C8/10 concrete (also designated as GEN1) is the lowest strength general-purpose concrete grade commonly used in UK construction. This classification indicates a characteristic compressive strength of 8 N/mm² (cylinder test) or 10 N/mm² (cube test) at 28 days. C8/10 complies with Building Regulations and BS 8500:2015+A2:2019 for non-structural applications.
C8/10 is primarily specified for blinding layers beneath foundations, kerb bedding and backing, drainage works, trench fill around services, and mass concrete cavity fill where structural strength is not required. Its low cement content makes it the most economical concrete grade, ideal for high-volume non-structural applications in 2026 construction projects.
What is C8/10 Concrete?
The C8/10 designation follows the European standard BS EN 206 concrete classification. The "C" indicates concrete strength class, "8" represents the characteristic cylinder strength in N/mm² (8 MPa), and "10" indicates the characteristic cube strength in N/mm² (10 MPa). This is the minimum strength specification for designated concrete mixes in the UK.
Compressive Strength
Cylinder Strength: 8 N/mm² (8 MPa)
Cube Strength: 10 N/mm² (10 MPa)
Test Period: 28 days standard cure
Classification: Lowest strength designated mix under BS 8500
Historical Designation
Former Name: GEN1 (General Purpose Grade 1)
Previous Standard: GEN0 / C7.5 (now rarely specified)
Old Classification: Grade 10 or C10P
Note: GEN1 terminology still widely used by suppliers
BS 8500 Classification
Designated Concrete: GEN 1
Minimum Cement Content: 150-180 kg/m³
Maximum Water/Cement Ratio: 0.80
Exposure Class: XC1 (dry or permanently wet, non-aggressive)
Typical Mix Proportions
Cement (CEM I): 160-180 kg/m³
Aggregates: 1900-1950 kg/m³
Water: 140-160 litres/m³
Slump: S3 (100-150mm) or S4 (160-210mm) for blinding
Primary Applications of C8/10
C8/10 concrete is exclusively used for non-structural applications where its low strength (10 N/mm² cube) is adequate. The primary benefit is cost-effectiveness due to reduced cement content, making it ideal for large-volume applications like blinding layers and trench filling.
| Application |
Typical Thickness/Depth |
Purpose |
Standards Reference |
| Foundation Blinding Layer |
50-75mm thickness |
Leveling, protection for DPM, clean working surface |
BS 8500, NHBC Chapter 4.2 |
| Kerb Bedding & Backing |
100-150mm bed, 150-300mm haunch |
Support and alignment for roadside kerbs |
Highway specifications |
| Trench Fill (Services) |
Variable depth around pipes/cables |
Protection and support for buried services |
Utility specifications |
| Drainage Surrounds |
150mm minimum around pipes |
Bedding and haunching for drainage pipes |
Building Regulations Part H |
| Mass Concrete Fill |
Variable (void/cavity filling) |
Non-structural volume filling |
General construction practice |
| Temporary Pathways |
50-75mm thickness |
Light pedestrian traffic during construction |
Site management practices |
| Post Supports (Non-Critical) |
300-400mm depth around posts |
Fence posts, temporary signage (not structural) |
General construction |
| Over-Site Below Suspended Floors |
75-100mm thickness |
Void protection, moisture barrier base |
NHBC Chapter 5.1 |
Foundation Blinding Layer
Thickness
50-75mm
Purpose
Level surface + DPM protection
Standard
BS 8500, NHBC 4.2
Kerb Bedding & Backing
Thickness
100-150mm bed
Purpose
Kerb support & alignment
Standard
Highway specs
Drainage Surrounds
Thickness
150mm minimum
Purpose
Pipe bedding & haunching
Standard
Part H Drainage
Blinding Concrete Explained
The most common use of C8/10 is as a blinding layer (also called leveling concrete). Blinding is a thin layer of weak concrete poured over excavated ground before foundation construction begins. It provides a clean, level working surface and protects the damp-proof membrane (DPM) from puncture by stones or soil.
What Blinding Does
Leveling: Creates flat surface for accurate formwork placement
DPM Protection: Prevents membrane puncture from sharp stones
Clean Working Surface: Keeps reinforcement and formwork clean
Reference Level: Provides datum for foundation depth checks
Typical Blinding Specification
Grade: C8/10 (GEN1)
Thickness: 50mm minimum, 75mm typical
Extent: Extends 150-300mm beyond foundation footprint
Finish: Troweled smooth, no particular level tolerance
Curing: Minimal requirements (protect from rain/frost)
When Blinding is Required
Strip Foundations: Essential for DPM protection beneath concrete
Raft Foundations: Required before reinforcement placement
Slab Foundations: Recommended for ground slabs with DPM
Not Required: Mass trench-fill foundations (no DPM beneath)
Alternative to Blinding
Sand Blinding: 50mm sharp sand (cheaper but less effective)
Lean Mix Concrete: Site-mixed weak concrete (not certified)
Geotextile Membrane: Heavy-duty fabric (specialist applications)
Recommendation: C8/10 provides best combination of cost and performance
📐 Calculating Blinding Concrete Volume:
- Formula: Length (m) × Width (m) × Thickness (m) = Volume (m³)
- Example: 10m × 8m foundation with 75mm blinding = 10 × 8 × 0.075 = 6 m³
- Add Overhang: Blinding extends 150-300mm beyond foundation edges
- Typical House: 50-100m² footprint requires 4-8 m³ of C8/10 blinding
- Wastage: Add 5-10% for uneven ground and spillage
- Minimum Order: Many suppliers have 1-2m³ minimum (small load surcharge applies)
C8/10 Mix Design Specifications
C8/10 concrete uses significantly less cement than structural grades, making it economical for large-volume applications. The low cement content (160-180 kg/m³) compared to C20/25 (240 kg/m³) reduces cost by approximately £15-25 per cubic meter.
📊 Standard C8/10 Mix Proportions (per m³):
- Portland Cement (CEM I 42.5N): 160-180 kg (approximately 3-4 × 50kg bags)
- Fine Aggregate (Sand): 800-900 kg
- Coarse Aggregate (20mm gravel): 1100-1200 kg
- Water: 140-160 litres (water/cement ratio 0.75-0.80)
- Total Yield: Approximately 1 cubic meter
- Density: 2200-2350 kg/m³ (typical fresh concrete)
Ready-Mix vs Site-Mixed C8/10
Ready-Mix C8/10 (Recommended)
Advantages: Certified compliance, consistent quality, rapid placement, volumetric accuracy
Minimum Order: 1-2m³ typical minimum (small load surcharge)
Cost 2026: £90-115 per m³ delivered (cheaper than higher grades)
Best For: Blinding layers for foundations, kerb work, drainage projects
Site-Mixed C8/10 (Small Quantities)
Use Cases: Very small repairs (< 0.5m³), remote sites, post supports
Mix Ratio: Approximately 1:10 cement:all-in aggregate by volume
Cost 2026: Materials £50-70 per m³ plus labor and mixer hire
Risk: Quality not certified, inconsistent batching, lower reliability
⚠️ Important: When NOT to Use C8/10
- Structural Elements: Never use for foundations, slabs, beams, columns (use C20/25 minimum)
- Ground Bearing Slabs: Not suitable for floors carrying building loads (use C20/25)
- Driveways/Parking: Insufficient strength for vehicle traffic (use C25/30 or C30/37)
- Reinforced Concrete: Cover and bond requirements need C25/30 minimum
- Exposed Conditions: Poor durability in freeze-thaw or aggressive environments
- Permanent Pathways: Will crack and deteriorate under regular foot traffic
Pricing and Costs 2026
C8/10 is the most economical concrete grade due to low cement content. Prices reflect typical UK ready-mix rates for 2026. The grade's cost advantage makes it ideal for high-volume blinding and kerbing projects where structural strength is not required.
| Order Quantity |
Price per m³ |
Delivery Notes |
Total Cost Example |
| 1-2 m³ (Small Load) |
£105-125/m³ |
Small load surcharge £30-50 |
2m³ = £210-250 + £40 surcharge = £250-290 |
| 3-5 m³ (Standard) |
£95-110/m³ |
Standard delivery included |
4m³ = £380-440 |
| 6-8 m³ (Full Load) |
£90-105/m³ |
Best value, no surcharges |
6m³ = £540-630 |
| 9+ m³ (Multiple Loads) |
£85-100/m³ |
Volume discount possible |
10m³ = £850-1,000 |
| Cost Saving vs C20/25 |
£15-25/m³ cheaper |
Due to lower cement content |
10m³ project saves £150-250 |
Small Load (1-2 m³)
Price per m³
£105-125
Surcharge
£30-50
Example (2m³)
£250-290
Standard Order (3-5 m³)
Price per m³
£95-110
Surcharge
None
Example (4m³)
£380-440
Full Load (6-8 m³)
Price per m³
£90-105
Surcharge
None
Example (6m³)
£540-630
Cost Comparison: C8/10 Blinding vs Alternatives
✓ Economic Analysis for 50m² Blinding Layer (75mm thick = 3.75m³):
- C8/10 Ready-Mix: 4m³ @ £100/m³ = £400 (recommended)
- Sand Blinding: 4 tonnes sharp sand @ £30/tonne + labor = £180-250 (cheaper but inferior)
- Site-Mixed Weak Concrete: Materials £60/m³ + mixer hire £50 + labor 8 hours @ £25/hr = £490 (not recommended)
- C20/25 (Over-Specified): 4m³ @ £120/m³ = £480 (wasteful - no benefit over C8/10 for blinding)
- Conclusion: C8/10 ready-mix is optimal for cost and performance
Placement and Finishing
C8/10 concrete has high workability (slump 100-150mm or higher) making it easy to place and level. For blinding applications, minimal finishing is required as the surface will be covered by DPM and structural concrete. Proper placement prevents delays and ensures adequate coverage.
Blinding Layer Placement
Ground Preparation: Excavate to formation level, remove loose material
Compaction: Firm ground (not necessarily heavily compacted)
Thickness: 50-75mm (use depth pegs or laser level)
Finishing: Basic trowel finish, smooth enough for DPM placement
Kerb Bedding Technique
Bed Thickness: 100-150mm compacted bed beneath kerbs
Laying: Place kerbs on semi-wet concrete, tap to level
Haunching: Backfill haunch (150-300mm) to 2/3 kerb height
Alignment: Use string lines for straight kerb runs
Drainage Work Applications
Pipe Bedding: 100-150mm beneath pipes on firm ground
Haunching: Side fill to pipe crown, compact around pipes
Surround: Minimum 150mm all around drainage pipes
Curing: Cover with soil after 24 hours (minimal curing needed)
Working Time and Set
Discharge Time: Place within 2 hours of mixing (1 hour in hot weather)
Initial Set: 4-6 hours (trafficking should wait 12-24 hours)
DPM Placement: Can proceed after 24 hours minimum
Foundation Pour: Structural concrete can be placed after 24-48 hours
Strength Development and Curing
C8/10 concrete gains strength more slowly than higher grades due to lower cement content. However, for non-structural applications like blinding, early strength is not critical. The concrete reaches adequate working strength within 24-48 hours.
Strength Gain Timeline
24 Hours: 15-20% of final strength (~2 MPa)
3 Days: 35-45% of final strength (~4 MPa)
7 Days: 60-70% of final strength (~7 MPa)
28 Days: 100% design strength (10 MPa minimum)
Curing Requirements
Protection: Cover from rain for 6 hours minimum
Frost Protection: Protect from freezing for 24 hours
Water Curing: Not typically required for blinding
Hot Weather: Damp down if temperature exceeds 25°C
⚠️ Cold Weather Precautions:
- Temperature Minimum: Do not pour below 5°C air temperature
- Frost Forecast: Protect with insulating blankets if frost expected within 48 hours
- Frozen Ground: Never pour on frozen ground (thaw first)
- Winter Work: Consider rapid-hardening cement or admixtures for cold weather
- Heated Enclosures: May be required for critical winter foundation work
Quality and Compliance
While C8/10 is non-structural, ready-mix suppliers still provide certified mixes compliant with BS EN 206 and BS 8500. Delivery tickets confirm mix specification, ensuring Building Control approval where required.
✓ Ready-Mix Delivery Documentation:
- Delivery Ticket: Records mix designation (C8/10 or GEN1), quantity, time of mixing
- Compliance Certificate: Confirms BS EN 206 and BS 8500 conformity
- Mix Design: Details cement content, aggregate sizes, water/cement ratio
- Producer Certification: QSRMC (Quality Scheme for Ready Mixed Concrete) membership
- Traceability: Batch numbers for quality control records
- Building Control: Delivery tickets may be requested for foundation inspections
Specification and Ordering
When ordering C8/10 concrete from suppliers, specify the application (blinding, kerbing, drainage) to ensure appropriate workability. Clear communication ensures correct mix delivery and avoids delays.
📋 Information to Provide When Ordering C8/10:
- Grade: C8/10 or GEN1 (both accepted by suppliers)
- Quantity: Volume in cubic meters (calculate area × thickness, add 10% wastage)
- Application: Blinding / kerb bedding / drainage / trench fill
- Slump: S3 or S4 (high workability for easy placement)
- Maximum Aggregate Size: 20mm standard
- Delivery Date/Time: Confirm excavation is complete and labor ready
- Site Access: Ensure mixer truck can reach placement area
- Discharge Method: Direct pour, wheelbarrows, or pump (if access restricted)
C8/10 Concrete FAQs
What is C8/10 concrete used for?
C8/10 concrete is used exclusively for non-structural applications including foundation blinding layers (50-75mm), kerb bedding and backing, drainage pipe surrounds, trench fill around buried services, mass concrete cavity fill, and temporary pathways. It is NOT suitable for structural foundations, floor slabs, driveways, or any load-bearing elements. Its low strength (10 N/mm² cube) and economical cement content make it ideal for high-volume applications where structural strength is not required.
What is the difference between C8/10 and GEN1?
C8/10 and GEN1 are identical - just different terminology for the same concrete grade. GEN1 is the older British designated mix classification (General Purpose Grade 1), while C8/10 is the current European standard designation under BS EN 206. The "8" represents 8 N/mm² cylinder strength and "10" represents 10 N/mm² cube strength. Suppliers understand both terms, though C8/10 is the technically correct specification for 2026.
How much does C8/10 concrete cost in 2026?
C8/10 ready-mix concrete costs £90-110 per cubic meter delivered for standard orders (3-6m³) in the UK. Small loads (1-2m³) cost £105-125/m³ plus £30-50 small load surcharge. This is approximately £15-25 per m³ cheaper than C20/25 due to lower cement content (160-180 kg/m³ vs 240 kg/m³). For a typical foundation blinding project requiring 4-6m³, expect total cost of £400-600 including delivery.
What thickness should blinding concrete be?
Blinding concrete should be 50mm minimum thickness, with 75mm being typical and recommended. The blinding layer should extend 150-300mm beyond the foundation footprint on all sides. For a house foundation of 50m² footprint, you'll need approximately 3.75-4.5 m³ of C8/10 concrete (allowing for overhang). Thicker blinding (100mm) is sometimes used on very uneven ground but is generally unnecessary.
Can I use C8/10 for a shed or garage base?
No, C8/10 is NOT suitable for shed or garage floor slabs. Its low strength (10 N/mm²) will crack and fail under building loads and foot traffic. For shed and garage bases, use C20/25 minimum (100-125mm thickness with A142 mesh). C8/10 can only be used as a blinding layer BENEATH a structural floor slab, not as the slab itself. Using C8/10 as a finished floor will result in rapid deterioration and structural failure.
How long before I can pour foundations on C8/10 blinding?
You can place damp-proof membrane (DPM) and pour structural foundations on C8/10 blinding after 24-48 hours in normal weather conditions (15-20°C). The blinding needs sufficient strength to support workers and avoid damage during DPM placement and formwork installation. In cold weather (5-10°C), wait 3-5 days. The blinding does not need to reach full 28-day strength before proceeding with foundation work.
Can I mix C8/10 concrete on-site myself?
Site-mixing C8/10 is possible for very small quantities (< 0.5m³) using approximately 1 part cement to 10 parts all-in aggregate by volume. However, for blinding layers requiring 3-6m³, ready-mix is far more practical and economical. Site-mixing this volume would take many hours with multiple mixer loads, and quality will be inconsistent. Ready-mix C8/10 costs £90-110/m³ delivered, which is comparable to site-mixed materials plus labor and mixer hire.
Is sand blinding better than C8/10 concrete blinding?
No, C8/10 concrete blinding is superior to sand blinding in most cases. Concrete provides a stable, level surface that won't shift, better protects the DPM from puncture, and creates a clean working platform. Sand blinding (50mm sharp sand) is cheaper (£30-50 vs £100-150 for typical blinding) but can be disturbed during DPM placement, offers less puncture protection, and provides no structural contribution. C8/10 is the professional standard and recommended by NHBC.
Can C8/10 be used for driveways or pathways?
No, C8/10 is NOT suitable for driveways or permanent pathways. Its low strength (10 N/mm²) will crack and deteriorate rapidly under vehicle or even regular foot traffic. For driveways, use C25/30 or C30/37 minimum (100-125mm thickness). For pathways, use C20/25 minimum (75-100mm thickness). C8/10 can only be used for temporary construction pathways that will be removed, not permanent access routes.
What is the slump specification for C8/10 blinding?
C8/10 blinding typically uses S3 slump (100-150mm) or S4 slump (160-210mm) for easy placement and leveling. The high workability allows the concrete to flow and self-level with minimal effort, reducing labor requirements. For kerb bedding, S2 slump (50-90mm) may be specified for firmer consistency. Specify the intended application when ordering - suppliers will adjust workability accordingly using plasticizers if needed.
