Glossary (p. IV)

Neutralization rate: for sodium silicate gels, the proportion of sodium neutralized by the reactant

Newtonian fluid: a true fluid that exhibits constant viscosity at all rates of shear. A Newtonian fluid has no yield point

Non-displacement grouting: see Definitions

Overburden: the thickness of rock and soil material overlying the stage of the hole being grouted

Packer: a device inserted into a drill hole or sleeve pipe to isolate one part of the hole from another. A packer is usually an expandable device activated mechanically, hydraulically or pneumatically

Particle size distribution: the distribution by weight of particles of grouting material among various sizes; usually expressed in terms of cumulative percentage larger or smaller than each of a series of diameters (sieve openings) or the percentages between certain ranges of diameters (sieve openings)

Particulate grout: a grout containing particles, larger than colloids, suspended in the liquid

Pass: injection of a given length of hole without interruption

Penetrability: the ability of a grout to penetrate a ground

Penetration grouting: see Definitions

Permeability: a measure of the ease with which a fluid passes through a porous medium. See also Coefficient of permeability

Permeation grouting: see Definitions

Phase: grouting activity, with defined criteria which is a part of a sequence

Polyurethanes: chemical resins reacting to produce foams. Their viscosity is largely similar to that of epoxy resins and they harden very quickly (0,5 min to 10 h). One component polyurethanes harden upon reaction with water. Two-component polyurethanes usually foam up in contact with water, the foaming process causes a kind of self-injection which ensures a better adhesive strength and a certain deformability

Porosity: the ratio, usually expressed as a percentage, of the volume of voids of a given soil or rock mass, to the total volume of the soil or rock mass

Pot life: see Setting time

Pozzolane: a siliceous or siliceous and aluminous material, which in itself possesses little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties

Pulverized fuel ash (pfa): by-product of burning of coal for electric power generation with high content of mineral matter

Resin: a material that constitutes the base of an organic grout system, such as acryl, epoxy, polyester and urethane

Rheological properties: the properties governing the flow of a fluid or plastic solid

Rheopectic: the viscosity (structuring) of rheopectic fluids increases with increasing shear rate (loading) and returns to its initial value after a certain time of rest

Rotary viscometer: in rotary viscometers the viscosity and yield point are determined on the basis of the relationship between torque and rotation speed, respectively shear stress and shear gradient. The viscosity is derived from the ratio of shear stress to shear rate

Sedimentation: the accumulation of grout particles at the bottom of a container when left unagitated as a result of gravitational forces

Segregation: the non-uniform distribution of particles within a grout or mortar due to sedimentation

Sequence: the order in which different grout types are injected in different holes over time, or programmed succession of grouting phases

Set: the condition reached by a grout when it has lost plasticity to an arbitrary degree, usually measured in terms of resistance to penetration or deformation; initial set refers to first stiffening and final set refers to an attainment of significant rigidity

Set time (Setting time): the time between mixing and the achievement in a significant change in the rheological properties. The setting time is volume and temperature dependent and is measured in a number of ways

Shearometer: an instrument for measuring the shear strength of fluids or weak gels

Shear strength: the stress at which a material can no longer resist the applied shear force

Shear stress: τ is the shear force applied per unit area

Shrinkage: a reduction in volume of grout

Single packer: a single packer comprising one seal. See Packer and Double packer

Sleeve grout: a grout which fills the annulus between the sleeve pipe and the borehole wall

Sleeve pipe (tube): a grout pipe perforated at regular intervals. The perforations are covered externally by sleeves acting as non-return valves

Sleeve pipe (TAM) grouting: grouting method using sleeve pipes, which allow repetitive placement of grout

Slump test: test for assessing the consistency of a mortar by use of an Abram's cone. The cone is filled with mortar to a given height, the cone lifted and the distance of initial height of the cone to final height of the mortar mound measured

Solution: a liquid formed by completely dissolving a chemical in water to give a uniform fluid without solid particles. Solutions are Newtonian liquids with neither rigidity nor particles and harden in a predetermined period of time, called the 'setting time'. They can be true or colloidal solutions. In the case of colloidal solutions, large molecules are contained in the liquid

Split spacing: the procedure by which additional grout injection holes are located at half the distance from previously grouted holes

Stable suspension: see Definitions

Stage: a given injection length

Stage grouting: sequential grouting of a hole in separate stages as opposed to grouting the entire length at once

Superplasticizer (Plasticizer): additive, which increases the workability of mortars and reduces the viscosity of suspensions

Suspension: a mixture of liquid and solid materials. Behaves as a Bingham fluid during flow, possessing both viscosity and cohesion (yield strength). Particulate suspensions contain particles larger than clay size, while colloidal suspensions contain particles of clay size

Suspending agent: an additive that decreases the settlement rate of particles in liquid

Syneresis: the expulsion of liquid (generally alkaline water) from a set gel which is not stressed, accompanied by a contraction of the gel. Syneresis occurs over a period of a few months