IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Characterization of compacted silty soils by means of nuclear magnetic resonance
Autor/es:
MONTORO M.A.,CERIONI, L.M.C., PUSIOL, D.J.
Reunión:
Conferencia; 18th ISMAR 2013/14th NMR Users Meeting; 2013
Institución organizadora:
ISSMAR
Resumen:
Compacted soils are widely employed as construction material
for different facilities such as highways, dams and
landfills. The aim of soil compaction procedure consists in
obtaining the maximum dry unit weight of a particular soil.
Resulting dry unit weight depends on the compaction energy
and the water content. Maximum dry density can be
reached only at the optimum water content, in consequence
it can be possible to have compacted soils with the same
dry unit weight (same porosity) compacted with different
moisture. Soils compacted dry from optimum use to present
flocculated fabric characterized by open and big pores, while
soils compacted wet from optimum use to present dispersed
fabric characterized by small pores. In this work we present
a study of soil compaction using Time Domain Nuclear
Magnetic Resonance (TD-NMR). We measured samples of
compacted silty soils with different molding water content
using a low field (12 MHz) spectrometer (SLK-100). We measured
the transversal relaxation times (T2) using a CPMG
pulse sequence (inter-echo spacing time 400 _s, 1200 echoes
and 160 repetitions) in samples with moisture content between
10 and 22%. The amplitude of the obtained signal was
correlated with the sample moisture content and comparing
cross correlations between the different signals with the one
registered for the sample compacted at the optimum moisture
content assessed the compaction degree. A high linear
correlation between the signal amplitude and moisture content
was determined (r2 = 0.9537). The relation between the
cross-correlations of the signals and the dry unit weight of
the samples presented a non-linear behavior. T2 distribution
curves allowed to identify different pore sizes distribution in
sample with the same porosity but compacted either dry or
wet from optimum.