Do you sometimes wonder what your concreter is talking about?  Redicrete has put together a 'Terms of the Trade' guide to provide you with that tradie insight!

Terms of the Trade

A

Accelerator – An additive that is used to quicken the strength development process and/or reduce the time it takes for the concrete to set.

Acetone – Is a solvent available in both powder and liquid form. It is normally used when a ‘deep colour’ needs to be achieved in a short period of time indoors.

Acid Etching – A process in which acid is used to clean a surface.

Acid Stain – A staining process in which hardened concrete can be given a permanent, transparent colour that will not scale or peel.

Adhesive Stencils – A vinyl or plastic based pattern with an adhesive backing to keep the design in place while an effect (e.g. acid stain, dye, sandblasting etc…) on a concrete surface.

Admixture – An ingredient of concrete that is used to modify the properties of freshly mixed, setting or hardened state concrete.

Aggregate – A material such as gravel, sand, rock, crushed stone etc… that are added to concrete to enhance its structural performance and improve flow and formation.

Air Content – Usually provided as a percentage of the total volume of air that is trapped in concrete.

Air Entrainment – The process where an air-entraining mixture is added to fresh concrete with the purpose of creating microscopic air bubbles.  The end result is hardened concrete that is more durability and freeze-thaw resistant.

Apron – A concrete slab that extends beyond a building’s entrance.

B

Bleed Through – Is the change in colour which is generally caused by the diffusion of colour from an underlying surface.

Bleed Water - The water that rises to the surface when freshly placed concrete is placed is known as bleed water (or bleeding).

Bond – The level of adhesion that a material (E.g. Coating, Topping or Sealer) has with an existing surface.

Bonding Agent – An adhesive agent that improves the adherence of a coating or topping to an existing surface.

Bond Breaker – A material that inhibits the adhesion of materials to a concrete substrate.

Broom Finish – A surface texture finish which is created by moving a broom across freshly laid concrete.

Bull Float – A tool with a blade that is normally made of wood, resin, aluminium or magnesium and assists in levelling out freshly placed concrete.  Long handles can also be clipped or screwed into the float to enable it to be used in a middle of a slab when it cannot be reached.

C

Cast in Place – Concrete that is poured and finished in the one location.

Cement – Concrete and cement are not the same.  It mainly consists of finely ground materials.  When mixed with water, it becomes the binding agent that is required in the manufacturing of concrete.

Chalking – Refers to a powdery substance which is created when the surface of concrete deteriorates, which results in a powdery substance.

Colour Chips - Plastic chips that are available in various colour and sizes and are placed onto epoxy resin floors to create a multi-coloured effect.

Compressive Strength - Is the maximum compressive strength that concrete is able to withstand.  The strength is normally expressed as psi (pounder per inch).

Consistency – This measure of consistency is termed slump and relates to the ability of fresh concrete to flow.

Construction Joint when two sections of concrete meet, it is known as a construction joint.  Construction joints are typically used in slabs to minimise the change of movement and/or transfer load.

Contraction Joint – A groove which is either sawed or tooled in a concrete slab used to regulate the location of cracking.

Cracking Chasing – Is when a saw or angle grinder is used to channel out cracks in concrete, which are later filled with a repair material.

Crack Stitching - A process in which holes are drilled on either side of a crack as a means of repairing the crack.  The holes are grouted in wire or metal strips.

Cracks, moving – These are cracks that are active or still moving in concrete.  They are generally structural cracks and impact the entire depth of the concrete.

Cracks, static – These cracks do not move and are random.  They are normally hairline cracks and only impact on the surface of the concrete.

Craze Cracks – There are comprised of a series of random cracks, as a result of the surface mortar shrinking.

Crusting – This situation occurs when the surface of freshly placed concrete dries too quickly.  This is often due to high temperatures, exposure to direct sunlight or wind.

Curing – The actions taken to ensure that moisture and temperature conditions are maintained for freshly placed concrete is known as curing.  This action ensures that the concrete hardens correctly.

Curing Compound – A liquid which forms a membrane on the surface of freshly placed concrete or penetrates the concrete to delay the evaporation of water.

D

Decorative Concrete – Refers to concrete that has had colour(s), pattern(s), texture(s) or a combination of these applied.

Delamination – Is when the topping (or a coating) separates from the substrate (this normally occurs due to poor adhesion) or alternatively the horizontal splitting/separation of the upper surface of a concrete slab. 

Diamond Grinding – A staged process in which a polished concrete surface is produced.  A range of grits are used, moving from coarser to finer until a desired level of sheen is accomplished.

Drying Shrinkage – The reduction in the volume of concrete as it dries, due to the loss of moisture.

E

Efflorescence – When soluble calcium hydroxide leaches from concrete and combines with carbon dioxide, it results in a crystal-like deposit of salts on the surface.  It is usually quite noticeable on darker toned concrete surfaces.

Epoxy Injection – A method where epoxy adhesive is injected into concrete to seal or repair a crack.

Evaporation retarder – A spray application that reduces the loss of moisture on concrete surfaces.

Exposed Aggregate – A surface finish that is achieved by removing the surface mortar, exposing the underlying aggregate.

F

Finishing – The process where newly placed concrete is compacted, levelled, smoothed and treated (e.g. Colour additive).

Flexural Strength – This is the capacity of set concrete or overlay to resist failure in bending.

Float Finish – Refers to the normally rough surface texture finish when a bull or hand float is used.

Fly Ash – Sometimes used as the cement component in concrete.  Fly ash is a by-product of ground or powdered coal. 

G

Grout – A mixture of cement based materials and water with the option of adding aggregate if a desired effect is required.  The paste can be blended with colours and used to define joints and sawcuts in slabs and walls.

H

Hand Float – A handheld float which is normally 30 to 45 cm long.  It’s a great tool to use in tight spots or along the edges.

Hard-Trowelled Finish – A surface finish which is obtained by using a trowel with a steel blade to get a flat and smooth surface finish.

High-pressure Water Blasting – Used for both cleaning or adding a roughened effect to concrete surfaces.  This is done by using a tool such as a Gerni which delivers a stream of water at high pressure.

Hover Trowel – A trowel used specifically for finishing epoxy, polymer and cement based overlay systems.

Hydration – Refers to the chemical reaction when cement and water are mixed, which causes the material to harden.

I

Integral Colour – A colour based agent that is premixed into fresh concrete a topping before placement.

Iron Oxide  A mineral based pigment that is often used to colour toppings or decorative coatings.

J

Joint (control, expansion, or isolation) – A joint can be formed, cut, or tooled in a concrete slab and is used to control the location of cracking and/or enable expansion or movement of connecting surfaces and structures.

Joint Filler – A rigid material normally used in saw-cut joints which is installed once the concrete slab has shrunk as much as possible. It aids in supporting the edge of joint that maybe exposed to high traffic.

K

Kneeboards – A board which is commonly used by concreters during the finishing process to kneel on when hand floating or trowelling the concrete surface. 

M

Material Safety Data Sheet (MSDS) – A document that provides health and safety information about a product.  The information generally includes chemical ingredients of the product, safe storage and handling, emergency procedures and disposal recommendations.

Mix Design – The amount of ingredients required (e.g. cement, aggregates, water etc…) to produce a concrete with a set of characteristics which is applicable for its application.

O

Overlay – A layer of material that is placed over existing concrete.  This is generally done to restore, level or improve the appearance of the substrate surface.

P

Patterned Concrete – Concrete that has been patterned with mats, skins or tools in order to achieve a certain look (e.g. brick, slate, stone etc…).

Penetrating Sealer – A sealer that has the ability to penetrate a concrete surface to increase the ability to repel water and resist stains.  This sealer is usually used on decorative concrete to provide an ‘invisible’ level of protection without changing the appearance of the surface.

Permeability – The degree of which a coating will enable the penetration of a liquid or gas.

Pigment – A natural or synthetic particle that is used to add colour and opacity to a coating or topping.

Pinholing – Refers to a defect in the coating which is characterised by pinhead-sized holes that show the substrate material.

Plasticity – A reference to the ease of molding or resistance to deformation of freshly mixed concrete/cement paste or mortar.

Polished concrete – A finish that is attained by using floor polishers which are fitted with diamond discs to grind down surfaces until a shine and flatness is achieved.  The end result can be likened to polished stone.

Profile – The act of preparing a surface in order to achieve a level of roughness.

R

Ready-mixed Concrete – Concrete that is mixed (or batched) at a plant prior to being delivered to a job site is regarded as ‘Ready-mixed Concrete’.

Rebar – If flexural strength is required in a slab or wall, rebar (ribbed steel bars) are cast-in-place to assist in achieving the desired result.

Reinforced Concrete – Refers to a concrete construction that has rebar or wire mesh embedded into the formwork to improve the structural properties (tension and flexural stress) of the concrete.

Release Agent – Is a liquid or powder based agent that is applied to stamping mats/texturing skins before the stamping process is undertaken.  This is to ensure that the mats do not stick to freshly laid concrete or overlay.

S

Scaling – When a hardened concrete surface experiences flaking or pieces breaking away. 

Seeding – The process in which decorative aggregates are spread onto the surface of freshly laid concrete or overlay.

Segregation – When wet concrete is handled excessively, it can result in the separation of the concrete mix components.

Set - The state reached by concrete when plasticity is absent and the concrete attains full rigidity.

Setting – The chemical reaction that occurs when water is added to the cement based mixture, resulting in a steady firming of the mixture.

Slump – Refers to the consistency of freshly mixed concrete, as well as the flow.  The consistency is measured by using a mould, also known as a slump cone.  The cone is placed on a hard surface and filled with concrete in three stages.  During these stages, the concrete is tamped with a rod.  Once the process is complete, the cone is twisted back and forth to minimise disruption to the concrete and lifted off the ground.  As concrete subsides, the amount that it has ‘slumped’ from the top of the cone to its new height, is known as the slump.

Spalling – References the break-away of concrete at joints.  This normally occurs when the joints are not constructed or installed correctly.

Static Cracks – These are randomised hairline cracks that only impact the surface of concrete.

Stenciled Concrete – A decorative finish that can be applied to concrete using stencils with patterns.  The stencils are pressed lightly into fresh concrete and can be follow up with colour application to obtain a required look.  When the stencil has been removed, the uncoloured section imitates mortar joints.

Surface Preparation – The process in which concrete surfaces are prepared prior to any resurfacing or application work (e.g. decorative coating).

T

Tint – A colour wash that has been diluted and used to add colour to decorative concrete.

Translucent – A finish where the surface has some level of transparency.

Trowel – A flat, steel hand towel that is used to compact the top layer of concrete/topping to achieve a smooth and flat finish.

V

Viscosity – A means of measuring the fluidity of a liquid based material.  So the more ‘viscosity’ is present in a material, the less it will flow.

W

Water-cement ratio – This references the portion of water that is combined with a portion of cement to make the concrete mixture.  This is one of the key factors in ensuring specified outcomes are achieved.  For example, keeping the water-cement ratio low assists in producing high quality decorative concrete.

Water Reducer – An admixture that can be used to either increase the slump of freshly mixed concrete, whilst not increasing the amount of water or alternatively can be used to maintain the workability of the concrete without impacting on the strength of the concrete.

Wet Polishing – A method used in polishing concrete that uses water to cool the diamond abrasives discs and remove grinding dust.  Dry polishing is a much more common approach, as the downside to wet polishing is the creation of slurry (cement dust and water) that needs to be collected and removed from the job site.

Workability – The degree of ease in which concrete or like materials can be mixed, placed, and finished.

Working Time – The amount of time available for placing and finishing the concrete before the material begins to set.