Glossary (p. II)

Dn, dn: the largest size of the smallest n % of soil grains and the largest size of the smallest n % of grout particles

Degree of settling: see Sedimentation rate

Design strength: the strength required to fulfil the design requirements for the grout or grouted ground

Displacement grouting: see Definitions

Double packer: a device consisting of a pair of seals (packers) fitted to a grouting pipe at a predetermined distance apart, used to limit grout injection to the ground between the two packers, i.e. the packed-off length or stage

Downstage (Descending stage) grouting: a grouting technique where a given distance (stage) is drilled and grouted before the borehole is advanced by further drilling or packers are employed to start grouting at the top of the borehole and advance the grouting process progressively down the hole

Durability: resistance to mechanical and chemical attack. Mechanical durability is usually measured by either slake durability tests or flow durability tests, during which ground water is flown through a bore in a specimen of cemented host material. Chemical durability tests are usually conducted on ground samples of the cemented host material which are kept in the ground water

Effective pressure: see Definitions

Emulsifier: a substance that modifies the surface tension of colloidal droplets, keeping them from coalescing, and keeping them suspended

Emulsion: a system containing dispersed colloidal droplets

Epoxy grout (resin): a multi-component resin grout that usually exhibits very high tensile, compressive and bond (adhesive) strengths

False set: the rapid development of rigidity in a freshly mixed grout without the evolution of much heat. Such rigidity can be dispelled and plasticity can be regained by further mixing without the addition of water. Premature stiffening, hesitation set, early stiffening, and rubber set are other terms that refer to the same phenomenon

Filler: an inert material added to a grout to modify its properties or to replace a component

Film time: see Setting time

Filter cake: a concentrated solid or semi-solid material that is separated from a liquid and remains on the filter after pressure filtration

Filter press: an instrument used for measuring the filter-loss characteristics of a grout

Filtration water: quantity of water which comes out of a grout in a given time during a filtration test

Final set: a degree of stiffening of a grout mixture greater than the initial set, 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

Fissure grouting: see Definitions

Flash set: the rapid development of rigidity in a freshly mixed grout, usually with the evolution of considerable heat. This rigidity cannot be dispelled nor can the plasticity be regained by further mixing without addition of water; also referred to as quick set or grab set

Flow cone: a device for measurement of grout consistency in which a predetermined volume of grout is permitted to escape through a precisely sized orifice, the time of efflux (flow factor) being used as the indication of consistency

Flow rate: the volume of fluid (grout) passing through a unit area per unit time

Fluidifier: an additive which improves the flow characteristics of a grout

Fly ash: a fine residual product derived from the combustion of ground or powdered coal. Similar to Pulverized fuel ash

Foam: foams used in grouting are solid structures encapsulating air, usually in closed pores. They are obtained either by injecting a gas into a grout or by a reaction between the grout and the ground water which liberates a gas

Fracturing: see Hydraulic fracturing

EN 12715:2000 Execution of special geotechnical work – Grouting