Dry building mixtures – making the right choice

Recommendation points

• The mixture of sand, cement and water must be carefully calibrated
• Composition of dry cement-based mortars
• Application of dry cement-based mortars

Who among us has never in my life faced repair work in an apartment, house or in the country? Are there such homeowners? And there are no such – repairs, even cosmetic ones, have to be done, otherwise your beloved apartments will decay to the point of impossibility. Repairs are carried out within their means: someone hires a team of finishers, and someone does everything himself, based on their abilities. However, in all cases – independent or professional repair – the owner of the living space is faced with the need to choose building materials, which sometimes has the most general idea..

And studying the estimate of the necessary building materials, drawn up by the foreman of the finishers or a more experienced acquaintance (relative), the homeowner draws attention to the dry building mixtures present there, reacting like this: – And what is this? Why do you need to overpay for some packaged cement mixture, if you can make it yourself ?! Yes, this is a robbery in broad daylight! I will not pay exorbitant prices for packaged cement with sand!

The mixture of sand, cement and water must be carefully calibrated

I note right away that even a mixture of cement and sand, prepared and packaged in the factory, has better building properties than a mixture of that sand and cement prepared by builders directly at the work site. The thing is that the builders make up the mixture according to the principle “as God puts it on the soul”, keeping in mind the main recipe – 1 part of cement, 7 parts of sand and a sufficient amount of water. You need more plasticity, for example, when applying plaster – the builder-finisher will increase the amount of cement in the mixture. And all the ingredients – by eye, using the simplest working tool – a shovel, a bucket and a trough.

Understanding perfectly well that the “life” of the building will depend on the quality of the cement mortar, some customers of construction work take the decision on themselves. Their representatives order the usual mixture of sand and cement from manufacturers of dry building mixtures with the conditions – strict compliance with the brands of cement and sand, verified proportions in the mixture, laboratory tests for each batch. This method is more expensive, but gives a significant guarantee of the quality of the mortar, which means the masonry.

Composition of dry cement-based mortars

Each manufacturer develops the exact recipe independently, keeping it secret. Each dry mixture, in addition to sand and cement, contains modifying substances of chemical production that improve a number of properties of the mixture – they keep water in solution, increase plasticity, slow down or accelerate hardening, prevent shrinkage, etc..

The total share of chemical modifiers in dry mixtures does not exceed 2-3%, despite this, their presence in mixtures significantly affects the cost of each package – a kilogram of Western-made modifier is expensive for a manufacturer of mixtures, and they cannot be done without them when it comes to quality mixes.

The composition of cement dry mixes includes sand of a certain brand and fraction. Before being added to the mixture, the sand undergoes a preparation during which coarse sand grains and dirt particles are separated. For example, in the composition of the finishing cement plaster, the maximum size of particle-fractions cannot be more than 3 mm, otherwise it will not be possible to apply a thin layer.

Each cement mixture uses its own brand of cement – for masonry mixtures there is M100 cement, for tile adhesives – M200 and M300, for plaster mixtures – M200, for a grout – M500 (white).

The thoroughness with which serious manufacturers prepare ingredients for dry building mixtures will allow repairs to be carried out in a short time and with a high result – the tile adhesive will reliably hold the tiles for many years, the plaster will not peel off, etc..

Application of dry cement-based mortars

It is important to follow the instructions – if the mixture solution is not designed for application with a thickness of more than 5 mm, then when applied in a thicker layer it will dry longer, or it may not dry at all.

This is due to the action of a chemical modifier – cellulose ether, which is capable of retaining large amounts of water. This component is needed if the applied layer of the cement-sand mixture is thin, so its rapid drying and hardening is delayed – for leveling.

Most often, the dissatisfaction of consumers of dry mixtures is associated with violations of the technology of their use by them..

Each type of mixture includes various additives that determine its properties, so you should always follow the instructions for use of the dry mixture on the package. This is especially true of the amount of water required to prepare the solution. Many buyers who carry out renovation work prefer to increase the presence of water in the solution – so supposedly it is possible to increase the amount of solution, which means that it can cover a large area. I will disappoint everyone who practices such actions – nothing will come of it, moreover, excess water will worsen the quality of the mixture. Don’t try to outperform the manufacturer! The formulation of the mixture, where cement acts as a binder, undergoes multi-stage tests before the dry mortar is on store shelves.