Decorative concrete is an inexpensive and beautiful alternative to other materials used for siding or to poured and simply sanded concrete. You can get many different designs, and with proper design you can get the look you want for your project.
Steps
Step 1. For the concrete it is necessary to choose a color and a consistency that go well with the natural environment and the structures that surround it
Even the escape routes to be grouted must be appropriately studied as regards their orientation, in particular for the repetitive designs created by curbs, bricks or pebbles. Generally, the area to be treated should be decorated in such a way that the long lines of the design run perpendicular to the length of the project. In this way you can minimize errors in drawing straight lines, and you can give a more beautiful and pleasant overall appearance. Typically the texture is made up of straight lines, even if the sidewalk or driveway were to be curved. Before proceeding with the casting, it is always advisable to test by laying the decorating panels. Workers should know in advance where the first panel is to be placed, where standard-sized panels will not fit, and in which direction the decoration is to be oriented. The initial design must be done in such a way as to ensure the best possible final result. Furthermore, it is of fundamental importance to have in mind the points where the expansion and control joints are positioned (the thin lines that are always seen in a concrete product), as they could compromise the final visual result that has been designed.. Often the installers, knowing the tricks of the trade, can provide useful advice.
Step 2. Setting up the concrete
Standard procedures must be followed, casting a screed and the base on which to cast the concrete, also observing local regulations in the design regarding the mixture used, the depth of the base and the reinforcement. Normal, delayed drying, low water content mixtures can be used, but mixtures containing calcium chloride should not be used in any case. In addition, mixtures without chloride accelerators and those that retain air can also be used. For the appropriate advice regarding the type and quantity of the mixture to be used, refer to the instructions provided by the manufacturer (note that some particular mixtures have effects on the coloring of the concrete). The thickness of the concrete should not be less than ten centimeters.
Step 3. Coloring the concrete
There are two basic techniques:
- Integrated dyes: These are liquid dyes that are poured directly into the mixer. With this procedure, the dye is mixed with the cement before casting, and the concrete will be completely colored.
- Sprinkled Dyes: Dye hardener powder is sprinkled directly over the freshly poured concrete. This hardener penetrates about 3 mm on the surface of the concrete and colors it.
Step 4. After the first leveling of the concrete, once the excess water has been absorbed, the dye hardener should be sprinkled making large movements with the arm in order to distribute the powder as much as possible over a wide area every time. concrete area
Leave for a few minutes for the hardener to be absorbed, until the powder gets wet enough to let the color seep when applied with a wooden or magnesium spatula. A single sweep of the trowel should be sufficient; concrete should not be worked on for too long. If necessary, this procedure can be repeated in areas where the natural cement still remains visible. Once the desired color has been achieved, the concrete can be finished with a trowel.
Step 5. Apply the dye release agent
Decorating panels do not work without the aid of a release agent. This specially designed powder prevents the panel from sticking to freshly poured concrete. Usually 16 kg of powder are needed for every 10 square meters. The release agent should be applied while the concrete reaches the right degree of dryness to be decorated. It should be sprinkled with brush strokes on the panels so that it can penetrate them to reach the surface of the concrete. Between the concrete and the panels there should be a uniform layer of release agent, thick enough to prevent moisture that oozes from the concrete from impregnating the panel, but thin enough so as not to compromise the details of the decoration.
Step 6. The choice of the color of the release agent should be made in relation to the color of the concrete
A darker release agent than the dye used with the concrete will make the finished product a deep, hazy color. The release agent will largely be removed by washing with the pressure washer. The predominant color will be that of the concrete, and only about 20% of the release agent will adhere to the treated surface.
Step 7. Decorating the concrete
When the best time for decoration comes, there is no need to apply particularly strong pressure to the panels laid on top of the concrete. The right timing is an element critic, therefore the processing should proceed without delay, once the decorative phase has begun. Likewise, the areas already treated should be periodically checked to carry out any retouching as soon as possible.
Step 8. The panels should be installed with the help of a team of workers
Below is a possible scheme of how to make a group of 4 people work, suggested for very large castings, around 40 square meters. Teams of skilled workers may be able to cast and decorate up to 65 square meters at a time, however it is advisable to start working on smaller areas. The process can however be adapted to the needs of each specific project.
- Worker 1: takes care of checking that the release agent is well positioned throughout the process. He sprinkles it, identifies the areas that need any retouching, lends a hand to all the other companions.
- Worker 2: Place the decorative panels. The first panel must be aligned at the starting point of the project being very careful, it must be positioned and pressed onto the concrete. The procedure must be repeated by placing the second panel next to the first. The panels must be placed well adherent to each other, in order to avoid messy grouting. The work continues with the other panels, alternating them in rotation, while they are removed from the already decorated concrete and repositioned on what still needs to be worked. For small castings, at least three panels must be used. The larger the project, the more panels will be needed.
- Worker 3: Press the panels as they are placed on the concrete. In this operation, no more force than necessary should be used to press the panels in contact with the concrete. Avoid excessive pressure!
- Worker 4: gently lifts the already pressed panels, gradually lifting them on one side to counteract the suction effect. He then passes the panels to the worker 1 who prepares them for subsequent positioning.
Step 9. Approximately 24 hours after the concrete has begun the solidification process, a high pressure cleaner is used (3000 PSI is recommended, equivalent to approximately 200 bar, but special care must be taken not to damage the concrete)
This cleaning serves to remove excess release agent from the concrete surface. To remove the unevenly released agent, the distance of the lance from the concrete can be varied. You can try to direct the jet of water so that some of the release agent remains in the escape routes and deeper marks of the decoration. In this way you will get a more antiqued, natural and three-dimensional effect.
Step 10. Following the manufacturer's instructions, the concrete should be sealed with suitable decorative products
When the surface is perfectly dry, it can be painted with a transparent protective coat using a roller; 4 liters should be enough to treat over 18 square meters. To avoid the formation of unwanted lines, the first coat should be applied in one direction, and the second in the direction perpendicular to the first. Care must be taken to avoid build-up of sealant in the corners.
Step 11. Three-dimensionally decorated concrete is also known as "artificial rock", as it combines concrete decoration techniques with hand sculpting techniques
For this type of applications, integrated dyes are not used, but water-based paints or acid dyes.
Advice
- The release agent, in the period from its packaging to the opening of the box for use, tends to settle. Therefore, before using it, it is a good idea to mix it in the jar with one hand, to give it the right soft and airy consistency, and to dissolve any lumps.
- When applying any type of hardener, there should be no standing water on the concrete surface at all. Do not the concrete must be leveled excessively with the trowel, otherwise a further loss of water will be obtained, reducing the intensity of the coloring. On concrete Not it should be sprinkled with rain or nebulized water, otherwise its color could be changed. Do not use a plastic sheet to cover the casting. The dye hardeners, in the period from their packaging to the opening of the box for use, tend to settle. Therefore, before using them it is a good idea to mix them in the jar with one hand, to give them the right soft and airy consistency, and to dissolve any lumps.
- Always pay attention to time. If rain is forecast, it is preferable to postpone the work.
- The overall coverage for the area to be treated may vary in relation to the color chosen and the desired intensity. Usually 27 kg is enough for the treatment of 9 square meters, although for more muted and pastel colors it could be necessary up to 45 kg for 9 square meters. Two thirds of the hardener should be applied with the first coat, while the remaining third should be kept for the second coat after retouching.
- For every cubic meter of concrete, at least 5 bags of cement must be used; granular aggregates (for example gravel) should not exceed 10 mm in diameter; the other aggregates should not be reactive; the amount of water used should be la minimal possible; the drop in concrete should not exceed 10 cm; and finally, mixtures that drastically reduce water should not be used.
- If using liquid dyes, level and finish the concrete following normal procedures. When using a hardener, the concrete should be finished following normal procedures, using a wooden or magnesium trowel and a leveling bar. The concrete surface should remain outdoors. Do not treat with a steel trowel until the final hardener has been applied.
- Use enough decorative panels to cover one and a half times the width of the surface to be treated at the same time.
