Fine concrete – information on properties and prices

Fine concrete – information on properties and prices

Fine concrete is a material that allows particularly fine contours and promises the same weather resistance as normal concrete. This makes this artificial stone an ideal material for creative design. However, it cannot be processed directly, as with fired clay, but only indirectly. You can find out how this works and what it costs in this guide.

Concrete is tough

Generally speaking, concrete is a mixture of sand, gravel, cement and water. It differs from mortar in the grain size and that it lacks a lime adhesive component. Normal concrete is mainly used to be able to withstand large compressive forces. This absorption capacity depends on the cement used and, above all, on the aggregates used. The “fatter” a concrete is, the more durable it is. The more pressure-resistant the aggregates are, the more resilient the resulting construction element will be. Normal concrete has various quartz gravel as an additive. Particularly solid concrete, which is used for safes or high-rise foundations, has blast furnace slag as an aggregate.

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Everything about fine concrete

Fine concrete is very different from its heavy-duty normal concretes. It uses a fine aggregate with a maximum grain size of four millimeters as the aggregate. From a technical point of view, fine concrete is therefore a cement mortar and can also be used for masonry or grouting outdoors. But that is not what it is intended for. Fine concrete is used to be poured into molds. It is not used for building structures but for objects that have to be highly stable and particularly weatherproof. Typical applications for fine concrete are:

  • Flowerpot
  • Flower boxes
  • Garden figures
  • Herbal pyramids
  • unusual cobblestones
  • Ornamental fountain
  • Bird baths

Filling and repair work

Textile concrete is a particularly creative way to work with fine concrete. In this way, flowing, organic structures can be created that are in no way inferior to normal concrete elements in terms of durability. Fine concrete is also particularly popular for repair work. Concrete remediation is big business. Many structures from the 1970s were built very negligently: Cement was often saved and the concrete cover of the reinforcement was not sufficient. Fine concrete is an excellently suitable material in order to effectively conceal structural steels that rust through and thus preserve the structure.

Translucent concrete

If glass fibers are incorporated into the aggregate of fine concrete, something fantastic is created: Fine concrete allows the production of particularly thin wall elements. This material, known as “translucent concrete”, is a new application, the possibilities of which have not yet been fully explored. These elements are not stable, but can achieve particularly interesting effects: The light is guided “around the corner” through the fiber optics. With the help of translucent concrete panels, particularly efficient and fascinating lighting can be achieved in a room.

Varieties of fine concrete

When it comes to fine concrete, there is not a particularly large selection of different types. It’s basically plain concrete with a fine aggregate. You can also make fine concrete yourself with quartz sand and cement. Mix both components in a ratio of 1: 4, add sealant and you get fine concrete. If you prefer ready-made solutions, then ideally you are working with good planning. 

For comparison:
A 2.5-kilo bucket of ready-mixed fine concrete from the craft shop can cost 15 euros.

In contrast, a whole 25-kilo sack from a brand company costs just under 6 euros. However, concrete is very demanding when it comes to its storage: Cement always needs absolute dryness. The humidity in the room is enough to start the setting process. If you have any spare concrete, sell it or give it away. If you store it, it will harden into a useless lump within a few weeks, no matter how well you preserve it.

Creative with dyes

The list of additives is therefore more interesting than the question of the different types of fine concrete.

Fine concrete is used for exterior applications. That is why it makes sense to use sealant to make it particularly weatherproof. One kilogram of sealant, called “waterproof concrete” in technical terms, costs 8 euros and is sufficient for 50 kilograms of fine concrete.

But it gets particularly creative when you work with dye. To this end, the trade offers a range of metal oxide-based dyes. Since these dyes are made from corroded metal, the rain will not wash them out. They are permanent and stain the entire structure. Repainting is no longer necessary. They are added to the concrete mix in a proportion of 3-5%. The more color pigments are added, the darker the color becomes. As with fine concrete itself, the price of color pigments differs enormously, depending on which container size is selected. The following prices are common:

  • 200 g can: 8.00 EUR = 40.00 EUR per kg / sufficient for 4 kg of concrete
  • 1 kg can: 24.30 EUR = 24.30 EUR per kg / sufficient for 20 kg of concrete
  • 2 kg bucket: 37.30 EUR = 18.65 EUR per kg / sufficient for 40 kg of concrete
  • 25 kg sack: 238.80 EUR = 9.55 EUR per kg / sufficient for 500 kg of concrete

The density of lightweight concrete is 2000 kilograms per cubic meter. You can use it to easily calculate how much concrete and therefore how much dye you will need. Please note, however, that fine concrete is rarely processed into solid material. As a rule, this material is used for thin-walled, filigree products. The volume of information can therefore be deceiving.

A limiting factor for metal oxide pigments is their durability. They will clump together over time, especially if they are in a humid environment. The manufacturers usually give an unopened pack a shelf life of two years.

Other materials

If you want to use fine concrete for mending and filling damaged old concrete, you need a suitable adhesive. New cement doesn’t stick to old concrete easily, so you’ll need an intermediary. The eight-kilo container in the dry mix costs around 25 euros. Also, keep in mind that it should be used up completely when the container is open.

So that you don’t get any nasty surprises when stripping your works of art, don’t use release agents too sparingly. The formwork is moistened on the inside before it is filled with concrete. You can use a spray bottle or just a brush to do this. As with all building materials, the prices fall with the container size.

  • A 100 ml bottle costs 2.50 euros, which corresponds to 25 euros per liter
  • A 2-liter canister costs around 17 euros, which means that only 8.50 euros per liter are incurred
  • A 10-liter canister costs only 35 euros

After all, a 20-liter canister is already available in stores for 2.60 per liter.

But since very little oil is needed for a formwork, the purchase should also exactly meet the needs.

Fiber mats for thin-walled, freely curved elements are for fine concrete professionals. They give great opportunities to develop your creativity. However, you should not dare to approach this art form without training. Otherwise, you run the risk of not producing anything useful except a lot of waste.

Glass fiber mats for textile concrete have the following price range:

  • 3 sqm mat: (approx. 100 x 300 cm) = 18.20 EUR / corresponds to 6.07 EUR per m²
  • 6 sqm mat: (approx. 100 x 600 cm) = 31.10 / corresponds to EUR 5.18 per m²
  • 100 sqm roll: 98 cm wide = 349.00 EUR / corresponds to 3.56 EUR per m²

Here, too, you can see that you save a lot of money if you order appropriately economically. Working with fine concrete is a good way of looking for a team of like-minded people. This way, the hobby becomes particularly beautiful by saving together.

Processing of fine concrete

Except for working with textile fibers, making concrete figures is very easy. Find a formwork from a store that you like, spray it with a release agent and fill it with concrete. After a day, you can open the formwork and you have your new garden cultivation, flower pots, or whatever other fine concrete products you want.

Fine concrete is mixed in a mortar tub. These are available for 12 euros in any hardware store. Always use a new tub so that no old leftovers can spoil the result. The concrete is best mixed with a whisk and a powerful drill. First, fill the prescribed amount of water into the tub and gradually sprinkle the ready-mixed concrete into it. This will prevent lumps from forming. Fine concrete can be worked for around 25 minutes at an outside temperature of 15 ° C. Hurry up anyway. Once tightened, fine concrete is no longer suitable for filigree structures.

If you want to get creative yourself, you can also make your own concrete forms with the help of plaster of paris and silicone. However, this is a very creative challenge that will require some practice. You are completely in line with the trend of the times if you use a 3D printer to produce the positive cores. However, this is not exactly cheap in the size that concrete cultures made of fine concrete usually have.

Tips for readers in a hurry

  • Always buy fine concrete and other building materials in the largest possible containers
  • only buy as much as can be processed – consider the shelf life
  • Process or sell or give away leftover materials as quickly as possible
  • Pay attention to safety: always wear eye protection when handling liquid concrete
  • Always have the emergency kit, especially the eye shower, close at hand
  • if the eyes are injured with cement, call the ambulance immediately – otherwise, there is a risk of blindness
  • Use rabbit wire to reinforce thin-walled hollow molds