Concrete pour into molds


Concrete is a building material that many do-it-yourselfers discover for themselves. In addition to the classic fields of application, there are many new possibilities for processing concrete. A wide field of activity offers itself in the concrete in forms to pour.

The classic processing of concrete

Whether the frost-proof casting of concrete foundations, the concrete screed or the concrete terrace edging, even the classical processing possibilities of the artificial stone are enormously diversified. In recent years, the awareness of concrete has changed a lot.

The changed awareness of concrete

The building material is also perceived in its purist aesthetics and has become an important style-setting element. So today applications have been added that would have been unthinkable just a few years ago, at least in the current quantity:

  • Lamp stands and even concrete lampshades
  • Desk utensils from the cement mixture
  • Kitchen worktops and whole kitchens made of concrete
  • Washbasin cushions and concrete sinks
  • Wall reliefs, stepping stones, paving and other garden and patio accessories made from the building material

Cast concrete objects and building materials into molds yourself

Especially the latter are bought by less and less do-it-yourselfers. The trend towards the independent casting of components and objects made of concrete or cement paste not only continues unabated, it is also gaining more and more followers. Meanwhile, it is even observed that more and more tinkerers and hobbyists even make the silicone molds for the subsequent pouring with concrete itself.

Prepare the pouring of concrete into molds well

However, pouring concrete into molds is not quite as easy as many suppliers of silicone molds would like to convey it. First of all, it depends on the correct consistency of the concrete. Many do-it-yourselfers, who are working with concrete for the first time, think the more fluid the better. Finally, liquid concrete can be cast much better.

Too much water is harmful

However, average (conventional) cement can chemically and physically bind around 40 percent of water. The rest, the surplus water, has to come out of the concrete again. This is clearly visible when the concrete is bleeding. Numerous capillary pores form in the interior of the concrete. This makes the material more unstable and, in the medium term, more susceptible to external influences (oxygen, water, dirt particles, etc.). Therefore, liquid cast concrete also tends to crack for molding in molds.

The right consistency of concrete for casting molds

For the right stiffness, the concrete should rather have a viscous consistency. Then there is not so much water in the concrete and less pores are formed. The subsequent expulsion of air is then much easier. This compacting of the concrete also supports the stability and thus longevity of the concrete cast in molds. Ultimately, you will need to practice something until you find the right consistency for yourself. Again and again comparisons can be heard in the optimal consistency with that of Quark. He is also known to be more fluid than flowable.

Treat molds with release agent

Also important is the use of a release agent, with which you coat the casting mold. There are special concrete release agents, but also penetrating oil such as WD40 is ideal. Single pieces, so if the preservation of the mold is rather secondary, can even be coated with ordinary salad oil. Ultimately, you have to decide what is best for your project. After the concrete has been poured into the mold, you still have to compact it.

Devices and tools for compacting

Shake tables are suitable for molds for paving slabs, wall panels, balustrades, columns or even smaller objects such as vases or spheres. But you can also use internal compressors, but they are slightly more expensive to buy.

Do not compact concrete too long or too short

Again, it is important to "experience" the optimal time to compact. Only a thin layer of cement veil may form on the concrete surface. Otherwise, if you condense the concrete too long in the mold, heavy materials such as gravel may settle down and form undesirable layers with poor concrete properties. Depending on the ambient temperature and curing time, you must also periodically water the concrete until it is removed from the casting mold.

Curing or drying of the concrete in the mold

Read more about the drying time of concrete here. At this drying time, which is better described as curing time, it is important that the cement is not depleted of too much water by evaporation. This, too, can have a negative effect on the stability of the finished concrete casting.

Tips & Tricks

Especially with accessories or worktops that you want to pour into molds, it is recommended to oil or wax from the concrete. If, on the other hand, you are pouring paving slabs or similar functional concrete parts, you should impregnate or seal this concrete.

Molds of silicone or durable plastic are often used for casting. You can also use other materials such as wood or metal. However, when using wood, the absorbency must be taken into account - as well as with a corresponding shuttering of the concrete. In addition, you must consider the shrinkage of the concrete, if you want to build complex inner shapes.


Video Board: Concrete Pour Into Latex Molds