The Aggregates & Recycling Information Network

Glossary: C

  • Cable

    A number of insulated conductors protected by armouring and other covering.

  • Cable Ducts

    Concrete, earthenware, plastic or steel pipes through which cables are drawn and in which they rest.

  • CAD

    abbr. computer-aided design.

  • Cage Motor

    An induction motor having a rotor with a squirrel-cage winding, ie a series of bars accommodated in slots in the rotor, all the bars being connected at each end to a common conducting ring. This type of motor is most reliable but has a poor starting torque.

    Also: squirrel-cage motor

  • Calcareous

    Containing significant amount of calcium carbonate.

  • Calcite

    Calcium carbonate, CaCO3. Occurs in a variety of crystal forms which are usually white or yellowish in colour. Rhombohedral; relative density 2.7; hardness 3. It is the main constituent of chalk, limestone and marble.

  • Calendered Rubber

    Rubber which has been passed through a machine, generally consisting of a number of vertical rollers, in order to ensure uniform thickness.

  • Calfdozer

    A small bulldozer.

  • California Bearing Ratio

    A relative value which expresses the bearing capacity of a soil or pavement layer in comparison with a result obtained by using a standard crushed rock material. It is determined by the test procedures defined in BS 1377.

    abbr. CBR

  • Caliper

    An instrument used in conjunction with a microlog which, when lowered down a borehole, measures and records the internal diameter throughout its depth.

  • Calorie

    The quantity of heat required to raise the temperature of 1 gramme of water by 1°C. This is the unit quantity of heat on the CGS system and is replaced by the joule on the SI system.

    1 calorie = 4.186J.

  • Calorific Value

    The amount of heat given out when unit mass of a fuel (or unit volume in the case of a gas) is burned completely. In fuels containing hydrogen the value must be related to the temperature at which the measurements are made, because on this depends whether or not the water vapour produced is condensed, giving up latent heat. Units: kJ/kg and kJ/m3.

  • Calyx Drilling

    A method of rotary drilling using a toothed cutting bit or chilled shot.

  • CAM

    abbr. computer-aided management.

  • Camber

    The convexity given to the curved cross-section of a carriageway etc.

  • Cambrian

    The earliest period of the Palaeozoic era between about 590 and 505 million years ago, and the corresponding system of rocks.

  • Candela

    The SI unit of luminous intensity which is the quantity that describes the capacity of a source or illuminated surface to emit light in a given direction.

    Symbol: cd.

  • Cantilever

    A beam which is firmly secured at one end and free at the other.

  • Cap

    A device for producing detonation in a high-explosive charge, and initiated by safety fuse, electrical current or shock.

    Also: detonator

  • Capacitance

    The capability of two conductors separated by an insulator to store an electric charge.

    Symbol: C.

    Units: farads.

  • Capacitor

    A circuit element which when charged stores electrical energy.

  • Capital

    Money invested in a business by its owners to earn income.

  • Capped Fuse

    A detonator fitted with a length of safety fuse.

  • Carbon Monoxide

    A highly poisonous, tasteless, odourless gas which is a product of incomplete combustion of inorganic material, eg when an internal combustion engine is idling. It is also created when explosive materials are detonated. Excessive carbon monoxide is caused by an inadequate amount of oxygen in the explosive mixture (excessive fuel).

    Symbol: CO.

  • Carboniferous

    The geological period of time 360 to 286 million years ago and the corresponding system of rocks. In Britain Carboniferous rocks are an important source of crushed rock aggregate.

  • Cardan Shaft

    A propeller or driving shaft which conveys the power from the gearbox to the differential of a motor vehicle. It is usually connected through universal joints to permit displacement of the rear axle on the suspension.

  • Cartesian Co-ordinates

    Rectangular co-ordinates measured perpendicularly from axes which are at right-angles to each other. In surveying, the distances measured to the east are positive and called eastings or departures and those to the north are positive and called northings or latitudes.

  • Cartridge

    An individual unit of explosive, usually wrapped in the form of a cylinder.

  • Cartridge Dust Collector

    An alternative to a bag filter which uses lower filtration velocities and is more compact.

  • Case-hardening

    Surface hardening of steel by heating in a carbonaceous medium to increase the carbon content in the surface layers, then quenching.

  • Cash Flow

    The movement of cash into and out of a company.

  • Casing

    Piping used to support the sides of a borehole. Flush-coupled casing is joined with a coupling which has the same outside diameter as the casing, but has two male-threaded ends. Flush-joint casing has a male thread at one end and a female thread at the other; no coupling is used.

  • Casing Drive Hammer

    A weight used to drive casing down a hole.

  • Cast Iron

    An iron-carbon alloy containing more than 1. 7% and usually above 2.5% carbon including substantial amounts of graphite. It is very fluid when molten and is suitable for making intricate castings by pouring into sand moulds. Applications include: cylinder blocks, hydraulic cylinders, crusher frames etc.

  • Catchment Area

    The area drained by a stream or river or supplying a reservoir.

  • Catenary

    The curve into which a uniform, inextendable rope falls when suspended from its ends.

  • Cavitation

    The formation of a cavity between the impeller blades of a centrifugal pump and the water normally in contact with it. This leads to the liberation of oxygen and corrosion of metal parts.

  • CBGM

    abbr. cement-bound granular material.

  • CBR

    abbr. California bearing ratio

    A relative value which expresses the bearing capacity of a soil or pavement layer in comparison with a result obtained by using a standard crushed rock material. It is determined by the test procedures defined in BS 1377.

  • CECE

    abbr. Committee for European Construction Equipment.

  • Cement
    1. The matrix of a sedimentary rock.
    2. The manufactured powder which, through the addition of water, binds together aggregate particles into concrete.
  • Cement Stabilization

    The consolidation of a foundation layer through the use of low cement content with fill material or subsoil.

  • Cement-bound Macadam

    A form of road construction in which a mortar of Portland cement and sand is added to coarse aggregate.

  • Cementation

    The injection of cement grout under pressure into fissured rocks to strengthen and make them impervious to water.

  • CEN

    abbr. Comite Europeen de Normalisation.

    The European Community standards organization.


    abbr. Comite Europeen de Normalisation Electrotechnique.

    The European Community electrical standards body.

  • Centi.

    A prefix meaning one hundredth.

  • Centre Of Gravity

    The point in a body at which the entire mass of the body may be regarded as being concentrated.

  • Centrifugal Force

    The reaction to a centripetal force, acting radially outwards from the centre of rotation.

  • Centrifugal Pump

    A pump with a rotating impeller which imparts an angular acceleration to the liquid, causing it to flow outwards from the centre to the periphery.

  • Centripetal Force

    The force which must be applied to a body to cause it to follow a circular path. The centre of the path produced lies in the direction of the applied force, hence the name centripetal or centre-seeking force.

  • Ceramics

    Articles produced by the firing of minerals, especially clay, at very high temperatures.

  • Chain Block

    Lifting tackle consisting of two chain wheels of different diameters turning together on the same shaft and over which an endless chain passes. The chain wheel is rotated by a hanging loop and this shortens a second loop which supports the pulley to which the load is attached. A large mechanical advantage is obtained and the chain cannot run back.

    Also: differential pulley block

  • Chain Survey

    A linear survey in which no angles are measured, only lengths.

  • Chain-curtain Feeder

    [img_assist|nid=11800|title=|desc=|link=none|align=right|width=115|height=149]A feeder in which loops of heavy chain suspended from a rotating drum control the rate of flow of material from the chute into the primary crusher.

  • Chainage

    A length measured by means of a chain or steel tape.

  • Chalcedony

    Cryptocrystalline silica.

  • Chamber
    1. An excavation to accommodate an explosive charge.
    2. The cavity within a crusher in which the rock is subjected to crushing action.
  • Chambering

    A blasting method in which a succession of charges is fired in a blasthole to open up a chamber. This is now prohibited in quarries.

    Also: springing

  • Charge

    The quantity of explosives in a particular shothole.

  • Check Valve

    A valve which allows flow in a pipe in one direction only. One use of this type of valve is on the delivery side of a pump used to dewater a deep pit to prevent the column of water in the delivery pipe flowing back. In hydraulic systems the valve element is usually a ball which is returned to its seat by a light spring when flow ceases.

    Also: non-return valve

  • Cheek Plates

    The liners on the two sides of the crushing chamber of a jaw crusher.

  • Chequered Plate

    Patterned or perforated metal plate used to make non-slip flooring in mineral preparation plants, power stations etc.

  • Chert

    Cryptocrystalline silica

  • Chilled Shot Bit

    A flat-surfaced bit used with hardened steel shot to drill rock by a milling action.

  • China Clay

    White, or nearly white, clay of various origins including the decomposition of feldspar.

    Also: kaolin

  • Chippings

    Single-size aggregate nominally between 3mm and 25mm inclusive.

  • Chisel Bit

    A percussive drill bit having a single cutting edge.

  • Chlorite

    Series of hydrous, magnesium, iron and aluminium silicates.

  • Choke

    A coil the primary characteristic of which is the property of inductance.

    Also: inductor

  • Choke-fed

    The sustained feed to a cone crusher which ensures that the crushing zone remains over-full at all times. This results in a more cubical-shaped product, with the best shape occurring in the aggregate size at the crusher setting.

  • Choking

    A stoppage of the downward flow of rock through a crusher usually caused by the packing of compressed fines near the discharge point.

  • Churn Drill

    A cable drill used to drill vertical holes by raising and dropping the heavy drilling tool on the end of a steel wire rope.

  • Circuit Tester

    An instrument used to test series circuits in electrical shotfiring for continuity and resistance.

  • Circuit-breaker

    A device for automatically making or breaking an electrical circuit under both normal and abnormal conditions, such as when a short circuit occurs.

  • Circular Saw

    Machine with revolving steel disc, rimmed with various abrasive elements.

  • Circulating Fluid

    The fluid, which may be water, mud or air, circulated through the apparatus during drilling. Its chief functions are to remove cuttings, to cool the bit and, in the case of mud, to support the sides of the hole.

  • Clamping Screw

    On surveying instruments a screw for clamping a vernier before the tangent screw can be used for fine adjustments.

  • Clamshell

    A twin-jawed bucket used with a crane jib for digging and loading loose material, eg sand and gravel from a flooded deposit.

  • Clarifier

    A thickener used to separate slimes and wash water.

  • Classification

    The separation of particles according to their size, density and shape by control of their settling rate through a fluid medium.

  • Classified Tip

    An obsolete term for a tip registered under the Mines and Quarries (Tips) Regulations 1971 because of its hazard potential, see notifiable.

  • Clastic

    Deposits consisting of broken fragments of earlier rocks.

  • Clay Minerals

    Silicate minerals which are mainly formed by the weathering or alteration of feldspars and other primary minerals. Kaolin is one example.

  • Cleaner Cells

    Flotation cells used in the retreatment of a rough concentrate to improve its quality.

  • Cleavage
    1. In a crystalline mineral, one or more series of parallel planes along which the mineral tends to split.
    2. In a rock, definite parallel closely spaced planes along which it may split, and which may be highly inclined to the bedding planes.
  • Cleavage Plane

    Plane along which certain rocks can be split readily.

  • Clevis

    A V-shaped metal bar drilled in a number of places. One of its uses is to hold the shank of a ripper in any of several positions so that depth and tooth angle may be adjusted to meet prevailing conditions.

  • Clinker
    1. The fused product from a cement-making kiln which is subsequently ground into powder.
    2. Sintered or fused furnace ash which may be used for hard core or aggregate for concrete blocks.
  • Clinometer

    An instrument used to determine the amount and direction of deviation of a blasthole from the vertical or a hand-held instrument for the measurement of angles of slope.

  • Closed Circuit
    1. An electrical circuit that provides an uninterrupted path for the current.
    2. A system in which the product from a crusher passes to a screen, the overflow from which is returned to the crusher for further treatment and the underflow released from the closed circuit.
  • Closed Traverse

    A traverse which begins and ends at the same point; its accuracy can therefore be checked.

  • Closing Error

    In a closed traverse, the discrepancy between the starting point and the finishing point as calculated from the measurements taken. The error, if small enough, may be distributed throughout the series of measurements.

  • CMR

    abbr. continuous maximum rating

    The load at which an electric motor can be continuously operated without overheating.


  • Co-ordinates

    Rectangular co-ordinates are measured perpendicularly from axes which are at right-angles to each other. In surveying, the distances measured to the east are positive and called eastings or departures and those to the north are positive and called northings or latitudes.

    See also: Cartesian co-ordinates and rectangular co-ordinates

  • Coal Measures

    Uppermost division of Carboniferous system consisting of coal seams interstratified with sandstone and shales.

  • Coal Preparation

    Collectively, physical and mechanical processes applied to coal to make it suitable for a particular use.

  • Cobblestone

    Stone naturally rounded by erosion; applied loosely to stone roughly squared for paving, paving sett.

  • Competent

    As defined by the Quarry Regulations 1999, in relation to a person means a person with sufficient training, experience, knowledge and other qualities to enable him/her to properly undertake the duties assigned to him/her.

  • Compression Crushers

    Crushers in which the rock is subjected to a squeezing action. This group includes gyratory, jaw and smooth rolls crushers.

  • Compression Test

    Test in which specimens of the material under test (eg concrete) are subjected to increasing compressive force until they fail by buckling, cracking or disintegration.

  • Concrete

    A mixture of stone, sand, water and a binder, usually Portland cement, which hardens to a stone-like mass.

  • Concrete Aggregates

    Grading limits for concrete aggregates are given in BS EN 12620

  • Condition

    In relation to a planning consent, a limitation imposed by the Mineral Planning Authority to achieve some desirable effect in relation to the permitted development.

  • Condition Monitoring

    A series of engine assessment techniques based on oil testing.

  • Conditioning

    The preparatory stage in the flotation process in which the reagents are brought into intimate contact with the solids of the pulp.

  • Conductivity Meter

    An instrument which gives a continuous readout of the chloride ion content of wash water used in marine aggregate processing.

  • Conduit

    Pipe or trough to contain and protect cables or wires.

  • Conglomerate

    A rock consisting of rounded pebbles held together by a natural cement.

  • Construction Joints

    A joint between fresh concrete and concrete which has already hardened. Concrete on either side of the joint is usually united by reinforcement crossing the joint.

  • Contact Metamorphism

    Changes brought about in a rock by contact with intruded or extruded molten igneous material.

  • Contactor

    A device for repeatedly opening and closing electrical circuits.

  • Continuous Maximum Rating

    The load at which an electric motor can be continuously operated without overheating.

    abbr. CMR

  • Continuous Mixer

    A concrete mixer which receives a ribbon feed of raw materials at one end, discharging continuously through the other end.

  • Contour

    A line on a plan joining points of equal altitude.

  • Contraction Joint

    A break made in concrete work to allow for shrinkage during drying. Provision of these joints in long concrete structures prevents the formation of cracks.

  • Contraflow
    1. Water flow in the opposite direction to that of the mineral being treated in a washer.
    2. The direction of vibration of an inclined screen to retard the passage of material along the screen.
  • Control Valve

    In a hydraulic system, the valve which directs the flow of oil to operate the service in the direction required and connects the opposite service line to the reservoir.

  • Controlled Blasting

    Techniques used to control overbreak and produce a competent final excavation wall.

    Also: pre-splitting or cushion blasting

  • Conveyor System

    A movable or stationary item of plant designed for the conveying of materials continuously from one location to another.

  • Coolant

    Material used to remove heat from an electrical device or equipment, eg air, hydrogen, oil and water.

  • Copper Loss

    The heat energy loss in a conductor not intended to produce heat. This loss is proportional to the square of the current passing through the conductor and its resistance.

  • Cordtex

    Detonating fuse.

  • Core
    1. The cylindrical sample of rock bored out during core drilling.
    2. The part of an electromagnetic circuit situated within the winding.
  • Core Barrel

    A length of pipe immediately above the bit of a rotary core drill. Double-core barrels have an inner portion mounted on a bearing so that it remains stationary and does not damage the core to the same extent when drilling is in weak friable strata.

  • Core Box

    A long wooden box divided into sections wide enough to accommodate the cores taken from a borehole in the order they are removed for retention/examination.

  • Core Drilling

    A method of rotary drilling in which a core is recovered.

  • Core Lifter

    A spring clip at the base of the core barrel which grips the core, allowing it to be broken off and brought out of the hole.

  • Core Loss

    In an alternating current system, the eddy current and hysteresis losses developed as heat in the ferromagnetic core of a machine or transformer.

    Also: iron loss

  • Core-balance Protection

    A system of earth-fault protection applied to circuits in an ac electrical system having a neutral point earthed and utilizing a core-balance transformer to detect the earthleakage current.

  • Core-balance Transformer

    A form of current transformer, the primary windings of which are connected in each phase of a circuit. The flux resulting from an out-of-balance current in the primary winding induces a voltage in a secondary winding.


    abbr. Control of Substances Hazardous to Health Regulations.

  • Cost-plus

    A form of contract used for urgent work by which the client pays for on-site labour, materials and plant costs plus an agreed sum to cover the contractor’s overheads and profit.

  • Coulomb

    The quantity of electricity transported in one second by a current of one ampere.

    Symbol: C.

  • Counterbalance Valves

    Hydraulic pressure-maintaining valves used to prevent a load causing a cylinder to move faster than under the influence of pump flow.

  • Country Rock

    The rock adjacent to a mineral vein or igneous intrusion.

  • Cryptocrystalline

    Composed of crystals so fine that they can be distinguished only under a high power microscope.

  • CSS

    abbr. closed-side setting

    Also: setting

  • Cycle Of Operations

    A series of several separate operations in a system of quarrying carried out in a predetermined order.

  • Cyclone

    A conical classifying device into which pulp is fed so as to take a circular path. Coarser and denser fractions of solids report to the apex of the cone, while finer particles overflow from the central vortex. Cyclones are also used for dewatering and in the removal of dust particles from air and other gases.

    Also: hydrocyclone 

  • Cyclone Dust Collector

    An apparatus for the separation by centrifugal means of fine particles suspended in air or gas.