Glossary | ConcreteMaths.com

Plain-English concrete terms, BS EN 206 definitions, BS 8500 references and UK site vocabulary for homeowners, builders, engineers and specifiers — reviewed for 2026.

🇬🇧 UK Concrete Terms
BS EN 206 Explained
BS 8500 Context
A–Z Definitions

206BS EN Concrete Standard Family
8500UK Complementary Concrete Standard
C30/37Common Strength Class Format
50+Terms, Standards & Site Phrases Explained

UK Concrete Glossary 2026 — Why These Terms Matter

ThisUK Concrete Glossaryexplains the terms that appear on ready-mix tickets, structural notes, Building Control drawings, supplier quotes, mix design reports and concrete guide results. Concrete terminology can feel technical because one word often affects several practical decisions: cost, volume, strength, durability, curing, reinforcement, drainage, finish quality and long-term safety.

For example, a homeowner may ask for “strong concrete” when the supplier actually needs astrength class, aconsistence class, anaggregate size, anexposure classand sometimes acement type. A builder may say “C30” on site, while the standard strength class may appear asC30/37. A structural engineer may specifyXC3/4,maximum w/c ratio,minimum cement contentorchloride class, all of which influence the exact mix supplied.

Quick 2026 Note

In UK concrete specification, BS EN 206 is normally read together with BS 8500. BS EN 206 gives the European concrete framework, while BS 8500 gives UK-specific ways to specify and select concrete for real British site conditions.

This page is designed as a practical translation layer. It does not replace a structural engineer, a ready-mix technical department, Building Control, a ground investigation or a full project specification. It helps you understand the vocabulary before you order concrete, compare quotes, use a guide or read a drawing.

A–Z Concrete Terms and Definitions

The glossary below focuses on concrete, mortar, aggregates, reinforcement, fresh concrete tests and common UK specification language. Use it to decode supplier documents, guide results and site instructions. For a deeper working workflow, use theFree UK Concrete Guidesguide or theConcrete Grades UK guide.

ABCDEFGHLMPRSW
A
Aggregate

Granular material used in concrete and mortar. Fine aggregate is sand; coarse aggregate is gravel or crushed stone. Aggregate grading, shape and cleanliness affect workability, finish, strength and shrinkage.

Air entrainment

A controlled system of tiny air bubbles added to concrete, commonly for freeze-thaw resistance in exposed paving, external slabs and some highway concretes. It is not the same as accidental trapped air.

B
Ballast

A combined sand and gravel aggregate used for small-batch concrete. Ballast is convenient for DIY work, but controlled ready-mix is preferred for structural concrete because grading and moisture are better managed.

Batch

One measured quantity of concrete or mortar ingredients. A batch can be a ready-mix truck load, a mixer load or a small site-mixed quantity. Accurate batching reduces variation between loads.

Bleeding

Upward movement of water in fresh concrete after placing. Minor bleeding can be normal, but excessive bleeding weakens the surface, delays finishing and may indicate too much water or poor grading.

C
CEM I

Portland cement with high clinker content. It is widely used as a reference cement in concrete strength discussions because it gains strength relatively quickly compared with some blended cements.

CEM II

Portland-composite cement containing Portland clinker plus another main constituent. It can reduce embodied carbon and alter strength gain, workability and durability depending on the blend.

CEM III

Blastfurnace cement containing a high proportion of slag. It can improve durability and reduce heat of hydration, but early strength gain may be slower in cold weather.

Cement content

The amount of cement or cementitious binder in concrete, normally stated as kg/m³. Minimum cement content is often controlled by durability and exposure requirements, not just strength.

Characteristic strength

The strength value below which only a small proportion of valid test results are expected to fall. Concrete classes such as C25/30 and C30/37 are based on characteristic compressive strength.

Chloride class

A limit on chloride content in concrete. It matters because chlorides can accelerate corrosion of steel reinforcement, especially in marine, de-icing salt and aggressive environments.

Compaction

The process of removing trapped air from fresh concrete. Poor compaction leaves voids, honeycombing and weak zones. Vibration, rodding or self-compacting mixes may be used depending on the pour.

Concrete cover

The thickness of concrete between reinforcement and the outside surface. Cover protects reinforcement from corrosion and fire and helps the member achieve its intended durability life.

Consistence

The flow or workability of fresh concrete. It may be specified by slump class, flow class, Vebe class or other test methods depending on the type of concrete and placement method.

Curing

Actions taken after placing to retain moisture and control temperature while concrete gains strength. Curing is essential for slabs, external concrete and thin sections exposed to sun, wind or frost.

D
Designated concrete

A UK specification route for common applications such as GEN, RC, FND and PAV concretes. It is intended to simplify ordering where the use and exposure conditions fit standard categories.

DPM

Damp-proof membrane. A sheet layer used beneath many slabs to reduce moisture movement from the ground into the slab or building floor construction.

E
Exposure class

A code describing the environment affecting durability. Examples include XC for carbonation, XD/XS for chlorides, XF for freeze-thaw and XA for chemical attack.

F
FND concrete

Foundation concrete used where ground conditions require a designated foundation mix. The correct FND selection depends on sulfate/chemical ground assessment, not just load or trench size.

G
GGBS

Ground granulated blastfurnace slag, a supplementary cementitious material used to replace part of Portland cement. It can improve durability and lower embodied carbon but may slow early strength gain.

H
Honeycombing

Voids or stony areas in hardened concrete caused by poor compaction, congested reinforcement, harsh mix design or leakage from formwork. Serious honeycombing may need structural assessment.

Hydration

The chemical reaction between cement and water that forms hardened cement paste. Hydration continues for a long time when moisture and temperature conditions are favourable.

L
Lean mix

Low-cement concrete used for blinding, bedding or non-structural fill. Lean mixes should not be used where a structural grade or durability class is required.

M
Mortar class

A masonry mortar strength designation such as M2.5, M5, M10 or M15. Mortar strength must suit the masonry units, exposure and structural design.

P
Plasticiser

A water-reducing admixture used to improve workability without adding extra water. It helps keep the water-cement ratio low while making concrete easier to place.

R
Ready-mix concrete

Concrete produced at a batching plant and delivered by truck. It gives better control of strength, consistence and traceability than most small site-mixed concrete.

Reinforced concrete

Concrete containing steel reinforcement or mesh. Concrete carries compression well, while steel carries tension. Reinforced concrete requires correct cover, grade, placement and curing.

S
Screed

A sand-cement or flowing layer used to create a level floor surface. Screed is not the same as a structural concrete slab unless specifically designed as one.

Segregation

Separation of coarse aggregate from mortar in fresh concrete. Segregation can happen when a mix is too wet, dropped from excessive height or poorly proportioned.

Slump

A measured settlement of fresh concrete in a slump test. It gives a practical indication of workability for many ordinary concretes.

Strength class

A standard concrete class such as C20/25 or C30/37. The first number is cylinder strength and the second is cube strength, both in N/mm².

W
Water-cement ratio

The ratio of water mass to cement mass. Lower ratios generally improve strength and durability, but workability may need admixtures rather than extra water.

BS Standards and UK Concrete Documents Explained

Concrete standards are not just paperwork. They define how concrete is specified, tested, produced and accepted. The most important practical point for UK users is thatBS EN 206andBS 8500work together. BS EN 206 sets the broad concrete specification and conformity framework, while BS 8500 adds UK-specific guidance, designated concretes and national specification practice.

For homeowners and small contractors, the key lesson is simple: do not order only by strength if the concrete is external, reinforced, exposed to freeze-thaw, placed in aggressive ground or used for a structural element. The specification may need exposure class, cement type, consistence, aggregate size, minimum cover and durability limits.

BS EN 206-1:2026MeaningConcrete specification, performance, production and conformity. It covers requirements for constituent materials, concrete properties, production control, delivery and conformity assessment for structural concrete applications.UseSpecification
BS EN 206-2:2026MeaningThe conformity assessment and certification part of the EN 206 framework. It supports factory production control and assessment routes for concrete production.UseSpecification
BS 8500-1:2023MeaningUK complementary standard to BS EN 206 giving methods of specifying concrete and guidance for specifiers, including UK durability and designated concrete context.UseSpecification
BS 8500-2:2023MeaningUK complementary standard covering constituent materials and concrete specification details used alongside BS EN 206 in the UK.UseSpecification
BS EN 197 seriesMeaningCement composition, specification and conformity standards. These standards help define cement types such as CEM I, CEM II and CEM III.UseSpecification
BS EN 12350 seriesMeaningFresh concrete test standards, including slump, flow and other consistence tests used before or during placement.UseSpecification
BS EN 12390 seriesMeaningHardened concrete test standards, including compressive strength testing of cubes or cylinders.UseSpecification
BS EN 998-2MeaningMasonry mortar specification standard used when discussing designed and prescribed masonry mortar classes.UseSpecification

Standard / Document: BS EN 206-1:2026; Plain-English Meaning: Concrete specification, performance, production and conformity. It covers requirements for constituent materials, concrete properties, production control, delivery and conformity assessment for structural concrete applications.; Typical Use: Reference
Standard / Document: BS EN 206-2:2026; Plain-English Meaning: The conformity assessment and certification part of the EN 206 framework. It supports factory production control and assessment routes for concrete production.; Typical Use: Reference
Standard / Document: BS 8500-1:2023; Plain-English Meaning: UK complementary standard to BS EN 206 giving methods of specifying concrete and guidance for specifiers, including UK durability and designated concrete context.; Typical Use: Reference
Standard / Document: BS 8500-2:2023; Plain-English Meaning: UK complementary standard covering constituent materials and concrete specification details used alongside BS EN 206 in the UK.; Typical Use: Reference
Standard / Document: BS EN 197 series; Plain-English Meaning: Cement composition, specification and conformity standards. These standards help define cement types such as CEM I, CEM II and CEM III.; Typical Use: Reference
Standard / Document: BS EN 12350 series; Plain-English Meaning: Fresh concrete test standards, including slump, flow and other consistence tests used before or during placement.; Typical Use: Reference
Standard / Document: BS EN 12390 series; Plain-English Meaning: Hardened concrete test standards, including compressive strength testing of cubes or cylinders.; Typical Use: Reference
Standard / Document: BS EN 998-2; Plain-English Meaning: Masonry mortar specification standard used when discussing designed and prescribed masonry mortar classes.; Typical Use: Reference
Standard / Document: BS 4449; Plain-English Meaning: Steel reinforcement standard commonly referenced for reinforcing bar used in UK concrete construction.; Typical Use: Reference
Standard / Document: Approved Document A; Plain-English Meaning: Building Regulations guidance for structure, including foundations, walls, floors and roofs. It is not a concrete mix standard, but it shapes structural compliance.; Typical Use: Reference

Avoid “Standard Name Only” Specifications

Writing “concrete to BS EN 206” is not enough by itself. A useful UK specification also states the concrete strength class or designated concrete, exposure requirements, consistence, aggregate size, delivery method and any additional project constraints.

Concrete Grade, Strength and Mix Terms

Concrete strength is usually expressed using a class such asC20/25,C25/30orC30/37. The “C” means concrete, the first number is the characteristic cylinder strength and the second number is the characteristic cube strength, both measured in N/mm². In day-to-day UK construction, many people still use simplified phrases such as “C25 concrete”, “C30 mix” or “RC35”, but the formal class gives more precise information.

Strength Class

A label such as C25/30 or C30/37. It tells you the characteristic compressive strength used for specification and quality control.

Cube Strength

The second number in the class, traditionally common in UK site testing. A C30/37 concrete has 37 N/mm² cube strength.

Cylinder Strength

The first number in the class. This is widely used in European design checks and Eurocode-style references.

Strength class should not be chosen in isolation. A strong concrete can still fail prematurely if it has the wrong exposure class, poor curing, inadequate cover, too much site-added water or insufficient compaction. That is why durability language appears beside strength language in modern concrete specifications.

C8/10 to C12/15MeaningLean or low-strength concreteUseBlinding, bedding, non-structural fill
C20/25 to C25/30MeaningCommon domestic and general structural rangeUseSlabs, paths, foundations, light reinforced work
C30/37 to C35/45MeaningHigher structural/durability rangeUseDriveways, reinforced slabs, external structures

Term: C20/25; Meaning: 20 cylinder / 25 cube strength; Common UK Use: General domestic slabs and light work; Watch Point: Check exposure and reinforcement needs
Term: C25/30; Meaning: 25 cylinder / 30 cube strength; Common UK Use: Foundations, slabs, many domestic projects; Watch Point: Often confused with “C30” shorthand
Term: C30/37; Meaning: 30 cylinder / 37 cube strength; Common UK Use: External slabs, driveways, reinforced work; Watch Point: Needs correct curing and finishing
Term: GEN; Meaning: General designated concrete; Common UK Use: Non-specialist applications; Watch Point: Not automatically suitable for all exposure
Term: RC; Meaning: Reinforced concrete designated range; Common UK Use: Reinforced slabs, beams and walls; Watch Point: Cover and chloride limits matter
Term: FND; Meaning: Foundation designated concrete; Common UK Use: Foundations in ground conditions; Watch Point: Ground sulfate class must be assessed

Fresh Concrete, Site and Placement Terms

Many concrete problems happen after the truck arrives. The mix may be correctly specified, but poor handling can still cause defects. Site terms such as slump, compaction, curing, bleeding and segregation are therefore just as important as strength class. If you understand these words, you can ask better questions before the pour and avoid common mistakes during placement.

Delivery Ticket

The ready-mix document showing concrete type, time batched, quantity, consistence, strength class and other specification details. Keep it for project records.

Placing

Moving fresh concrete into position using barrows, chute, pump or skip. Placement method affects consistence choice and labour planning.

Curing

Protecting concrete after finishing. Curing helps the surface develop strength and reduces cracking, dusting and early drying damage.

Slumpis probably the best-known fresh concrete term. It describes how much a cone of fresh concrete settles during a slump test. Low slump concrete is stiff and needs more effort to place. High slump concrete flows more easily, but that does not mean you should add water. Modern mixes can use plasticisers or superplasticisers to improve workability while keeping the water-cement ratio under control.

Compactionmeans removing trapped air after placing. Poor compaction can create honeycombing, exposed aggregate pockets and weak zones, especially around reinforcement. For reinforced work, congested mesh, narrow formwork and complicated shapes need more careful planning.

Curingstarts after placing and finishing. In warm, windy or dry conditions, concrete can lose moisture quickly. In cold weather, hydration slows and frost can damage young concrete. Curing membranes, damp hessian, polythene sheeting, insulated blankets or controlled curing periods may be needed depending on the job.

Best Practice Tip

Before ordering, write down the concrete grade, volume, slump/consistence, aggregate size, delivery method, access constraints, curing plan and testing requirements. This is more reliable than asking for “a strong mix” over the phone.

Durability, Exposure and Compliance Terms

Durability language explains how concrete resists the environment over time. A slab inside a dry garage does not face the same risks as a driveway exposed to rain, frost, de-icing salts and vehicle traffic. A foundation in aggressive ground may need different concrete from a simple garden path. Exposure classes help translate these risks into specification requirements.

XC — CarbonationRiskCO₂ reduces alkalinity and can lead to reinforcement corrosion
XD / XS — ChloridesRiskDe-icing salts or marine salts can attack reinforcement
XF — Freeze-ThawRiskRepeated freezing and thawing can scale exposed concrete
XA — Chemical AttackRiskAggressive ground or groundwater affects foundations

Code: XC; Plain-English Meaning: Carbonation exposure; Typical Example: Reinforced concrete in dry, wet or cyclic conditions; Specification Impact: Cover, w/c ratio and minimum grade matter
Code: XD; Plain-English Meaning: Chlorides not from seawater; Typical Example: De-icing salts near roads or parking areas; Specification Impact: Lower permeability and chloride limits needed
Code: XS; Plain-English Meaning: Chlorides from seawater; Typical Example: Coastal or marine concrete; Specification Impact: Enhanced durability specification required
Code: XF; Plain-English Meaning: Freeze-thaw attack; Typical Example: External paving, drives, exposed slabs; Specification Impact: Air entrainment may be required
Code: XA; Plain-English Meaning: Chemical attack; Typical Example: Sulfates in ground or groundwater; Specification Impact: Ground investigation and correct FND/DC class

Important Safety Note

Do not use a glossary page to self-design retaining walls, suspended slabs, beams, columns, underpinning, deep foundations or major structural repairs. These need engineering design, checks and project-specific compliance.

Concrete Testing and Quality Terms

Testing terms appear on quality records, cube reports and method statements. For ordinary domestic work, formal testing may not always be required, but for structural, commercial, civil engineering or warranty-controlled projects, testing records can be essential. The two broad categories arefresh concrete testsbefore the concrete hardens andhardened concrete testsafter curing.

Slump Test

A fresh concrete test used to assess consistence. It helps confirm whether the delivered concrete matches the expected workability.

Cube Test

Concrete cubes are cast, cured and crushed to measure compressive strength. Results are often checked at 7 and 28 days.

Conformity

The process of checking whether concrete production and test results meet the specified standard and project requirements.

A28-day resultis common because concrete strength class is traditionally verified at 28 days. This does not mean concrete stops gaining strength after 28 days. It means 28 days is the standard reference age used for many specifications and test comparisons. Some modern mixes, especially those using slower-reacting cementitious materials, may have different early-age performance and should be planned accordingly.

Non-conformancemeans a result or delivery does not meet the specified requirement. It does not always mean demolition is required, but it does mean the issue must be assessed properly. The response may involve review of records, cores, structural checks, supplier investigation or remedial action.

How to Use This Glossary Before Ordering Concrete

Start with the purpose of the concrete. Is it a blinding layer, path, garage base, driveway, extension foundation, reinforced retaining wall, floor slab or commercial structural element? Then identify the terms that control that purpose. A non-structural blinding layer may focus on volume, access and finish. A reinforced external slab needs strength, cover, exposure, curing and crack-control language. A foundation in aggressive ground needs ground investigation language and the correct foundation concrete route.

Step 1 — Define the element:slab, footing, wall, beam, screed, base, paving, infill or repair.
Step 2 — Choose the specification route:designed concrete, designated concrete, prescribed concrete or proprietary system.
Step 3 — Confirm strength language:use the full class such as C25/30 or C30/37 where possible.
Step 4 — Check durability language:exposure class, cover, freeze-thaw, chlorides, sulfate ground and drainage.
Step 5 — Plan fresh concrete language:slump/consistence, pumpability, aggregate size, delivery timing and access.
Step 6 — Record site actions:compaction, finishing, joints, curing and protection from rain, sun, wind or frost.

For more detailed planning, use theConcrete Project Planner. For quantities, use theConcrete Volume Guide. For strength selection, read theWhen to Use Each Grade of Concreteguide.

Glossary Definitions Are Guidance — Not a Structural Design

Use this page to understand words and compare specifications. For load-bearing structures, retaining walls, beams, suspended slabs, foundations in difficult ground or commercial work, get competent project-specific design advice.

UK Concrete Glossary FAQs

Common questions about concrete terms, BS EN 206, BS 8500, strength classes, slump, curing and UK site vocabulary.

What is BS EN 206 in simple terms?+

BS EN 206 is the main European concrete standard used for specifying, producing and assessing concrete. In the UK it is normally used with BS 8500, which adds UK-specific guidance for exposure, durability, designated concretes and specification practice.

What does C30/37 mean in concrete?+

C30/37 means a concrete strength class with 30 N/mm² characteristic cylinder strength and 37 N/mm² characteristic cube strength. UK site discussions often still refer to cube strength, but the full BS EN class uses both values.

What is the difference between GEN, RC and C grades?+

C grades are strength classes such as C25/30. GEN, RC, FND and PAV are UK-style designated or standardised concrete descriptions used for common applications. GEN is general purpose, RC is reinforced concrete, FND is foundation concrete for certain ground conditions and PAV is paving concrete.

What does slump mean?+

Slump is a simple fresh concrete test that estimates consistence or workability. A higher slump is easier to place, but extra water should not be added on site unless approved because it can reduce strength and durability.

What is water-cement ratio?+

Water-cement ratio is the mass of water divided by the mass of cement in the mix. It strongly affects strength, permeability, shrinkage and long-term durability.

What is an exposure class?+

An exposure class describes the environment that concrete will face, such as carbonation risk, freeze-thaw attack, chlorides or chemical attack. The exposure class influences minimum strength, cement content, maximum water-cement ratio and cover requirements.

What is cover in reinforced concrete?+

Cover is the distance from the concrete surface to the reinforcement. It protects steel from corrosion and fire exposure. Required cover depends on exposure, fire rating, structural design and workmanship tolerance.

What is curing?+

Curing means keeping concrete moist and at a suitable temperature while hydration develops. Poor curing can cause dusty surfaces, early cracking, reduced strength and weaker durability even when the ordered concrete grade was correct.

What is the difference between mortar and concrete?+

Concrete contains cement, water, fine aggregate and coarse aggregate. Mortar normally contains binder, water and fine aggregate only, and is used for masonry bedding, pointing, rendering or repair tasks rather than large structural pours.

Are glossary definitions enough for structural design?+

No. This glossary explains common terms for planning and specification, but structural design still needs project-specific working, Building Control approval where required and competent professional advice for load-bearing work.

Which standards should a UK concrete spec mention?+

A typical UK ready-mix specification may mention BS EN 206, BS 8500, strength class, consistence/slump, exposure class, aggregate size, chloride class, cement type, placement method and any special requirements such as pumpability or air entrainment.

How often should concrete terminology pages be reviewed?+

A standards glossary should be reviewed whenever BS EN 206, BS 8500, Building Regulations, Eurocodes or major product guidance changes. For SEO and user trust, a visible 2026 review note helps readers understand the page is current.