Glossary (p. I)

The following glossary contains definitions of terms which are of importance in the field of grouting and which are often subject to discussion and misunderstanding. It supplements the definitions in clause 3.

Action radius: theoretical distance travelled by the grout from the injection point

Additive (Admixture): any grout ingredient (e.g. liquifiers, stabilizers) other than the basic components of a grout mix (water, aggregates, or cementitious material), which is used to modify the liquid and solid state properties of the grout

Agitator tank: a tank with rotation paddles used to prevent segregation of grout after preparation

Area grouting: see Blanket grouting

Ascending grouting: see Upstage grouting

Batch: quantity of grout mixed at one time

Bentonite: a clay composed principally of minerals of the montmorillonite group, characterized by high water adsorption and a very large volume change upon saturation or drying. They are clays with a content of swellable smectites of at least 70 % and a water absorption capacity of more than 500 %. A distinction is made between natural, sodic, calcic, modified, and activated bentonites

Bentonite-cement grout: a grout having bentonite, cement and water as its basic ingredients

Binder: a substance which causes cohesion in loosely assembled substances

Bingham fluid: a substance which possesses both viscosity and cohesion

Blanket (or area) grouting: the creation of a grouted mass whose lateral dimensions greatly exceed its depth

Bleeding: the autogenous flow of mixing water within, or its emergence from, newly placed grout

Bleeding rate: the rate at which water is released from grout by bleeding

Bonding (bond) strength: strength developed between the grout and its host material

Casing: a lining tube used to support unstable ground during drilling

Cement grout: a grout in which the primary bonding agent is cement

Chemical grout: any grouting material characterized by being a solution, i.e. having no particles (other than impurities) in suspensions

Circuit grouting: a grouting method where grout is supplied to a hole or group of holes, leaving excess grout travelling back through a return line into a holding tank

Circulation grouting: a grouting method by which grout is circulated through a pipe extending to the bottom of the hole and back up the hole via the annular space outside the pipe. The excess grout is diverted back to the agitator tank. The method is used where holes tend to cave and sloughing material might otherwise clog openings to be grouted

Claquage or Claquage grouting: see Hydraulic fracturing in Definitions (French terminology)

Coefficient of permeability (hydraulic conductivity): the rate of discharge of water under conditions of laminar flow through a unit cross-sectional area of a porous medium under a unit hydraulic gradient and standard temperature conditions, usually 20 °C. Intrinsic permeability, k, is a property of the material and measured in [m²]. Hydraulic conductivity is measured as the proportionality constant, K, between flow velocity, v, and hydraulic gradient, i and has units of [m/s]:

Cohesion: see Figure B.1

Colloid: a substance consisting of very small particles dispersed in a continuous medium. A colloidal particle is generally accepted as having a size between 5 and 5 000 Ångström

Colloidal grout: a grout with an artificially induced cohesiveness, in which the solid particles or large molecules (colloids) are totally dispersed and remain in suspension, i.e. a grout mixture that does not segregate or bleed

Compaction grouting: see Definitions

Compensation grouting: a term employed for controlled displacement grouting with the aim to counteract ground settlement induced by excavation works. This term refers to a number of grouting methods

Consistency: the relative mobility or ability of freshly mixed mortar or grout to flow. The usual measurements are slump for stiff mixtures and flow for more fluid grouts

Consolidation grouting: this term refers to several injection methods including impregnation, fissure grouting, bulk filling, hydraulic fracturing and compaction grouting, whereby the aim is to strengthen the soil or rock mass

Contact grouting: see Definitions

Continuous mixing: a process in which the ingredients of the mixture are fed without interruption and from which the mixed product is discharged in a continuous stream

Cover: see Overburden