Mixing concrete by hand is one of those jobs that looks straightforward until you end up with a crumbly heap or a soupy puddle. The good news is that with the right ingredients, a consistent measuring method and a bit of elbow grease, you can produce perfectly usable concrete for fence posts, small slabs, steps, path edging and repairs. This guide walks you through the process as if you were standing beside me in the garden.

When Hand Mixing Makes Sense

Hand mixing is ideal for jobs up to about one cubic metre, or roughly twenty-five to thirty 25kg bags of cement. Any bigger, and you should seriously consider ready-mixed concrete delivered by lorry. It saves your back, your time and usually gives a more consistent result. Hand mixing also suits awkward access, small patches and jobs where you only need a wheelbarrow or two at a time.

Use it for: fence posts and gate posts, small shed bases, steps, repairing concrete paths, setting drainage covers, and bedding kerbs. Avoid it for large driveways, house extensions or anything structural without proper advice.

The Four Ingredients and the Golden Ratio

Concrete is cement, sand, gravel and water. Not cement and sand alone, which gives mortar, and not gravel alone. For general-purpose concrete, the traditional mix is 1 part cement, 2 parts sharp sand and 3 parts gravel by volume. Use 20mm gravel or all-in ballast. Sharp sand has angular grains that lock together; builder's sand is too fine and soft for concrete.

• Cement: fresh ordinary Portland cement, lump-free. Old, damp cement loses strength.
• Sharp sand: also called grit sand or concreting sand. Not building sand.
• Gravel: 20mm washed gravel, or use 5 parts ballast instead of 2 parts sand and 3 parts gravel.
• Water: clean and drinkable. Dirty water can weaken the mix.

Measure with buckets, not shovels, for consistency. A 25kg bag of cement is roughly one bucket. With a 1:2:3 mix, that bag will make about 0.1 cubic metres of concrete, enough for a small slab or several fence posts. For stronger concrete, use 1:1.5:3. For a leaner mix under a shed base, 1:3:6 is fine.

Tools, Safety and Preparation

You do not need a cement mixer, but you do need a few basics. A wheelbarrow or a large mixing board works well. A board on a firm, flat surface is easier on the back, but a wheelbarrow lets you move the mix to the job. Have a shovel, a sturdy bucket for measuring, a watering can or hose with a gentle flow, and a trowel or float for placing.

• Safety: cement is alkaline and can burn skin. Wear gloves, eye protection and a dust mask when opening bags.
• Surface: mix on a clean board or hard surface, never on grass or soil, or you will pick up dirt and lose cement.
• Water: have it ready but add it gradually. It is much easier to add water than to remove it.
• Timing: mix only what you can place and finish within about 30 to 45 minutes.

Step-by-Step: Mixing by Hand

• Step 1 — Measure: Put one bucket of cement, two buckets of sharp sand and three buckets of gravel on your board or into the wheelbarrow.
• Step 2 — Dry mix: Turn the pile with your shovel, folding it over and over until the colour is uniform and no streaks of sand or cement remain. This usually takes three or four minutes.
• Step 3 — Form a crater: Push the dry mix into a ring with a hollow centre, like a volcano. This stops water running off.
• Step 4 — Add water: Pour in about three-quarters of your water. Add the rest gradually. Too much at once makes a soupy mess.
• Step 5 — Mix thoroughly: Fold the dry mix into the water from the outside in. Keep turning the pile, chopping any dry pockets with the shovel. Scrape the board or barrow as you go.
• Step 6 — Check texture: The concrete should be workable, like thick porridge, and hold its shape when you make a groove with a trowel. If it is crumbly, add a splash more water. If it slumps and runs, add a little more dry mix.
• Step 7 — Use it: Place and compact the concrete within 30 to 45 minutes. Do not keep adding water to revive a stiff mix; it weakens the final concrete.

Common Mistakes and Curing

The single biggest mistake is adding too much water. It makes concrete easier to shovel but reduces strength and causes shrinkage cracks. Aim for a stiff, workable mix. Other common errors include not dry mixing first, using builder's sand instead of sharp sand, and mixing on soil. Always clean your tools immediately after use, as concrete sets hard quickly.

Curing is not optional. Once placed, cover the concrete with plastic sheeting or damp hessian and keep it damp for at least three days, ideally seven. This helps it reach full strength. In cold weather, do not mix concrete below 5°C, and protect it from frost. In hot weather, keep it shaded and damp. With patience and the right ratio, your hand-mixed concrete will be every bit as good as a delivered load for small jobs.