The term used to describe natural mineral materials used in construction, road building and industry. The most commonly recognized forms are sand, gravel, crushed stone and crushed slag. Under the Aggregate Resource Act, defined as gravel, sand, clay, earth, shale, stone, limestone, dolostone, sandstone, marble, granite, rock or other prescribed material.


Black to brown solid cementitious material that gradually liquefies when heated, in which the constituents are bitumens occurring in solid or semisolid form in nature or obtained by refining petroleum.

Asphalt Cement

Refined asphalt or a combination of refined asphalt and flux, of suitable constituency for the manufacturing of asphaltic concrete.

Asphalt(ic) Concrete

Plant mix of asphalt cement with coarse and fine-graded mineral aggregate, used in the construction of asphalt pavements.

Armour Stone

Large, angular blocks of quarry stone up to approximately 10 tonnes that are placed and fitted on the base of a dike, breakwater or pier. They provide armouring against the erosive action of breaking waves.


Crushed stone or gravel used in stabilizing a roadbed or railroad bed.

Blending Sand

A sand used for blending with another fine aggregate to produce a blended fine aggregate having the desired properties, usually referred to as the minor sand in the blend. See primary fine aggregate.


Fine-grained soil having particles smaller than 2 pm that exhibit plasticity (putty-like property) within a range of water contents, and which exhibits considerable strength when dry.

Clear Stone

A graded aggregate intended for use in drainage, backfill, bedding, and other applications.

Coarse and Fine Aggregates

Coarse aggregate is that which is retained on the 4.75 mm (No. 4) sieve. Fine aggregate is that which passes the 4.75 mm (No. 4) sieve.


Rock fragments, usually rounded or subrounded by abrasion during transport, with an average dimension between 75 mm (3 inches) and 200 mm (8 inches). In glossary of geology uses 64-256 mm. In UK, the dimensions 60-200 mm have been used.


The process of densifying soils or base materials, forcing the particles together, increasing internal friction, resistance to deformation and load-carrying capacity.


A composite material that consists essentially of hydraulic cement and water, often with admixtures, as a binding medium within which is mixed coarse and fine sand and gravel, crushed stone, or by-product aggregates.

Control Chart

A graphical method used to monitor the central tendency and the variability of a material characteristic in order to control production. MTO has published guidelines for control chart construction and use in LS-624.

Crushed Gravel

The product resulting from the crushing of gravel with most coarse particles having at least one face resulting from fracture.

Crushed Particles

A piece of coarse aggregate with at least one well-defined face resulting from fracture. The area of the crushed face should be at least 20 per cent of the total surface area and the edges should be sharp. Particles with smooth faces and rounded edges, or with only small chips removed, are not considered crushed.

Crushed Stone

The product resulting from the crushing of bedrock, boulders or large cobbles, substantially all faces of which resulted from crushing.

Fine Aggregate

Fine aggregate is that material which passes the 4.75 mm (No. 4) sieve.

Fineness Modulus

An empirical factor used to measure the fineness (or coarseness) of fine aggregate. The fineness modulus is defined by both CSA and ASTM. A low number indicates a fine sand, a high number a coarse sand. For supply of concrete fine aggregate, it has been found that a Fineness Modulus of between 2.3 and 3.1 will normally give satisfactory workability. It is good practice to keep the Fineness Modulus within 0.2 to ensure reasonably consistent supply.


Material finer than the 75 pm (No. 200) sieve, composed of very fine sand, silt and clay. Sometimes called dust or dirt.

Flat Particle

A particle whose greatest width, compared to the thickness in a plane perpendicular to the longitudinal axis, exceeds a specific ratio.

Gabion Stone

Durable broken rock or concrete fragments graded in size from 75 mm minimum to 200 mm maximum, used to fill wire gabion baskets for erosion protection works and fortification of slopes and banks.

Granular Subbase

Compacted sand and gravel used immediately under a granular base. In Ontario, specified as Granular B.

Granular A

Ontario Provincial Standards Specifications 1010, granular base material. Mixtures of sand and crushed gravel, crushed rock, blast furnace slag or nickel slag, reclaimed Portland cement concrete, reclaimed asphalt pavement (RAP), crushed post-consumer glass, and/or crushed ceramic material, produced within specific gradation bands, 100% passing by mass through the 26.5 mm (1 inch) sieve. Limits on fines of a maximum of 8% (10% for quarried material) and a requirement for a minimum of 50% crushed particles.

Granular B

Ontario Provincial Standard Specifications 1010, granular subbase material. Mixtures of sand and gravel, crushed rock, blast furnace slag, or nickel slag, reclaimed Portland cement concrete, reclaimed asphalt pavement (RAP), crushed post-consumer glass and/or crushed ceramic material, produced within specified gradation bands, 100% passing by mass through the 150 mm (6 inch) sieve. Granular B Type I does not require crushing. Granular B Type II is 100% crushed and hence may only be obtained from quarried rock, blast furnace slag, or nickel slag. Maximum size of Granular B Type II may be 150 106, or 75 mm. Granular B Type III is similar to Type I except it does not allow the use of uniform or poorly graded fine sands.

Granular C and Granular D 

Ontario Provincial Standard Specifications 1004, an aggregate intended for use as granular fill. Usually fine-grained poorly graded sands for low quality use. 

Granular M 

Ontario Provincial Standard Specifications 1010, granular material. Mixtures of sand and crushed gravel, crushed rock, blast furnace slag or nickel slag, reclaimed Portland cement concrete, reclaimed asphalt pavement (RAP), crushed post-consumer glass, and/or crushed ceramic material, produced within specified gradation bands, 100 per cent passing by mass through the 19 mm (3/4 inch) sieve. Used for construction and maintenance of gravel roads or gravel shoulders adjacent to asphalt pavement. 


Granular material consisting of rounded, water-worn rock fragments 2 mm to 75 mm in diameter, usually found intermixed with sand. Or a mix of stone, sand and fine sized particles used as sub-base, base or surfacing on a gravel road. In some regions, it may be called aggregate. 

High-Density Aggregate 

Aggregate of high relative density used to make high-density concrete. Usually used in counterweights for bridges or for shielding against nuclear radiation. In Ontario, magnetite (iron oxide) and illmentite (titanium dioxide) have been used. 

Hot Mix Asphalt (HMA) 

Hot mixed, hot laid, asphaltic concrete. The terms are used interchangeably. HMA may include recycled or specialty mixes. 


Natural rock of sedimentary origin composed principally of calcium carbonate (calcite). 

Manufactured Sand 

Processed fine aggregate derived from crusher screenings. Processing may include blending of other sands, washing, or classification. Manufactured Sand (OPSS): fine aggregate produced by crushing bedrock or containing crusher screenings. OPSS 1002 requires a minimum acid insoluble residue of 50% if used in concrete pavement exposed to vehicular traffic. Acid insoluble materials (quartz, feldspar) resist polishing. 

Pea Gravel 

Rounded gravel that is hard, durable, opaque, and free of sand, clay or other foreign substances. Pea gravel usually consists of particles between 25 mm and 2.36 mm in diameter (1 inch and No. 8). 

 Physical Property 

An inherent attribute or feature of an aggregate material. Tests are carried out to determine a material’s resistance to weathering or degradation. Physical properties are generally not affected by aggregate production processes. 

Pit (ARA) 

Land or land under water from which unconsolidated aggregate is being or has been excavated, and that has not been rehabilitated , but does not mean land or land under water excavated for a building or structure on the excavation site or in relation to which an order has been made under subsection (3) of the ARA. 

Pit Run 

Material excavated directly from an existing bank in a pit and delivered to the jobsite without further processing e.g. crushing, screening, washing and classifying. 


A surface defect on concrete or asphalt surfaces. A piece of coarse aggregate breaks apart due to freezing and thawing. The overlying concrete mortar of asphalt is forced off the surface, leaving a scar and small conical depression with the offending aggregate at the base of the depression. Usually caused by frost-sensitive aggregate types such as: shale, clay, shaley limestone, chert, porous sandstone, serpentinite, weathered limestone. Popouts can sometimes be cause by alkali-silica reactive aggregate or other chemical reactions such as hydration of lime or magnesium oxide (periclase). 

Quality Assurance (QA) 

A system or series of activities carried out by the Owner to ensure that materials received from the Contractor meet the specified requirements. 

Quality Control (QC) 

A system or series of activities carried out by the Contractor to ensure that materials supplied to the Owner meet the specified requirements. 

Reclaimed Asphalt Pavement (RAP) 

The processed HMA material that is recovered by partial or full depth removal. 

Reclaimed Concrete Material (RCM) 

Removed or processed old Portland cement concrete. 

Recycled aggregate 

Aggregate produced by reclaiming or recovering existing building materials such as asphalt or hydraulic cement concrete and processing the materials to make a new aggregate. Permitted to be used in Granular base and sub-base materials in OPSS 1010 with various restrictions. 


A fractured rock or crushed reclaimed concrete intended for use as slope protection in hydraulic channels placed to prevent erosion or scour. 


Granular material ranging in size from 4.75 mm to 75 pm resulting from natural disintegration of rock or from crushing of rocks. 


Consists entirely of the fine by-product of the crushing of stone, including fines (dust). 


Separation of coarse and fine materials and is not a uniform blend usually caused by poor stockpiling techniques. 

Select Subgrade Material 

Ontario Provincial Standard Specifications 1010 granular fill material. Non-plastic granular or sandy type soil. Used for fill under the granular base and subbase particularly in swamp fill applications. 


Particles passing a 75 pm (No. 200) sieve that are non-plastic or very slightly plastic and that exhibit little or no strength when air-dried. 


Any natural rock deposit or formation of igneous, sedimentary, and/or metamorphic origin, usually employed as a building material. Normally classed as material larger than the 4.75 mm sieve. 


A fertile soil containing a mixture of inorganic material and organic humus. 

*Source: OSSGA Materials Reference Guide.