Waterproofing cement screed DIY

waterproof brick mortar

Many times, the word cement is used when we actually mean grout or mortar. Cement is a raw material which is processed by mixing it with other materials (e.g., sand, lime and, optionally gravel) and water into mortar, grout, or concrete. Cement is not used for the masonry of bricks, or the filling of joints, but for mortar of which cement is a component. This article describes how to make mortar, and then how to waterproof mortar. Because without additional measures, concrete and mortar eventually will be affected by rising moisture.

Making mortar

Cement itself is a finely grounded bonding agent (consisting mainly of calciumhydrogensilicate), which, together with water, forms a hard plastic mass, both in open air or in water. By mixing it with other substances, in particular masonry sand or lime, we can make mortar which can be used for laying brick walls, etc. Concrete is also made based on cement. But to make concrete, the cement is mixed with less sand and more gravel.

For mortar the standard ratio is: 1 part cement and 3 parts sand. The exact composition, however, is often a matter of knowledge and experience, and is in part determined by the application for which the mortar is used. For the masonry of exterior walls with hard brick one often uses 1 part cement, 3.5 parts sand, 0.25 part lime. While for the same job, but with much softer limestone, a completely different mixing ratio is advised, namely 1 part cement, 9 parts sand, 2 parts lime. The correct ratio for cement mortar must therefore be determined on the basis of the type of brick and the location of the building (inside or outside). Of course you also have to add water. Adding more water makes the mortar more liquid and easier to apply. But too much water means the bonding force decreases, and after drying there may occur cracks due to shrinkage. In general, well-made mortar sticks to a wall and does not bleed.

Cementmix makes mortar and concrete 100% waterproof
freeze and thaw damaged in concrete.

To make mortar, you need a masonry tub, a bucket, and – certainly in larger quantities – preferably a mixer. If you do not have a mixer, you can also use the trowel to mix the mortar. You already need that tool for the masonry itself, and it can also be used for the mixing. First, the dry substances – cement, sand and lime – are properly mixed with each other. Only then, water may be added. Always use clean materials, pollution reduces the quality of the mortar.
While making the mortar, the ratio can be conveniently controlled by creating a ditch in the container with mortar. If the ditch retains its shape and is not filling with water, the proportions are right. To prevent the mortar from drying out, never make more mortar than you can process in one hour.

For the do-it-yourselfer, bags with masonry cement are available to which you can add water and sand in a ratio of your choice. In addition, there are bags of ready-made mortar available where only water or Cementmix needs to be added to.

Making waterproof mortar

The usual method for making cement, or rather mortar, is described above. Although it is the most used method and works fine, it does have one major drawback: the mortar is in fact not waterproof. The brickwork is not waterproof and rising damp is not stopped. With concrete, which is also made from cement, the reinforcement can be affected by moisture, with decay of your reinforced concrete as a result.

Fortunately, there is an effective solution to this problem: Cementmix. Cementmix is a fluid that replaces water when mixing the mortar or concrete. You can add the Cementmix directly into the mixing container, bucket or cement mill, in the same proportion as you would use water. The product works from inside the mix and connects all the particles in the concrete, mortar, and grout together. With Cementmix any kind of cement, mortar or concrete, can be waterproofed, made water repellent and stop rising damp.

The vapor permeability remains maintained, which is important for good climate and humidity management in buildings. With Cementmix, water can never penetrate into the reinforced concrete, which prevents concrete decay. With Cementmix you have permanent and complete protection against water penetration. Cementmix is people- and environmentally friendly and also helps to prevent the penetration of oils, fats and acids into the masonry and concrete.

Cementmix is easy to use for the do-it-yourselfer. It is available in several packs of 1 to 25 liters, and is suitable for any type of mortar. Since the drying process is slightly faster than with plain water, you can start with making a sample when you make it for the first time. This way you get a good feeling on how to use the product. After that, you can use Cementmix in the same manner for the manufacturing of concrete art, mortar or grout. The result will fascinate you, because now, you, as a do-it-yourselfer, has made a waterproof floor, bathtub, kitchen sink, garden ornament, statue, etc. which you can cherish for years.

Example Cementmix

The left column is mixed with Cementmix and the right with water. After 24 hours standing in water, this is the result. It is clear to see that the right-hand column has absorbed water while the left column, which has been created with Cementmix, has remained dry.

waterproof cement with cementmix


  • Cementmix replaces water in the mixing process of concrete and cement. 5 litre Cementmix represents 5 litre of water.
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