How to Mix Concrete in a Concrete Mixer

A concrete mixer is a device that homogeneously combines cement, aggregate such as sand or gravel, and water to form concrete.

How to Mix Concrete in a Concrete Mixer

• Make sure you have all your materials in the correct quantities on site
• Make sure you have enough fuel for your concrete mixer handy
• Keep your bags of cement away from moist and water by covering the bags with plastic.

• Start the machine running with the drum at about 45°.
• Add about half the course aggregate required.
• Add a small amount of water and allow it to wash around with the course aggregate for a minute or two.
• Add about half the fine aggregate (sand) required.
• Add all the required cement.
• Add the remaining course and fine aggregate and allow it to mix for a minute or two.
• Gradually add more water giving it a chance to mix in and keeping an eye on the consistency. A good mix should be smooth and plastic, not wet and  dry and crumbly. If parts of the mix stick to the side and 'goes over the top', the mix is too dry; if the mix on the inside goes about ¾ of the way up to the top and then falls back into the mix, it is about right; if the mix is not taken up the side, the mixture is too wet. 

Note: One of the most common mistakes made when mixing concrete is adding too much water. Add it in small quantities and the contents of the drum will suddenly be the right consistency. If the mixture does get too wet, sprinkle in handfuls of ballast and cement in the rough proportions until it firms up. 

• When the mixing is complete, place a wheelbarrow under the drum and empty it into a wheelbarrow.
• When the job is complete, or you wish to take a break of half an hour or more, the cement mixer must be cleaned; never leave the cleaning up until later,the same applies to wheelbarrow, buckets and other tools which have come into contact with the ingredients or final mixture. 
  Always clean inside the drum; put a shovel load of ballast and some water in the drum and run it for 5 minutes, tip the whole load and then hose the inside of the drum and, with the mixer switched off, use an old brush to clean out any awkward corners.