Sustainable
Precast Concrete
Terminology and References

Terminology

admixtures
those ingredients in concrete other than Portland cement, water, and aggregates that are added to the mixture immediately before or during mixing.

anthropogenic
effects or processes that are derived from human activities, as opposed to natural effects or processes that occur in the environment without human influences.

blast-furnace cement
mixture comprised of Portland cement and higher percentages of blast-furnace slag.

dead load
a static load representing the weight of a structure.

durability
the ability of a structure or a structural element to maintain adequate performance for a given time under expected actions and environmental influences, including air, water, land, natural resources, flora, fauna, humans and their interrelations.

eco-toxicity
an environmental test/study of the toxic effects on nonhuman organisms, populations or communities.

entrain
trap and retain; gas bubbles in liquid or solid or air in concrete

environmental aspect
element of an organization's activities, products and services that can interact with the environment.

environmental burden
an adverse environmental impact.

environmental conditions
chemical, biological or physical influences on a structure that may deteriorate the materials constituting the structure that may affect its reliability in an unfavorable way.

environmental declaration
a presentation of environmentally relevant product information.

environmental impact
any change to the natural environment, whether adverse or beneficial, wholly or partially resulting from an organizations activities, products or services.

eutrophication
a process by which a water body becomes rich in dissolved nutrients

fly ash
finely divided residue resulting from the combustion of ground or powdered coal that is transported from the firebox through the boiler by flue gases. Fly ash is a by-product of coal-fired electric generating plants.

functional unit
the quantified performance of a product system for use as reference unit.

heat capacity
also called thermal capacity, is the ability of matter to store heat. It is the amount of heat required to raise the temperature of one gram of a material one degree Celsius.

high performance concrete (HPC)
concrete made with appropriate materials (superplasticizer, retarder, fly ash, blast furnace slag and silica fume) combined according to a selected mix design and properly mixed, transported, placed, consolidated, and cured to give excellent performance in some properties of concrete, such as high compressive strength, high density, low permeability, long-term mechanical properties, early age strength, toughness, volume stability, or service life in severe environments.

hydraulic cement
the term cement is also commonly used to refer more specifically to powdered materials that develop strong adhesive qualities when combined with water. These materials are more properly known as hydraulic cements. Gypsum plaster, common lime, hydraulic limes, natural pozzolana, and Portland cements are the more common hydraulic cements, with Portland cement being the most important in construction.

integral cost
the sum of environmental burden and economic cost.

life cycle
consecutive and interlinked stages of a product system, from raw material acquisition or generation of natural resources to final disposal.

life cycle assessment (LCA)
a compilation and evaluation of the inputs, outputs and the potential environmental impacts of a product system throughout its life cycle.

life cycle cost (LCC)
all costs associated with the product's life cycle. These include all costs involved in acquisition (research & development, design, production & construction, and phase-in), operation, support and disposal of the product.

life cycle inventory analysis (LCI)
the phase of life cycle assessment involving the compilation and quantification of inputs and outputs for a given product system throughout its life cycle.

live load
all the loads in a building not part of the structure: furniture, people, snow, wind.

material resistance factor
The factored resistance of a concrete member, its cross section and its connections shall be taken as the resistance as calculated using the material resistance factors specified in A23.3.

off-gassing
also known as outgassing, is the emission of chemicals from building materials, furniture, textiles, bedding or other products in a home.

Portland cement
Portland cement is the most common type of cement in general use, as it is a basic ingredient of concrete and mortar. It consists of a mixture of oxides of calcium, silicon and aluminum. Portland cement and similar materials are made by heating limestone (as source of calcium) with clay or sand (as source of silicon) and grinding the product. The resulting powder, when mixed with water, will become a hydrated solid over time.

post-tensioned concrete
a method of reinforcing concrete using high strength stressed tendons to apply compression to concrete after the curing process.

pozzolan cement
A fine powdered material that is added to non-hydraulic lime mortars to accelerate the set. The material possesses little or no cementitious value, but in a finely divided form it will react with calcium hydroxide (lime putty) in the presence of moisture to provide a chemical set.

precast element
a concrete unit cast and cured in a place other than the final location in a structure.
Note: The precast elements described in this section are assumed to be manufactured in a permanent production facility, as opposed to units cast at a building site.

precaster
the organization in charge of the manufacturing of precast elements.

precast product
a precast element designed and manufactured in accordance with a product standard such as CSA Standard A23.4.

prefabrication
the process of manufacturing precast elements.

prestressed concrete -a method for overcoming concrete's natural weakness in tension. Prestressing can be used to produce beams or slabs with a longer span than is practical with ordinary reinforced concrete. Prestressing tendons (generally steel bars or strands) are used to provide a clamping load that produces a compressive stress that offsets the tensile stress that the concrete member would otherwise experience due to a bending load. Prestressing can be accomplished in two ways: pretensioned or post-tensioned concrete.

pretensioned concrete
high tensile steel prestressing tendons (bars or strands) are tensioned in forms before the concrete is placed. The cured concrete adheres and bonds to the tendons. When the tension is released the prestress force is transferred to the concrete as compression.

raw material
a primary or secondary material used to produce a product.

recycling
the collection or processing of waste from a system, that results in a useful application of a product either in the same system or in a different system.

Recycling is the reuse of materials that would otherwise be considered waste. Recycled materials can be derived from pre-consumer waste (materials used in manufacturing) or post-consumer waste (materials discarded by the consumer)

sandwich panels
Insulated precast wall panels consisting of two reinforced or prestressed concrete wythes with a continuous layer of rigid insulation sandwiched between.

self-consolidating concrete (SCC)
a concrete mixture that can be placed purely by means of its own weight with little or no vibration.

supplementary cementing materials (SCM)
fly ash, ground granulated blast-furnace slag, silica fume, and natural pozzolans, such as calcined shale, calcined clay or metakaolin, are materials that, when used in conjunction with Portland or blended cement, contribute to the properties of the hardened concrete through hydraulic or pozzolanic activity or both. These materials are generally categorized as supplementary cementing materials (SCM's) or mineral admixtures. Supplementary cementing materials are added to concrete as part of the total cementing system. They may be used in addition to or as a partial replacement of Portland cement or blended cement in concrete, depending on the properties of the materials and the desired effect on concrete.

setting time
the time required for a specimen of concrete, mortar or cement paste, prepared and tested under standardized conditions, to attain a specified degree of rigidity.

slag
a by-product of smelting ore to purify metals. Slags can be considered to be a mixture of metal oxides. Slag can contain metal sulphides and metal atoms in the elemental form. Slags are generally used as a waste removal mechanism in metal smelting, however they can also serve other purposes such as assisting in smelt temperature control and to minimise re-oxidation of the final bullion product before casting.

slag cement
a supplementary cementitious material often included in contemporary concrete mixes. Slag cement is a hydraulic cement.

surplus material
material left over at the end of a production process.

sustainable development
development that meets the needs of the present without compromising the ability of future generations to meet their own needs.
The three pillars of sustainability are:
(1) Environmental quality,
(2) Social equity and cultural issues
(3) Economic constraints

thermal inertia
a measure of the response of a material to temperature changes within a substance.

triple bottom line
an expanded spectrum of values and criteria for measuring organizational (and societal) success - economic, environmental and social. In practical terms, triple bottom line accounting usually means expanding the traditional company reporting framework to take into account not just financial outcomes but also environmental and social performance.

volatile organic compounds (VOC)
organic chemical compounds that have high enough vapour pressures under normal conditions to significantly vaporize and enter the atmosphere. VOCs are an important outdoor air pollutant.

waste
unwanted or undesired material left over after the completion of a process.

References

  • The Cement Sustainability Initiative – Our Agenda for Action, World Business Council for Sustainable Development, July 2002
  • Canadian Cement Industry Fact Sheet, Portland Cement Association, 2003
  • Guide to Sustainable Design with Concrete, Cement Association of Canada
  • The BREEAM Green Leaf Environmental Assessment Protocol for Multi-residential Buildings, Technical Series 2001-119, Canada Mortgage and Housing Corporation (CMHC)
  • Environmental issues in prefabrication, state-of-art report, bulletin 21, fédération internationale du béton (fib), January 2003
  • Infrastructure Construction Technical Guide, Canadian Precast/ Prestressed Concrete Institute
  • Slag Cement and the Environment, Slag Cement in Concrete No. 22, Slag Cement Association, 2003
  • CSA S478-95(R2000) Guidelines on Durability in Buildings, Canadian Standards Association
  • ATHENATM Environmental Impact Estimator, Athena Sustainable Materials Institute: http://www.environmental-expert.com/
  • Green Building Part II: Precast Concrete LEED Certification, AWARD Magazine, Canada Wide Magazines and Communications Ltd., February 2005
PreCAST CONCRETE... SUSTAINABLE STRUCTURES FOR TOMORROW!
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