Mixing and working with concrete

In short: Concrete is made from cement, sand, gravel, and water in the correct mixing ratio. For smaller DIY projects like foundations or garden paths, hand-mixed or pre-mixed dry concrete is usually sufficient.

In more detail: The mixing ratio directly affects the strength and workability of the finished concrete.

In detail

• Mixing ratio: A common rule of thumb is one part cement to two parts sand to three parts gravel, depending on the application.
• Water addition: Too much water significantly weakens strength, too little makes it harder to work with.
• Working time: Mixed concrete must be worked within a limited time before it begins to set.
• Compaction: Tapping or vibrating removes air bubbles and significantly increases later strength.
• Setting time: Initial strength usually develops after one to two days, full strength only after about 28 days.
• Curing: Fresh concrete should be kept moist in the first few days to avoid cracks from drying out too quickly.
• Ready-mixes: Bagged pre-dosed dry concrete significantly simplifies smaller projects compared to mixing individual ingredients yourself (werkzeug-grundausstattung-fuer-zuhause, tuerschloss-wechseln-grundlagen).