8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 1/21

The Dynamic Cone Penetrometer “The DCP” 

What is it, how does it work, and how

can it help you?

Gavin P. Gautreau, P.E.Geotechnical Research ManagerLouisiana Transportation Research Center (LTRC)

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 2/21

• What is it?

 – Purpose & Concept

 – Parts• How does it work?

 – Operation/Technique

 – Data Recording/Analysis• How can it help you?

 – Layer Stiffness

 – Layer Thickness – Acceptance & Verification

 – Forensics

 – Correlations (CBR, Mr, etc.)

Presentation Objectives: 

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 3/21

• Purpose & Concept

 – Dynamic Cone Penetrometer

 – Shallow Pavement Applications – Measures Stiffness, mm/blow

 – Simple Concept

• Like hammering a nail

• Stiff material requires more drops

• Weak material requires fewer drops

 – Non Nuclear

 – Possible Method for Acceptance

 – Quick and Cost Effective

 – Another “Tool for the Toolbox”

What is it? 

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 4/21

• Parts – Handle

 – Upper Rod (5/8” dia) – Hammer

• 17.8 pounds (8kg)

• 22.6 inch drop

 – Anvil & Lower Rod

 – Cone Tip (60 degree, ¾” dia)

 – Measuring Rod with cm & mm divs.

 – Other

• Hammer Drill

• Generator

• Farm Jack

What is it? 

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 5/21

(A)(B)

How does it work? 

• Operation

 – Assemble DCP

 – Drill thru Asphalt or Concrete ifnecessary

 – Record reference readings (A)

• Rod remains stationary

 – Lift hammer to handle

 – Release hammer

 – Record rod reading after each

hammer drop (B) – Repeat drop, read, and record

process thru pavement layers

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 6/21

(A)(B)

How does it work? 

• Technique

 – Keep straight (vertical)

 – Avoid banging hammerinto handle during lift.

• Can lose disposable cone

• Damage to device – Spin rod after each blow.

 – Keep measuring rod inone spot during test.

 – Record reading afterevery hammer drop.

(X)

(Y)

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 7/21

How does it work? 

• Operation (Prep & Planning)

 – Hammer Drill

• Quickly thru Asphalt or Concrete

• Minimal Intrusion

• Various Length bits

• Dry vs wet coring rig

 – Crew Size• Hammer Operator

• Reader

• Recorder

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 8/21

How does it work? 

• Data Recording

 – Project Information

• Site Location

• Station #

• Distance from Centerline

• Elevation (if available)

 – Pavement Information (as available)• Cross-Section Thickness Information

• Material Types (classification and gradation)

• Compaction Info (Proctor Moisture and Density) as available

• Nuclear Gauge Information if available

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 9/21

(A) 46.0(B) 46.3

How does it work? 

47.55

????

46.93

46.62

47.24

Top of Asphalt/Concrete

Top of Testing Surface

(bottom of drilled hole, if applicable)

Reading after First Blow

Reading after Second Blow

Anytown, LA – Hwy 1, Sta. 19+00 RL

NA0

46.0(A)0

RodReading

Blow#

Reading after Fourth Blow

Reading after Third Blow

Reading after Last Blow

Reading after Fifth Blow

• Data Recording, example

1 46.3(B)

,cm

Stone

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 10/21

How does it work? • Data Calculations (without drilling)

46.93

46.6246.31

NA0

46.00

47.86

47.55

47.24

RodReading, cm

Blow#

0.90.90.3

0.60.60.30.30.30.3

cm

can plot as inches or elev.

cm

Running Total

cm

this timesten = DCPI

equal to tip location

below surface0.00.0

1.81.80.3

1.51.50.3

1.21.20.3

Distance below SurfaceCumulativePenetration

Distanceper Blow

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 11/21

How does it work? • Data Calculations (drilling occurred)

46.93

46.6246.31

38.40

46.00

47.86

47.55

47.24

RodReading, cm

Blow#

8.50.90.3

8.20.60.37.90.30.3

cm

can plot as inches or elev.

cm

Running Total

cm

tip location

below pavement surface0.07.6Drilled depth

9.41.80.3

9.11.50.3

8.81.20.3

Distance below SurfaceCumulativePenetration

Distanceper Blow

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 12/21

0

5

10

15

20

25

30

35

40

0 20 40 60 80Number of Blows

   C  u  m  u   l  a   t   i  v  e   P  e  n  e   t  r  a   t   i  o  n ,  c  m

Anytown, LA – Hwy 1, Sta. 19+00 RL

3 mm/blowLayer Change

Layer Change

36 mm/blow

11.2 mm/blow

Number of Blows

   D  e  p   t   h  o   f   P  e  n  e   t  r  a

   t   i  o  n ,  c  m

• Data Analysis

 – Plotting Data

 – Layer Changes

 – Average mm/blow

Example, cont’d

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 13/21

Advantages:• Determines Stiffness in mm/blow

• Plotted slope = Stiffness in mm/blow

• Flatter Slopes indicate stiffer layers

• Steeper Slopes indicate weak layers

• Layer Changes identified by Slope Changes

• Thicknesses can be determined/verified

• Weak layers identified

• Minimal disturbance• Test lower pavement layers without removal of upper layers

• Test different materials (Stone, Sand, Clay, and Silt)

• Compare time differences or adjacent sites

Disadvantages:• Not for use on large stone, shell, asphalt, and concrete

• Damage can occur (repetitive blows in very stiff & improper removal)

• Does not measure moisture content or density – measures stiffness

   D  e  p   t   h

Blow Count0

How can it help you? 

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 14/21

How can it help you? 

• Advantages:

• Possibly another way to adjust pay, based on

Stiffness of in-place layers• Non “Nuclear”

• Not rocket science

• Correlations to CBR, Mr, etc.• Another “tool for the toolbox”… spread the word

• Simple reliable, cost-effective tool for shallowpavement applications

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 15/21

• Develop a comprehensive implementation plan ofDCP with procedures that DOTD can use in its dailyproduction

• Develop or modify current DOTD specifications toaccommodate such changes.

LTRC Project: 06-4GT 

Objectives: 

This is a comprehensive follow-up studyafter four LTRC research projects on

involving DCP applications.

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 16/21

ALF Lane 4 

Base, Treated Subase, & Subgrade

Field & Laboratory Test Summary

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 17/21

Cross-Section 

• Asphalt Surface (2”)

• Base (8.5”) – Stone

 – BCS with 10% Slag

 – BCS with FlyAsh (small untreated area at end) – Foamed Asphalt

• Treated Subbase (12”) – Lime

 – Cement

• Untreated Subgrade C    o    n    s     t    r    u    c     t     i    o    n

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 18/21

SUBGRADE DCP VALUES

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

20-Nov 10-Dec 30-Dec 19-Jan 8-Feb

TIME, DATE

   A   V   E   R   A   G   E   M   M   /   B   L   O

1A AVERAGE

2A AVERAGE

2A 0+10

1B AVERAGE

2B AVERAGE

3A AVERAGE

3B AVERAGE

NovemberAverage =28.9

FebruaryAverage =13.6

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 19/21

TREATED SUBBASE DCP VALUES

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

20-Nov 10-Dec 30-Dec 19-Jan 8-Feb

TIME, DATE

   A   V   E   R   A   G   E   M   M

   /   B   L   O

1A AVERAGE

2A AVERAGE

2A 0+10

1B AVERAGE

2B AVERAGE

3A AVERAGE

3B AVERAGE

LimeInitialAverage= 31.8

CementAverage= 5.3

CementInitialAverage= 20.3

LimeAverage= 7.3

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 20/21

BASE DCP VALUES

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20-Nov 10-Dec 30-Dec 19-Jan 8-FebTIME, DATE

   A   V   E   R   A   G   E   M

   M   /   B   L   O

1A AVERAGE

2A AVERAGE

2A 0+10

1B AVERAGE

2B AVERAGE

3A AVERAGE

3B AVERAGE

BASE DCP VALUES

BCS & Slag

BCS & Fly Ash

BCS (Raw)

Stone

Stone

Foamed Asphalt

Foamed Asphalt

Each point represents 3 testsper section per date.

8/8/2019 The Dynamic Cone Penetrometer the DCP

http://slidepdf.com/reader/full/the-dynamic-cone-penetrometer-the-dcp 21/21

Thanks! 

• Questions?