Preparing cement mortar by manual process

Manual mixing of cement mortar is done for small works, when a mixer is not available. For a 1:6 cement-sand mortar (1 part cement to 6 parts sand by volume), the steps are as follows.

Materials and tools

Cement (OPC 43 grade), clean river sand (passing a 4.75 mm sieve, free from silt and organic matter), clean water; a watertight platform (masonry or steel sheet, 3 m × 3 m), shovels, trowels, a gauge box, buckets.

Procedure

1. Measure the sand: Measure the volume of sand with a gauge box (e.g. 6 boxes for 1 bag of cement; 1 bag of 50 kg = 0.035 m³).
2. Spread the sand: Spread the sand in a uniform layer, 150 to 200 mm thick, on a clean, hard platform.
3. Add cement: Spread the cement evenly over the sand.
4. Dry mixing: Mix the sand and cement with shovels, turning the heap over at least 3 times, until the mix has a uniform colour.
5. Making a crater: Form the dry mix into a ring with a hollow at the centre.
6. Adding water: Add water slowly into the centre, without letting it escape, using just enough to get a workable consistency (too much water weakens the mortar).
7. Wet mixing: Turn and re-mix 3 to 4 times with a shovel until the mortar is uniform and has the correct consistency.
8. Use: Use the mortar within 30 minutes of adding water (before the initial set). Hardened mortar must not be re-tempered; unused mortar is discarded.
9. Cleaning: Clean the platform and tools after use.
10. Curing: Cure the finished work for at least 7 days.

 1. sand layer   2. + cement   3. dry mix
 ~~~~~~~~~~~~~   ===========   (turn x3)
 4. crater -> add water -> turn x3-4 -> mortar