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ACPA - American Pavement Glossary
Category: Architecture and Buildings > concrete terms
Date & country: 25/09/2008, USA
Words: 597


Joint Shape Factor
Ratio of the vertical to horizontal dimension of the joint sealant reservoir.

Joint, Construction
See Construction Joint

Joint, Contraction
See Contraction Joint

Joint, Expansion
See Expansion Joint

Jointed Plain Concrete Pavement
Pavement containing enough joints to control all natural cracks expected in the concrete; steel tie bars are generally used at longitudinal joints to prevent joint opening, and dowel bars may be used to enhance load transfer at transverse contraction joints depending upon the expected traffic.

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. See also Tongue and Groove.

Laitance
A layer of weak material containing cement and fines from aggregates, brought to the top of overwet concrete, the amount of which is generally increased by overworking and over-manipulating concrete at the surface by improper finishing.

Layer
See Course

Lean Concrete
Concrete of low cement content.

Life-Cycle Cost Analysis
The process used to compare projects based on their initial cost, future cost and salvage value, which accounts for the time value of money.

Lift
The concrete placed between two consecutive horizontal construction joints, usually consisting of several layers or courses.

Liquid Sealant
Sealant materials that install in liquid form and cool or cure to their final properties; rely on long-term adhesion to the joint reservoir faces.

Load Transfer Device
See Dowel

Load Transfer Efficiency
The ability of a joint or crack to transfer a portion of a load applied on side of the joint or crack to the other side of the joint or crack.

Load Transfer Restoration
See Retrofit Dowel Bars.

Load-Transfer Assembly
Most commonly, the basket or carriage designed to support or link dowel bars during concreting operations so as to hold them in place, in the desired alignment.

Longitudinal Broom
Surface texture achieved in similar manner as transverse broom, except that broom is pulled in a line parallel to the pavement centerline.

Longitudinal Joint
A joint parallel to the long dimension of a structure or pavement.

Longitudinal Reinforcement
Reinforcement essentially parallel to the long axis of a concrete member or pavement.

Longitudinal Tine
Surface texture achieved by a hand held or mechanical device equipped with a rake-like tining head that moves in a line parallel to the pavement centerline.

Lot
A defined quantity.

Map Cracking
1) Intersecting cracks that extend below the surface of hardened concrete; caused by shrinkage of the drying surface concrete which is restrained by concrete at greater depths where either little or no shrinkage occurs; vary in width from fine and barely visible to open and well-defined. 2) The chief symptom of chemical reaction between alkalis in cement and mineral constituents in aggregate withi...

Maximum Size Aggregate
The largest size aggregate particles present in sufficient quantity to affect properties of a concrete mixture.

Membrane Curing
A process that involves either liquid sealing compound (e.g., bituminous and paraffinic emulsions, coal tar cut-backs, pigmented and non-pigmented resin suspensions, or suspensions of wax and drying oil) or non-liquid protective coating (e.g., sheet plastics or 'waterproof' paper), both of which types function as films to restrict evaporation of mixing water from the fresh concrete surface.

Mesh
The number of openings (including fractions thereof) per unit of length in either a screen or sieve in which the openings are 6 mm or less.

Mesh Reinforcement
See Welded-Wire Fabric Reinforcement

Method and Material Specification
Specification that directs the contractor to use specified materials in definite proportions and specific types of equipment and methods to place the material.

Mix
The act or process of mixing; also mixture of materials, such as mortar or concrete.

Mix Design
See Proportioning

Mixer
A machine used for blending the constituents of concrete, grout, mortar, cement paste, or other mixture.

Mixer, Batch
See Batch Mixer

Mixer, Horizontal Shaft
A mixer having a stationary cylindrical mixing compartment, with the axis of the cylinder horizontal, and one or more rotating shafts to which mixing blades or paddles are attached; also called Pugmill.

Mixer, Non-tilting
A horizontally rotating drum mixer that charges, mixes, and discharges without tilting.

Mixer, Open-top
A truck-mounted mixer consisting of a trough or a segment of a cylindrical mixing compartment within which paddles or blades rotate about the horizontal axis of the trough. See also Mixer, Horizontal Shaft.

Mixer, Tilting
A rotating drum mixer that discharges by tilting the drum about a fixed or movable horizontal axis at right angles to the drum axis. The drum axis may be horizontal or inclined while charging and mixing.

Mixer, Transit
See Truck Mixer

Mixing Cycle
The time taken for a complete cycle in a batch mixer; i.e., the time elapsing between successive repetitions of the same operation (e.g., successive discharges of the mixer).

Mixing Plant
See Batch Plant

Mixing Speed
Rotation rate of a mixer drum or of the paddles in an open-top, pan, or trough mixer, when mixing a batch; expressed in revolutions per minute (rpm), or in peripheral feet per minute of a point on the circumference at maximum diameter.

Mixing Time
The period during which the mixer is combining the ingredients for a batch of concrete. For stationary mixers, the time is measured from the completion of batching cement and aggregate until the beginning of discharge. For truck mixers, mixing is given in term of the number of revolutions of the drum at mixing speed.

Mixing Water
The water in freshly mixed sand-cement grout, mortar, or concrete, exclusive of any previously absorbed by the aggregate (e.g., water considered in the computation of the net water-cement ratio). See also Batched Water and Surface Moisture.

Mixture
The assembled, blended, commingled ingredients of mortar, concrete, or the like, or the proportions for their assembly.

Modulus of Rupture
A measure of the ultimate load-carrying capacity of a beam, sometimes referred to as 'rupture modulus' or 'rupture strength.' It is calculated for apparent tensile stress in the extreme fiber of a transverse test specimen under the load that produces rupture. See also Flexural Strength.

Moist
Slightly damp but not quite dry to the touch; the term 'wet' implies visible free water, 'damp' implies less wetness than 'wet,' and 'moist' implies not quite dry. See also Damp and Wet.

Moisture Barrier
A vapor barrier.

Moisture Content of Aggregate
The ratio, expressed as a percentage, of the weight of water in a given granular mass to the dry weight of the mass.

Moisture-free
The condition of a material that has been dried in air until there is no further significant change in its mass. See also Mass and Overdry.

Mortar
Concrete with essentially no aggregate larger than about 3/16 inch.

Mud Balls
Balls of clay or silt ('mud').

Must-Grind Bump
In a rideability specification, any bump exceeding a certain height in 25 feet (requirement may very between 0.3 and 0.5 in. bump height).

Natural Sand
Sand resulting from natural disintegration and abrasion of rock. See also Sand and Aggregate, Fine.

NCHRP
National Cooperative Highway Research Program

Neat Cement Grout
Grout consisting of portland cement and water.

NHI
National Highway Institute

Nominal Maximum Size
In specifications for and descriptions of aggregate, the smallest sieve opening through which the entire amount of the aggregate is permitted to pass; sometimes referred to as 'maximum size (of aggregate).'

Non-agitating Unit
A truck-mounted container for transporting central-mixed concrete that is not equipped to provide agitation (slow mixing) during delivery. (Dump truck)

Non-air-entrained Concrete
Concrete in which neither an air-entraining admixture nor an air-entraining cement has been used.

No-Slump Concrete
Concrete with a slump of 6 mm or less. See also Zero-slump Concrete.

NRMCA
National Ready Mixed Concrete Association

Open-Graded Subbase
Unstabilized layer consisting of crushed aggregates with a reduced amount of fines to promote drainage.

Ovendry
The condition resulting from having been dried to essentially constant weight, in an oven, at a temperature that has been fixed, usually between 221 and 239o F (105 and 115o C).

Overlay
The addition of a new material layer onto an existing pavement surface. See also Resurfacing

Overlay, Bonded
See 'Bonded Concrete Overlay.'

Overlay, Unbonded
See 'Unbonded Concrete Overlay.'

Overlay, UTW
See 'Ultra-thin Whitetopping'

Overlay, Whitetopping
See 'Whitetopping'

Over-Sanded
Containing more sand than would be required for adequate workability and satisfactory finishing characteristics.

Over-Vibrated
Concrete vibrated more than is necessary for good consolidation and elimination of entrapped air.

Over-Wet
The consistency of concrete when it contains more mixing water and hence is of greater slump than is necessary for ready consolidation.

Partial-Depth Patching
Patches for restoring localized areas of surface deterioration; Usually for compression spalling problems, severe scaling, or other surface problems that are within the upper one-third of the slab depth.

Partial-Depth Repair
See 'Partial-Depth Patching'

Particle-Size Distribution
The division of particles of a graded material among various sizes; for concrete materials, usually expressed in terms of cumulative percentages larger or smaller than each of a series of diameters or the percentages within certain ranges of diameter, as determined by sieving.

Paste
Constituent of concrete consisting of cement and water.

Pattern Cracking
Fine openings on concrete surfaces in the form of a pattern; resulting from a decrease in volume of the material near the surface, an increase in volume of the material below the surface, or both.

Pavement
A layer of concrete over such areas as roads, sidewalks, canals, airfields, and those used for storage or parking. See also Rigid Pavement.

Pavement Structure
The combination of surface courses and base/subbase courses placed on a prepared subgrade to support the traffic load.

Paving Train
An assemblage of equipment designed to place and finish a concrete pavement.

PCA
Portland Cement Association

PCC
Portland Cement Concrete

Pea Gravel
Screened gravel the particle sizes of which range between 3/16 and 3/8 inch in diameter.

Percent Fines
Amount, expressed as a percentage, of material in aggregate finer than a given sieve, usually the No. 200 (75 m m) sieve; also, the amount of fine aggregate in a concrete mixture expressed as a percent by absolute volume of the total amount of aggregate.

Performance-Based Specification
Specification that describes the desired levels of fundamental engineering properties (for example, resilient modulus and/or fatigue properties) that are predictors of performance and appear in primary prediction relationships (i.e., models that can be used to predict pavement stress, distress, or performance from combinations of predictors that represent traffic, environmental, roadbed, and struc...

Performance-Related Specification
Specification that describes the desired levels of key materials and construction quality characteristics that have been found to correlate with fundamental engineering properties that predict performance. These characteristics (for example, strength of concrete cores) are amenable to acceptance testing at the time of construction.

Permeable Subbase
Layer consisting of crushed aggregates with a reduced amount of fines to promote drainage and stabilized with Portland cement or bituminous cement.

Phasing
The sequences used by a contractor to build elements of a project.

Pie Tape
Tape used to measure the circumference of the grinding head blades on diamond grinding equipment.

Pitting
A localized disintegration taking the form of cavities at the surface of concrete.

Placement
The process of placing and consolidating concrete; a quantity of concrete placed and finished during a continuous operation; also inappropriately referred to as Pouring.

Placing
The deposition, distribution, and consolidation of freshly mixed concrete in the place where it is to harden; also inappropriately referred to as Pouring.

Plain Bar
A reinforcing bar without surface deformations, or one having deformations that do not conform to the applicable requirements.

Plain Concrete
Concrete without reinforcement.

Plain Pavement
Concrete pavement with relatively short joint spacing and without dowels or reinforcement

Plane of Weakness
The plane along which a body under stress will tend to fracture; may exist by design, by accident, or because of the nature of the structure and its loading.

Plastic
A condition of freshly mixed concrete such that it is readily remoldable and workable, cohesive, and has an ample content of cement and fines, but is not over-wet.

Plastic Consistency
Condition of freshly mixed cement paste, mortar, or concrete such that deformation will be sustained continuously in any direction without rupture; in common usage, concrete with slump of 3 to 4 inches (80 to 100 mm).

Plastic Cracking
Cracking that occurs in the surface of fresh concrete soon after it is placed and while it is still plastic.

Plastic Deformation
Deformation that does not disappear when the force causing the deformation is removed.

Plastic Shrinkage Cracking
Cracks, usually parallel and only a few inches deep and several feet long, in the surface(s) of concrete pavement that are the result of rapid moisture loss through evaporation.

Plasticity
That property of fresh concrete or mortar which determines its resistance to deformation or its ease of molding.

Plasticizer
A material that increases the plasticity of a fresh cement paste, mortar, or concrete.