HOW TO MIX CONCRETE BY HAND

Special precautions should be taken when mixing concrete by hand. Ideally, ten per cent more cement should be used than you would if mixing were done by machine. Also the mixing should be long and thorough, to ensure that materials are uniformly distributed, and every particle of sand and coarse material is completely covered with cement paste.

Some guidelines:

• Concrete should be mixed on a hard surface like a concrete floor, wooden platform, or metal tray-never on the ground – otherwise earth and dirt will get into it.

• Spread the measured quantity of sand evenly on the mixing platform, then dump the cement on the sand – also distributing it evenly.

• Mix the two over and over again, using a spade, so that the mixture shows an even colour, free from streaks of brown and gray.

• Now spread this mixture evenly, and then spread – don’t dump – the measured quantity of coarse material, otherwise the bigger particles may roll out.

• Mix the dry material, shoveling from the centre to the side, then back to the centre, and again to the side. This process should be repeated at least three times.

• Next make a hollow in the centre of the mixture, and pour half to three-fourth of the total quantity of water required – turning the material in towards the centre. Add the remaining water, turning the mixture over and again, until the colour and consistency are uniform. It is best to use a gardener’s water-can with a rose head to pour the water, rather than using a bucket which will result in the water running away and taking the cement with it. The concrete is now ready for placing where needed.

• One final point, at the end of the day. Wash clean the mixing platform otherwise the remnants of the concrete will set overnight, making its removal hard the next day, with consequent loss of working time.