A - B - C - D - E - F -G - H - I - J - K - L - M - N - P - R - S - T - U - W
abrasion resistance
The ability not to wear out when in contact with other materials, such as truck tires on a highway or water running in a culvert. Strong concrete (one with a high compressive strength) will resist abrasion better than weak concrete. Compressive strength depends on the amount of cementing material in the mix and the way it was cured. The aggregate used will also affect abrasion resistance, because soft aggregates erode faster than hard aggregates.
additions
Also called additives. Chemicals or minerals that are added to cement to enhance product qualities and performance. Examples: adding gypsum to control the setting time of the cement or an air-entraining agent to give freeze thaw resistance. The additions are introduced in the finish milling circuit when the clinker is ground. See admixtures, which are added to the concrete mix.
additives
see additions.
admixtures
Those ingredients in concrete other than Portland cement, water, and aggregates that are added to the mixture immediately before or during mixing. Admixtures are chemical formulations added to the concrete mix that affect the way the plastic or hardened concrete performs, such as freeze-thaw resistance, strength, workability, set time, corrosion inhibition, shrinkage reduction, permeability or flowability. Admixtures also include pigment that give a color to the finished concrete. Compare with additives, which are added to the clinker when it is ground to make cement.
aerated concrete
A low density concrete made of portland cement, cement-silica, cement-pozzolan, lime-pozzolan, lime-silica paste or a combination of these materials. The concrete has a homogeneous cell structure, visible to the eye. Also called cellular concrete. Not to be confused with air-entrained concrete, in which air bubbles are microscopic in size.
aggregates
The general term for the sand and rock used in construction. Fine aggregates are sand and coarse aggregates are gravel or crushed stone. Aggregates are size graded and sold by set size categories, measured as inches or millimeters.
AIA
The American Institute of Architects (AIA) is a professional organization that provides guidance, service and standards to architects around the world. The AIA strives for quality, consistency and safety in the built environment.
AIA/CES
AIA developed a continuing education system (CES) to emphasize learning and participation in professional learning activities. AIA/CES enables architects to keep current, master new knowledge and skills, plan for the future and responsibly meet the role society entrusts to a professional. The Lehigh companies partner with AIA chapters to help architects enhance their knowledge of building practices and technical advancements in cement and concrete.
air entrained concrete
Air-entrained concrete contains billions of microscopic air bubbles that enable the concrete to resist the damaging effects of freezing and thawing. This is achieved by the addition of an air-entraining agent to the cement at the cement plant or to the concrete at the ready-mixed concrete plant. Air- entrained concrete should be used whenever concrete will experience freezing, so is essential for driveways, patios, footpaths and roads in cold or temperate climates. Air-entrainment cannot be achieved when mixing concrete by hand. Not to be confused with aerated concrete, in which the bubbles are visible to the naked eye.
alkali-silica reactivity
Alkali-silica reactivity (ASR) is a reaction between the active mineral constituents of some aggregates and the sodium and potassium alkali hydroxides in concrete. The reactivity is potentially harmful only when it produces significant expansion.
alternative fuels
High heat converts raw materials to cement compounds in the rotary cement kiln. Many materials, sometimes thoughtlessly thrown away by modern society, contain energy that can replace fossil fuels, such as coal. Because of the very hot temperatures (3500 °F or 1800 °C) in the kiln, these alternate fuels are completely combusted. To assure stable production and product quality control, fuel characteristics and burning conditions are constantly monitored. Emmision test results show no significant differences among the different fuel choices. The Lehigh companies replace fossil fuels with expired seed corn, certain fly ashes, carpet remnants, wood chips, old automobile tires, Class A Biosolids, landfill gas, nut shells, used oils, latex paint pigments and selected plastics to make cement.
architectural concrete
Concrete that is permanently exposed to view, and therefore requires special care during preparation, placement and curing. The materials selected for the concrete mix will affect the final look of the concrete, as will the finishing techniques.
ASR see alkali-silica reactivity.
ASTM
Originally founded as American Society of Testing and Materials over 100 years ago, the organization is now called ASTM International. But many citations simply refer to ASTM. The organization expanded beyond the US to provide an open and trustworthy forum for the development of international standards. ASTM International standards have an important role in the information infrastructure that guides design, manufacturing and trade in the global economy.
For example, ASTM International standards define the content of products and the way in which tests are performed to prove the efficacy of products. When testing for compressive strength, slump or other characteristics of cement and concrete, technicians rely on the procedures set down by ASTM International to obtain reliable results.
bag of cement
A common way to ship cement in small quantities for small jobs or for homeowner use. A bag of portland cement is 94 lb (43 kg). Other specialty cements, such as masonry cement, come in smaller quantities, as indicated on the bag.
baghouse
A device that removes dust particles from an air stream before it is discharged to the atmosphere. The baghouse uses the same principle as a home vacuum cleaner, where the dust is collected in bags made of various fabrics, depending on the temperature, abrasiveness or other qualities of the air stream. A small baghouse at a cement plant may be two to three foot wide and ten feet tall. The baghouse for the kiln will be much larger, perhaps 100 feet on a side.
ball mill
Horizontal, cylindrical mill that rotates and grinds materials into raw feed (raw mill) or cement (finish mill) at a cement plant. The grinding media are various sizes of hardened steel balls that break down the material on impact.
barrel of cement
A now-obsolete term once used to measure cement shipped for commerce. A barrel equalled 376 pounds (or four bags). At present, most cement is shipped in bulk by the ton (2000 lbs) or tonne (1000 kg).
batch plant
A central location at which cement, water, aggregates and selected admixtures are mixed to make concrete. The batch is delivered directly to a concrete truck, used to transport the fresh concrete to the job site. The revolving drum of the truck insures complete mixing during transit, so that the concrete is ready for immediate use at the job site. See also ready mixed concrete.
blended hydraulic cements
Cement containing combinations of portland cement, pozzolans, slag or other hydraulic cement.
calciner
A part of the pyro-processing system at a cement plant. A special vessel, usually in line with the kiln, burns fuel to drive off carbon dioxide from the carbonate minerals in the raw mix. In kiln systems without a calciner, the kilns are much longer and calcination occurs in the kiln itself.
calcium aluminate
A special type of cement made with low amounts of iron and slica. These cements are highly resistant to heat and are used to make refractory brick and other materials used to line high temperature processing units, such as blast furnaces at steel plants or ovens at glass factories.
cast-in-place concrete
Cementitious mixture that is deposited as plastic concrete, which will harden as part of the structure, as opposed to pre-cast concrete.
cement see hydraulic cement or portland cement.
Cement Association of Canada
The Cement Association of Canada (CAC) represents 100% of Canada's cement producers.
The Association's mission is to support the effective use of cement and concrete in Canada, thereby contributing to the country's competitiveness and Canadians' quality of life. CAC markets cement and concrete solutions, participates in public affairs and provides technical and engineering support to the users of concrete and other cement-based solutions.
cement paste
Constituent of concrete, mortar grout, plaster consisting of cement and water.
cement plant
An integrated facility that prepares the raw mix, feeds it to the pyro-processing system (kiln), and then grinds the clinker from the kiln system into various cement products. Finished cement is stored in large silos on site or bagged for small quantity use. The cement is shipped by truck, rail or barge to customers, or to regional terminals for customer pick-up. Most cement plants have quarries located nearby to supply the limestone and other raw materials.
Cement Sustainability Initiative
The Cement Sustainability Initiative (CSI) was formed by a group of the major global cement companies and the World Business Council for Sustainable Development to address the challenges of sustainable development. The cement companies are:
- exploring what sustainable development means for the cement industry
- identifying and facilitating actions that companies can take as a group and individually to accelerate the move towards sustainable development
- providing a framework through which other cement companies can participate
- providing a framework for working with external stakeholders
cementitious material
Any material having cementing properties, which contributes to the formation of hydrated calcium slicate compounds. When mixing concrete, the following have cementitious properties: portland cement, blended hydraulic cement, fly ash, ground granulated blast furnace slag, silica fume, calcined clay, metakaolin, calcined shale, and rice husk ash.
class H cement see oil well cement.
clay
Natural mineral having plastic properties and composed of very fine particles. The clay mineral fraction of the soil is usually considered to be particles smaler than 2 µm. Clay minerals are generally hydrous aluminum silicates or occasionally hydrous magnesium silicates.
clinker
The end product of a portland cement kiln. The intense heat of the kiln chemically changes the fine, powdery raw feed to hard, marble-sized nodules. These nodules are quickly air-cooled and then conveyed to the finish mills, where they are finely ground with gypsum and other additives to make various cement products.
coarse aggregate
Natural gravel, crushed stone, or iron blast last-furnace slag, usually larger than 5 mm (0.02 in.) and commonly ranging in size between 9.5 mm and 37.5 mm (3/8 in to 1 1/2 in.)
colored concrete
Concrete containing white cement instead of the more common gray cement. A wide palette of colors is available, depending on the mineral oxide pigments added to the mix. You can make colored concrete by buying cement that has already been proportioned with pigments to give true color, or by adding pigments to the concrete mix.
compaction see consolidation.
compressive strength
The maximum resistance that a concrete, mortar or grout speciment will sustain when loaded axially in compression in a testing machine at a specified rate. Usually expressed as a force per unit of cross-sectional area, such as megapascals per square inch (Mpa) or pounds per square inch (psi). Independent scientific organizations, such as ASTM, set specific procedures that companies must use when performing strength tests, so that all results are fair and comparable.
concrete
Mixture of binding materials and coarse and fine aggregates. Portland cement and water are commonly used as the binder for normal concrete mixes. Other cementitious materials, such as pozzolans and slag, along with other admixtures maybe present in the concrete mix. Normal density concrete has a density of 150 lb/ft3 (2400 kg/m3). see also lightweight concrete and high-density concrete.
consolidation
The process of inducing a closer arrangement of solid particles in freshly mixed and placed concrete, mortar or grout, by reducing voids. The voids are removed through vibration, tamping, rodding, puddling or a combination of these techniques. Also called compaction.
construction joint
A stopping place in the process of construction. A true construction joint allows for good bonding between the existing and the new concrete and prohibits movement at the joint. In structural applications, the location of construction joints must be determined by a structural engineer. In slab and grade applications, construction joints are often located at contraction (control) joint locations and are constructed to allow movement and perform as a contraction joint.
contraction joint
A weakened plane to control the cracking that naturally occurs due to the expected volume change as concrete sets. Such joints may be grooved, sawed or formed. Also called a control joint for concrete flatwork.
crushed stone
Crushed stone is the product resulting from the artificial crushing of rocks, boulders or large cobblestones. The crushing produces faces, all of which possess well-defined edges. Crushed stone comes in a variety of graded sizes depending on the desired application, such as road base, drainage, concrete mixes, or decorative stone.
crusher
A heavy piece of machinery at a quarry that breaks up large rock into smaller pieces. Primary crushers are the first crushers that break up the rock from the quarry. Screens separate out the smaller rock pieces and send them to the secondary crushers, where they will be broken down into yet smaller pieces. Cement plants and rock quarries use various kinds of crushing machinery, including gyratory crushers, impact crushers and hammermills.
curing
The process of maintaining freshly placed concrete, mortar, grout or plaster moist and at a favorable temperature for a suitable period of time during the early stages so that the desired properties can develop in the concrete. Curing helps assure that the satisfactory hydration and hardenening reactions occur in the cementitious materials at an optimal rate.
durability
The ability of portland cement concrete, mortar, grout or plaster to resist weathering action and other conditions, such as chemical attack, freezing and thawing and abrasion. Durability of concrete contributes to the sustainability of structures.
expansion joint
Separation provided between adjoining parts of a structure to allow movement. Such movement often results from changes in temperature.
false set
Rapid development of stiffness in freshly made concrete without an evolution of heat. The rigidity is easily dispelled and plasticity restored by mixing, without adding more water. Also called premature stiffening, hesitation set, early stiffening or rubber set.
ferrocement
One or more layers of steel or wire reinforcement encased in portland cement mortar creating a thin section composite material.
fibers
Thread or threadlike material ranging from 0.05 to 4 mm (0.002 to 0.16 in) in diameter and from 10 to 150 mm (0.5 to 6 in) in length and made of steel, glass, synthetics (plastics) or natural materials. The fibers give added flexibility and strength to the concrete.
fine aggregate
Natural gravel, crushed stone, or iron blast last-furnace slag, usually larger than 5 Mm (0.02 in.). Fine aggregate entirely passes the 9.5 Mm (3/8 in) sieve, and almost passes the 4.75 Mm (no. 4) sieve and is almost completely retained on the 75Mm (No. 200) sieve
finishing
Mechanical operations like screeding, consolidating, floating, troweling, or texturing that establishes the final appearance of any concrete surface.
finish mill
Large rotating cylinder that grinds the cement clinker and selected additives into finished cement. The finished cement is finer that face powder when placed in the silos or packaged in bags.
flatwork
Term used to describe concrete floors, slabs and other flat surfaces for which a finish is usually required.
fly ash
A by-product from coal-fired electric power generating plants. The mineral constituents in coal, such as clay, quartz and shale, do not burn. Instead, they fuse and chemically recombine to form various crystalline and glassy phases of fly ash. The fly ash cools into spherically-shaped particles, usually hollow, where it's collected by electrostatic precipitators or bag houses at the power plant. The fly ash has physical and chemical properties which are advantageous to cement and concrete. Cement and concrete made with fly ash are examples of sustainable development, whereby waste products from one industry are used as feedstock for another industry.
footing
Structural member that transmits load directly to the soil. see also foundation.
forms
Temporary supports for keeping fresh concrete in place until it has hardened to such a degree that it is self-supporting (the structure is now able to support a dead load).
foundation
The structural elements through which load of a structure is transmitted to the earth.
foundry sand
A byproduct of metal casting. Sand is used to make molds for forming molten iron into machinery parts at foundries. With time, the sand can no longer be used. The spent sand contains two of the essential elements for making cement: silica and iron. Cement plants are an ideal end-user of the spent sand, which would otherwise be landfilled.
freeze-thaw resistance
Ability of concrete to with stand cycles of freezing and thawing (see also air-entraining agent and air-entrained concrete).
fresh concrete
Concrete that has been recently mixed and is still workable and plastic.
granulated blast-furnace slag
Glassy, granular material formed when molten slag from the blast furnace is rapidly cooled, such as by quenching by immersion in water. Blast furnace slag contains non-ferrous minerals, primarily calcium silicates and calcium aluminosilicates, that melt at the extreme temperatures present when iron is produced in a blast furnace. Because these minerals are lighter than iron, they separate from the molten iron and float as a liquid layer on top of the molten iron. If the slag is quickly cooled when it is poured off, it provides an excellent raw material for a cement or concrete plant. see ground granulated blast-furnace slag.
Gravel
Gravel is a granular mineral material naturally occurring in water borne geological deposits or manufactured by crushing rock. Gravel is the material predominately retained on the 4.75 mm (No. 4) sieve. A common component of concrete, gravel is often used in road base, backfill or to support utility piping.
green building
Term that refers to designing and building structures that are environmentally sound and follow the tenets of sustainability. Such buildings consume less energy, are durable and can be recycled. During all phases, the building saves resources and places fewer burdens on the environment, protects workers and minimizes health exposures.
green concrete
Concrete that has set, but has not thoroughly hardened. It will not support any significant load without deformation.
ground granulated blast-furnace slag (GGBFS)
Finely ground granulated blast-furnace slag that has hydraulic cement properties.
grout
A mixture of cementitious material and water, with or without aggregate, proportioned to create a pourable consistency, without a segregation of the components.
gypsum
A natural mineral, di-hydrated calcium sulfate, that is added to clinker in the finish milling circuit. (see additive). Gypsum helps control the rate at which concrete hardens by slowing down the hydration reactions. The slower rate gives concrete finishers enough time to work the plastic concrete before it hardens. Cement plants can also add synthetic gypsum, a recycled byproduct from the electric power industry, to control the set time in its finished products.
hardened concrete
Concrete that is in a solid state and has developed a certain strength.
heat island effect
Elevated temperature observed in an area, especially urban settings. The concentration of energy use, combined with a density of heat absorptive surfaces and lack of natural cooling breezes, causes structures to retain heat and temperature to rise locally. The heat island effect can be as much as 10°F. Light-colored surfaces on buildings and pavements, such as achieved with concrete, significantly reduce the heat island effect.
heat of hydration
Heat evolved by chemical reactions with water. For example, the setting and hardening of concrete generates heat, when the cementitious materials react with water. The heat evolved by the reaction is called the heat of hydration.
high-density concrete
Concrete, usually made with very dense (heavy) aggregates, such as those made from barite, magnetite or hematite, so that the density of the concrete is very high. High density concrete has special applications, for example, radiation shielding.
high early strength cement
Portland cement that reaches a given level of strength earlier than normal portland cement. Used in lining tunnels or other applications where the concrete must attain an adequate strength level quickly. see Type III cement.
high-strength concrete
Concrete with a designed compressive strength of at least 41 MPa (6,000 psi). Some high-strength concretes are well over 70 Mpa (10,000 psi) in compressive strength.
hydration
In concrete, mortar, grout and plaster, the chemical reaction between hydraulic cement and water in which new compounds with strength-producing properties are formed. The hydration reaction is exothermic, or generates heat. see heat of hydration.
hydraulic cement
Cement that sets and hardens by chemical reaction with water, and is capable of doing so under water. (see also portland cement)
Insulated Concrete Forms
Insulated Concrete Forms (ICFs) are forms for cast-in-place, reinforced concrete walls. The forms, usually made with interlocking plastic blocks, are left in place permanently as thermal and acoustic insulation and space to run electrical wiring and plumbing. The forms also serve as backing for gypsum panels or other finishing materials on the inside and stucco, brick or siding on the outside.
isolation joint
Separation that allows adjoining parts of a structure to move freely from one another, both in the horizontal and vertical directions.
kiln
Rotary furnace used in cement manufacture to heat and chemically combine raw inorganic materials, such as limestone, sand and clay, into calcium silicate and calcium aluminosilicate clinker. The kiln is an inclined, long cylinder, lined with refractory. Raw feed is introduced to the elevated end. The rotation of the kiln gradually moves the raw feed down the slope of the kiln. The kiln is fired at the lower end and the exhaust hot gases travel up the kiln. The counter-current flow transfers the heat in the gases to the incoming raw feed, so that the raw feed chemically changes into portland cement clinker.
LEED®
Leadership in Energy and Environmental Design (LEED) is a voluntary, consensus-based standard in the US to develop high-performance, sustainable buildings. Members of the U.S. Green Building Council representing all segments of the building industry developed LEED and continue to contribute to its evolution. LEED provides a complete framework for assessing building performance and meeting sustainability goals.
lightweight aggregate
Lightweight aggregate is made by heating up certain kinds of shale. Gases in the shale expand, causing the shale to bloat. The product now has lots of bubbles, making it much lighter than normal aggregates. Lightweight aggregate, with a specific gravity of about 1.7, is stable, unreactive, chemically resistant, with a ceramic matrix and a non-interconnected void system. The pieces are crushed, sized and graded for special applications where a combination of strength and reduced weight are needed. Our lightweight aggregates are manufactured to comply with the applicable ASTM International Standards.
lightweight concrete
Concrete, usually made with lightweight aggregates, so that the density is less than normal concrete. The oven-dry density of lightweight concrete is less than 50 lb/ft3 (80 kg/m3).
lime sludge
A waste product generated by the paper recycling industry and usable as a alternative raw material for cement making.
limestone
Sedimentary rock, composed primarily of calcium carbonate. When finely ground, one of the primary components of the raw feed to a cement kiln, usually providing 80 to 90%, by weight, of the raw feed.
low-heat cement
Portland cement that has a low heat of hydration, also called Type IV cement. Specifiers will use this cement when they wish to control the amount of heat generated in the concrete as the cement hydrates, such as in very large pours.
masonry
Concrete masonry units, clay brick, structural clay tile, stone, terra cotta, and the like, or combinations, bonded with mortar, dry-stacked, or anchored with metal connectors to form walls, building elements, pavements and other structures.
masonry cement
Hydraulic cement, primarily used in masonry and plastering construction, consisting of a mixture of portland cement or blended hydraulic cement, and plasticizing materials (such as limestone, hydrated or hydraulic lime) together with other materials introduced to enhance one or more properties such as setting time, workability, water retention and durability.
mill scale
Recycled from the iron and steel industries and used as an ingredient in the raw mix at a cement plant. As heated slabs of raw steel are shaped or rolled into coils, small flakes form on the edges of the steel slab. Workers at the steel plant collect the flakes where they become useful raw material for the cement kiln.
mix design
Preferably called mixture proportion. The proportions of ingredients in a concrete mixture that are the most economical combination, while still providing the necessary qualities and performance desired in the concrete.
moderate heat cement
Portland cement in which a moderate amount of heat is generated as the cement hydrates in the concrete mix. Also known as Type II cement or modified cement.
mortar
Mixture of cementitious materials, fine aggregates and water, which may contain admixtures, and is usully used to bond masonry units, such as concrete block, clay brick or natural stone.
mortar cement
Hydraulic cement, primarily used in masonry construction, consisting of a mixture of portland or blended hydraulic cement and plasticizing materials (such as limestone, hydrated or hydraulic lime) together with other materials introduced to enhance one or more properties such as setting time, workability, water retention and durability. Mortar cement and masonry cement are similar in use and function. However specifications for mortar cement usually require lower air contents and they include a flexural bond strength requirement.
MSDS
Material Safety Data Sheet. A document required in the US and Canada for almost all products to help protect worker health and safety. The MSDS contains basic information about the composition of the material, health and safety precautions that workers should use and information about the proper disposal of the material.
natural cement
A hydraulic cement made by calcining an argillaceous limestone (limestone containing clay or shale minerals). Because sintering temperatures are not reached in natural cement kilns, the cement is deficient in the di- and tri-calcium aluminosilicates present in portland cement. Natural cement was widely used in Europe and North America between the 1820s and 1890s and was an improvement over earlier lime-based cements. As the technology for making portland cement became more widespread, and its superior qualities became appreciated, portland cement replaced natural cement. By 1920, almost all hydraulic cement sold in the US was portland cement.
normal portland cement
Used in the US to denote the most commonly used type of portland cement. Also known as Type I cement.
normal weight concrete
Class of concrete made with normal density aggregates, usually crushed stone or gravel, having a density of approximately 2400 kg/m3 (150 lb/ft3) (see also lightweight concrete and high density concrete.)
no-slump concrete
Concrete having a slump less than 6 mm (1/4 in). Such concrete is very stiff, with an extremely dry consistency.
oil well cement
A special hydraulic cement suitable for use under high pressure and temperature. This cement is commonly required for sealing water and gas pockets, and setting casing during the drilling and repair of wells. The cement will often contain retarders to meet the performance standards. It is also known for its ability to expand as it cures, so that it forms a good seal. Commonly called Class H cement.
paver
Pre-cast concrete brick, of suitable shape and color for use in paving projects, especially sidewalks and driveways.
pervious concrete
Also called no fines concrete or porous concrete. Concrete containing insufficient or no fines to fill the voids between aggregate particles in a concrete mixture. The coarse aggregate particles are coated with a cement and water paste to bond the particles at their contact points. The resulting concrete contains an interconnected pore system allowing storm water to drain through the concrete to the subbase below. Pervious concrete is an example of sustainability, where the built environment incorporates methods to protect and enhance the environment. The stormwater travels through the pavement, so that it can recharge the groundwater directly.
placement/placing
Process of depositing, distributing and consolidating fresh concrete into the place it will harden. Sometimes called by the obsolete name "pouring."
plaster
Cementitious material, or a mixture of cementitious material and very fine aggregate that forms a plastic coating on a surface when mixed with water. The plastic mixture adheres to the surface and hardens. Before it hardens, the finisher (or plasterer) will treat the surface to give a desired finish. Also refers to the finished, hardened surface material.
plasticity
That property of freshly mixed concrete, mortar, grout or plaster that determines its workability, resistance to deformation and molding characteristics of the resultant mortar, plaster or stucco.
portland blast-furnace slag cement
Hydraulic cement consisting of: (1) an intimately interground mixture of portland-cement clinker and granulated blast-furnace slag; (2) an intimate and uniform blend of portland cement and fine granulated blast furnace slag; or (3) finely ground blast furnace slag, with or without additions.
portland cement
Calcium silicate hydraulic cement produced by pulverizing portland cement clinker and usually containing calcium sulfate and other compounds. (see also hydraulic cement.) When first patented in Egland in 1836, the new product received the name portland cement, because concrete made with the new cement resembled building stone from the Isle of Portland off the coast of England.
pozzolan
Siliceous or siliceous and aluminous materials like flyash or silica fume, which in itself possesses little or no cementing value. If the material is in a finely divided form water is present, it will chemically react with calcium hydroxide at ordinary temperatures to form compounds with cementitious properties. There are both natural such as volcanic ash and manufactured such as silicefume pozzolans.
pre-cast concrete
Concrete cast in forms in a controlled environment and allowed to achieve a specified strength prior to placement on location. Compare with cast-in-place concrete.
preheater
A part of the pyro-processing sytem at a cement plant that preheats the fine raw mix before calcination occurs. Usually a tower of one or more vessels in which the raw feed enter the top and exhaust gases from the kiln enter from the bottom. The counter-current flow transfers heat from the gases to the raw feed. The preheater is in line with the kiln so that the heated raw feed enters the kiln after passing through the preheater.
prestressed concrete
Concrete in which compressive stresses are induced by high-strength steel tendons or bars in a concrete element before loads are applied to the element which will balance the tensile stresses imposed in the element during service. This may be accomplished by the following: post-tensioning - a method of prestressing in which the tendons or bars are tensioned after the concrete has hardened; or pre-tensioning - a method of prestressing in which the tendons are tensioned before the concrete is placed.
raw mill
Large rotating cylinder that grinds the raw materials, such a limestone, sand, clay, shale, and mill scale, into the raw feed mixture that is fed to the pyro-processing system. The raw feed is extremely fine, much finer than flour. It is so fine that it flows like water.
ready mixed concrete
Concrete made for delivery to a purchaser or job site in a fresh state. See also batch plant.
recycled concrete
Hardened concrete that has come to the end of its life is crushed and the steel removed. The steel is recycled to a steel plant and the concrete is screened and sized for the use as aggregate. Road base is one of the most common uses for recycled concrete.
reinforced concrete
Concrete to which tensile-bearing materials such as steel rods or metal wires are added to increase the tensile strength of the concrete.
retarder
Admixture to concrete that will slow down the setting time and hardening of the concrete.
roller-compacted concrete (RCC)
A zero-slump mix of aggregates, cementitious materials and water that is consolidated by rolling the plastic concrete with vibratory rollers. RCC is used to make dams, industrial pavements, storage areas and composite pavements for highways and streets.
Roman cement
Misnomer for certain brown-colored natural cements produced in the 1800s. The brown color yielded a brown concrete, which resembled the weathered concrete of structures dating back to Roman times. The Romans used a mixture of lime and volcanic ash (a natural pozzolan) that performed as a hydraulic cement. The Romans did not use "Roman cement."
Sand
Sand is a fine mineral material occurring naturally or manufactured with a particle size passing the 9.5 mm (3/8" sieve) and almost passing the 4.75 mm (No. 4) sieve. This material is predominantly retained on the 75 µ m (No. 200) sieve and results from the natural erosion of sandstones or from processing sandstone and other types of rock. Sand is mainly used as a component of concrete or used to facilitate drainage or provide stability under concrete slabs, sidewalks and driveways
scaling
Disintegration or flaking of the surface of concrete, usually due to freeze-thaw exposure or the application of de-icing chemicals.
self-consolidating concrete
Also called self-compacting concrete. Concrete with a high workability that requires very little or no vibration or other mechanical means to consolidate the plastic concrete. This type of concrete is especially useful where it would be difficult or inadvisable to apply vibration, due to shape or location.
silica fume
Very fine non-crystaline silica which is a by-product from the production of silicon and ferrosilicon alloys in an electric arc furnace. Used as a pozzolan in concrete.
slag cements
Hydraulic cement made from a uniform blend of ground, granulated blast furnace slag, with or without portland cement or hydrated lime.
slump
Measure of the consistency of freshly mixed concrete. The technical specialist prepares a cone of fresh concrete and then measures the amount that the cone subsides. This difference, usually measured in inches, is the slump. A zero slump concrete would not subside significant amount (less than ¼ in or 6 cm).
soil cement
Mixture of soil and metered amounts of portland cement and water compacted to a high density. The mixture is primarily used as a base for pavement. Also called cement-stabilized soil.
solidification/stabilization
Addition of cementitious materials to a semi-wet or liquid mass. The hydration reactions incorporate much of the excess water, rendering the mass more stable and able to bear weight. Often used in low areas, prior to construction. The waste management industry uses cement to help solidify waste materials so they no longer pose a threat to human health or the environment.
stucco
Also called portland cement plaster. The term "stucco" is widely used to describe the cement plaster used for coating exterior surfaces of buildings. However, in some geographical areas, "stucco" only refers to the factory-prepared finish coat mixtures.
sulfate resistance
Ability to resist sulfate attack. Special cements, with low tri-calcium aluminate content, are used in the concrete mix to withstand the attack by dissolved sulfates present in water or soils that may later come in contact with the concrete. Called Type V cement in the US. The sulfates react primarily with calcium aluminum hydrates in the concrete and cause the concrete to deteriorate.
sustainable
Sustainability refers to the ability to build for today and tomorrow without depleting future resources. A growing global population is beginning to strain the finite resources available on the planet. Sustainability seeks to balance the economic, social and environmental impacts, recognizing that population growth will continue. Sustainable development brings this evaluation to the design and construction industry.
tensile stength
The amount of stress that concrete is able to withstand when loaded axially, before breaking. Usually expressed as a force per unit of cross-sectional area, such as megapascals per square inch (Mpa) or pounds per square inch (psi). Independent scientific organizations, such as ASTM, set specific procedures that companies must use when performing strength tests, so that all results are fair and comparable.
terrazzo
Concrete made with a marble aggregate that is later ground to a very smooth finish for decorative walls and floors. Terrazzo may be pre-cast or cast-in-place.
Type I cement see normal portland cement.
Type II cement see moderate heat cement.
Type III cement see high early strength cement.
Type IV cement see low heat cement.
Type V cement see sulfate resistance or oil well cement.
US Green Building Council
US Green Building Council (USGBC) is the leading coalition in the US construction industry that promotes buildings that are environmentally responsible, profitable and healthy places to live and work. USGBC formulated the LEED® program to guide architects, engineers and others on ways to create sustainable buildings.
water to cementing materials ratio
Ratio of the mass of water to the mass of the cementing materials in concrete, including portland cement, blended cement, hydraulic cement, slag, fly ash, silica fume, calcined clay, metakaolin, calcined shale and rice hull ash.
water to cement ratio (w/c)
Ratio of the mass of water to the mass of cement in a concrete mix.
white portland cement
Portland cement made with very low amounts of iron and fired in a reducing flame. Such cement requires very pure raw materials so that the resulting cement produces a true white concrete or cement paste. Such cements are desired by architects or other users who wish to produce white concrete. Pigments added to white cements yield true colors, not affected by the gray base color of other portland cements.
white-topping
Practice where a failed paved surface, most commonly asphaltic roadways, is removed and replaced with an overlay of concrete. The asphalt is ground away until a stable base is reached, usually about two to four inches and replaced with an equal thickness of concrete. The practice is a fast, efficient and cost-effective way to restore badly-rutted or damaged asphalt roadways that were not able to withstand heavy traffic.
workability
That property of fresh-mixed concrete, mortar, grout or paster that determines its working characteristics. Workability relates to the ease with which concrete is mixed, placed, molded and finished.
Credits:
ACI handbook 116R-16
PCA www.cement.org
CAC www.cement.ca
