Civil Engineering Technical Terms and Meaning - For J to P - ObjectiveBooks

Civil Engineering Technical Terms and Meaning - For J to P

For ‘J’

JOINT SEALANT: A material used as a filler in concrete pavement joints to prevent infiltration of water, soil and other fine particles.

JOIST: A horizontal wooden, steel or precast concrete beam directly supporting a floor.

For ‘K’

KEYWAY: A recess or groove in one lift or placement of concrete which is filled with concrete of the next lift, giving shear strength to the joint, also called a key.

KINETIC ENERGY: The energy of a moving body due to its mass and motion.
K.E. = W × V / 2 g.

For ‘L’

LAITANCE: A layer of weak and non-durable cement concrete caused by bleeding as a result of excessive vibration of concrete or over trowelling the mortar. It is weaker than the rest of the concrete and should be cut away and covered with a pure cement wash before laying more concrete on it.

LANDSLIP OR LANDSLIDE: A sliding down of the soil on a slope because of an increase of loading (Due to rain, new building, etc.), or a removal of support at the foot due to cutting a railway or road or canal. Clays are particularly liable to slips.

LEAN CONCRETE BASE (LCB): A mixture of aggregate, cement and water used directly under concrete pavement. The mixture has a lower modulus of rapture than the concrete pavement, and a higher compressive strength than cement treated base.

LEDGE: A horizontal projection or cut forming a shelf, cliff or rock wall.

LIME: Calcium oxide (CaO).

LIQUID LIMIT: The moisture content at the point between the liquid and the plastic states of a clay.

LIQUIDATED DAMAGES: The amount prescribed in the contract specifications, to be paid to the State (Client) or to be deducted from any payments due or to become due the Contractor, for each day's delay in completing the whole or any specified portion of the work beyond the time allowed in the contract specifications.

LLOYD DAVIES FORMULA: A method for calculating the run-off, from which the sizes of sewers are calculated (Runoff water in cubic feet = 60.5 × area drained in acres × rainfall in inches per hour × impermeability factor).

LOESS: Deposit of very porous and cavitated wind-blown silt and clay.

LONG COLUMN: A column which fails when overloaded, by buckling rather than by crushing. In reinforced-concrete work this is assumed to happen when columns which are longer than fifteen times their least dimension.

LONGITUDINAL JOINT: A joint normally placed between traffic lanes in rigid pavements to control longitudinal cracking.

LOSS OF PRESTRESS: Losses of pre-stressing force after transfer arise mainly through elastic shortening, shrinkage and creep of the concrete and creep of the steel.

LOT: An isolated quantity of material from a single source.

LUMINAIRE: Complete lighting device for the highway.

For ‘M’

MARSHES: Low lying wet land; swamp.

MATERIALS: Any substance specified for use in the construction of the project and its appurtenances.

MAXIMUM DRY DENSITY: The dry density obtained by a stated amount of compaction of a soil at the optimum moisture content.

MEAN: An arithmetic mean is an average in which all signs are taken as positive. In an algebraic mean the signs of the quantities are considered and the mean may be either positive or negative.

MEDIAN: That portion of a divided highway separating the travelled ways for traffic in opposite directions including inside shoulders.

MEMBRANE: A thin film or skin, such as the skin of a soap bubble or a waterproof skin.

MILLING: (1) Removing a specified thickness of an existing pavement surface by grinding with a milling machine. (2) Removing metal shavings from a surface by pushing it on a moving table past a rotating toothed cutter.

MIST: Very thin fog.

MOISTURE CONTENT: The weight of water in a soil mass divided by the dry weight of the solids and multiplied by 100.

MONOLITHIC CONSTRUCTION: Constructed as one piece.

MORTAR: A paste of cement, sand and water laid between bricks, blocks or stones.

MOVEMENT JOINTS IN CONCRETE: Movement joints may be of five types, though it is possible for one to combine the properties of one or more others. They reduce or prevent cracking or buckling caused by temperature changes, shrinkage, creep, subsidence and so on. Their location is important. Where possible, they should be placed at points where cracking (or buckling) might start. The five types of joints are: contraction, expansion, hinge or hinged joint, settlement and sliding joints.

MULCH: Mixes of wet straw and leaf peat.

MUNICIPALITY: City, town or county.

For ‘N’

NEGATIVE MOMENT: A condition of flexure (Bending) in which top fibers of a horizontally placed member (Beam), or external fibers of a vertically placed exterior member (Column), are subjected to tensile stresses.

NEOPRENE: Synthetic rubber resistant to chemical compound, oil, light, etc.

NEUTRAL SURFACE: In a beam bent downwards, the line or surface of zero stress, below which all fibres are stressed in tension and above which they are compressed. The neutral axis passes through the center of area of the section (Centroid), if it is of homogeneous material.

For ‘O’

OFFSET: A horizontal distance measured at right angles to a survey line to locate a point off an edge line.

OPTIMUM MOISTURE CONTENT: That moisture content of a soil at which a precise amount of compaction produces the highest dry density. It is particularly important to achieve this in soil stabilization before the road is completed. It is the percentage of moisture at which the greatest density of a particular soil can be obtained through compaction by a specified method.

OVERBURDEN: Material of inferior quality which overlies material of desired quality and which must be removed to obtain the desired material quality.

OVERLAY: One or more courses of asphaltic concrete layers placed over existing worn or cracked pavement.

For ‘P’

PARAPET: Any protective railing, low wall or barrier at the edge of a bridge, roof, balcony or the like.

PARKWAY: An arterial highway for non-commercial traffic, with full or partial control of access, usually located within a park or a ribbon of parklike development.

PASSIVE PRESSURE: A pressure acting to counteract active pressure.

PAVEMENT: The uppermost layer of material placed on the travelled way or shoulders. This term is used interchangeably with surfacing.

PAVEMENT STRUCTURE: The combination of sub-base, base course, and surface course placed on a sub-grade to support the traffic load and distribute it to the sub-grade.

PEAT: Plant material partly decomposed by action of water.

PEBBLES: Smaller pieces of material (0.12 to 0.25 inch minimum size) which have broken away from a bedrock..

PEDESTAL: An upright compression member whose height does not exceed three times its average least lateral dimension.

PERFORATED: Pierced with holes.

PERMEABILITY: That property of a material which permits a liquid to flow through its pores or interstices.

pH VALUE: An index of the acidity or alkalinity of a soil in terms of logarithm of the reciprocal of hydrogen ion concentration (e.g., a pH indication of less than 7.0 is acidic, whereas a reading of more than 7.0 is alkaline).

PIER: A wide column or a wall of masonry, plain or reinforced concrete for carrying heavy loads, such as a support for a bridge.

PIER CAP: The top part of a bridge pier which uniformly distribute the concentrated loads from the bridge over the pier .

PIER SHAFT: The part of a pier structure which is supported by the pier foundation.

PILE: A long slender timber, concrete, or steel structural element, driven, jetted, or otherwise embedded on end in the ground for the purpose of supporting a load or compacting the soil.

PIT: Any borrow pit, mine, quarry or surface excavation to obtain sand, clay, gravel, etc.

PLANS: The official project plans and Standard Plans, profiles, typical cross sections, cross sections, working drawings and supplemental drawings, or reproductions thereof, approved by the Engineer, which show the location, character, dimensions and details of the work to be performed. All such documents are to be considered as a part of the plans, whether or not reproduced in the special provisions.

PLASTICITY: The property of a soil which allows it to be deformed beyond the point of elastic recovery without cracking or appreciable volume change.

PLASTICITY INDEX (PI): Numerical difference between the liquid limit and the plastic limit. This is an indication of the clay content on a soil or aggregate.

PLASTICIZER OR WATER REDUCER: An admixture in mortar or concrete which can increase the workability of a mix so much, that the water content can be low and the mortar or concrete strength can thus be increased.

PLASTIC LIMIT: The water content at the lower limit of the plastic state of a clay. It is the minimum water content at which a soil can be rolled into a thread of 1/8 inch diameter without crumbling.

PLAT: A small plot of land.

PORTLAND CEMENT: A product obtained by pulverizing clinker consisting mainly of hydraulic calcium silicates. Many different cements now use Portland cements or at least contain some, the varieties include: Ordinary, Rapid-hardening, Ultra-high-early-strength, Portland blast-furnace, Sulphate-resisting and Water-repellent cements, apart from Colored cements.

POST-TENSIONING: A method of pre-stressing concrete in which the cables are pulled or the concrete is jacked up after it has been placed. This method is usual for bridges and heavy structures which are placed in place.

POTABLE WATER: Drinking water.

POTENTIAL ENERGY: Energy due to position such as the elevation head of water or the elastic energy of a spring or structure caused by its deformation.

PRECISION: Of a measurement, the fineness with which it has been read, therefore, precision is different from accuracy.

PRECAST CONCRETE: Concrete beams, columns, lintels, piles, manholes, and parts of walls and floors which are cast and partly matured on the site or in a factory before being placed in their final position in a structure. Where many of the same unit are required, pre-casting may be more economical than casting in place, may give a better surface finish, reduce shrinkage of the concrete on the site and make stronger concrete.

PRESSURE: A force acting on a unit area.

PRESTRESSING: A process of preparing concrete slabs and beams for extra strength by placing the mix over tightly-drawn special steel wire rope or rods which are later released to provide strong dense concrete. Pre-stressing accomplished by applying forces to a structure to deform it in such a way that it will withstand its working loads more effectively or with less total deflection. When concrete beams are pre-stressed they deflect upwards slightly by an amount about equal to their total downward deflection under design load. Downward deflection is thus less than half that of a reinforced-concrete beam of the same shape. The struts or braces to deep excavations in bad ground are pre-stressed to prevent settlement of the surface and damage to neighboring structures.

PRESTRESSED CONCRETE: Concrete in which cracking and tensile forces are eliminated or greatly reduced by compressing it by stretched cables, wires or bars within it. Two main methods for pre-stressing are: post-tensioning and pre-tensioning. Pre-stressed concrete is economical for spans which are large or where the beam depth must be reduced to a minimum.

PRIME COAT: The initial application of a low viscosity bituminous material to an absorbent surface, preparatory to any subsequent treatment, for the purpose of hardening or toughening the surface and promoting adhesion between it and the superimposed constructed layer.

PROFILE GRADE: The trace of a vertical plane intersecting the top surface of the proposed wearing surface, usually along the longitudinal centerline of the roadbed. Profile grade means either elevation or gradient of such trace according to the context.

PROFILOGRAPH: An instrument for measuring smoothness of a surface (as of metal casting, or a highway or road) by amplification of the minute variations from the plane or arc of smoothness.

PROJECT: The specific section of the highway together with all construction to be performed thereon under the contract.

PROPOSAL: The offer of a bidder, on the prescribed forms, to perform the work and to furnish the labor, equipments and materials at the prices quoted.

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