Aggregate Aggregates are the most mined materials in the world. Aggregates are a component of composite material such as concrete and asphaltic concrete; the aggregate serves as reinforcement to add strength to the overall composite material. Due to the relatively high hydraulic conductivity value as compared to most soils, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and road side edge drains. Aggregates are also used as base material under foundations, roads, and railroads. In other words, aggregates are used as a stable foundation or road/rail base with predictable, uniform properties (e.g. to help prevent differential settling under the road or building), or as a low-cost extender that binds with more expensive cement or asphalt to form concrete.
Alligator Cracks Interconnected cracks forming a series of small blocks resembling an alligator’s skin or chicken wire, and caused by excessive deflection of the surface over unstable subgrade or lower course of the pavement.
Asphalt Asphalt concrete commonly called asphalt, blacktop, or pavement in North America, is a composite material commonly used to surface roads, parking lots, and airports. It consists of mineral aggregate bound together with asphalt, laid in layers, and compacted.
Asphalt Leveling Course A course of hot mix asphalt of variable thickness use to eliminate irregularities in the contour of and existing surface prior to placing the subsequent course.
Asphalt Milling Small pieces of asphalt produced by mechanically grinding asphalt surfaces are referred to as asphalt millings. Large millings that have a rich, black tint indicating high asphalt cement content are best for asphalt recycling purposes. Surface millings are recommended over full depth millings when choosing asphalt millings to recycle.
Asphalt pavement Structure All of the courses of asphalt-aggregate mixtures placed above the subgrade or improved subgrade.
Asphalt Pavements Pavements consisting of a surface course of asphalt concrete over supporting courses such as asphalt concrete bases, crushed stone, slag, gravel, portland cement concrete, brick, or block pavement.
Backfill Materials used in refilling a cut or other excavation.
Base Course The base course or basecourse in pavements is a layer of material in an asphalt roadway, race track, riding arena, or sporting field that is located directly under the surface layer.
Binder Course The HMA course immediately below the surface course, generally consisting of larger aggregates and less asphalt (by weight) than the surface.
Bitumen The primary use (70%) of asphalt/bitumen is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.
Cast in Place Concrete placed and finished in its final location.
Cement A powdery substance made with calcined lime and clay. It is mixed with water to form mortar or mixed with sand, gravel, and water to make concrete.
Cement Aggregate Ratio The ratio, by weight or volume, of cement to aggregate in concrete.
Coal Tar A dark brown to black cementitious material produced by the destructive distillation of bituminous coal.
Cold Joint The term ‘cold joint’ applies to the interface between an existing asphalt layer and a freshly laid asphalt layer. The temperature of the existing asphalt layer is considerably less than that of the freshly laid asphalt.
Cold Mix A high quality mixture of a binder liquid, with rock, sand and gravel, which is used for asphalt repair work, but does not need to be kept or stored “hot”, like a “hot mix” asphalt. Usually it is used for temporary repairs.
Compaction Compaction is the process by which the bulk density of an aggregate of matter is increased by driving out air. For any soil, for a given amount of compactive effort, the density obtained depends on the moisture content. At very high moisture contents, the maximum dry density is achieved when the soil is compacted to nearly saturation, where (almost) all the air is driven out. At low moisture contents, the soil particles interfere with each other; addition of some moisture will allow greater bulk densities, with a peak density where this effect begins to be counteracted by the saturation of the soil.
Compaction Testing Soil compactors are used to perform test methods which cover laboratory compaction methods used to determine the relationship between molding water content and dry unit weight of soils. Soil placed as engineering fill is compacted to a dense state to obtain satisfactory engineering properties such as, shear strength, compressibility, or permeability. In addition, foundation soils are often compacted to improve their engineering properties. Laboratory compaction tests provide the basis for determining the percent compaction and molding water content needed to achieve the required engineering properties, and for controlling construction to assure that the required compaction and water contents are achieved.
Concrete Concrete is a composite material composed mainly of water, aggregate, and cement. Often, additives and reinforcements are included in the mixture to achieve the desired physical properties of the finished material. When these ingredients are mixed together, they form a fluid mass that is easily molded into shape. Over time, the cement forms a hard matrix which binds the rest of the ingredients together into a durable stone-like material with many uses.
Contamination Refers to a condition where a lesser quality road material permeates and mixes with a higher quality road material. An example of contamination would be mixing native, organic soils with clean imported structural fill material.
Crack An approximately vertical random cleavage of the pavement caused by traffic loading, thermal stresses and/or aging of the binder.
Crack Filler A material that is placed in a pavement crack or joint to fill but not necessarily seal the void created by the crack or joint.
Crack Sealant A material that has adhesive and cohesive properties to seal cracks, joints or other narrow openings (less than 1 ½” wide) in pavements against the entrance or passage of water or other debris.
Curing The development of mechanical properties of the asphalt binder. This occurs after the emulsion has broken and the emulsion particles coalesce and bond to the aggregate.
Emulsion Mechanically produced combination of ingredients which do not normally mix.  For example, asphalt emulsions are made by a procedure which mechanically mills the warm asphalt into minute globules, dispersing them in water, and adding a small amount of an emulsifying agent.
Expansive Potential The potential of a soil to expand (increase in volume) due to absorption of moisture.
Exposed Aggregate Surface texture where cement paste is washed away from concrete slab surface to expose durable chip size aggregates for the riding surface.
Fabric A crack retardant used when overlaying existing pavement. Fabric is placed on the existing surface of pavement before overlaying with new asphalt.
Finished Grade Any surface which has been cut to or built to the elevation indicated for that point. Surface elevation of lawn, driveway or other improved surfaces after completion of grading operations.
Fly Ash A finely divided siliceous material formed during the combustion of coal, coke, or other solid fuels.  May be used to stabilize subgrade.
Fog Seal A process of applying a highly diluted asphalt emulsion in a fine spray (fog) to a roadway surface.  Restores blackness and seals hairline cracks, may prevent or slow oxidation. Not generally used for parking facilities due to tracking. 
Footing Made of concrete and used under chimneys and columns as well as under foundation walls to distribute the weight of the structure over a greater area and thus prevent settling. Footings are placed below the frostline to prevent movement during freezing.
Foundation The lower part of a structure that transmits loads to the soil or bedrock.
Frost Depth The depth at which the ground becomes frozen during the winter season.
Full Depth Asphalt The term full-depth asphalt certifies that the pavement is one in which asphalt mixtures are employed for all courses above the subgrade or improved subgrade. A full-depth asphalt pavement is placed directly on the prepared subgrade.
Grade The soil prepared to support a pavement structure or a pavement system. It is the foundation of the pavement structure.
Grade Beam A foundation element or wall, typically constructed of reinforced concrete, used to span between other foundation elements such as drilled piers.
Green Concrete Concrete that has set but not appreciably hardened.
Groundwater Subsurface water found in the zone of saturation of soils or within fractures in bedrock.
Grout A fluid mixture of portland cement, aggregate and water which is poured into hollow cells or joints in masonry walls to encase steel and bond units together.
Hairline Cracking Barely visible cracks in random pattern in an exposed concrete surface which do not extend to the full depth or thickness of the concrete, and which are due primarily to drying shrinkage.
Heave Upward movement.
Hot Mixed Asphalt (HMA) High-quality, thoroughly controlled hot mixture of asphalt binder (cement) and well-graded, high-quality aggregate, which can be compacted into a uniform dense mass.
Hydration The reaction of cement with water to form a chemical compound in concrete development.
Joint A plane of weakness to control contraction cracking in concrete pavements. A joint can be initiated in plastic concrete or green concrete and shaped with later process.
Joint Cracks Longitudinal separations along the seam between two paving lanes.
Laydown The portion of the asphalt paving process where the asphalt is placed or “laid down” by a paving machine.
Lift A layer or course of paving material applied to a base or a previous layer.
Lime Treatment A subgrade preparation technique in which the subgrade soil and added lime are mechanically mixed and compacted to produce a higher-modulus base material than the in situ material.
Mat, Asphalt A term used to describe the fresh asphalt surface behind the paving machine.  Most commonly used to refer to the asphalt during the laydown and compaction phase of construction.
Moisture Barrier A vapor barrier used under concrete to deter moisture vapor transmission migration.
Native Grade The naturally occurring ground surface.
Native Soil Naturally occurring on site soil sometimes referred to as natural soil.
Overlay An HMA overlay constructed for the purpose of increasing the structural value and ride quality of the pavement system.
Paving Machine (paver) The piece of equipment used to place the asphalt or concrete materials in their finished position.  In asphalt construction these machines should be the appropriate size for the project.  The machine must be able to place a consistently smooth, even finish at the proper depth and provide initial compaction.
Petromat (Paving Fabric) Used as moisture barrier and stress absorbing interlayer beneath asphalt overlay or a chip seal. Petromat is designed to extend the life of all paved areas, including highways, parking areas and airport pavements. Petromat protects pavements from moisture damage while extending the time before the development of pavement cracking by layering the pavement and by providing a stress absorbing interlayer. These cost effective pavement interlayer products significantly lower the life cycle cost of pavements.
Portland Cement Cement consisting predominantly of calcium silicates which react with water to form a hard mass, then transforming into a concrete or cementious product.
Pothole Bowl-shaped openings in the pavement resulting from localized disintegration.
Proctor A method developed by R.R. Proctor for determining the density/moisture relationship in soils. Important in concrete base construction. It is almost universally used to determine the maximum density of any soil that specifications may be properly prepared for field construction requirements.
Prime Coat A coating of asphalt oil, either cutback or specialized emulsion, used to seal the sub-base and/or base material and enhance bonding to the asphalt course.
PSI 1) Pounds per square inch; a measure of the compressive, tensile or flexural strength of concrete as determined by appropriate test. 2) In pavements, the Performance Serviceability Index.
RAP (recycled asphalt product) Recycled Asphalt Pavement, sometimes just called “Recycle”. This is old asphalt, crushed to appropriate specifications, and used either as a loose surface material like Base Course, or more usually as a material as component of new asphalt mixes, whether a Hot Mix or Cold Mix. Old asphalt is 100% recyclable.
Raveling The gradual roughening of the surface texture. As the fine particles “wash” away it leaves the pavement with course rock on the surface and a much rougher texture than when asphalt first laid.
Reflective Cracking Cracks in asphalt overlays that reflect the crack pattern in the pavement structure below it.
Reinforced Concrete Concrete containing adequate reinforcement and designed on the assumption that the two materials act together in resisting forces.
Remove and Replace The act of removing existing pavement or concrete and replacing with new pavement or concrete to restore pavement or concrete to its former condition or to an improved state.
Routing Enlargement of pavement cracks using a specialized machine.  This provides a uniform width reservoir for the sealant.  Proper choice of bit size will result in the proper depth to width ratio.  Properly used this procedure greatly increases the effectiveness and durability of crack sealing.
Sawcut A method to cleanly cut and remove hard pavement under repair.
Scarify To mechanically loosen soil or break down existing soil structure.
Scope of Work The objective and extent of work to be accomplished by the contractor.
Sealcoat A thin surface treatment used to improve the surface texture and protect an asphalt surface. The main types of seal coats are fog seals, sand seals, slurry seals, microsurfacing, cape seals, sandwich seals, and chip seals.
Segregation Segregation is the non-uniform distribution of coarse and fine aggregate components within the asphalt mixture.
Settlement Downward movement.
Slump Test Test used to determine concrete workability.  
Slurry Seal A sealcoating process generally used on runways, streets, and roadways.  In this process the coating is manufactured by the application equipment as it is being applied.  A closely specified blend of graded asphalt emulsion, additives, and aggregate slurry seal classified as Type I, II, or III depending on the size of aggregate used.  A large aggregate slurry seal with additional polymers may also be referred to as micro-surfacing.  Used infrequently on parking areas due to the potential for tracking in hot weather.
Sub-base The strata of material between the underlying native sub-grade and upper base course. Sub-base material is larger than base course. The strata of material between the underlying native subgrade and upper base course. Sub-base material is larger than base course
Subgrade The soil prepared to support a pavement structure or a pavement system. It is the foundation of the pavement structure.
Tack Coat A spray applied asphalt product used to bond the new asphalt to existing surfaces.
Trenching Long and narrow excavation.