The Aggregates & Recycling Information Network

Glossary: L

  • Lake Asphalt

    A highly viscous natural asphalt found in well defined surface deposits.

  • Latent Heat

    The heat required to change the state of a substance from solid to liquid, or from liquid to gas, without change in temperature.

    See also: specific heat of fusion and specific heat of vaporization

  • Laterite

    Highly weathered residual soil material rich in oxides of aluminium and iron, traditionally useful for brickmaking.

  • Latitude

    The distance in metres north or south of an axis which runs east and west. May also be referred to as northing, in which case all distances to the north are regarded as being positive.

    See also: co-ordinates and latitude

  • Lay

    The lay of a wire rope describes the way in which the wires and strands are twisted to form the rope.

    See also: Lang’s lay and ordinary lay

  • Lay Shaft

    A secondary shaft parallel to the main shaft of an automobile gearbox to and from which the drive is transferred by gear wheels of varying ratio.

  • Leaching
    1. Selective removal of soluble constituents from soil or rock by the action of surface water penetrating downwards.
    2. The removal of soluble salts or metals from material by the use of a suitable solvent.
  • Leader

    In linear surveying, the man holding the leading end of the tape and who is aligned by the follower.

  • Leading

    The use of a piece of lead on the end of a string dropped into the chamber of a crusher to determine the setting.

  • Lenz’s Law

    The direction of the electromotive force induced in a circuit by a changing magnetic flux is such that the direction of any current produced opposes the change producing it.

  • LGP

    abbr. low ground pressure.

  • LHD

    abbr. load-haul-dump

    Used to describe vehicles, such as bowl scrapers, which carry out all three functions.

  • Lift

    In a quarry or opencast site may be used to denote the configuration of the face, eg multiple lift (= several benches).

  • Lifting Tackle

    Lifting blocks, ropes, chains, hooks, slings etc.

  • Lightweight Aggregates

    Aggregates used in the production of lightweight concretes. Natural types include pumice and diatomite and manufactured ones furnace clinker, foamed slag, expanded slate, expanded perlite, expanded vermiculite and plastic particles.

  • Lignite

    Coal of low rank with high inherent moisture and volatile matter.

  • Lime Concrete

    Concrete in which the cementing agent is burnt and ground lime.

  • Limit Switch

    A safety device fitted to electrically operated lifts, travelling cranes etc which prevents them passing a certain point by cutting off the power supply.

  • Limited Liability Company

    A business established under the provisions of the Companies Acts in which the shareholders’ liability is limited by shares or guarantee.

  • Limiting Friction

    Limiting friction occurs when the moving force and the force opposing motion are equal; any addition to the moving force will cause slipping. The limiting frictional force is proportional to the normal reaction between the contacting surfaces and is independent of the area of contact.

  • Limonite

    Hydrated iron oxide.

  • Line Voltage

    The voltage between two of the power conductors of a three-phase system.

  • Lithification

    Process of conversion of sediment into sedimentary rock.

  • Lithology

    The character of a rock expressed in terms of its mineral composition, structure, grain size and arrangement of its component parts.

  • Lithosphere

    The Earth’s crust and overlying superficial deposits.

  • Littoral Deposit

    A marine deposit laid down between low and high tide marks usually consisting of boulders, pebbles and coarse sand.

  • Littoral Drift

    The movement of boulders, pebbles and sand along a shore belt by the action of currents and waves.

  • Live Load

    All loads applied to a structure other than its own weight, eg the load applied to a bridge by the traffic moving over it.

  • Load
    1. The power output of a generator, motor, transformer etc or the power carried by a circuit.
    2. The weight supported by a structure. See also: dead load and live load
  • Load Factor

    The ratio of the energy units used in a given time to the units used, had the maximum demand been continuous during the same time.

  • Load-cells

    Load-measuring elements utilizing electrical or hydraulic effects which are remotely indicated or give digital read-outs.

  • Load-haul-dump

    Used to describe vehicles, such as bowl scrapers, which carry out all three functions.

    abbr. LHD

  • Loading Density

    The mass of explosive per unit length of blasthole measured in kg/m.

  • Loam

    Mixture of clay and sand.

  • Loan Capital

    Long-term liabilities such as loans and debentures.

  • Lock Nut

    A second nut screwed on to a bolt to prevent the first nut from loosening under vibration.

  • Lock Valves

    Hydraulic valves which permit free flow in one direction and will allow flow in the reverse direction when a piston receives a pressure signal.

  • Locked Coil Rope

    A high-strength wire rope of all-steel round and shaped wires. Used for heavyduty winding and aerial ropeways.

  • Lode

    A mineral body, thin in relation to its other dimensions, which cuts across the bedding and in which the minerals are later than the country rock. 

    Also: vein

  • Log-washer

    [img_assist|nid=11973|title=|desc=|link=none|align=right|width=151|height=158]A long water tank set at a slope, in which one or two shafts, or logs, fitted with paddles set helically rotate. The feed is introduced at the lower end of the tank, the paddles break it up and subject it to a tumbling action; dirty water and fines are discharged at the lower end and washed aggregate at the upper end. These washers are used where there is conglomerate or a high proportion of clay among the gravel.

  • Longitudinal Waves

    Waves where particles of the medium vibrate parallel to the direction of wave travel.

  • Los Angeles Abrasion Test

    A test for mechanical strength in which an aggregate sample is rotated in a horizontal drum with a charge of steel spheres. The percentage of the original sample which passes a standard sieve after 500 revolutions is reported as the percentage of wear. Adopted as an European standard BS EN 1097 Part 2.

  • Low Explosive

    An explosive, such as black powder, which can be fired by simple ignition. Propagation is by rapid combustion and the rate of travel of the flame front is relatively slow, producing a heaving type of explosion.

  • Low Wall

    In a surface mining operation, the spoil slope where overburden is dumped into an excavated area.

  • Lowerator

    A machine used in an automated concrete block making plant for moving blocks from the curing zone to the stacking and packaging section.

  • Lumen

    The flux emitted within a unit solid angle of one steradian by a point source having a uniform intensity of one candela.

    Symbol: lm

  • Luminous Efficacy

    The ratio of the luminous flux emitted by a lamp to the power consumed by it.

    Symbol: K

    Units: lumens per watt (lm/W)

  • Luminous Flux

    The quantity of light emitted by a source related to the solid angle over which the measurement is made.

    Unit: lumen (lm)

  • Luminous Intensity

    The quantity which describes the capacity of a source or illuminated surface to emit light in a given direction.

    Symbol: I

    Unit: candela (cd)

  • Lux

    An illumination of one lumen per square metre.

    Symbol: lx