Many people use “cement” and “concrete” as if they mean the same thing. They don’t. Understanding this difference matters whether you’re planning a DIY project, talking to contractors, or simply want to know what you’re actually buying.
The simple answer: Cement is an ingredient in concrete, not the final product. Think of cement like flour in bread – essential, but not the whole story.
What Is Cement?
Cement is a fine powder that acts as a binding agent. When mixed with water, it creates a paste that hardens and binds other materials together.
Types of Cement
Portland Cement is the most common type, making up about 95% of all cement used in construction. It’s made by heating limestone, clay, and other materials in a kiln at temperatures reaching 1,450°C.
Other cement types include:
- Rapid-hardening cement – Sets faster than ordinary Portland cement
- Low-heat cement – Produces less heat during setting
- Sulphate-resistant cement – Withstands chemical attack from sulphates
- White cement – Used for decorative purposes
How Cement Works
When cement mixes with water, a chemical reaction called hydration occurs. This process creates calcium silicate hydrate (C-S-H) gel, which binds everything together. The reaction continues for months, making concrete stronger over time.
What Is Concrete?
Concrete is a composite material made by mixing cement, water, sand, and gravel (or crushed stone). The cement acts as the glue, whilst the aggregates provide strength and bulk.
Standard Concrete Mix Ratios
| Component | Typical Percentage |
|---|---|
| Cement | 10-15% |
| Water | 15-20% |
| Sand (fine aggregate) | 25-30% |
| Gravel/crushed stone | 40-50% |
Types of Concrete
Ready-mix concrete arrives at your site pre-mixed and ready to pour. It’s convenient but more expensive per cubic metre.
Site-mixed concrete is mixed on location. You control the quality but need equipment and expertise.
Precast concrete is cast in a factory under controlled conditions, then transported to site. Examples include concrete blocks, pipes, and architectural panels.
Key Differences Between Cement and Concrete
Composition
- Cement: Single material – fine powder made from limestone and clay
- Concrete: Composite material containing cement, water, sand, and aggregate
Function
- Cement: Binding agent that holds other materials together
- Concrete: Complete building material ready for construction use
Strength
- Cement: Relatively weak on its own, prone to cracking
- Concrete: Much stronger due to aggregate reinforcement
Cost
- Cement: £6-8 per 25kg bag
- Concrete: £65-90 per cubic metre delivered
Applications
- Cement: Used to make concrete, mortar, and grout
- Concrete: Used for foundations, driveways, buildings, and infrastructure
Common Misconceptions
“Cement Driveways”
No such thing exists. What people call “cement driveways” are actually concrete driveways. Pure cement would crack and fail quickly under vehicle loads.
“Stronger Cement Means Stronger Concrete”
Not necessarily. Concrete strength depends on the entire mix design, including water-to-cement ratio, aggregate quality, and curing conditions.
“Cement and Mortar Are the Same”
Mortar is cement mixed with sand and water, but no coarse aggregate. It’s used to bind bricks and blocks, not as a structural material like concrete.
When to Use Each Material
Use Cement When:
- Making your own concrete mix
- Creating mortar for bricklaying
- Preparing grout for tiles
- Mixing repair compounds
Use Concrete When:
- Laying foundations
- Creating driveways or paths
- Building retaining walls
- Constructing structural elements
Practical Applications and Examples
Home Projects
Garden Path: You need concrete, not cement. A typical mix uses 1 part cement, 2 parts sand, and 3 parts gravel.
Brick Wall: You need mortar (cement + sand + water) to bind the bricks, plus a concrete foundation beneath.
Fence Posts: Concrete provides the strength to hold posts securely. Pure cement wouldn’t provide adequate support.
Commercial Projects
Building Foundations: Structural concrete with specific strength requirements, often reinforced with steel bars.
Road Construction: High-strength concrete designed to withstand heavy traffic loads and weather conditions.
Quality and Standards
In the UK, cement must meet BS EN 197-1 standards. This ensures consistent quality and performance across different manufacturers.
Concrete quality is measured by its compressive strength, typically ranging from C16/20 (16 Newton/mm² at 28 days) for domestic use to C50/60 for heavy structural work.
Environmental Considerations
Cement production accounts for about 8% of global CO₂ emissions. The industry is developing lower-carbon alternatives:
- Fly ash concrete – Uses industrial waste as partial cement replacement
- Ground granulated blast furnace slag – Steel industry byproduct used in concrete
- Limestone cement – Reduces CO₂ emissions by up to 10%
Buying Guide
For Small DIY Projects
Buy pre-mixed bags of concrete. They cost more per kilogram but eliminate mixing errors and waste.
For Medium Projects
Buy cement, sand, and aggregate separately. You’ll need:
- Cement mixer or mixing tools
- Wheelbarrow for transport
- Basic understanding of mix ratios
For Large Projects
Consider ready-mix concrete delivery. It’s often cheaper than buying materials separately and guarantees consistent quality.
Storage and Handling
Cement Storage
- Keep cement bags dry and off the ground
- Use within 3 months for best results
- Avoid storing in damp conditions – cement can set in the bag
Concrete Mixing
- Add water gradually to avoid over-wetting
- Mix thoroughly for uniform colour and strength
- Use concrete within 30-60 minutes of mixing
Troubleshooting Common Issues
Concrete Cracking
Usually caused by:
- Too much water in the mix
- Rapid drying (inadequate curing)
- Ground movement beneath
Poor Concrete Finish
Often results from:
- Incorrect cement-to-aggregate ratio
- Inadequate mixing
- Wrong consistency for the application
Regional Variations
UK Specifications
British concrete standards differ from European norms in some areas. Always specify BS standards when ordering materials.
Climate Considerations
UK weather requires concrete mixes that can handle freeze-thaw cycles. This typically means air-entrained concrete for exposed applications.
Professional vs DIY
When to DIY
- Small decorative projects
- Garden features under 1 cubic metre
- Non-structural applications
- Areas where imperfections won’t matter
When to Use Professionals
- Structural work requiring building control approval
- Large areas requiring consistent finish
- Time-critical projects
- Applications requiring specific strength grades
Cost Analysis
Material Costs (Approximate UK Prices)
- Cement: £6-8 per 25kg bag
- Ready-mix concrete: £65-90 per cubic metre
- Concrete blocks: £1-3 each depending on size
- DIY concrete mix: £40-60 per cubic metre in materials
Labour Costs
Professional concrete laying typically costs £15-25 per square metre, not including materials.
Future Trends
The construction industry is moving towards:
- Carbon-neutral cement by 2050
- 3D-printed concrete structures
- Self-healing concrete containing bacteria that repair cracks
- Recycled aggregate concrete using construction waste
Frequently Asked Questions
Can I use cement without aggregate?
No, for structural applications. Pure cement is weak and will crack. For filling small gaps, cement paste works, but concrete is always stronger.
How long does concrete take to cure?
Concrete reaches about 70% strength in 7 days and 90% in 28 days. However, it continues strengthening for months.
What’s the difference between concrete and mortar?
Mortar uses fine sand but no coarse aggregate (gravel). It’s designed to bond masonry units, not provide structural strength.
Can I add more cement to make stronger concrete?
Up to a point, yes. But too much cement makes concrete more prone to cracking. Proper mix design is crucial.
Why does concrete sometimes fail?
Common causes include incorrect mix ratios, poor curing, inadequate preparation, or using concrete beyond its design limits.
Is ready-mix concrete worth the extra cost?
For projects over 1 cubic metre, usually yes. You get consistent quality, save time, and often end up with lower total costs.
Can I colour concrete?
Yes, using integral colour additives or surface stains. Add colourants during mixing for uniform results.
How do I calculate how much concrete I need?
Measure length × width × depth in metres. Add 10% for waste. A cubic metre covers 10 square metres at 100mm depth.
Summary
Understanding the cement vs concrete difference is fundamental to any construction project. Cement is the binding ingredient, whilst concrete is the complete building material. Each serves specific purposes, and using the wrong one can lead to project failure.
For most home projects, you’ll be using concrete – whether pre-mixed bags for small jobs or ready-mix delivery for larger ones. Cement alone is primarily used for making mortar or as an ingredient in custom concrete mixes.
When planning your next project, remember: if you need something strong and durable for construction, you want concrete. If you’re mixing materials to create that strong, durable product, then you need cement as one of your ingredients.
The key to success lies in choosing the right material for your specific application and understanding how each component contributes to the final result. Whether you’re laying a garden path or building a foundation, this knowledge will help you make informed decisions and achieve better results.