Control• Compactive Energy

• Moisture Content

• Material Type

• Compact Lift Thickness

• Underlying Conditions

Why Use IC?

3

Why Use IC?

Not used in pavement design A layer-specific spot test providing

no info on the uniformity of compaction over the entire section

Only measured after compaction is complete providing no feedback in real time

4

Can We Do A Better Job?

Why Use IC?

Lose the track of rolling pass counts Compaction job becomes guesswork

Inconsistent and non-uniform density

Under/over compaction Premature pavement failure

5

Before

After

TxDOT IC ProjectsFort Worth (7)FM156; US287 ; FM1938;

FM731; SH267; IH35W;

and IH30

El Paso (1)FM1281

Amarillo (1)LP335

Paris (2)US75SH24

Atlanta (1)FM450

Houston (1)SH35

6

FM156, Fort Worth, TX

FHWA/TPF IC Study

SG, Lime Stabilized SG, and Flex Base

Ammann/Case padfoot drum IC roller

Dynapac singlesmooth drum IC roller

Ammann/Case smooth drum IC roller

FM156 Project

7

Case/Ammann single-drum

padfoot IC roller

Ks shows compaction progress and a soft spot

FM156 Project – Identify Soft Spots

Screen shots of kSΙPD maps for different passes on TB 1

8

FWD

LWD

FM156 Project – IC vs. Conventional Tests

DCP

9

Benefits

Covers 100% of the area compacted

Monitors pass counts Identifies areas of poor compaction Intelligently picks areas to test for QC/QA Improves productivity and minimizes cost Improves safety in construction zones

10

Extensive training for DOT and contractors FHWA training workshops

Data management difficulties VEDA

More expensive than ordinary IC retrofit kit

High moisture variation No strong correlation b/w stiffness and density

Challenges

11

Workshops/Webinars and pilot projects in districts

Revise IC specification–Short Term: density based on

IC proof mapping–Long Term: stiffness based on

IC proof mapping

12

Future Plans

Summary

1. IC is a continuous compaction control process.2. IC is only for QC so far.3. IC measures stiffness, not density.4. IC reports both stiffness and pass count. 5. IC does not measure moisture.6. IC measurements are sensitive to moisture.7. IC improves safety in construction zones.

13

QUESTIONS?

Jimmy Si, Ph.D., P.E.

512-506-5901

Jimmy.Si@txdot.gov

Thank You!