WORKED MIX DESIGN EXAMPLE

M30 concrete ratio and mix design

Explore an M30 mix design with wet aggregate corrections, cement and water quantities, batch scaling and a transparent calculation worksheet.

M30 · Severe exposureReinforced concrete · OPCIllustrative materials · Not a tested mix

Scale the worked example

Required concrete volume · m³

This M30 example uses sand at 5% total moisture and coarse aggregate at 1%, with the entered absorptions of 1% and 0.5%. It shows why the mixer-water amount is lower than the design free-water budget.

All material assumptions are listed below. Open the full lab to change them.

M20 example →M25 example →

YOUR M30 EXAMPLE · BATCH QUANTITIES

2,458.55kg for 1 m³ designed concrete

Target mean strength38.25 MPa

Final water / cement0.42

SSD ratio by mass1 : 1.82 : 3.29

Ratio is total binder : fine aggregate : coarse aggregate for this example. Batch weights below use the entered aggregate moisture.

Material	Your batch · kg
Cement	375.54
Fine aggregate (as batched)	711.76
Coarse aggregate (as batched)	1,243.03
Water to add at mixer	124.46
Chemical admixture	3.76

Adjust this M30 design in the lab →

Keeping the water balance correct with wet aggregates

Wet aggregates bring both solid particles and water into the mixer. Their batch weights increase while the separately added water decreases. Correct both sides of that balance: subtracting water without adjusting the aggregate weight would change the intended solid quantities.

Severe reinforced-concrete exposure is selected. The displayed ratio and minimum content are selected durability checks, not a complete exposure assessment. Sulphate conditions, chlorides, constituent conformity and the project specification require separate review.

Material and design assumptions

Slump / aggregate: 100 mm / 20 mm angular, Zone II
Specific gravities: Cement 3.15; sand 2.65; stone 2.74
Entrapped air: 1% of concrete volume
Water reduction / dosage: 20% trial assumption / 1% of binder
Sand: absorption / moisture: 1% / 5% of oven-dry mass
Stone: absorption / moisture: 0.5% / 1% of oven-dry mass
Cement-strength curve: Expected cement strength 43 to <53 MPa; approximate reference
Admixture SG / water fraction: 1.145 / 0% — replace with supplier data
Binder / statistical basis: OPC only; assumed standard deviation; good control

These are example inputs, not a material test certificate. No fly ash, GGBS, silica fume, pump reduction or binder uplift is applied. The reference ratio is selected from the approximate curve, rounded down to 0.01 and checked against the selected durability cap.

Why does the M30 water-to-add value differ from free water?

Free water includes water contributed by aggregate surfaces and liquid admixture. Mixer water is what remains to be added separately after those contributions are accounted for. This example uses a zero admixture-water fraction as a visible placeholder assumption; replace it with supplier data.

Follow the M30 calculations

1. Set the target mean strength

IS 10262:2019 · 4.2, Tables 1–2

f′ck = max(fck + 1.65S, fck + X)max(30 + 1.65 × 5.00, 30 + 6.50) = 38.25 MPa

Assumed standard deviation 5.00 MPa. The larger margin governs; characteristic and target strengths are different.

2. Select and check the water/binder ratio

IS 10262 · 5.1 / IS 456 · Table 5

r = min(strength-based ratio, durability limit)min(0.42, 0.45) = 0.42

The ratio is interpolated from approximate Figure 1 readings and rounded down to 0.01. It is a preliminary selection, not a measured strength prediction.

3. Estimate the free water

IS 10262 · 5.3, Table 4

W = (W₀ − shape adjustment) × slump factor × (1 − reduction)(186 − 0) × 1.060 × 0.80 = 157.7 kg/m³

The starting water estimate is for SSD aggregates. The 3% change per 25 mm slump and admixture reduction are preliminary; actual workability must be measured.

4. Calculate and allocate the binder

IS 10262 · 5.4 / IS 456 · Tables 5–6

B = max((W ÷ r) × trial increase, durability minimum)max((157.73 ÷ 0.42) × 1.00, 320.00) = 375.5 kg/m³

Final w/b is 0.420 after minimum-content or trial adjustments. Replacement percentages are fractions of total binder mass.

5. Close the absolute-volume balance

IS 10262 · 5.2, 5.7

Vagg = 1 − Vair − Σ [mᵢ ÷ (Gᵢ × 1000)]1 − 0.0100 − 0.2802 = 0.7098 m³

Use specific gravity, not loose bulk density. Water carried inside the chemical admixture is counted once, within that product’s volume.

6. Split the aggregate volume

IS 10262 · 5.5, Table 5

pCA = [p₀ + 0.2(0.50 − w/b)] × (1 − reduction)[0.62 + 0.2 × (0.50 − 0.420)] × 1.00 = 63.6% coarse / 36.4% fine

SSD masses: fine 684.6 kg and coarse 1236.9 kg per m³. The optional reduction is a trial adjustment up to 10%, not an automatic pumpability guarantee.

7. Correct for aggregate moisture

SSD mass balance · IS 10262 Annexes A–B

mOD = mSSD/(1+A); mwet = mOD(1+MC); Wsurface = mOD(MC−A); Wmixer = Wfree − Wsurface,sand − Wsurface,stone − Wadmixture

Sand surface water: 677.9 × (5−1)/100 = 27.11; stone surface water: 1230.7 × (1−0.5)/100 = 6.15; mixer water: 157.73 − (27.11) − (6.15) − 0.00 = 124.5 kg/m³ mixer water

All water quantities above are kg per m³. A and MC are fractions in the formula; entered percentages are divided by 100. Total moisture and absorption use an oven-dry mass basis. Surface water 33.3 kg plus admixture water 0.0 kg is deducted from the free-water budget. Negative surface water represents aggregate absorption demand.

8. Scale and test the trial batch

IS 10262 · 5.8

Batch quantity = quantity per m³ × batch volumeEach constituent × 1.000 m³ = 1.000 m³ trial batch

Measure workability, fresh density, yield and strength; inspect segregation and bleeding. Revise the mix and record trials before project approval.

Checks and assumptions to review

Admixture water contribution is set to 0%. Enter the supplier’s measured water fraction when applicable; do not assume a liquid product is water-free.

Method: IS 10262:2019; selected durability provisions: IS 456:2000. BIS-authored third-party source copies. Verify applicable editions, amendments and project requirements. No independent professional approval is claimed.