Cement, Sand, Aggregate Quantities & Costs 2026
Concrete mix ratios express proportions of cement : sand : aggregate required for specific strength grades. The notation 1:2:4 indicates 1 part cement, 2 parts sand, and 4 parts aggregate by volume, producing M15-M20 grade concrete suitable for foundations and general construction. Mix ratios determine final concrete strength, workability, and durability with stronger ratios using more cement relative to aggregates.
Dry volume calculation multiplies wet concrete volume by 1.54 factor accounting for 54% increase from material bulking when water fills voids between particles. This conversion ensures accurate material quantities preventing shortages during mixing. Cement converts from cubic metres to 25kg bags using 0.0167 m³ per bag factor while sand and aggregate measure in tonnes using standard bulk densities of 1.6 tonnes/m³ and 1.5 tonnes/m³ respectively.
M10 (1:3:6) suits non-structural applications including garden paths, shed bases, and trench fill requiring minimal strength. M15-M20 (1:2:4) provides general purpose concrete for strip foundations, garage bases, and retaining walls. M20 (1:2:3) supports driveways, workshop floors, and moderate load applications. M25 (1:1.5:3) delivers structural grade concrete for beams, columns, and suspended slabs demanding higher compressive strength.
Portland cement (CEM I 42.5N or 52.5N) provides standard strength development suitable for all applications. Sharp washed sand ensures clean fine aggregate free from clay or organic contamination weakening concrete. 20mm clean gravel or crushed stone aggregate maximises packing density and bond strength. All-in ballast simplifies mixing combining sand and aggregate at 1:4 or 1:5 cement ratios equivalent to standard volumetric mixes.
Dry mix cement, sand, and aggregate thoroughly achieving uniform colour before adding water gradually. Target water-cement ratio of 0.45-0.60 produces workable concrete without excess water compromising strength. Mixer rotation continues 2-3 minutes after water addition ensuring complete coating of all particles. Test workability using slump cone achieving 50-100mm slump for general purpose concrete suitable for most construction applications.
| Mix Ratio | Grade | Strength | Applications |
|---|---|---|---|
| 1:3:6 | M10 | 10 N/mm² | Paths, sheds, trench fill |
| 1:2:4 | M15-M20 | 15-20 N/mm² | Foundations, garage bases |
| 1:2:3 | M20 | 20 N/mm² | Driveways, floors |
| 1:1.5:3 | M25 | 25 N/mm² | Beams, columns, slabs |
| Material | Density | 2026 Price | Notes |
|---|---|---|---|
| Cement (25kg bag) | 0.0167 m³ | £7.00-8.50 | 42.5N or 52.5N grade |
| Sharp Sand | 1.6 t/m³ | £32-38/tonne | Washed, clean |
| 20mm Aggregate | 1.5 t/m³ | £26-32/tonne | Gravel or crushed stone |
| All-in Ballast | 1.7 t/m³ | £22-28/tonne | 1:4 or 1:5 cement ratios |
Wet volume × 1.54 = dry volume accounting for 54% material bulking when water fills voids.
One cement bag occupies 0.0167 cubic metres for volume-to-bag conversion accuracy.
Standard sharp sand bulk density for accurate tonne calculations from volume.
20mm gravel/crushed stone density ensuring precise material ordering quantities.
Optimum ratio balancing workability and maximum concrete compressive strength.
Accounts for spillage, bulking variations, and mixing losses during construction.
1:2:4 (M15-M20) provides adequate strength for garden sheds and light structures. 100-150mm depth with good sub-base preparation ensures long-term performance without cracking or settlement issues.
Dry materials occupy 54% more volume than wet concrete due to air voids between particles. Water fills these voids during mixing reducing total volume - 1.54 factor ensures correct dry quantities.
Hand mixing suitable up to 0.2m³ batches. Concrete mixer recommended above 0.5m³ ensuring uniform mixing and consistent strength. Ready-mix economical for volumes exceeding 3m³ total requirement.
Add water gradually achieving workable consistency without excess free water. Target 50-100mm slump test result. Too much water significantly reduces final concrete compressive strength.
Yes, 1:4 or 1:5 cement to ballast ratios equivalent to 1:2:4 or 1:3:6 mixes. Simplifies ordering but slightly less control over sand/aggregate proportions compared to separate materials.
Use within 2 hours maximum from water addition. Initial set begins after 45-90 minutes depending on temperature. Do not retemper with additional water - discard unused concrete after working time expires.
Materials suppliers: Wickes | Travis Perkins | Jewson | Standards: Concrete Centre