Search results for "Clay"
showing 10 items of 349 documents
Microstructure Characteristics of Unsaturated Compacted Scaly Clay
2012
Microstructure characteristics of unsaturated compacted scaly clay are investigated by MIP tests on freeze dried samples and observation of SEM photomicrographs. Effects of scale microstructure and increasing compaction stresses, and microstructure changes induced by loading and unloading paths and clay saturation are analysed.
Novel organo-modifier for thermally-stable polymer-layered silicate nanocomposites
2015
A new novel approach for the stabilisation of polymer-clay nanocomposites has been investigated based on reacting chemically an antioxidant function, a hindered phenol moiety, with an organic modifier based on a quaternary ammonium salt. The chemically linked antioxidant-containing organic modifier (AO-OM) was then introduced into natural montmorillonite (MMt) through a cation-exchange reaction resulting in antioxidant-containing organo-modified clay (AO-OM-MMt). The new antioxidant-containing modified clay, along with other organo-modified clays having a similar organo-modifier but without the reacted antioxidant, were characterised by spectroscopic, thermogravimetric and x-ray diffraction…
Suction controlled drying and wetting cycle effects on the volumetric behaviour of a lime-treated high plasticity clay
2016
The paper presents some experimental results collected on samples recovered from an experimental embankment obtained by compacting a lime-treated clay. Samples were collected soon after the in situ compaction and they were cured in controlled environmental conditions for at least 18 months. Mercury intrusion porosimetry tests (MIP) were carried out on freeze-dried specimens to characterize the microstructure of the material. In order to assess the durability of the improved material, laboratory tests focused on the effects of cyclic variations of the degree of saturation on the water retention properties and the volumetric behaviour of the stabilized clay. Collected results show that the li…
Numerical investigation on water exchange of shale samples
2020
Interest in the hydraulic and mechanical characterization of shales has grown in recent years, because of their application in the context of energy geotechnics. In the frame of nuclear waste disposal shales are considered as host formations for the placements of nuclear waste at high depths. In the frame of hydrocarbon production they are considered as unconventional reservoirs, from which extracting natural gas. Understanding how fluids flow through shales is then a key aspect for both fields of application. This paper focuses on the analysis of the transport of water vapour through laboratory samples. After reviewing the balance and flow laws that govern the transport of fluid in unsatur…
Microbiological Stability of Bio-Based Building Materials
2021
The aim of this paper was to study the microbiological stability of bio-based composite building materials, which are made using organic-rich lake sediments (further – sapropel) with lime and magnesium cement as binders and hemp shives as filler. The microbial stability properties of the obtained composite materials were investigated and compared to similar composites. Because of their high organic content, these materials are prone to biodegradation; therefore, they were coated with ALINA LIFE TM organoclay coating, which helps to extend the product life, reducing the rate of biodegradation compared to the biocides used in industry. The effect of the coating on the resistance to decay by t…
The microstructure of bentonite clay
2018
Bentonite is a common clay having many applications. One of them will be in the spent nuclear fuel repository, as a buffer material between host rock and the canisters containing the radioactive waste. This application has high requirements for the material used, ranging from, among others, appropriate mechanical properties, chemical stability, fine porous structure to sufficient hydraulic conductivity. The material should maintain its properties over time as the life span of the repository is hundreds of thousands years. The aim of this thesis was to investigate the structure of bentonite clay in a condition similar to expected in the repository. The research focused mainly on the pore str…
Properties-morphology-processing relationships in polymer based clay nanocomposites
2009
On the volumetric response of a compacted clay subjected to wetting and drying cycles
2009
Experimental evidence on the volumetric response of a compacted clay was collected in controlled suction oedometric tests, with the aim to assess the volumetric response of this soil when subjected to wetting and drying cycles. The overall soil behaviour seems mainly to depend on the double structural arrangement observed in the compacted specimens. Selected results are presented and discussed focusing on the influence of the stress history on the volumetric response. Test results are simulated by a double-structure suction-dependent elasto-plastic constitutive model, in which the mechanical response is related to micro and macrostructural deformations and their mutual interactions. The pro…
Caratterizzazione geotecnica del comporportamentodi una grande frana in argille varicolori in Sicilia
2014
Si illustrano le misure degli spostamenti e delle pressioni neutre raccolte in un paio d’anni di osservazione del comportamento di un esteso corpo di frana in una formazione di argille varicolori in Sicilia. L’analisi delle misure raccolte indica che la riattivazione riguarda zone distinte del corpo di frana, nelle quali gli spostamenti si sviluppano con velocità e direzioni differenti. L’evoluzione degli spostamenti è manifestamente dipendente dalle condizioni climatiche, dal momento che essi aumentano al crescere delle pressioni interstiziali, a loro volta regolate dalle piogge, e rallentano nella stagione secca, spesso senza annullarsi del tutto. Analisi a ritroso effettuate in una delle…