The Different Grades of Concrete

Whether you’re laying the groundwork for a large family home , a barn restoration, or a commercial space in the city, picking the right concrete mix is the most important part when starting a new building project. Curious about what those concrete grades mean or just need the perfect blend for your next job? This guide breaks down the essentials of concrete grades and their practical uses for different construction projects. For expert advice or a bespoke mix, reach out to Concrete In Cornwall today

What Are Concrete Grades?

Concrete grades tell you how strong and tough a mix will be after it’s had 28 days to cure. They’re measured in megapascals (MPA), where the “M” stands for mix and the number reflects its compressive strength. Think of it as a strength scorecard: the higher the number, the more muscle the concrete’s got. In the chart listing concrete grades, psi stands for pounds per square inch. It’s a unit of pressure used to measure the compressive strength of concrete, indicating how much force the concrete can withstand before it fails or crushes.
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Grades climb in steps of 5, starting at M5 and stretching up to M70 and beyond. Each grade comes from a specific recipe of cement, sand, and aggregates. For example, M20 mixes at a 1:1.5:3 ratio, balancing the ingredients for solid performance. Lower grades lean on simpler ratios, while higher ones often use custom “design mixes” for extra oomph. Check out the table below for a snapshot of how some these grades stack up:

Grade	Mix Ratio	Compression Strength
M5	1:5:10	5MPA / 725PSI
M10	1:3:6	10MPA / 1450PSI
M20	1:1.5:3	20MPA / 2900PSI
M30 (Standard)	Design Mix	30MPA / 4350PSI
M40	Design Mix	40MPA / 5800PSI
M50	Design Mix	50MPA / 7250PSI
M60 (High)	Design Mix	60MPA / 8700PSI

​Matching Grades to Your Project

Choosing the right concrete grade isn’t guesswork; it’s about knowing your build’s needs. Here’s a rundown of common grades and where they shine in homes, farms, and businesses:

• C10 (10 MPa)
  Perfect for low-stress jobs like patio slabs, garden paths, or non-structural fillers. It’s a lightweight domestic and commercial pick—ideal for a seaside terrace or a shed base.
• C15 (15 MPa)
  Steps up for pavement edges, kerbs, or blinding layers under floors. It’s tough enough for wet weather, making it a go-to for both home and small business projects.
• C20 (20 MPa)
  A domestic favourite for lighter foundations, garage floors, driveways, or workshop bases. It’s sturdy without overkill—great for a cottage or barn conversion.
• C25 (25 MPa)
  The all-rounder for foundations in homes and commercial builds. This multi-purpose mix handles Cornwall’s clay-heavy soils or sandy coastal patches with ease.
• C30 (30 MPa)
  Built for roads and pathways that take a beating. It’s the lightest grade for heavy traffic, offering weather resistance for stormy days—think rural lanes or farm tracks.
• C35 (35 MPa)
  A commercial heavy-hitter for external walls, slabs, polished concrete floors or structural piles. It’s got the grit for bigger builds, like warehouses or commercial offices, standing firm against the elements.
• C40 (40 MPa)
  The toughest of the bunch for commercial foundations, beams, and roads. It resists chemical wear too—perfect for industrial farms with slurry or septic systems that need staying power. Sometimes called 'farmers concrete' in reference to its high strength.

Higher grades like M50 to M70? Those are bespoke blends for mega-projects—think bridges or towers—where extreme strength is non-negotiable.

Why Grades Matter in Cornwall

Cornwall’s mix of damp air, rocky ground, and salty breezes demands concrete that’s up to the task. At Concrete In Cornwall, we craft mixes that match your site, whether it’s a windy cliffside or a boggy moor. Lower grades (C10-C20) keep costs down for simple domestic jobs, while C25-C40 tackle the heftier demands of commercial builds or tricky soils. The right grade means your project lasts—saving you headaches and repairs down the line.

​Beyond the Basics: High-Strength Mixes

For jobs needing more than standard grades, high-strength mixes (M50-M70) step in. These design mixes, tailored to precise specs, hit strengths of 50 MPa or more. They’re rare in everyday home builds but vital for industrial feats or structures facing brutal loads. Think of them as the elite squad of concrete, custom-made and ready for the toughest challenges.

​Picking Your Perfect Mix

Not sure where to start? Consider your project’s scale, location, and load. A garden path won’t need C40’s might, but a farmyard road shouldn’t settle for C15. Soil type matters too, clay shrinks and sand shifts, so test your ground first. Concrete In Cornwall’s team can guide you, mixing and pouring the exact grade your build calls for, from a humble patio to a rugged roadway.

Conclusion

Concrete grades aren’t just numbers they’re the key to a build that stands strong. From C10’s gentle touch on a pathway to C40’s grit under a farm shed, each mix has a role. Understanding these options helps you pick smart, whether you’re sprucing up a home or raising a commercial business warehouse. Want to dig deeper? Explore our blog for more tips or get in touch, we’re here to pour the perfect solution for you.