How to make polished concrete

Advice: just make a polished concrete floor yourself.

Concrete slabs or floors that you cast yourself are required, for example, when building pavilions, terraces, garages or carports. Furthermore, they serve as a foundation for garden and tool shelters in the private sector. The basic materials are water, gravel and cement. If these materials are mixed in the correct ratio, this mixture hardens to form concrete.

But before that, there is still some preliminary work to be done before pouring a concrete foundation. The exact ground plan of the foundation is to be staked out with the help of stakes and a guideline. Then the pit is dug with a spade and shovel. The depth of the excavation depends on the planned thickness of the concrete slab (15 to 20 cm are sufficient for a terrace or garden house). In addition, about 20 cm must be added for the ballast layer underneath (it is important to ensure that the ballast is frost-proof). This prevents moisture from rising. To prevent the foundation from sinking later, it must be tamped down well. For larger projects, the use of a vibrating machine is worthwhile. For the required cladding, a further 10 cm must be added all around. When shuttering with shuttering boards, use a spirit level to ensure an exact and horizontal alignment.

Normal concrete usually has a mixing ratio of 4: 1 (4 parts of gravel with a grain size of up to 32 mm and 1 part of cement as a binding agent). The amount of water required corresponds to about half the amount of cement used (with half a bag of cement, about 12.5 kg, this is about 6 liters of water). Water is carefully added to the mixture. It is important to ensure that the concrete does not become too liquid. Then the gravel, cement and water are either mixed vigorously with a trowel or, alternatively, with a mortar mixer. If the liquid concrete does not yet have the required consistency, just carefully add more water.

The next step would be a possible reinforcement from steel mesh. These are necessary when the subsequent floor slab is exposed to high loads (e.g. in garages, carports, gazebos or tool sheds). Then the required amount of concrete is mixed. Since the hardening of the concrete begins immediately after pouring out, further processing must be started immediately afterwards. The mass is to be distributed so evenly that the possible formation of cavities is prevented. The best way to prevent such cavities is to pierce the concrete several times with a shovel or screed. Then the concrete slab is compacted with a hand tamper or a vibrating plate. However, you should proceed with caution here, because concrete has the property that if it is shaken for too long, it will separate again. This is the case when a layer of water forms on the surface. Finally, the surface is smoothly peeled off over the edges of the cladding with a peeling board.

A possible additional step would be the smoothing of the concrete slab. This compensates for any inclines and unevenness on the surface. The right time is given when the concrete has just hardened enough to support the weight of the concrete processing machine and its user. Such grinding systems are made possible, for example, by using Becosan. The smoothing and final surface polishing gives the concrete slab a dust-free and easy-to-clean surface.