Metric Concrete Mix & Moisture Calculator
The Metric Concrete Mix & Moisture Calculator adjusts concrete batch quantities when aggregates arrive wetter (or drier) than their absorption level. After you enter slab dimensions in metres and millimetres, mix ratio, water-to-cement ratio and each aggregate's absorption and moisture content, the calculator:
- inflates finished volume by 54 % to obtain loose-dry volume
- distributes that volume according to the mix ratio
- converts ingredient volumes to mass using standard bulk densities (1440 kg/m³ cement, 1536 kg/m³ sand, 1590 kg/m³ gravel)
- computes batch water from the w/c ratio, then subtracts the "free" water present on the aggregates' surfaces
- returns adjusted aggregate weights plus net water to add in kilograms, cubic metres and litres
Self-Mix from Volume Metric Calculator with Moisture
Calculator
- enter the mixing ratio for cement, sand, and gravel
- the water-to-cement ratio to control the workability
- enter the volume of concrete needed in cubic meters
- the absorption rate for the fine aggregates (sand)
- the moisture content of the sand
- the absorption rate for the course aggregates (gravel)
- the moisture content of the gravel
Results
- the total volume of concrete required
- the volume and weight of cement in cubic metres and kilograms
- the volume and weight of the sand in cubic metres and kilograms
- the volume and weight of gravelin cubic metres and kilograms
- the volume of water needed in cubic metres (calculated from the cement-to-water ratio)
- the weight of water in kilograms (1 litre of water equals 1 kilogram)
- the amount of water in litres (calculated as 1000 litres per cubic metre)
- the total weight of cement, sand, gravel, and water (the total mass of the concrete mix in kilograms)
- the weight of the fine aggregate (sand) adjusted by the amount of water it absorbs
- the weight of the coarse aggregate (gravel) in kilograms adjusted by the amount of water it absorbs
- the free water weight in kilograms and volume in litres
- adjusted water weight in kilograms and volume in litres
Metric Concrete Mix & Moisture - Calculation Formulas
$$V = L\,W\,\frac{D}{1000}$$
$$V_{\text{dry}} = 1.54\,V$$
$$P = c+s+g$$
$$V_c=\frac{c}{P}V_{\text{dry}},\;
V_s=\frac{s}{P}V_{\text{dry}},\;
V_g=\frac{g}{P}V_{\text{dry}}$$
$$M_c = 1440\,V_c,\;
M_s = 1536.491\,V_s,\;
M_g = 1589.981\,V_g$$
$$M_w = \left(\frac{w}{c}\right)M_c$$
$$V_w = \frac{M_w}{1000}$$
$$\text{FMC}_{s}= \max(0,m_s-a_s),\;
\text{FMC}_{g}= \max(0,m_g-a_g)$$
$$M_{s\_adj}=M_s+M_s\frac{a_s}{100},\;
M_{g\_adj}=M_g+M_g\frac{a_g}{100}$$
$$M_{\text{free}} = M_s\frac{\text{FMC}_{s}}{100}+M_g\frac{\text{FMC}_{g}}{100}$$
$$M_{w\_adj} = \max(0,M_w-M_{\text{free}})$$
$$M_{\text{total}} = M_c+M_s+M_g+M_w$$
Worked example
Slab 4 m x 3 m x 100 mm, mix 1 : 2 : 3, w/c 0.55, sand abs 1 %, sand moist 4 %, gravel abs 0.5 %, gravel moist 2 %.
| Item | Result |
|---|---|
| Finished volume V | 1.200 m³ |
| Dry volume | 1.848 m³ |
| Cement mass | 444 kg |
| Sand mass (dry) | 946 kg |
| Gravel mass (dry) | 1469 kg |
| Batch water | 244 kg (244 L) |
| Free water in agg. | 38 kg (38 L) |
| Net water to add | 206 kg (206 L) |
This calculator provides essential moisture correction, ensuring the water content and aggregates are accurately adjusted based on their absorption and moisture levels. It's an effective tool for onsite self-mixing to create durable, high-quality concrete.