Mixing cement mortar and what to consider for prebagged material

Cement and cement mortar are both important materials in the construction industry, but have different properties and uses. Cement is a finely ground powder made from limestone, clay and other minerals. It is a binder that hardens on contact with water and serves as an adhesive for building materials.

Cement mortar, on the other hand, is a mixture of cement, sand and water. It is often used as a filler or adhesive in masonry construction to bond bricks, stones or other building materials together. Compared to pure cement, cement mortar is filled with sand and therefore has a thicker consistency and is usually easier to work with.

Mortar and concrete are both building materials made from cement, sand and water. The main difference lies primarily in their aggregates. Concrete also contains gravel or chippings, which gives it greater stability. In contrast, mortar consists only of sand, cement (or lime) and water. Mortar is therefore mostly used for bonding masonry, as plaster for wall surfaces or as screed, with sand aggregate. Concrete is mostly used for load-bearing structures, such as floor slabs, ceilings, piers or bridge girders. The proportion of aggregate in the concrete can vary in grain size (up to 32 mm), depending on requirements. This increases the compressive strength or load-bearing capacity of the components, for example. Larger quantities are usually delivered to the construction site ready-mixed in a truck mixer as ready-mix concrete. If concrete is mixed directly on the construction site, it makes sense to do this in a concrete mixer or forced-action mixer.

Ready-mixes in bags have the great advantage of ensuring that the cement mortar mixtures are of the same quality time and time again. The building material, packed in bags, is already filled in the correct ratio of the individual components (cement and sand). When mixing the powdered material, first add the water to the mixing bucket and then the powder. With the right equipment or a mixer, mixing cement mortar becomes an easy and effort-saving process.

Cement mortar is a basic building material used in construction, as it provides for the connection and sealing of building elements. Cement is a hydraulic binder that is the adhesive for the individual components. Another mineral binder for mortar is lime. If this is used, it is called lime mortar.

If ready-mix mortar is not used, the correct mixing ratio of the ingredients for the mortar is decisive for the durability of the end product. This factor is heavily dependant on the correct mix as well as the processing. A defective mixture, an incorrect mixing ratio or improper processing can endanger the durability of the mortar and thus the stability of the structure.

The production of cement mortar from individual ingredients with a machine requires precise measurement of the ingredients to be mixed. First, cement and sand are placed into the mixing machine. The quantity required depends on the type of mortar and what it is to be used for. For example, a masonry mortar requires more cement than a grout. Then add the correct amount of water and start the mixer. The ready-for-use mortar must be moist, soft and malleable throughout.

If the mortar is to be mixed in a bucket with a mixer (e.g. Collomix mixer), the water must be added to the bucket first, followed by the dry material. A mixing paddle suitable for the material (e.g. Collomix paddle WK) is essential to ensure that the mixture is stirred evenly. Make sure that the mixture is not too liquid or too dry. For mixing ready-mix mortar, important instructions for processing can be found in the manufacturer's data sheets

When making cement mortar, several points must be taken into account. The right ratio of ingredients is crucial, especially when the cement and sand mixture is made up from the individual components. This may vary depending on the intended use of the mortar. However, a ratio of one part cement to three parts sand is common. More cement in the mix increases the strength of the mortar to a certain extent.

The amount of water needed for the mixture must be carefully observed. This is especially true when prebagged material is processed. Basically, too much water reduces the strength of the mortar. The so-called cement-water value is then no longer correct. A consequence of this can be the formation of cracks in the mortar surface. This can be caused by adding too much water or by the mortar drying too quickly. This is referred to as "plastic shrinkage" of the mortar. It is therefore important to remove the water from the mortar slowly. Direct sunlight on freshly applied surfaces should therefore be avoided. Not all of the water in a mortar mix evaporates. Part of the water is chemically bound in a reaction with the cement. This process is called hydration of the mortar. As a general rule, it is not advisable to mix the mortar again with more water once it has been completely mixed.

Under good conditions, cement mortar sets within a few hours. This creates “cement crystals” that bond firmly with the aggregates. You should allow around five hours drying time per centimeter of mortar layer. As soon as the surface of the mortar is dry, you can continue working. However, a dry surface does not mean that the mortar has completely set. You should wait until the mortar is completely dry before applying sealing coats. The complete curing time is approx. 24 to 48 hours, depending on the layer thickness.

Ready mixes in the form of prebagged material offer advantages that make them an attractive option for construction and renovation projects. Firstly, they are very practical and easy to use. All you have to do is add water, mix and the mortar is ready to use. Secondly, they offer consistent quality. The pre-made powder blends are carefully measured and mixed to ensure you get the same result every time. The choice of mixing technique used is important here. Depending on the quantity required, you can mix the powder material with the water until if is free from lumps using an electric mixer (e.g. Collomix mixer) and the appropriate paddle (e.g. Collomix paddle). For larger quantities of ready-mix mortar, the use of a conventional concrete mixing machine or a compact mixer is recommended. In any case, you achieve a homogeneous mixture of the mortar or plaster and save yourself time-consuming manual work. Thirdly, the material comes in bags. This makes overall handling of the material easier, cleaner and requires less storage space. This procedure is usually more economical and space-saving than mixing individual components manually.

 Mortar groups are a classification of mortars based on their composition and intended use. There are four main groups