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Admixtures for concretes and mortars

The performance of concretes required for large civil works is such that additives have been used for a very long time in concrete plants. However, very similar performances can be obtained for its own masonry work by adding admixtures during the preparation of concretes and mortars.
Presented in liquid or powder form, these adjuvants are added in small amounts in the mixture of cement, sand, granules and water. They make it possible to modify the consistency of concretes and mortars, improve their resistance and often add other properties such as better sealing or good resistance to frost.
Here is the list of the main adjuvants that you can find in resellers for professionals and individuals.

Adhesion resins

Addition of adjuvant dosed to the mortar

Addition of adjuvant dosed to the mortar

Mortar screeds are most often applied on a support (slab) made of concrete or masonry. To avoid blistering and separation between the two embodiments, particularly in case of significant delays between these two elements, it is necessary to apply an adhesion resin to make the binding.
This is the role of SikaLatex® (slurry) that will be spread on the slab (mixed with 2/3 water). It can also be mixed with mortar, just like Sika ViscoBond®, to improve its consistency or resistance to the screed.

Adjuvant mortar for hot weather

Adjuvant mortar for hot weather

To maintain the fluidity of the concrete in hot weather, the retarding admixtures improve handling and delay the onset of concrete setting. In hot weather, they allow to maintain the fluidity of the concrete during its implementation.

Antifreezes

Different adjuvants in sachets

Different adjuvants in sachets

In cold weather, the setting of concretes and mortars is strongly slowed down and can even be stopped by frost. Antifreeze additives, such as SikaCim® Antifreeze, accelerate the cement reaction process by activating the setting. The heat released in the concrete or the mortar ensures the complete hardening and makes it possible to finish the work.
A dose of 0.5 liters per 35 kg bag of cement is sufficient, but if the temperature drops below -5° C, use two doses per bag of cement.

Plasticizers

Drawing a slab facilitated by the addition of a plasticizer

Drawing a slab facilitated by the addition of a plasticizer

To facilitate the use of concretes and mortars and to reduce the amount of mixing water, the addition of an air-plasticizer such as SikaCim® Plastifluid can be very useful. In addition to faster implementation, concretes and mortars become creamy, more resistant and more impervious. The air entrainment function also disperses in the concrete or mortar fine air bubbles that offer better resistance to the freeze-thaw cycle.

Waterproofing for concretes and mortars

Seat assembly with water-repellent mortars

Seat assembly with water-repellent mortars

If the absolute watertightness is the essential quality of a pond, it is not obligatory for the construction of a house. However, the addition of water-repellent admixtures during the preparation of concrete and mortars for foundations, pavements, screeds or coatings avoids many future problems of moisture and seepage!
By sealing the capillaries of concretes and mortars, SikaCim® Hydrofuge or Sika® Liquid Hydrofuge will make your mortars watertight without changing the setting.

Fibers

A trellis bag!

A trellis bag!

In new or renovation, the risk of cracking or crazing is ubiquitous. By incorporating into the concrete reinforced synthetic fibers, Sikafibre Force 54mm type, it reinforces the latter with the same strengths as welded mesh much more cumbersome. What to ensure a certain durability to the slabs of terraces or fence posts. For screeds, more fine synthetic fibers (SikaCim® Fibers) will be added during the mixing process to avoid surface cracking.
These fibers are mixed with the dry elements (sand, aggregates, cement) before being mixed with water or admixtures.

The dyes

Tinted concrete terrace floor

Tinted concrete terrace floor

Very popular among architects, dyes have also become very common among individuals. Available in powder (SikaCim® Color) or paste (SikaColor Paste), they have been specially developed for the coloring of concrete and mortar: screed mortars, grouting mortars, plaster. A preliminary test is always recommended, the hue varying according to the different constituents (aggregates, cement) or the climatic conditions.
7 colors are available: red, yellow, ocher, black, brown, green and blue.

Ready-mixed adjuvanted mortars

Repairing a window sill

Repairing a window sill

If you do not own a mixer or when it comes to small repairs, the ideal is to turn to mortars ready for use. Depending on their function, these mortars already contain sand, cement and a battery of pre-dosed admixtures giving them much better performance than conventional mortars.
For a broken nosing or a "skinned" corner of the window, the Sika® MiniPack Repair Mortar can be used to prepare a mortar that is easy to apply and resistant over time. Also available in Sika® MiniPack Waterproofing mortar to create waterproof coatings (cellars, basements) or in Sika® MiniPack Rapid Mortar to quickly block water coming in or to make solid seals of hinges or railings.

(photos / visuals: © Sika, except special mention)

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