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Papers by Stephan Jefferis

Geotechnique, May 1, 2018

ARCH HYDROTECH, 1983

DES COULIS ONT ETE PREPARES AVEC DEUX BENTONITES ANGLAISES DISPONIBLES DANS LE COMMERCE (BERKBENT... more DES COULIS ONT ETE PREPARES AVEC DEUX BENTONITES ANGLAISES DISPONIBLES DANS LE COMMERCE (BERKBENT ET BREBENT), A DIFFERENTES CONCENTRATIONS, POUR DIFFERENTES ENERGIES DE MALAXAGE ET POUR DIFFERENTES DUREES DE MALAXAGE ET DE CONSERVATION. ON A ETUDIE LA VITESSE DE SECHAGE, L'ABSORPTION ET LA RETENTION D'EAU, PAR DIFFERENTES METHODES. LES RESULTATS ONT ETE INTERPRETES SUR LA BASE DE L'ENERGIE D'INTERACTION ET DE L'EQUILIBRE DES FORCES ENTRE LES ELEMENTS DE LA STRUCTURE ET ON EN A TIRE DES CONCLUSIONS DIRECTES ET INDIRECTES CONCERNANT LA MICROSTRUCTURE.

Przegląd Geologiczny, 1984

CRC Press eBooks, Aug 30, 1990

Spon Press eBooks, Nov 1, 1993

... Please use this identifier to cite or link to this item: http://qcite.qub.ac.uk/handle/ 12345... more ... Please use this identifier to cite or link to this item: http://qcite.qub.ac.uk/handle/ 123456789/22853. Title: In-Situ Bioremediation of Cyanide, PAH's, and Heterocyclic Compounds using Engineered Sequenced (SEREBAR) Techniques. ...

Springer eBooks, 1995

In many countries, the initial approach to determining the need for remediation has been to base ... more In many countries, the initial approach to determining the need for remediation has been to base standards on the projected health impact on the population at large using cautious interpretations at each step in the process. While this may have the appearance of being easy for legislators to defend on moral grounds, the appearance of morality is misleading. As is now appreciated, such cautious standards lead to unreasonable decisions with the expense of remediation outweighing any realistic benefit. Moreover, the interesting question becomes: would a greater improvement in health follow if the proposed remediation funds were spent on (say) a neighborhood health centre? The moral position of excessively conservative remediation standards is dubious once we recognize that financial constraints on society as a whole. Also the risks during a remediation may exceed the benefit gained.

Elsevier eBooks, 2003

This chapter is intended to be an introduction to some of the major features of cement and chemic... more This chapter is intended to be an introduction to some of the major features of cement and chemical grouts and in particular to demonstrate that they are neither just fluids that will set to fill any void into which they have been injected nor concrete without the aggregate. In particular, the volume changes that occur prior to and during setting and hardening of the grout are complex and their significance will depend on the form of the void to be grouted. At the present time there is a lamentable lack of advice on the design of grouts and there are many different empirical test methods. This makes the exchange of test data and other things difficult. Further work is needed on the in-situ behavior of grouts and particularly their durability in contaminated soils and groundwater. Finally grout specifications must be appropriate to the grout material. A specification drafted for a chemical grout may be wholly inappropriate to a cement grout.

Jet-grouting and other ground treatment can occasionally give rise to unexpected consequences. Th... more Jet-grouting and other ground treatment can occasionally give rise to unexpected consequences. This paper describes a case study in which an annulus of jet-grout was formed in advance of tunnelling works in soft marine clay. When the tunnels were excavated inside the annulus, some six to twelve months after grouting, it was found that the ground temperature was 15 degrees higher than the ambient temperature, and ammonia gas pervaded the tunnel. Compressed air working was mandatory and working conditions within the tunnel became very unpleasant. The mechanisms of heat generation and dissipation and the generation of ammonia are discussed. (A) For the covering abstract see ITRD E121676.

Geotechnique, Oct 1, 2016

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Dec 31, 1997

The concept of the reactive treatment zone whereby pollutants are attenuated as they move along a... more The concept of the reactive treatment zone whereby pollutants are attenuated as they move along a pathway in the ground has enabled a re-thinking of many of the concepts of containment. In particular it offers the potential for the control of the flux from a contaminated area by controlling the contaminant concentration in the pathway(s) as well as or instead of using a low permeability barrier. The paper outlines the basic concepts of the reactive treatment zone and the use of permeable and low permeability reactive systems. The paper then gives a case history of the installation of a permeable barrier using an in-situ reaction chamber.

Geosynthetics: Protecting the Environment, 2003

ON THE INFLUENCE OF MICROSTRUCTURE UN THERMAL BEHAVIOR OF BENTONITE Summary Indications were obta... more ON THE INFLUENCE OF MICROSTRUCTURE UN THERMAL BEHAVIOR OF BENTONITE Summary Indications were obtained by SEM and other methods that in a bentonite slurry (sodium smectite) either flocs or clusters or parallel structure may form, depending on the stirring energy and storing time of the slurry, thus depending on particle interactions. Thermal behaviour and water sorption depend as well on preparation of the slurry, thus they are related to microstructural features (Stepkowska and Jefferis, 1983). On the external surface of samples of bentonite slurries dried at 45°C there was formed a crust of parallel structure. Its quantity was dependent on preparation of the slurry (concentration, stirring storing time energy). This structure indicated increased sorption properties. When heated at 800°C (1 hr or 18 hrs) this external crust did not change colour and indicated an increased Na2O content (7.64% as compared to 5.62% in powder sample). By SEM of heated samples either parallel particle ar...

Proceedings of the conference organized by the Institution of Civil Engineers and held in London on 25–26 November 1992, 1994