1263
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
1
Applicability of the Geogauge, P-FWD and DCP for compaction control
Étude d
es conditions d’
application du Geogauge, DP et PDL dans le contrôle du compactage
Conde M.C., Lopes M.G.
ISEL, Lisboa, Portugal
Caldeira L., Bilé Serra J.
LNEC, Lisboa, Portugal
ABSTRACT: Soil compaction is a critical issue in the construction of highway, airport and dam embankments and foundations. The
current specifications address embankment compaction in terms of dry density and moisture content. However, achieving a certain
dry density and moisture content does not guarantee performance adequacy. So, a comprehensive experimental testing program is
under development, on compacted layers to investigate the feasibility of developing a stiffness-based specification for embankment
soil compaction quality control. The field test program includes 11 test points on the upstream shell and 6 points on the downstream
shell on an earth dam during construction. In each point, 3 geogauge, 10 portable falling weight deflectometer (P-FWD) and 4
dynamic cone penetrometer (DCP) tests were performed. This paper aim is to analyze the experimental data and to show the
feasibility of employing these devices for earth work evaluation.
RÉSUMÉ : Le compactage des sols est un point critique dans la const
ruction des fondations et remblais d’autoroutes
, aéroports et
barrages. Le contrôle classique du compactage se fait par la mesure du poids volumique sec et de la teneur en eau. Cependant les
mesures de ces paramètres ne garantissent pas une bonne capacité portante des couches compactées. Ainsi, un programme
d’essais
est
en cours pour étudier la faisabilité de remplacer le contrôle du compactage par des paramètres liés à la portance du sol. Le programme
d'essais comprend 11 points de mesure sur la recharge amont et 6 points de mesures sur la recharge en aval
d’un
barrage en terre en
cours de construction. À chaque point ont été pris 3 mesures avec le geogauge, 10 mesures avec le déflectomètre portable (DP) et 4
mesures avec le pénétromètre dynamique léger (PDL).
L’objectif
principal de cet article est d'analyser et de comparer les résultats
obtenus par le geogauge, le DP et le PDL et de montrer la faisabilité d'employer ces appareils pour le contrôle in situ du compactage.
KEYWORDS: soil compaction, compaction control, Geogauge, P-FWD and DCP.
1 INTRODUCTION
Soil compaction is essential in the construction of highways,
airports, bridges and embankment dams. Usually, compaction is
controlled by measuring the dry density and the water content of
the compacted soil. These physical properties are compared
with reference values so that adequate mechanical and hydraulic
properties may be ensured. An alternative approach based on
soil stiffness modulus has been emerging, particularly in
transportation infrastructures construction. This approach is
supported by the concept that the performance requirements
(e.g. soil compressibility) may not correspond to the maximum
soil dry density at its optimum water content.
This paper focuses on a comprehensive experimental testing
program aiming to correlate the data from three devices, i.e.
geogauge, portable falling weight deflectometer (P-FWD) and
dynamic cone penetrometer (DCP), for stiffness or penetration
measurement to dry density and water content of the compacted
soil. The latter experimental data was gathered by traditional
methods (sand cone density and microwave oven heating tests,
respectively).
The ultimate goal of this study is the assessment of the
applicability of earth work evaluation and control by stiffness
performance data, just described.
2 EXPERIMENTAL WORK
With the objective to evaluate the applicability conditions of
geogauge, portable falling weight deflectometer (P-FWD) and
dynamic cone penetrometer (DCP) in compaction control of
embankment layers, a series of tests was performed on
compacted layers of a zoned earth dam during construction at
Alentejo in the southern Portugal. A unique soil was used in
both upstream and downstream shells. For this purpose, a total
of 11 test points at the upstream shell and 6 test points at the
downstream shell were considered.
Soil samples from each test point were collected close to the
field test locations and stored for laboratory characterization.
2.1
Laboratory experimental program
Laboratory tests included index tests and Proctor compaction
tests, as summarized in Table 1. An example of the grain size
distribution and Proctor curve of upstream and downstream
material are shown in Figure 1 and Figure 2, respectively.
Figure 1. An example of a grain size distribution of shell material.
Figure 2. An example of a Proctor curve of shell material.
Table 1. Index properties and compaction tests results.
Location
d max
(kN/m
3
)
w
opt
(%)
w
L
(%)
PI
(%)
AASHTO
Classif.
USCS
Classif.
Shell material
18.32 14.5 N/P N/P A-1-b (0)
SM
