Suffusion in compacted loessial silts. Interaction with granular filters

Loess soils, which occupies much of central Argentina, is characterized by its high sensitivity to change in moisture. This condition categorized loess structure as internally unstable soil. Despite this natural condition, silts derived from loess are frequently used as material in roads and hydraulics constructions. In filtration processes, the soil should be shielded from erosion phenomena. The filter must have a particle size consistent with the ground to protect. In particular, sandy silts can be affected by phenomena of suffusion, or internal instability of the soil structure. The filter must control the loss of material and ensure the stability of flow. The present study shows the experimental results of flow applied to loessial silts, with low compaction. Tests have been conducted using filtration columns that simulate the soil-filter-drain. The test methodology applied aims to follow the research lines of similar studies worldwide. Studies have focused on analyzing the influence of variables such as degree of compaction, hydraulic gradient and composition of the filter material. The results obtained allow recommendations with reference to construction systems to be applied and the composition of the filter in order to properly control the suffusion.Fil: Terzariol, R. E. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Rocca, R. J. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Zeballos, M. E. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Otras Ingeniería Civi

Characterization and Engineering Properties of Dry and Ponded Class-F Fly Ash

Characterization studies conducted on Class-F fly-ash specimens gathered from different producers in the southeastern United States confirm general trends reported for fly ash worldwide. Additional tests and detailed analyses explain the spread in specific gravity (interparticle porosity cenospheres), highlight the tendency to segregation and layering, and show marked ferromagnetism. Furthermore, data show that early diagenetic cementation—within days after wetting—hinders densification and produces a fabric that is prone to collapse. New procedures are specifically developed to diagnose and characterize early diagenesis, including (1) pH measurements as an indicator of diagenetic potential, (2) test protocols to assess early diagenesis using oedometer tests and shear-wave velocity, and (3) procedures to determine realizable unit weights as reference values for the analyses of contractive or dilative tendencies and instability. In the absence of early diagenetic cementation, dilative fly-ash behavior is expected in the upper ≈20  m under monotonic shear loading. Flow instability may follow the failure of the containment structure if the ponded ash is saturated and has experienced hindered densification

Characterization and Engineering Properties of Dry and Ponded Class-F Fly Ash

Characterization studies conducted on Class-F fly-ash specimens gathered from different producers in the southeastern United States confirm general trends reported for fly ash worldwide. Additional tests and detailed analyses explain the spread in specific gravity (interparticle porosity cenospheres), highlight the tendency to segregation and layering, and show marked ferromagnetism. Furthermore, data show that early diagenetic cementation—within days after wetting—hinders densification and produces a fabric that is prone to collapse. New procedures are specifically developed to diagnose and characterize early diagenesis, including (1) pH measurements as an indicator of diagenetic potential, (2) test protocols to assess early diagenesis using oedometer tests and shear-wave velocity, and (3) procedures to determine realizable unit weights as reference values for the analyses of contractive or dilative tendencies and instability. In the absence of early diagenetic cementation, dilative fly-ash behavior is expected in the upper ≈20  m under monotonic shear loading. Flow instability may follow the failure of the containment structure if the ponded ash is saturated and has experienced hindered densification

Pore Habit of Gas in Gassy Sediments - Database (Part 3)

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Pore Habit of Gas in Gassy Sediments - Database (Part 4)

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Pore Habit of Gas in Gassy Sediments - Database (Part 2)

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Pore Habit of Gas in Gassy Sediments - Database (Part 4)

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