-
A
-
B
-
C
-
D
-
E
-
F
-
G
-
H
-
I
-
L
-
M
A
- Additives
-
Additives improve the properties of concrete: setting time, viscosity, porosity, mechanical resistance, etc. There are 9 families of additive: accelerators, retarders, plasticizers, flow promoters, air-entraining agents, anti-freezers, water-repellents and curing agents.
- Aggregates
-
Aggregates are small rock fragments (0.08 to 80 mm) of mineral origin. Aggregates come in different types: maritime, fluvial and terrestrial. They may be sand, gravel or crushed gravel. Aggregates, mixed with water and cement, are essential for the production of concrete.
B
- Ballast
-
The bed of stone, gravel or crushed rock laid down as the base for a railway line is called "ballast". Ballast can be recycled and used as an alternative material.
- Bauxite
-
Bauxite is an aluminum ore. It is named after the village of Baux-de-Provence, France, where it was discovered.
- Bituminous concrete
-
Bituminous concretes are made of gravel, sand, filler and bitumen (a petroleum product), which acts as a binder. They are generally used as the top layer of road surfaces.
- Bituminous concrete
-
Bituminous concretes are made of gravel, sand, filler and bitumen (a petroleum product), which acts as a binder. They are generally used as the top layer of road surfaces.
C
- Cantilever
-
Cantilever refers to the section of a construction which extends into an overhang, i.e. beyond its supports. A cornice or a balcony, for example, are cantilevered constructions.
- Carbon dioxide
-
Carbon dioxide (CO2) is a greenhouse gas. It is produced by the combustion of organic compounds and the respiratory systems of animals and plants.
The cement industry naturally emits CO2:
- 60% of emissions are due to the physical-chemical transformation of raw materials at high temperatures,
- 40% result from the combustion needed to heat the cement furnace to 1500°C.
- Cement
-
Cement is a hydraulic bonding agent which is obtained by heating, then grinding, a mixture of limestone and clay. Most cements are made from clinker and additives and are usually used in the form of a powder. Cement sets when mixed with water. Combined with sand and aggregates (sand or gravel), it turns into rock-hard concrete or mortar.
- Cement paste
-
An unhardened or hardened mixture of finely divided hydraulic cementitious material and water
- Cementitious
-
Called "cement additions", these minerals are used in varying proportions during the last phase of the cement production process. The additives make it possible to obtain a range of cements with different properties. They can be:
- of natural origin, for example limestone or volcanic and sedimentary rock (pozzolanic rock),
- of industrial origin, for example by-products of the steel industry (slag from blast furnaces), the microchip industry (silica fume), and coal-fired power plants (pulverised fuel ash).
The use of cementitious additives reduces CO2 emissions:
firstly, because using additives in cement production automatically reduces the proportion of clinker (the decarbonation phase of clinker production releases a lot of CO2), secondly, because it uses industrial waste which would otherwise have been discarded and treated by the local authority. - Clinker
-
Clinker is the main ingredient in cement. These hardened granules are obtained by firing a mixture of approximately 80% limestone and 20% clay to a high temperature. Cement is obtained by grinding clinker and, in some cases, supplementing it with additives.
- Compressive strength
-
Amount of "pressing" pressure a material can resist. It is measures in mpa, PSI or PSF.
- Concrete
-
Concrete is a building material made by mixing water, aggregates and sand with a binding agent (usually cement) and, if necessary, with additions. This mixture is made on building sites and factories.
The characteristics of a concrete can vary greatly depending on the choice of cement and cement-aggregate ratio, the type of aggregate used, the inclusion of additions, etc. The way concretes are used and surface treated can also have an impact on their performance and appearance. So concrete is reconstituted stone and is sometimes referred to as "liquid stone". - Concrete plant
-
Concrete plants are industrial sites where all of the raw materials for concrete production are brought together. They are often transported by barge.
In the mixing building, the raw materials and additions are dosed and put in the mixer, where they form a homogenous concrete mixture. The wet concrete is then transported to work sites in cement trucks equipped with revolving drums.
- Crushed gravel
-
Crushed gravel is produced by crushing hard rock. These gravel samples measure from 5 to 25 mm.
Crushed gravel is used as an aggregate during concrete manufacture and as a paving base for road surfaces. - Crushing and grinding
-
Crushing is one phase in the aggregate production process. After scalping (removal of unwanted clay, etc.), the materials are crushed and ground (broken into smaller pieces).
D
- Deck
-
Collection of components arranged side by side to form the floor of a walkway, footbridge, platform etc.
- Ductility
-
Ductility refers to a material's capacity to be stretched or bent without breaking. A material which does not have this quality is fragile.
E
- Early stiffening
-
Rapid loss of plasticity or rapid development of rigidity in freshly mixed hydraulic cement paste, mortar, concrete
- Early-day strength
-
Compressive strength measured on the first, third and seventh day
F
- False set
-
Early stiffening with little evolution of considerable heat, which cannot be dispelled by further mixing without the addition of water
- Fiber-reinforced concrete
-
Fiber-reinforced concrete contains an array of different fibers (polypropylene, metal, fiberglass, carbon, etc.) that create a reinforced mesh, improving the concrete's solidity and resistance to cracking. This is a rapidly developing approach to reinforcing concrete.
- Filler
-
An inert, finely ground mineral material that is included in paints and hydraulic binders (cement) to reduce costs and, in some cases, modify their physical characteristics. In this respect, they are considered to be a cement additive.
- Final Setting Time (FST)
-
The number of minutes it takes for cement, concrete or mortar to harden and start developing strength
- Fire retardant
-
A material is fire retardant if it prevents or slows the inflammation of a naturally combustible object. Fire retardant properties can result either from the addition of chemicals to the mass of a material or from the surface application of a fire retardant product. Gypsum has fire retardant properties.
- Fly ash
-
Fly ash is hydrophilic and can be used as a cementitious additive. The ash, which is collected from chimney filters in coal-fired power plants, is composed of vitreous silica, alumina, iron oxide and lime.
They can be used as a partial substitute for clinker and thus help to reduce CO2 emissions. - Forms (shuttering)
-
A form is a temporary mold into which liquid concrete is poured. The form is stripped away after the concrete has set. The form must be strong enough to bear the weight and/or pressure of the wet concrete without any change to its initial shape.
- Foundation
-
The foundations of structure distribute its weight and ensure its stability. They are made of poured concrete. The design of foundations must allow them to bear the weight of the construction and prevent any vertical or lateral shifting.
G
- Granular stacking
-
Granular stacking is a technique which improves the compactness and resistance of concrete and reduces porosity. Granular stacking is achieved by replacing part of the water with fine and ultra-fine grains that fill in the spaces between larger grains. The result is more consistent, more fluid concrete which becomes more compact upon setting.
- Grout
-
Grout is a mix of gypsum or cement mortar which is liquid enough to be poured or pumped to fill joints and fissures.
- Gypsum
-
Gypsum is a construction material made by firing the gypsum mineral in a kiln and then grinding it. It can be used as a paste or as pre-fabricated boards. Mixed with water, it forms a gel that sets within a few minutes and then hardens. It is widely used for interiors: coatings, dry partitions, ceilings and wall linings in the form of tiles or plasterboard. It has several important properties: accoustic and thermal insulation, fire resistance, etc.
H
- Hydraulicity
-
Hydraulicity is the extent to which a material hardens in the presence of water.
I
- Initial Setting Time (IST)
-
The number of minutes it takes for cement, concrete or mortar to start to lose its plastic properties
L
- Later-day strength
-
Compressive strength measured on the 28th and 56th day and beyond
- Life Cycle Assessment
-
A building's Life Cycle Assessment (LCA) quantifies its environmental impact according to several criteria:
- primary energy consumption,
- greenhouse gas emissions,
- air pollution,
- water consumption,
- transport,
- waste production,
- a material's lifecycle (from extraction to recycling or landfilling).
LCA is now a part of the Group's research methods. A truly scientific approach, this objective analysis uses a standardized methodology (ISO 14040), and questions many concepts taken for granted in construction. - Lime
-
Lime is a binding agent obtained from the calcination of limestone. Limes are divided into 2 categories depending on whether they are set by exposure to carbon dioxide (slaked lime) or to water (hydraulic lime).
Slaked lime is mainly used in traditional finishing plasters, pointing mortars and whitewashes. Hydraulic lime contains clay, giving it similar properties to cement and making it suitable for use as an undercoat or render.
M
- Mechanical resistance
-
A material's mechanical resistance is its resistance to tearing off, bending, water steam diffusion and various physical constraints.
- Mortar
-
Mortar is a mixture of cement, sand (an inert component which provides body) and water, which may be complemented with additives, supplements and colored pigments. Unlike concrete, mortar does not include aggregates. It may be prepared on site or delivered from a mixing plant. Mortars are used for bonding (to join cut or molded elements), for cladding (waterproofing and dressing of walls and coverings, finishing of floors), and for a number of other purposes including jointing, rendering, insulating, sealing and plugging.
N
- Natural gypsum
-
Natural gypsum is a mineral extracted from quarries in the form of small white crystals, clumped together in blocks. It comes from a sedimentary rock made of calcium sulfate dehydrate.
- Normal consistency
-
A degree of plasticity of a hydraulic cement paste that is appropriate for testing as measured by a stipulated method
P
- Physico-chemical resistance
-
A material's physico-chemical resistance is its resistance to various physical constraints such as impacts, abrasion wearing effects, corrosion by chemical agents, destruction by water, high temperatures, frost, wind, etc.
- Portland
-
The name ‘Portland' comes from a peninsula in Great Britain.
The gray stone of this area has a composition and appearance similar to that of cement. Portland cement is the generic name of basic, highly-efficient hydraulic cements. They are obtained by grinding clinker, which is made from firing a carefully-composed mixture of limestone, silica, alumina and, in some cases, other products. - Pozzolan
-
Pozzolan is named after Pozzouli, a region near Naples, Italy, which is rich in volcanic ash.
Natural pozzolan is a light siliceous mineral produced during basaltic volcanic eruptions. It contains silica, alumina and iron oxide (which gives it a red color), as well as lime and magnesium oxide. Pozzolan is used as a cement additive.
Artificial pozzolans with the same properties as natural pozzolans can be created by heating clays, basalts or schists. - Pre-stressed concrete
-
Steel reinforcements give concrete a higher tensile strength. This is the principle of reinforced concrete. However, the elasticity of steel is sometimes not enough to ensure the safety of a structure. In this case, specific reinforcing techniques are used.
These consist of stressing the reinforcement (like a spring) to compress the unloaded concrete before it enters service. The stretching takes place before the concrete is poured into the forms (pre-tensioning) or after pouring (post-tensioning).
Once the structure is in place and comes under stress, the reinforcing stretches out and the concrete tends to decompress. It is able to do so without bending because it was previously partially compressed. - Prefabricated concrete
-
An inconvenience of conventional concrete is its drying time, which slows construction on the building site and increases costs. Prefabricated or pre-cast concrete helps to speed up construction work. Concrete pieces (columns, beams or slabs) are formed and prepared in a workshop onsite or close to the site and then transported to the right location. This has the advantage of reducing the length of the construction phase and limiting the impact on local populations.
- Prestressing
-
The technique of combining concrete's high level of resistance to compression with steel cables' resistance to traction, by placing them in permanent opposition. With resistance equal to a traditional reinforced concrete beam, a prestressed beam allows a significant increase in weight and a reduction in the cost of load-bearing structures.
- Prestressing by post-tensioning
-
Post-tensioning is a prestressing technique, as opposed to prestressing by pre-tensioning. This procedure, also called "prestressing with cables", involves pouring concrete sections after placing tubular ducts into the mold. After the concrete has hardened, steel cable is passed through the duct and then tensioned. This technique is used for strong load-bearing elements (superstructures of art works, footbridges, very long or cantilevered beams, etc.)
- Prestressing by pre-tensioning
-
Pre-tensioning is a prestressing technique, as opposed to prestressing by post-tensioning. This procedure, also called "prestressing with tendons", involves pouring the concrete after placing steel tendons into the mold. After the shuttering is removed, the tension of the tendons does not relax inside the concrete section. This technique applies to sections of limited dimensions (girders, sleepers, posts, etc.)
R
- Raw mix
-
Raw mix is made of finely ground rock thinned with water. It is dosed and homogenized before being put into a kiln to make cement.
- Recycled and artificial aggregates
-
These materials are obtained during the demolition of buildings and roads or as a by-product of industrial processes. Their use reduces the consumption of nonrenewable, natural materials.
- Rehabilitation
-
In construction, rehabilitation refers to the renovation of a building which is dilapidated or no longer in compliance with safety standards.
- Reinforced concrete
-
Cement concrete is very resistant to compression but it is less resistant to tensile stress and bending. Steel, on the other hand, is very flexible thanks to its high tensile strength.
Reinforced concrete takes advantage of their different properties by combining steel and concrete to produce a material with high compressive and tensile resistance. - Render
-
Render is a layer of paste or mortar which is applied to a wall to improve its appearance. It protects the wall from the elements and gives an attractive, uniform finish. It also helps to insulate. It consists of a binder (lime, gypsum, cement or earth), aggregates and, sometimes, pigments to obtain a specific color.
S
- Screed
-
A screed is a thin layer of mortar (15 to 50 mm) that is spread over a base layer of slabs, tiling, etc. It gives a flat surface and is generally covered by another material, such as floor tiling.
- Screening
-
Screening is the phase following crushing and grinding. Gravel is sieved through a screen of a given size to produce a clean, homogenous mix of a particular size of granule.
- Sealing
-
Sealing is the masonry operation by which the end of a piece of wood or metal is inserted into a masonry wall, ceiling or floor. In general, a cavity is made into which the beam or post is placed. The area is then filled with quick setting mortar, plaster, lead or sulfur mortar.
- Self-compacting, self-consolidating concrete
-
A variant of self-placing concretes, self-compacting, self-consolidating concrete concretes have a specially formulated and graded composition to ensure a fluid spread. They form smooth-surfaced slabs with no need for vibration or float finishing (used to make a surface flat).
- Self-placing concrete
-
Self-placing concretes are special, highly-fluid concretes which settle into place by gravity alone and do not, therefore, require vibration. They are designed to be poured into watertight formwork. Even without vibration they cover reinforcements perfectly and provide extremely smooth facing.
- Solid rock
-
This rock comes from thick deposits of hard rock. Massive rocks are mainly old limestone formations or rocks of volcanic origin, called eruptive rock. This rock can be extracted to make aggregates. The extracted minerals are scalped before being crushed.
- Sustainable construction
-
Sustainable construction aims to limit the impact of buildings on the environment while enhancing their quality in terms of aesthetics, sustainability, durability and strength. Sustainable construction techniques apply across the entire lifecycle of a building, from the selection of initial materials to demolition and recycling.
Sustainable construction signifies in particular:- the use of recyclable materials to conserve natural resources,
- the integration of renewable energy sources into a building's design,
- the optimization of renewable energy sources.
