The entrainment of uncontrolled air into cement and gypsum based mortars is unavoidable and leads inevitably to a loss of quality in high performance systems. Undesired air voids weaken the system resulting in lower mechanical strength and reduced abrasion resistance.
In addition, surface air voids often compromise the desired quality requirements of a product.

Defoamers are preferably used for the prevention and removal of large air inclusions at the concrete’s surface and for rapid foam collapse in aqueous formulations. If, on the other hand, it is necessary to remove finely distributed air from a system, deaerators are the preferred alternative. However, practice has shown that a clear differentiation between defoamers and deaerators is usually not possible. Most defoamers also have a deaerating effect to some extent and vice versa.

Application areas

Defoamers are added to plasticizers and hybrid systems (on a chemical basis of lignosulphonates, naphthalenes, melamines or PCE’s) for the production of

• Floor systems (e.g. leveling compounds, screeds and decorative coatings)
• Tile adhesives
• Grouts (e.g. masonry mortars and joint fillers)
• Grouting and repair mortars
• Thermal insulation systems (EIFS/ETICS)

With the SITREN AirVoid® brand, we offer high- quality defoamers that allow air voids to be selectively removed from the system. This not only results in easier workability and an optimized surface finish but also in higher mechanical strength. Mortar systems defoamed with our products meet the highest demands of aesthetics and durability.

Air has a significant impact on the performance of cement and gypsum based building materials and mortars in both positive and negative terms. The manufacturing process of mortars generally requires mixing with water. The application of shear force combined with surfactant components in the mortar mix leads to the distribution and stabilization of air in the fresh mortar.

Air in mortars has a direct impact on

• Workability
• Mechanical properties
• Durability
• Aesthetics
• Slump properties
• Insulation properties
• Density

Contrary to what the current name indicates, the function of air entrainers is not to generate air voids but to stabilize the mechanically entrained air during mixing. Therefore, air void content is dependent on the mixing process and can vary depending on mixing device, mixing duration, time of mixing, temperature and the additives used. If the mortar, for example, is not mixed long enough during the production process, the mortar can contain unreacted air-entraining agents. With further mixing, these air-entraining agents are activated and the air content rises. Furthermore, the air void content is also temperature-dependent. It falls as the temperature increases.

Application areas

• Indoor and outdoor renders
• Insulating plaster
• Insulating plaster
• Restoration render
• Skim coats or decorative renders
• Repair mortar
• Thermal insulation systems (EIFS/ETICS)
• Lightweight construction

SITREN AirVoid® 651 is a highly effective air entrainer for mineral plasters, fillers, masonry and base coat mortars. It creates particularly fine and stable air voids that improve frost-resistance. Due to its wetting and dispersing properties, SITREN AirVoid® 651 also helps to provide easier manual processing and better pumpability of mortar mixtures.

Water repellents are used to provide mortar and rendering systems with durable protection against water and moisture. Our modern water repellents minimize the infiltration of water and dissolved pollutants, while maintaining the water vapor permeability at the same time.

Important requirements for water repellents

• High degree of alkaline stability
• Permeability to gas and water vapor
• Low surface tension
• No sticky surfaces
• Deep penetration depth

Application areas

• Floor compounds (thin and thick flooring)
• Decorative overlays
• Tile adhesives
• Stucco and render
• Skim coats or decorative renders
• Skim coats
• Grout (e.g. masonry mortar and joint filler)
• Technical grouts
• Repair mortar
• Thermal insulation systems (EIFS/ETICS)
• Waterproofing membranes

SITREN® water repellents are based on our organically modified silane and siloxane chemistry. Due to their chemical composition, our water repellents ensure an excellent beading effect and reduced soiling tendency in conjunction with outstanding long-term hydrophobing for mineral renders and mortars. Furthermore, our water repellents provide sustainable protection in relation to freeze/thaw resistance and crystallization pressure.

Shrinkage describes a volume reduction of cementitious based products due to a change in the water content.

In addition to environmental influences and internal dehydration, chemical/mineral reactions have a major impact on the quality of the final product. Depending on the application area, this volume reduction can play a decisive role in the final product. Therefore, in the case of large-area and thin-layer applications (e.g. floor compound systems) or strong bonding to the substrate, free shrinkage is hampered, resulting in the build-up of internal forces and tensions. These internal tensions can lead to a considerable impairment of the durability and functionality due to the formation of cracks, deformation or damaged bonding to the substrate.

The most important factors influencing shrinkage are low humidity, wind, solar radiation and unfavourable temperatures as well as the respective formulation composition and the thickness of the applied layer.

Application areas

• Floor compound systems such as SLU´s, thick flooring and decorative overlays
• Stucco and plasters (e.g. restoration render and decorative plaster)
• Skim coats
• Grouts such as masonry mortar and joint filler
• Technical grouts
• Repair mortars
• Sealing slurries

Evonik recognizes that sustainability is of utmost importance for all our futures. As a result, our product development focuses on high-performance products that are friendly to the environment. With this in mind, Evonik has developed a new generation of SITREN® shrinkage reducing agents. Thanks to their extremely low VOC content, SITREN® shrinkage reducing agents are able to meet the most stringent eco label requirements such as EMICODE EC1PLUS – without any dosage restrictions. Our SITREN® shrinkage reducing agents, developed in close cooperation with the dry mortar industry, stand out ecologically as well as technically. The reduction in the capillary pressure and the stress in the pore structure, results in markedly reduced shrinkage and thus, in the prevention of crack formation.