How do I make cement blocks strong

Tips for cleaning and caring for concrete blocks

To do this, you first have to be aware of what concrete blocks are. The main components of a stone made of concrete are gravel, sand, water and cement. Cement has a proportion of lime. A perfectly coordinated mixture of these ingredients makes every concrete block a robust, long-lasting building material. The addition of rich color pigments makes every stone unique.


It should not be forgotten that such natural raw materials, which are exposed to nature or are under heavy loads, can easily change their appearance after a while. Some changes are part of the normal aging process of the stones without affecting their stability. Other phenomena such as stains and discolorations, which can appear after a short time, are in most cases easy to clean and even to be specifically treated. We'll tell you how.

White spots on your stones could be so-called lime efflorescence, which occurs particularly in the younger years of a concrete block.


If water penetrates the stone, e.g. B. by rain, condensation or dew, lime can dissolve as a natural component of the stone. As a rule, this lime flows down into the gravel bed together with the water. In some cases, however, it is also transported to the surface in dissolved form as calcium hydroxide by capillary suction and remains behind as soon as the water evaporates. On the surface of the concrete, this calcium hydroxide, also known as hydrated lime, reacts with the carbonic acid in the air and forms a hard-to-dissolve calcium carbonate.


The good news: Provided that frost, base and bedding layers are installed in accordance with the rules or the correct grouting, your concrete block is absolutely healthy and "breathes". It promotes natural water seepage and protects the surface from puddles and black ice. The white spots are only temporarily visible and are gradually loosened and washed away by the slightly acid rain. Lime efflorescence is completely natural and has no influence on the robustness, water permeability or other mechanical properties of the stone. Since they disappear over time due to weathering and mechanical stress, they are not a reason for complaint in most cases.


If you don't want to wait for the natural cleaning process due to the weather and everyday use, you can alternatively use special cleaners that will quickly remove white stains from the concrete block. There are solvent-free and biodegradable cleaners that gently clean the concrete block, such as the specially developed one Special cleaner C. Gio shows you in our do-it-yourself video Step by step how to proceed. The also offers an acid-free, ecological alternative KalkEx-Öko at.


How to prevent: You can prevent lime efflorescence by shielding the “young” concrete block from water. Since paving stones are usually intended for outdoor use, this statement seems a bit contradicting at first. Paving stones should not be permanently exposed to a hydroclimate, but neither should they constantly stand with their "feet" in the water. When laying the stones, care must be taken to ensure that the rainwater can quickly drain away from the paved or terrace area and the pavement structure underneath.


Many of our plaster surfaces are hydrophobized at the factory. This counteracts the increased penetration of water into the concrete facing layer. Even if you impregnate or seal the surface, there is still no guarantee that water can get through the joints or core concrete into the stone. The best way to deal with limescale stains is still to gently clean the pavement for the first year of completion.


In this video there are even more tips on the subject of lime efflorescence:

When concrete blocks are exposed to the great outdoors, sooner or later green spots can develop. In most cases these are algae, lichen or moss deposits that have gradually built up. Lichen, algae and moss feel particularly at home in shady, more humid environments with plants and trees in the immediate vicinity.


If you are not sure whether your stones are infested with moss or algae because the location is very sunny and dry, your green patches could also be patches of grass. Read on for how to handle both.


With algae or lichen infestation

There are also special cleaners that gently clean the surface for these types of green spots on patio slabs or paving stones. To protect the stone and the environment, it is best to use solvent-free, biodegradable agents such as the Lichen remover. It is diluted with water, applied to the infected areas and works for about 3 to 5 days. Then simply remove the green covering with a broom without damaging the stone.


How to prevent: Lichen can only be prevented by a dry environment free of green. Also, make sure that the surface of the concrete block does not roughen up. Avoid excessive loads, cleaning with a high-pressure cleaner and aggressive, acidic solvents. You should also regularly clean your area of ​​dead plants to prevent lichen and algae from becoming a breeding ground. The cleaned surfaces should be finally impregnated for better protection.


For patches of grass

You can easily get rid of green discolouration of grass stains with a solvent-free special cleaner. The System cleaner intensive is diluted with water in a ratio of 1: 3 to 1:10 depending on the degree of soiling and brushed onto the soiled surface with a soft broom. After about 20 minutes it can be rinsed off with clear water. This step can be repeated until the stone is clean again.


This is how you can prevent it: After mowing, make sure that loose grass is not transported onto the concrete surface and can be stepped on later. Regularly clean your concrete blocks and remove grass and other plants from the joints.

Brown to reddish stains on concrete blocks could be rust that has rubbed off from rusty tools, decorative materials or other equipment. With the right rust remover, you can get rid of the stains quickly. Make sure, however, that you use an acid-free remover, such as the specially designed one Rust remover from EHL for concrete blocks.


How to prevent: Avoid working with rusty tools on the stones. Do not place any rust-sensitive decorative or household items or garden equipment on your pavement and only use rustproof nails, metal sheets and other building materials in the vicinity of concrete blocks.

With tire tracks

Black tire marks or tire scuffs in your driveway are extremely rare, but sometimes unavoidable. The good thing about them: they are easy to clean. Simply use a mild, solvent-free cleaner like this System cleaner intensiveto get rid of the stains. Depending on the degree of soiling, mix the cleaner with water and work it into the stone with a soft brush or sponge. Then let it take effect for up to 20 minutes and rinse the surface again with clear water.


How to prevent: Carefully drive onto and off the pavement. Do not let the vehicle's tires spin.


For lichens or spores

If the black spots are not from tires, but rather punctiform and spreading slowly, it could be lichen or spores. Unfortunately, simply cleaning with water is not enough here. Use an acid-free algae or mold remover like this Lichen remover. Allow the concentrate mixed with 3 parts of water to work into the concrete blocks and wait 5 days until the lichen has died and can be removed with a brush. To keep your concrete blocks clean over the long term, you should clean them regularly.


How to prevent: The only way to prevent lichen is usually through a dry, plant-free environment. A smooth surface of the stone also offers less surface for an infestation. Therefore, never clean the stones with a high pressure cleaner or strongly acidic solvent cleaners. Here, too, you can finally impregnate the surface coverings so that lichens have poorer growth conditions and can be removed more easily. Also, regularly remove dead plants from your paved area or patio.

If oil or food grease accidentally drips onto your patio tiles, use a kitchen towel to soak up the oil completely.


If the stain is still fresh, boil water and add soda (10 liters of water, approx. 100 grams of soda from the drugstore). Then brush the mixture onto the greasy surface with a soft brush and let the soda water work for up to 5 hours. Then rinse the surface with cold water.


If the grease stains are still there, use a special grease-dissolving cleaner for concrete blocks, such as this Oil remover. It is solvent-free and is also suitable for cleaning coated paving slabs.


How to prevent: If possible, always remove oil and grease stains immediately with an absorbent cloth and clean the surface promptly. A sealing of the stone is also a good way of preventing such stains from being drawn in and making them easier to remove later.

Do not use a pressure washer.

The hard water jet roughens concrete blocks and leaves a coarser surface that is more prone to dirt. In the long run, you will have to clean your stones more often.


Clean your stones regularly.

Especially in autumn, make sure that you regularly remove leaves from your patio or driveway. It is also worth clearing all joints of moss and weeds once a year. In this way, the green does not spread further on your area. Also make sure that you always remove oil or grease stains as well as stains from acidic or color-intensive foods and beverages immediately. This will prevent long-term discoloration.


Impregnate your stones regularly.

The smoother surface leaves, for example, less grip and surface for potential contamination. Impregnated concrete blocks are usually not only less prone to stains, but are also often easier to clean if they are lightly soiled. Read more about this in our Articles for the regular care of concrete blocks .