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.