C30 / PAV1
The grade C30 (?30 N/mm² after 28 days) steps up from standard mixes into more demanding load and exposure applications. When branded as PAV1, it typically denotes that the mix includes an air-entrainment additive to introduce carefully sized microscopic air voids designed to improve freeze–thaw resistance. This makes it well-suited for external slabs, driveways, garages, patios and similar.
In many ready mix supply schemes, PAV1 is the standard pavement or external specification.
Technical details
- Compressive strength ~30 N/mm² at 28 days (cylinder or cube depending on test)
- The air-entrainment improves durability where freeze-thaw or de-icing salts are present (microscopic bubbles give space for water to freeze without internal damage)
- Higher cement content and better aggregate grading usually than lower grades; often lower water/cement ratio to achieve improved performance. For example, in comparison discussions C30 may require W/C ~0.38 vs ~0.44 for C25
- For external slabs, good finish and compaction are critical – avoid surface shrinkage cracking, ensure suitable jointing, and curing is important.
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Typical applications & key benefits
Typical applications
- External slabs such as patios, terraces, garden areas
- Domestic driveways and garages (especially with occasional vehicle traffic)
- Light commercial slabs/pavements where freeze-thaw action or de-icing salts may be present
- Slabs subject to moderate vehicular load (cars, small access)
- Sub-bases for further surface finish (tiles, pavers) where evenness and durability are required
Key benefits
- Improved strength and durability compared to lower grades – longer life, less maintenance
- Air-entrained to resist freeze-thaw damage and de-icing salts – important in UK external environment
- Versatile enough for domestic and light commercial use
- Can be used with reinforcement or mesh if required
Specification & durability considerations
- External exposure class often more severe: consider exposure class (XF, XD) and ensure mix complies
- If heavy vehicle traffic is expected (forklifts, HGVs) then consider stepping up to RC range
- Jointing and proper placement are critical for external slabs to avoid cracking
- Curing is especially important for air-entrained mixes – ensure surface is protected from drying out too fast.
Ordering & delivery advice
Provide slab area and thickness, reinforcement or mesh, whether exposed to vehicles or pedestrian only, whether de-icing salts will be used, finish required (power-float, broom finish), pumping requirement, accessibility and reinforcement cover. Indicate timing for traffic or overlay if applicable.
