Like every industry concrete has jargon and terminology that is often unfamiliar to those who aren’t in the industry – here’s what we mean by the term…
Aggregates—The inert materials used in concrete such as sand, gravel, crushed stone, or even less-typical fillers such as chopped rubber, wood chips, and glass beads.
Air-cooled blast-furnace slag—The material resulting from the solidification of molten blast-furnace slag under atmospheric condition. The material is processed through a screening and crushing plant, and is used for aggregate in concrete.
Architectural cast stone—An architectural precast concrete building unit intended to simulate natural cut stone, used in unit masonry applications.
Architectural precast concrete—A variation on standard concrete that incorporates specialized materials and architectural surface finishes. Architectural precast concrete in this form is both structure and finish.
Architectural thin shell precast—A thin precast wall with a wood or metal stud frame attached. This product provides all of the natural benefits of precast while still allowing construction flexibility. Stud framing enables changes to be made in the future, for items such as electrical wiring and data boxes.
Bell (groove)—The portion of the end of a pipe that overlaps a portion of the end of an adjoining pipe to form a connection.
Beneficiation—(As used in reference to fly ash) the process of separating the by-product of electricity generation (fly ash) into a consistent lower carbon content fly ash product suitable for cement substitution and a carbon-rich material that can be returned as fuel. Blast-furnace slag (BFS)—Formed when iron ore, coke, and a flux (limestone or dolomite) are reduced together in a blast furnace.
Blended cement—A hydraulic cement typically produced by intergrinding portland cement with SCMs.
Bonded post-tensioning—Post-tensioning tendons consist of strands or bars in plastic or corrugated galvanized metal ducts that are grouted after stressing to provide bond with the surrounding concrete and corrosion protection.
Bonded post-tensioning—Uses grout in the duct to bond the strand to the concrete member after stressing. The grout also provides corrosion protection for the strand. Bonded systems are most commonly multi-strand tendons used in bridges; however, they may also be used in buildings.
Box culvert—A reinforced concrete pipe with a rectangular cross section. A culvert is a pipeline intended to convey water under a highway, road, slab, railroad, or other similar facility.
CO2 sequestration—Long-term or permanent storage of CO2 (in this case, within concrete).
Coarse aggregate (CA)—The coarse granular material (such as crushed stone or gravel) used in concrete. CA is defined by the percentage of material passing a certain sieve size (ASTM C33/C33M-08 [ASTM International 2008]).
Dry-mix shotcrete—The process illustrated in Fig. 3.78 in which a dry mixture of cementitious materials and aggregates is conveyed pneumatically through a delivery hose at the end of which water is injected at a nozzle. All ingredients, except water, are thoroughly mixed together before being conveyed through the delivery hose. The cementitious materials and aggregate mixture is fed into a special mechanical feeder or gun, called the delivery equipment. The material is then carried by compressed air through the delivery hose to a nozzle body. The nozzle body has an interior water ring, where water is introduced under pressure and thoroughly mixed with the other ingredients. The material is shot from the nozzle at high velocity onto the receiving surface. Mixing occurs in the nozzle and as the material impacts the surface.
Efflorescence—The white dust-like deposit that is sometimes found on the surface of concrete. As water brings soluble compounds to the surface, the moisture evaporates, leaving the precipitate.
Expanded polystyrene foam (EPS foam)—A closed-cell plastic foam made of pre-expanded polystyrene beads. It is made from a liquid hydrocarbon that is made from petroleum.
Extruded polystyrene foam (XPS foam)—Similar in composition to EPS, but is stiffer, denser, and has a lower thermal conductivity.
Fiber-reinforced concrete—A concrete containing short (typically 3/4 to 2 in. [19 to 51 mm]) discrete fibers of various materials that are distributed randomly throughout the concrete member. Fiber materials include synthetics, steel, carbon, glass, and natural fibers such as wood cellulose, jute, and bamboo.
Fine aggregate (FA)—The finer granular material (such as sand) used in concrete. FA is defined by the percentage of material passing a certain sieve size (ASTM C33/C33M-08 [ASTM International]).
Fly ash—The finely divided residue that results from the combustion of ground or powdered coal and is transported by flue gases from the combustion zone to the particle removal system.
Foundation wall systems—Support the floor slab above so the slab does not provide the entire support for the building. Foundation walls run underground to a footing below the frost line. This type of foundation is used in areas where the ground freezes. Foundation wall systems are also used in conjunction with basements.
Foundation—An element or system that supports a structure (such as a building). Concrete foundations can be cast-in-place or precast (including standard reinforcement and/or post-tensioned reinforcement), precast, or block. In residential construction, it is often both practical and economical to increase these foundations to enclose living space as basements or lower-level living.
Glass fiber-reinforced concrete (GFRC)—A cementitious composite consisting of alkali-resistant glass fibers in a mortar or cement paste matrix that is used in architectural precast concrete applications. Typically, GFRC is used in thin members as cladding or fascia with no structural load-bearing resistance. GFRC, however, can be incorporated as a part of a load-bearing panel with other materials.
Gunite—A term that refers to dry-mix shotcrete. The term was once a proprietary trade name, but became a generic name in 1967.
Heavyweight aggregate (HWA)—Ranges in specific gravity from approximately 3.5 to 7.5 and can produce concretes in a range of unit weight from approximately 180 to 350 lb/ft3 (290 to 560 kg/m3). Heavyweight aggregates are used for applications such as radiation shielding or as a counterweight. Examples of heavyweight aggregate include barite, magnetite, iron, and steel (ACI 221R-96 [ACI Committee 221 1996]).
Infiltration—The flow that enters a pipeline through its connections, joints, and appurtenances, with the flow coming from sources outside of the sewer system. One of these outside sources is groundwater (typically in reference to sanitary sewer pipe).
Insulating aggregate—A nonstructural lightweight aggregate that includes ultra-lightweight aggregates such as vermiculite with a bulk density between 5.5 and 10 lb/ft3 (88 and 160 kg/m3) (ACI 213R-03 [ACI Committee 213 2003]). ASTM C330/C330M-08, C331-05, and C332-09 (ASTM International 2008, 2005, and 2009) cover lightweight aggregate, masonry lightweight aggregate, and insulating aggregate, respectively.
Insulating concrete forms—Stay-in-place forms used with poured concrete walls. The forms are made of foam insulation material and come in a variety of shapes and sizes, including block, panel, and plank systems.
Joint—A connection of two pipeline components, usually pipes, manholes, or box section ends, to continue the flow. Joints can be made by several methods and materials.
Lightweight aggregate—The name given to the group of aggregates with a relative density lower than standard (normalweight) aggregates. These include structural lightweight aggregate and masonry lightweight aggregate, both with a bulk density of less than 70 lb/ft3 (1120 kg/m3) for fine aggregate, and less than 55 lb/ft3 (880 kg/m3) for coarse aggregate.
Metakaolin—A calcined kaolinite (a clay mineral). High reactivity metakaolin has potential advantages for concrete that include increased strength and durability, reduced permeability and shrinkage, and enhanced workability.
Natural pozzolans—Naturally occurring reactive materials such as volcanic ash, diatomaceous earth, pumice, and pumicite. With processing, these materials can serve as SCMs.
Normalweight aggregate—Ranges in density of approximately 75 to 110 lb/ft3 (1200 to 1750 kg/m3). This aggregate is the aggregate commonly used in normalweight concrete.
Nozzleman—The craftsman that physically directs the placement of the shotcrete. The nozzleman is responsible for the quality of the placed shotcrete, and is an important member of a shotcrete crew. The nozzleman must have an understanding of the equipment’s operation, safety procedures, and the material being placed. Critical to all applications of shotcrete is the knowledge and skill level of the nozzleman placing the shotcrete. In assessing nozzleman competency, a two-step qualification process has evolved. The ACI Shotcrete Nozzleman Certification is the industry-recognized credential for identifying individuals who possess the basic knowledge and skill level needed to apply shotcrete. For heavily congested projects, the nozzleman should possess current ACI Certification and be required to shoot test panels that simulate project conditions. Nozzleman Certification is only one part of a larger process to secure a qualified and experienced shotcrete contractor. The process of qualifying a shotcrete contractor should include a thorough check of the shotcrete contractor’s references and project work history, a thorough check of the project work history of the contractor’s key personnel, and resumes of nozzlemen that are to participate on the project. Finally, current ACI Certification should be verified for the on-site nozzlemen.
Pier and grade beam—An option in heavily sloped areas or areas with particularly poor soil. Piers can provide the load distribution down to competent soil for a stable foundation system.
Polyurethane foam—A thermoset plastic with a base composition material derived from a by-product of the oil-refining process.
Post-tensioned concrete—A form of prestressed concrete where the strand is in a duct or sheath and is tensioned after the concrete has hardened. The transfer of force to the concrete occurs at end anchors. Seven-wire strands (single or in groups within a duct) and bars are most common. A post-tensioned tendon includes the steel reinforcement, duct or sheath, and anchorage, in addition to any material inside the duct (such as grout or corrosion inhibiting post-tensioned grease).
Pozzolan—A siliceous (or siliceous and aluminous) material that chemically reacts with calcium hydroxide to form compounds possessing cementitious properties.
Precast concrete—Term used for concrete cast in a location other than its final building position. This includes plant-manufactured concrete products (delivered on site as hardened concrete units for placement) and tilt-up concrete (details in Chapter 22).
Prestressed reinforcement—Reinforcement that is used to precompress a hardened concrete member to resist loading. The precompression can maximize the efficiency of concrete by counteracting tensile forces that cause cracking. The reinforcement is typically high-strength steel seven-wire strand, bar, and, in some cases, wire or bundles of wire. Standard seven-wire prestressing strand is Grade 270 (with a guaranteed ultimate tensile strength of 270 ksi [1862 MPa]), and standard prestressed bar is Grade 150 (with a guaranteed ultimate tensile strength of 150 ksi [1034 MPa]). Seven-wire strands in sizes of 0.5 or 0.6 in. (13 or 15 mm) diameter are most common.
Pretensioned concrete—A form of prestressed concrete where the steel is stressed before casting the concrete. After the concrete hardens, the anchorage points are released, allowing transfer of the strand force through the concrete section.
Recovered mineral components (RMCs)—Recycled industry materials that are able to substitute for conventionally used ingredients, such as cement (primarily) or aggregates. The definition for RMC was introduced by the EPA (U.S. Environmental Protection Agency 2008b).
Recycled concrete aggregate—Aggregate produced from crushing concrete that is no longer in service. The process includes crushing, removal of foreign materials (such as steel reinforcement or wood), washing, and grading. Recycled aggregates tend to have a higher water absorption than virgin aggregates, and the resulting concrete may have lower strength because the aggregate strength is based on the original concrete (Hansen 1986).
Reinforcing bars—Bars that are embedded in concrete members to resist tensile stresses. Conventional reinforcement is a steel bar with deformations to increase bond between the bar and the surrounding concrete. Reinforcing bars can be coated with epoxy or other types of approved coatings to provide a barrier to corrosion. Other types of bars are available, including various corrosion-resistant metals and nonmetallic reinforcement (such as fiber-reinforced polymers).
Rice husk ash (RHA)—A by-product from the burning of rice husks/hulls that has been used as an SCM.
Sandwich wall panel—A wall system consisting of a rigid insulation layer between two layers of concrete. Mechanical connections are used between the interior and exterior layers of concrete.
Shotcrete—A process where concrete material is conveyed through a hose and pneumatically projected at high velocity onto a surface to achieve compaction. Shotcrete is used primarily in the construction of vertical and overhead surfaces. This process allows construction of walls and other structures using only a one-sided form. Tanks, swimming pools, tunnels, mines, sculptured rocks, structural walls, erosion control embankments, retaining walls, and shearwalls are all structures commonly built using shotcrete. In addition, a wide variety of repairs are done with shotcrete.
Silica fume—A very fine, dust-like material generated during silicon metal and ferrosilicon production (also referred to as microsilica or condensed silica fume).
Slab-on-ground—A foundation type that is essentially a slab poured without foundation walls below to transfer load to footings. A thickened edge portion of the slab serves as a footing. Post-tensioning is often used for this type of foundation. Slab-on-ground is appropriate only for areas where the ground does not freeze (unless used with a heated structure and proper insulation to prevent freezing).
Slag cement—Also called ground-granulated blast-furnace slag (GGBFS). GGBFS is dewatered and then screened and ground to form slag cement.
Slag—A broad term covering all nonmetallic by-products resulting from the separation of a metal from its ore. Only granulated blast-furnace slag is used as an SCM. Steel-furnace slag is not used in the production of concrete, but can be used as an additive in the production of portland cement.
Storm sewer—A pipeline that is intended to collect and convey storm water.
Structural lightweight aggregate (SLA)—A strong, stable aggregate that is appropriate for structural concrete applications. It can come directly from materials, such as pumice and scoria, that are mined from volcanic deposits, or can be produced from clays, slates, shales, fly ash, and blast-furnace slag.
Supplementary cementitious materials (SCMs)—Inorganic materials such as slag cement, fly ash, or silica fume, metakaolin, rice husk ash, volcanic ash, pumice, pumicite, and others that react pozzolanically or hydraulically. SCMs substitute for a portion of cement content in a concrete mixture and, for a given set of performance requirements, can reduce the portland cement content. Silica fume, fly ash, and slag cement meet both RMC and SCM characteristics, and have a proven track record in concrete.
Tilt-up concrete—The process of casting concrete building elements on site and lifting them from their casting location to their position in the structure. The concept is applied primarily to structural walls, but beams, columns, light shelves, and other building elements also fit the application.
Unbonded post-tensioning—Post-tensioning tendons consist of single strands protected by PT coating against corrosion and with extruded plastic sheathing to prevent bond with the surrounding concrete. External tendons attached to the concrete at anchorage and deviators only are also unbonded tendons.
Unbonded post-tensioning—Relies on the anchorage for transferring the strand force to the member throughout its life. Unbonded tendons are typically single strands in a sheath filled with a corrosion inhibiting grease. The tendons include an encapsulated anchorage that is also filled with grease. External grouted tendons used in bridges and for repairs for both buildings and bridges are also considered unbonded tendons because they are only attached to the structural member at the anchorages and at other discrete points such as deviators (where there is a change in tendon profile).
Veneered precast concrete (VPC)—Enables architectural precast panels to provide the look of masonry and stone products. VPC is created by attaching a thin layer of material to a precast concrete backing. This is typically done during casting of the precast. The attachment may be through direct bonding with concrete (common with clay products), or by mechanical anchorage with a bond breaker between the precast backer and the veneer (common with stone products). The precast units can be made into almost any shape (flat panels, column covers, curved sections, angled, or more detailed shapes). The thickness and final design of the units are based on the properties of the veneer material.
Welded wire reinforcement (WWR)—A prefabricated reinforcement consisting of a parallel series of high-strength, cold-drawn, or cold-rolled steel wires welded together in square or rectangular grids. Each wire intersection is electrically resistance-welded by a continuous automatic welder. Pressure and welding fuse the intersecting wires into a homogeneous section, and fix all wires in their proper position. Plain wires, deformed wires, or a combination of both may be used in WWR.
Wet-mix shotcrete—The process has all the ingredients—including cement, chemical and mineral admixtures, aggregate, and mixing water—thoroughly mixed together before being pumped into a delivery hose or pipeline. Compressed air is added at the nozzle to increase the material velocity. The mortar or concrete is then shot from the nozzle at high velocity onto the receiving surface.