Glossary (p. III)

Gel: the condition where a liquid grout begins to exhibit measurable shear strength. A colloidal material in which the dispersed substances form a continuous branching cohesive network. It may contain a proportion of liquid but possesses some properties of a solid. Some gels can be returned to the liquid phase by disturbance or mixing and will thereafter reform as a gel again (see Thixotropy)

Gel strength: the shear strength of a gel. This may be measured at a fixed time interval after mixing or breaking up of a gel or when the gel has fully developed

Gel time: the measured time interval between the mixing of a grout and the formation of a gel

GIN method: GIN stands for "Grouting Intensity Number". The method, applied in rock grouting, uses this number as a parameter for limiting grouting applications, notably in fissures, to a maximum given GIN value. This value is obtained by multiplying the injected grout volume (in litres) by the effective grouting pressure (in bar) per meter of borehole

Grain size distribution: the distribution by weight of the grain sizes of a medium; usually expressed as a cumulative percentage

Gravity grouting: see Definitions

Grout: see Definitions

Groutability: the ability of a ground to accept grout

Groutability ratio: the groutability ratio, GR, expresses the relationship between the particle size of the grout (suspension type grout) and the grain size of the soil to be grouted. The ratios, GR = D15/d85 or GR = D10/d90 are used, where: Dx = the size which x % of the soil particles are smaller than, dy = the size which y % of the grout particles are smaller than

Grout curtain: a grouted mass whose vertical dimensions greatly exceed the width

Grouting Intensity Number (GIN): the product of pressure and injected grout volume. See GIN Method

Grouting pressure: see Definitions

Grouting (trial) test: test injection prior to grouting operating to assess the groutability of a ground or the appropriateness of a given grout type

Grout mix: the constituents of a mixture normally expressed by weight or volume, or as a proportion of the quantity of water or other major constituents

Grout take: the measured quantity of grout injected into a unit volume of ground, or a unit length of grout hole, or a complete hole

Hardener: in a two component chemical grout, the component that causes the base component to cure

Hardening: increase in strength of a grout after setting

Hardening time: the time for a grout to reach its design strength

Hydration: the formation of a compound by incorporation of molecular water into a complex molecule with molecules or units of other species

Hydraulic binder: finely ground inorganic material which when mixed with water forms a paste which sets and hardens by means of hydration and which retains, after hardening, its strength and stability even under water

Hydraulic fracturing (fracture): see Definitions

Hydrofracture: see Hydraulic fracture. Term not recommended

Hydrostatic head: the fluid pressure expressed as an equivalent height of water above a given level

Impregnation: see Permeation in Definitions

Initial set: a degree of stiffening of a grout mixture generally stated as an empirical value indicating the time in hours and minutes that is required for cement paste to stiffen sufficiently to resist the penetration of a weighted test needle

Injection: see Definitions

Injection valve: openings along the injection string of a sleeve pipe, usually covered by a flexible sleeve, the whole of which acts as valves

Jet grouting: a process consisting of the disaggregation of the soil (or weak rock) and its mixing with, and partial replacement by, a cementing agent. The disaggregation is achieved by a high energy jet of a fluid which can be the cementing agent itself

Kasumeter: instrument for measuring the yield point

Layer hardening time: see Setting time

Lefranc test: in situ falling head permeability test, where the development of a water level in a standpipe is observed to calculate the permeability

Lugeon value: a relative unit of transmissivity representing the absorption of a water flow of one litre per minute, per metre of a 76 mm diameter borehole, at a pressure of 1 MPa in rock

Marsh funnel: see Flow cone

Marsh viscosity: viscosity tests are carried out with the Marsh cone. The duration of flow, of a given volume of liquid, expressed in seconds, is called the 'Marsh viscosity'. See also Flow cone

Micro-fine or ultrafine product: very fine product having a uniform, steep particle size distribution curve, where d95 < 20 µm

Moisture content: the ratio, expressed as a percentage, of the weight of water in a given grouting material to the weight of dry solid particles. Also called Water content

Mortar: a highly particulate grout containing sand

Mud cake: see Filtercake

EN 12715:2000 Execution of special geotechnical work – Grouting