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Concrete mix

For 1 m³ of structural concrete (1:2:3 ratio) you need about 7.4 bags of 50 kg cement, 0.5 m³ of sand, 0.8 m³ of gravel and around 160 L of water. Use the calculator below with your volume and mix type: it gives you each material and how many batches you'll run in a 1.5-bag mixer like the SQREVG365LTS or a 2-bag one like the SQREVG550LTS.

How much of each material, in what order, and why vibrating makes the difference.

Calculate your mix

Cement, sand, gravel and water — per m³ and per mixer batch.

1 · What are you pouring?
2 · How much concrete?
0.50m³≈ 8 barrows
Mixer

That's about ≈ 2 batches in the mixer.

● Cement● Sand● Gravel
You'll need

Cement

3.7

bags (50 kg)

Sand

0.3 m³

≈ 4 wheelbarrows

Gravel

0.4 m³

≈ 6 wheelbarrows

Water

81 L

max — don't exceed

Approximate values (dry-volume method). For structural work, follow your engineer's mix design.

Calculate with dimensions, 42.5 or 50 kg bags and batches per mixer, and share the result →

The fundamental

The extra water never leaves

Cement needs about 40% of its weight in water to hydrate. Anything beyond that reacts with nothing: it evaporates and leaves a pore exactly where it sat. Those pores are the strength you lost — no amount of curing or waiting brings it back.

Your mix, per cubic metre:

Water/cement ratio

0.50

28-day strength

42 MPa

≈ 6,136 psi

Normal working range

Where most structural site concrete lives.

What if you add one more bucket “so it flows”?

a/c 0.50 → 0.5542 → 37 MPa−13%

18 litres cost you 13% of the strength, permanently. If the mix won't flow, the answer is a plasticiser or more paste (cement AND water, keeping the ratio) — never water alone.

Strength

Falls exponentially: each extra tenth in the ratio costs about a quarter of it.

Shrinkage

More water to evaporate means more contraction — and more drying cracks.

Permeability

Pores connect. Water gets in, reaches the steel and rusts it.

Bleeding

Excess water rises and carries fines with it: a milky, weak top surface.

Estimate for well-cured concrete with class 42.5 cement. Real strength comes from 28-day cylinders — this is for deciding BEFORE the pour, not certifying after.

If the mix won't flow, don't add water

  • Plasticiser: makes the same mix flow without touching the water/cement ratio. The only fix that costs no strength.
  • More paste: raise cement AND water together, keeping the ratio. Costs more but doesn't weaken.
  • Vibrator: if the problem is getting it between the rebar, consolidate with vibration, not water.
  • Check the clock: a mix that has started to set won't come back with water. Discard it.

Practice

One bucket too many

Your batch comes out stiff and someone shouts «add water». Go ahead: it flows better. Then break the 28-day cylinder and see what it cost.

…

Step by step

The right mixing order

Concrete mixer parts, 1.5 vs 2 sacks and loading orderSide-view diagram of a concrete mixer with six numbered parts: 1, the drum or hopper; 2, the one-piece cast-iron ring gear that turns the drum; 3, the motor, Honda or electric; 4, the anti-vibration pads under the motor; 5, the reinforced “V” chassis; 6, the grease points and gear reducer. Comparison: the 1.5-sack mixer has a 365-liter drum and a Honda GX160 or electric motor; the 2-sack mixer has 550 liters and a Honda GX390. The 1.5-sack electric mixer mixes up to 358 liters. Loading order: part of the water first, then gravel, cement, sand and the rest of the water. Mix for 2 to 3 minutes.1234561Drum (hopper)2One-piece cast-iron ring gear3Honda or electric motor4Anti-vibration pads5Reinforced “V” chassis6Grease points and gear reducer1.5 sacks2 sacksDrum365 L550 LMotorHonda GX160or electricHonda GX390The 1.5-sack electric model mixesup to 358 L per batch.Loading order1Part of the water2Gravel3Cement4Sand5Rest of the waterMix for 2–3 min
Not to scale. Capacities and motors from the SIMAQ spec sheets; loading order from the mixing lesson.

Don't have a mixer yet? How to choose a concrete mixer · For indoor work, the electric SQREVE-365LTS mixer

  1. 1

    Water and gravel first

    Start the mixer with part of the water and the gravel: it cleans the drum and keeps cement from sticking.

  2. 2

    Add cement and sand

    With the drum turning, add cement and sand gradually so they blend evenly.

  3. 3

    Finish the water, carefully

    Add the rest of the water bit by bit. More water = easier, but LESS strength. Don't overdo it.

  4. 4

    Mix for 2–3 minutes

    Until you get uniform color and texture, with no lumps or dry cement balls.

  5. 5

    Check the slump

    Aim for a workable but not watery mix. Pour within 30–45 minutes and vibrate as you pour.

Demo

Why vibrate concrete?

Flip the switch and see the difference in the pour.

Honeycombs / voids
Trapped air
High
Strength
Down to −30%
Finish
Honeycombs & voids

Vibrating drives out the air trapped in the pour. Without it, you get honeycombs that weaken the structure and look bad. With the vibrator, the concrete consolidates dense, even and at its true strength.

How to vibrate properly, step by step: concrete vibration lesson

Watch it

The lesson, on video

More SIMAQ videos
  • Using the concrete mixer
  • SIMAQ concrete mixer

Shorts

Working with concrete? The SIMAQ line

Watch Shorts

FAQ

What people ask most

How much cement, sand and gravel is in 1 m³ of concrete?

For a 1:2:3 structural mix, about 7.4 bags of 50 kg cement, 0.5 m³ of sand, 0.8 m³ of gravel and around 160 L of water per m³. For footings (1:2:4) or subfloors (1:3:5) it changes: use this lesson's calculator with your volume.

Is there a concrete mix calculator?

Yes: this lesson's calculator gives you cement, sand, gravel and water per m³ and per mixer batch. Pick the mix type (subfloor, general, structural or high strength), the volume and the bags per batch.

What mix ratio do I use for slabs, beams and columns?

For slabs, beams and columns, the 1:2:3 structural mix (cement : sand : gravel), around 210 kg/cm². For footings and walls, 1:2:4 (~180 kg/cm²); for non-loaded subfloors, 1:3:5 (~140 kg/cm²).

In what order do materials go into the mixer?

First part of the water and the gravel, then cement and sand with the drum turning, and finally the rest of the water bit by bit. Mix 2–3 minutes until the color is even and pour within 30–45 minutes.

Can I add more water if the mix won't flow?

No: extra water evaporates and leaves pores that cost strength for good. If it won't flow, use a plasticiser, raise cement and water together, or consolidate with a vibrator.

Which mixer do I need, 1.5 or 2 bags?

For medium pours a 1.5-bag (365 L) mixer is enough: the petrol SQREVG365LTS, or the electric SQREVE-365LTS for indoor or noise-restricted sites. For big pours, the 2-bag SQREVG550LTS (550 L) needs fewer batches.

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