“control of soil compaction in pavement layers: a new approach
TRANSCRIPT
5TH INTERNATIONAL CONFERENCE ON GEOTECHNICAL AND GEOPHYSICAL SITE CHARACTERISATION
“Control of soil compaction in pavement layers: A new approach using the dynamic cone penetrometer
(DCP)”
A. BELINCANTAJ. A. LUKIANTCHUKI
J. H. C. REISDepartment of Civil Engineering
University of Maringa, Maringa, Parana, Brazil
September 2016
INTRODUCTION
Compaction is a widely used techniquefor the improvement of soil behavior in thepractice of pavement engineering
Improve soil properties (soil strength, drydensity, modulus resilience) with aconsequent reduction in soil volume andvoids
The control of the degree of compaction becomes extremely important
To ensure that compacted soil in the field acquires thesame properties achieved in the laboratory
INTRODUCTION
Usually, the compaction process in thefield is controlled through measurements ofthe density and water content of thecompacted soil layer.
Cylinder Test
Sand cone
Comparing field results with compactioncurve parameters, the degree ofcompaction of the layer can be estimated.
maxd
dDC
INTRODUCTION
Despite the importance of compaction control,effective control is not always achieved. This is becauseof cost, time and the required number ofmeasurements.
Therefore, the use of the dynamic conepenetrometer (DCP) is presented as a good alternativefor the indirect measurement of compaction quality
DCP is portable, does not require other accessoriesfor testing and provides a soil density estimate. Itsapplication in pavement projects is already wellestablished (ASTM D6951-03; Gabr et al., 2000;Salgado and Yoon, 2003; Herath et al., 2005)
PRESENT WORK
This paper presents the results of a study using thedynamic cone penetrometer for the control of theexecution of foundation layers in road pavements
Purpose: An equation that relates the penetrationindex as a function of the dry unit weight and thesoil moisture content
Soil typical of the Northwest region of Parana
Calibration of the proposed equation usinglaboratory tests and dynamic penetration tests inthe field, carried out in conjunction with dry unitweight and moisture content.
DYNAMIC CONE PENETROMETER TEST (DCP)
The State University of Maringa(UEM) developed the design andconstruction of a dynamic conepenetrometer (DCP). This equipmentis similar to the DCP developed inSouth Africa in 1956
DCP developed at UEM
The test consists of free fall of theweight on the driving head, providingpenetration of the conical tip in the soil
The dynamic penetration index (PI) isdefined as the penetration valuemeasured for each blow
PENETRATION INDEX (PI) FOR COMPACTION CONTROL
The value of PI is directly related to the dry unit weight (d)
As the d increases, the penetration per blow decreases
The PI index also depends on soil moisture content
As the soil moisture content increases, the PI index increases too
op
op
w
wwC
d
d eCPI2
max1
BELINCANTA AND REIS, 2008
Belincanta and Reis (2008), observed the PIis strongly influenced by the soil moisturecontent
CALIBRATION OF THE PROPOSED EQUATION
Calibration was carried out through a series of field and laboratory testsperformed on the soil in the city of Bandeirantes, Parana state, Brazil.
The testing program was developed as follows:
1. DCP tests in a compacted soil layer for pavement purposes. PI values weredetermined from this test;
2. At the same point, tests were performed to determine the dry unit weight in situ (Sand cone method);
3. The determination of the corresponding moisture content was carried out withthe oven method
CALIBRATION OF THE PROPOSED EQUATION
Compaction Test
(Normal energy)
dmax (kN/m3) wop(%)
16.1 - 16.5 22.2 - 24.7
16.3 23.5
Table 1. Compaction results From the results it was possible toderive the calibration for theconstants C1 and C2.
op
op
w
ww
d
d ePI
5.9
max10.2
CALIBRATION OF THE PROPOSED EQUATION
Figure. Penetration index versus moisture content (Calibration Equation 2).
The Equation used to describe thisbehavior showed a good fit for thepoints measured in the field andcompared with the laboratoryresults.
The results indicate that the DCPhas great potential for use in thecontrol of the execution ofpavement layers.
CONTROL OF COMPACTION
The degree of compaction in the field (DC) can beestimated as a function of the penetration index(PI) and the moisture content (w) in the field
5.26
5.265.9210
3.16100
w
d ePI
DC
Equation was used to graphically determinethe region where the compaction conditionsare acceptable considering a degree ofcompaction greater than 95%
Figure. Compaction control as a function of the PI and moisture content, considering a degree of compaction
greater than 95%.
CONCLUSION
Results obtained through field penetration tests and laboratory testing allowed forthe fit and calibration of an equation relating the penetration index, the dry weightand the soil moisture content
Data analysis shows that the proposal of Belincanta and Reis (2008), for use the DCPin control of compaction in the field, has great application potential.
The control can be performed in situ by measuring PI and soil moisture content, asthey are directly related to the degree of compaction of the layer
This study presents the results of the calibration of dynamic penetration testperformed with the DCP penetrometer, developed at UEM, Brazil. The followingconclusions can be stated:
CONCLUSION
Results indicate that the PI value is inversely proportional to the degree ofcompaction and that it is strongly influenced by the soil moisture content
The importance of the calibration of the equation parameters of the proposedequation for other types of soil was noted. The material presented in this studyrepresent the behavior of soils typical of Parana, Brazil
This study presents the results of the calibration of dynamic penetration testperformed with the DCP penetrometer, developed at UEM, Brazil. The followingconclusions can be stated:
