User Manual
Measuring
Road Pavement Strength and
Designing Low
Volume Sealed Roads using the
Dynamic Cone
Penetrometer
Unpublished Project Report
UPR/IE/76/06
Project
Record No R7783
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Measuring
Road Pavement Strength and Designing Low Volume Sealed Roads using the Dynamic
Cone Penetrometer |
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Sector: |
Transport |
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Theme: |
T2: Reduce overall transport cost by cost
effective road rehabilitation and |
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Project Title: |
Environmentally
Optimised Design |
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Project Reference: |
R7783 |
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Approvals |
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Project Manager |
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Quality Reviewed |
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Copyright
This document has been prepared as
part of a project funded by the UK Department for International
Development (DFID) for the benefit of developing countries. The views
expressed are not necessarily those of DFID. The Transport Research Laboratory and
ACKNOWLEDGEMENTS
The development of UK DCP software has been based upon the responses received to a questionnaire distributed to the members of the International Focus Group (IFG). We are extremely grateful to those who took the time to complete the questionnaire and return it to us. We are also grateful to Yogita Maini of DFID, Phil Page-Green of CSIR, South Africa, and Dr Simon Gillett of Roughton International who reviewed the project and provided useful feedback. The TRL team responsible for analysing the questionnaires, designing the software, writing the user manual and making UK DCP 3.1 available were Piouslin Samuel, Colin Jones, Simon Done, Dr John Rolt, Dave Weston and Trevor Bradbury. Dr Stephen Morris and his team from Tessella Support Service wrote this software.
April 2006
Contents
2.2.2 Installation from Transport Links website
3.1.2 Open an existing project
3.1.3 Closing a project and exiting UK DCP 3.1.
4.5.2 CBR Adjustment Factor (for moisture)
4.6 Alternative methods for inputting data
5.5 Analysis of drilled and very strong layers
6 Structural Number calculation
6.1.2 Base and Sub-base Test layers
6.2 Calculating the Structural Number
7.2 Displaying the Query results
7.2.2 Layer or Pavement Thickness
8.3.1 Determine Sections by parameter
8.3.2 Determine DCP Sections for the project
10.2 Displaying available design data
10.4 Design Section Properties
11.3.4 Parameters to use with design catalogue
11.3.6 Carriageway Surfacing and Materials
11.3.7 Shoulder Surfacing and Materials
12.3 Layer Strength Analysis report
12.6 DCP Section Properties report
12.8 Bill of Quantities report
Appendix A: DCP Test Data Form
List of Figures
Figure
3.3 Project Manager (without test data)
Figure
3.4 Project Manager (with test data and completed analysis)
Figure
3.5 Project Manager (with test data and completed design)
Figure
4.2 Illustration of Upper layers, Test layers and Removed layers
Figure
4.3 Penetration Data box (with test data)
Figure
4.4 Penetration Data box (with a drilled layer and an extension rod)
Figure
4.6 Project Manager (showing that test data has been input)
Figure
5.1 How Automatic analysis works
Figure
5.2 Layer boundaries box using Automatic analysis
Figure
5.3 Project Manager (showing that test data has been analysed)
Figure
5.4 Layer Boundaries box using Manual layer analysis
Figure
5.5 Project Manager (showing that test data has been analysed)
Figure
5.6 Double intersections
Figure
5.8 Line does not intersect the line of test points
Figure
5.9 Line drawn parallel to its intended position
Figure
5.10 Line moved laterally to its intended position
Figure
5.11 Lines overlap but do not intersect
Figure
5.12 Automatic analysis of a drilled layer
Figure
5.13 Manual analysis of a drilled layer and the use of gaps
Figure
5.14 Automatic analysis of a very strong layer
Figure
5.15 Manual analysis of a very strong layer and the use of gaps
Figure
6.1 SN Calculation box (before calculating SNs)
Figure
6.2 Layer Boundaries box
Figure
6.3 Adjusted Penetration Data box
Figure
6.5 SN calculation box (after calculations are complete)
Figure
6.6 Project Manager (showing that SNs have been calculated)
Figure
7.2 Structural Number histogram
Figure
7.3 Layer Thickness histogram
Figure
7.4 CBR histogram (Minimum)
Figure
7.5 CBR histogram (Less Than)
Figure
8.1 Sections box (before sectioning)
Figure
8.2 Uniform Sections box
Figure
8.3 Histogram of sectioning data
Figure
8.4 Uniform Sections box (with one section boundary added)
Figure
8.5 Sections box (after Sectioning)
Figure
8.6 Section Summary box
Figure
8.7 DCP Section Properties box
Figure
8.8 Section Summary box (with one DCP Section boundary added)
Figure
8.9 Project Manager (showing that DCP Sections have been defined)
Figure
9.1 Survey Data box (without data)
Figure
9.2 Survey Data box (with data)
Figure
9.3 Project Manager box (after entering survey data)
Figure
9.4 Design & Costs Data box (with data)
Figure
10.1 Design Sections box
Figure
10.2 Design Section Legend
Figure
10.3 Design Section box (with CBR)
Figure
10.4 Design Section Properties
Figure
10.5 Project Manager Box (after Design Sections have been defined)
Figure
11.1 Message on statistical parameters.
Figure
11.2 Pavement design box – before designing
Figure
11.3 Design (Section box)
Figure
11.4 Design catalogue (2<N<4)
Figure
11.5 Design catalogue (N>4)
Figure
11.6 Pavement design box – after design
Figure
11.7 Project Manager (after pavement design)
Figure
12.2 Penetration Data Report
Figure
12.3 Layer Strength Analysis report
Figure
12.4 Test Summary Report
Figure
12.5 Section Summary Report
Figure
12.6 DCP Section Properties Report
Figure
12.7 Pavement Design Report
Figure
12.8 Bill of Quantities Report
Figure
12.9 Maintenance Report
List of
Tables
Table
4.1 Penetration rate-CBR relationships.
Table
4.2 CBR Adjustment Factors
Table
4.3 Effect of moisture adjustment factor on Subgrade CBR
Table
5.1 Example of penetration data and cumulative sum analysis
Table
6.1 CBR-Strength Coefficient (a) relationships
List of
Boxes
Box 1.1 Key
points to know before using UK DCP 3.1
Box 4.1
Recording the removal of very thick Upper layers
Box 4.2
Calculating adjusted penetration data
Box 5.1 Should
penetration data be analysed automatically or manually?
Box 5.2
Corrected analysis of deep surface texture and disturbed soil
Box 5.3
Analysis of a drilled layer
Box 5.4
Analysis of a very strong but penetrable layer
Box 6.1 The
importance of checking the layer analysis against CBR Chart
Box 9.1
Recording of variations within data interval
Box 9.2
Determination of design traffic
Box 10.1
Determination of Design Sections
Box 11.1
Reassigning existing pavement layers
1
Introduction
When required to design improvement works, a pavement engineer needs to know the environment in which the road is located, the details of the pavement layers and the current condition of the road. These details are normally collected in stages, beginning with a desk study and field survey, progressing to non destructive testing and finally, if necessary, to destructive testing and laboratory studies.
The initial survey along the road helps to find changes, if any, in the surfacing, geometry, land use, drainage, and the crown height along the road and the influence that any of these may have, jointly or individually, on the pavement.
A
common method of pavement investigation is to dig test pits at suitable intervals
along the road. These are very useful as pavement thicknesses can be measured and
material can be removed for testing in a laboratory. However, test pits are time
consuming and expensive to dig and reinstate and as a result are rarely dug at
intervals of less than 2-3 kilometres. The Dynamic Cone Penetrometer (DCP) (Figure 1.1) is a quicker and cheaper way of investigating
the pavement which allows tests to be carried out at much more frequent
intervals.
After the road and the environment in which it is located have been surveyed and the condition of the pavement layers has been investigated, the road can be divided into sections which are uniform in a variety of characteristics and for each of which improvements can be appropriately designed.
UK
DCP 3.1 software is designed for two categories of user: those who wish to analyse
DCP data; and those who need to produce design for lengths of sealed roads used as spot improvements on
low trafficked roads. Chapters 1 to 3 describe functions, such as installation,
which are common to all users. Chapters 4 to 8 describe the analysis of DCP
data and Chapters 9 to 11 describe pavement design. Finally, Chapter 12
describes the reports which both categories of user may wish to produce. The
contents of each Chapter are described in the following table.
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Chapter |
Title |
Description |
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1 |
Introduction |
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2 |
Installation |
Obtain and install UK
DCP 3.1. |
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3 |
Start up |
Run UK DCP 3.1 and open
a new or existing project. The term ‘project’ refers to a set of related
sites, at each of which a penetration test has been carried out and which
will be analysed together. |
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4 |
Test
data input |
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5 |
Layer
analysis |
Analyse the penetration
data from a test to identify and determine the thicknesses of the distinct Test
layers within the pavement. Penetration data can be analysed manually or
automatically. |
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6 |
Structural
Number calculation |
Assign the Test layers
to specific pavement layers and calculate the Structural Number of each
pavement layer. |
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7 |
Query |
Produce histograms of
strengths and pavement layer thicknesses along the project. |
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8 |
Sectioning |
Divide the project into
sections which are uniform in thickness and/or strength. |
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9 |
Design
data input |
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10 |
Design
Sections |
Divide the project into
sections which are uniform in a variety of characteristics. |
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11 |
Pavement
Design |
Design the pavement improvement
for a low volume road. |
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12 |
Reporting |
Produce reports of the
analysis and design process for printing and/or export. |
1.1 The DCP
Tests using the DCP (Figure 1.1) generate data which can be analysed to produce accurate information on in situ pavement layer thicknesses and strengths. Tests can be carried out very rapidly and test sites can be reinstated extremely easily. When used for design purposes DCP testing should be carried out when the road pavement is considered to be in wettest condition. A typical DCP test team of 3 people may be able to carry out 20 tests in a day at a spacing of between 50 and 500 metres. The DCP can give information of sufficient quality and quantity to allow the pavement strength to be estimated and improvement works to be designed. Results from DCP tests can also be used to decide the most suitable positions to excavate test pits to gather additional information.
The DCP consists of a cone fixed to the bottom of a vertical rod. A hammer is repeatedly lifted and dropped onto a coupling at the mid-height of the rod to deliver a standard impact, or ‘blow’, to the cone and drive it into the pavement. A vertical scale alongside the rod is used to measure the depth of penetration of the cone. The penetration and the number of blows are recorded on a Test Data Form, shown in Appendix A: DCP Test Data Form. The penetration per blow, the ‘penetration rate’, is recorded as the cone is driven into the pavement and used to calculate the strength of the material through which the cone is passing. A change in penetration rate indicates a change in strength between materials, thus allowing layers to be identified and the thickness and strength of each to be determined. These layers are then grouped together into the pavement layers of base, sub-base and subgrade, guided by test pit or as-built records if available.
The
DCP cannot penetrate some strong materials such as hot mix asphalt or cement
treated bases. These layers must be removed before the test can begin and their
strength assessed using different criteria.
The strengths of all layers can then be combined into a Structural Number for each pavement layer and the entire pavement structure. Where tests are repeated along the pavement, a longitudinal picture of the pavement can be produced which allows changes in construction and condition to be identified. These changes can then be used to divide the road into uniform sections for each of which expected lifetimes can be estimated and improvements designed.
Figure 1.1 DCP instrument
1.2
UK
UK DCP
3.1 has two
The
design of these sections of sealed roads is based upon research carried out on
roads with design traffic of less than 1 million equivalent standard axles in
dry areas of
The
design function within UK DCP 3.1 compares the strength and thickness of the
existing pavement with a pavement shown in a design catalogue and, using layers
of the existing pavement as layers in the proposed pavement. If material in the
existing pavement is to be used as a base or sub-base in the proposed new pavement,
it is recommended that soaked CBR tests are carried out to accurately determine
its strength.
DCP
data can be collected from flexible pavements constructed with unbound
materials. Very little difficulty is experienced with the penetration of
granular pavement layers or lightly stabilised material.
UK
DCP 3.1 cannot analyse penetration data which includes two drilled layers below
the surface.
Thin
bituminous layers, such as a surface dressing, can be penetrated by the DCP,
although the data is not used to calculate the strength of such layers, and
therefore the strength coefficient of these layers must also be estimated and
manually input.
UK DCP 3.1 is not intended to replace normal engineering
judgment.
The
DCP instrument with an extension rod of 400 mm can be used to a depth of 1200
mm. Although the instrument can be extended beyond this depth, with additional
extension rods or an extension road longer than 400 mm, it is not recommended
that this is done as friction between the rod and the soil can give unreliable
data.
UK DCP 3.1 cannot produce designs when no DCP data is available,
although it can be used to estimate the cost of simply providing a layer of
gravel.
UK DCP 3.1 was written in Visual Basic and
uses a Microsoft Access database to store the data, although it is not
necessary for Microsoft Access itself to be installed on the computer. UK DCP 3.1
will run on Windows 98, NT, 2000 and XP operating systems
and ideally requires a computer with a minimum specification
of 400 MHz, 64 MB of memory and 45 MB of free disk space, although it should
still run successfully, albeit slightly more slowly, on a computer of lower
specification.
UK DCP 3.1 replaces version 2.2 which
was released by
No warranty can be given on the
validity of results and the ultimate responsibility for acceptance and
subsequent use of any results lies solely with the user.