This study explores the compression deformation characteristics of compacted loess after different wetting–drying (WD) cycles, by tracking microstructure changes by scanning electron microscope (SEM), laser particle size analyzer, Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). Experimental results show that, as the number of wetting–drying cycles increases, the compression deformation of the compacted loess upon mechanical loading increases and the yield stress decreases. The first wetting–drying cycle causes the largest change in terms of mechanical response. As long as the number of wetting–drying cycles increases, their effect is less significant. Microstructural analyses have been exploited to interpret the evolution of the mechanical properties at the laboratory scale. With the increase in the number of wetting–drying cycles, FTIR results showed that the functional group strength gradually decreased, implying a reduction of the cementation strength between the particles of the compacted material. SEM images showed that the contacts among loess aggregates (composed by particles) varied from “face to face” to “point to point.” NMR results demonstrated that the total and inter-aggregate pores volume increased, while the intra-aggregate pores volume decreased upon wetting–drying cycling. The microstructure nvestigation allowed understanding the major role played by cementation strength, aggregate contact type, and pore size distribution on the compression behavior of compacted loess after wetting–drying cycles.

Influence of wetting–drying cycles on the compression behavior of a compacted loess from microstructure analysis

Della Vecchia G.;
2022-01-01

Abstract

This study explores the compression deformation characteristics of compacted loess after different wetting–drying (WD) cycles, by tracking microstructure changes by scanning electron microscope (SEM), laser particle size analyzer, Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). Experimental results show that, as the number of wetting–drying cycles increases, the compression deformation of the compacted loess upon mechanical loading increases and the yield stress decreases. The first wetting–drying cycle causes the largest change in terms of mechanical response. As long as the number of wetting–drying cycles increases, their effect is less significant. Microstructural analyses have been exploited to interpret the evolution of the mechanical properties at the laboratory scale. With the increase in the number of wetting–drying cycles, FTIR results showed that the functional group strength gradually decreased, implying a reduction of the cementation strength between the particles of the compacted material. SEM images showed that the contacts among loess aggregates (composed by particles) varied from “face to face” to “point to point.” NMR results demonstrated that the total and inter-aggregate pores volume increased, while the intra-aggregate pores volume decreased upon wetting–drying cycling. The microstructure nvestigation allowed understanding the major role played by cementation strength, aggregate contact type, and pore size distribution on the compression behavior of compacted loess after wetting–drying cycles.
2022
Loess , Compression behavior, Wetting–drying cycles, Cementation strength, Pore size distribution
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1219910
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