Bentonite Handbook

Steffen Praetorius is a graduate geologist and deputy manager of research and development in the Utility Tunnelling department of Herrenknecht AG. In addition to research projects and geotechnical considerations, his duties also include technical and user-specific questions about the use of bentonite in tunnelling. Dr. Britta Scho?er is a researcher and lecturer at the Ruhr University, Bochum at the Chair of Tunnelling and Construction Management. The investigation of bentonite suspensions for construction use in utility construction and tunnelling belong to her specialist areas.

• Acknowledgement  VIIForeword  IXList of symbols used  XVI. Greek symbols  XVII. Latin symbols  XV1 Basics  11.1 Basics and technical implementation of bentonite lubrication systems  11.2 Annular gap lubrication in pipe jacking  51.3 Preliminary remarks about the ground 62 Bentonite and bentonite suspensions   92.1 Composition and structure 92.2 Hydration behaviour   102.3 Card house structure and thixotropy  112.4 Yield point, viscosity and gel strength  122.5 Stability 172.6 Usual types of bentonite   193 Additives 213.1 Polymers  213.2 Types of polymer additives   243.3 Overview of polymer additives and their functions   274 Correct preparation of bentonite suspensions  294.1 Mixing   294.2 Mixing equipment 334.3 Mixing instructions  344.4 Hydration tank 355 Properties of the suspension and measurement processes  375.1 Viscosity: Marsh funnel   375.2 Yield point: ball-harp rheometer  405.3 Viscosity and gel strength: Rotational viscometer  425.4 Filtrate water and thickness of filter cake: filter press  435.5 Density 455.6 Water hardness: test strips 465.7 pH value  465.8 Conductivity 465.9 Temperature  476 Ground and groundwater 496.1 Geology of solid rock 496.2 Geology of soils 656.3 Stability and stand-up time   856.4 Hydrogeology  886.5 Influence of various rock properties on the use of bentonite  996.6 Contamination in the ground, groundwater or mixing water  1007 Bentonite suspensions for annular gap lubrication  1057.1 Size of the annular gap  1057.2 Vertical position of the pipe string in the driven cavity  1077.3 Functions of the lubricant in the annular gap 1117.4 Adaptation of the bentonite suspension to the ground 1197.5 Rheological parameters of the bentonite suspension 1247.6 Suspension quantities 1327.7 Time-dependant loss volumes 1477.8 Lubrication strategies 1488 Lubrication technology  1558.1 Arrangement and spacing of the lubrication points in the pipe string 1558.2 Number and arrangement of the injection fittings per lubricating point in the pipe cross-section   1568.3 Non-return valves  1578.4 Lubrication circuit   1588.5 Interaction between the support pressure at the face and the annular gap pressure  1598.6 Bentonite supply in the starting area  1608.7 Lubricant pressure, lubricant quantity and pressure losses   1619 Reporting 1639.1 Which parameters should be documented for bentonite lubrication?  1639.2 Forms  16310 Lists of the required injection quantities  16710.1 Explanation of the lists  167Literature 197