BYK Logo

Frequently asked questions for

Construction Chemicals

Here are some of the most frequently asked questions with their answers from Construction Chemicals.


I am using organic thickeners to enhance anti-sag properties of my cementitious construction products. However, at lower temperature I see retardation of my system. Do you have any inorganic based rheology modifiers having less impact on cement hydration?

As you know, apart from others, organic modifications such as starch ether or cellulosic ether derivatives can negatively contribute to cement hydration, open time and water sensitivity of your cementitious products. You may need to lower the overall amount of your organic additive by partial substitution with OPTIBENT. In this case we would recommend OPTIBENT-1008, a rheology modifier, based on a natural occurring phyllosilicate which improves both, workability and anti-sag properties.

How can I improve the adhesion of an acrylic emulsion on paver blocks?

You can improve the penetration of the emulsion to the substrate by adding our BYK-3455, a fluorine-free, silicone-containing additive for improving substrate wetting and leveling properties in aqueous systems.

For one of our construction products based on bituminous emulsions I need a suitable defoamer and thickener.

As a suitable defoamer we recommend BYK-022 or BYK-018. As thickener OPTIGEL-CG or RHEOBYK-HV 80.

I need to improve surface and flow properties of my 3K PU cementitious self levelling system. My currently used liquid defoamer in the polyol seems to be too incompatible. A more compatible defoamer is not efficient enough. Do you have any recommendation?

Highly efficient defoamer very often cause phase separation in the PU binder system. Unfortunately a more compatible defoamer does not reduce the amount of air content sufficiently which contributes to a reduction of flow. We recommend following our novel defoaming concept by using our liquid defoamer BYK-1794 in the polyol and our solid defoamer BYK-1690 SD in the component C (powder mix). For further information please refer to our guide line formulation available on request.

How can I improve the defoaming and flowability properties of my 3K epoxy grouting formulation?

Apart from the binder being used, the flow properties could depend on the wettability of the aggregates/fillers but also on the air content. To increase the density and decrease air content, we would recommend BYK-S 732 as defoamer. BYK-9076 or BYK-W 996 would be recommended as wetting additive which furthermore will improve the flow properties of the system. Applied on the powder components, the latter can also help to de-dust the product. For further information please refer to our starting point formulations (SPF), available on request.

I would like to improve the application properties of a cementitious skim coat formulation without impacting anti-sag properties and open time. Do you have any additive recommendation?

For this purpose, we would recommend OPTIBENT-NT 10 or OPTIBENT-616, both rheology modifiers based on natural occurring layered silicates. While OPTIBENT-NT 10 can slightly reduce water sensitivity of the final product, OPTIBENT-616 can help to lower raw density to a certain extend improving overall workability and anti-sag properties.

I am working on an flexible, EPS-modified light weight render. The higher dosage level of adhesion promoter makes the system too sticky. Howe can I overcome this problem?

We would recommend OPTIBENT-1056 or OPTIBENT-1008 as highly sophisticated rheology modifiers.

I have a gypsum based plastering product, which shows from time to time lump formation in the wet stage. Any idea to overcome this issue?

If the lump formation is related to any wetting issues of the fine binder and other fillers, OPTIBENT-616 or OPTIBENT-NT10 is recommended

Specifically for our silicate formulations (lithium and sodium silicate) and colloidal silica (silica sol) we need an additive that reduces the surface tension of our water soluble formulations. We need a higher penetration depth. Both, the sodium silica and the silica sol are applied to concrete surfaces with low pressure spraying, and after the silica sol has a very short working time, high wetting is even more necessary.

Our recommendation for this application is BYK-DYNWET 800 N. This additive is silicone-free and based on alcohol ethoxylates. It improves the substrate wetting by reducing the surface tension.

We produce a mortar which consist of: CaCO<sub>3</sub> fillers + Acrylic dispersion + water. The material is casting into silicone moldes. I need an additive to increase the flowability of the system.

DISPERBYK-199 is a VOC-free wetting & dispersing additive for aqueous coatings and adhesives as well as pigment concentrates for organic and inorganic pigments and fillers.

Can you give me a general recommendation which of your products are used as anti-settling or anti-sagging additive in dry mix mortar applications? How can I improve the workability properties?

We recommend our OPTIBENT product range for dry mix mortar applications (i.e. plasters, renders, tile adhesives) and our OPTIGEL product range for liquid, polymer latex based construction products. Both product lines are supplied in powder form and are well known as rheology modifiers with shear-thinning application properties based on phyllosilicates for aqueous building material systems. For detailed product recommendation, please search for the individual brands.

How can I improve application properties (rheology) of my cementitious tile grouts?

We recommend OPTIBENT-NT 10, a rheology modifier with hydrophobic properties. Additionally, the product can help to partially substitute cellulosic ether derivatives helping to improve washability of the tiles after application of the tile grout.

Which defoamer can you recommend for a 2K water proofing slurry?

As a defoamer we would recommend BYK-014 for your liquid part or BYK-1691 SD for the solid part.

I am working on a new admixture formulation based on PCE. Unfortunately, I am facing phase separation or haziness in this formulation at elevated or low temperature. I need a compatible liquid defoamer, which works efficiently and long-lasting in the final concrete system.

Numerous defoamers are too incompatible and therefore cause phase separation in concrete admixtures. In contrast to this, BYK-1680 is a VOC-free liquid polymer defoamer, characterized by its excellent and long-lasting defoaming effect though showing a very good compatibility in aqueous polymer solutions and building material formulations.

I am a chemist working on the development of various types of cementitious tile adhesives. I would like to improve anti-sag properties of a cementitious, flexible tile adhesives C2TE for larger sized tiles.

For your purpose we would recommend OPTIBENT-6042. This product will lead to a buttery like feeling of the adhesive even at higher water amount allowing improved anti-sag properties and open time either, without harming the anti-sag properties.

I am working on a cementitous self levelling formulation with improved flow properties. I need a spontaneous defoamer with long-lasting defoaming properties which also can support flow.

BYK-1690 SD and BYK-1691 SD are solid, versatile, efficient, VOC- and silicone-free defoamers for cementitious construction material systems and are very compatible in various mineral binder systems. Even at low dosages, the additives show a consistent, good defoaming effect over a long period of time with optimum surface characteristics of the end product. Both product match the requirements for EMICODE® EC1 PLUS formulations.

I need to stabilize a water-based, alkaline slurry of light weight microspheres or other fillers. Do you have any recommendations?

OPTIGEL-WX is an excellent alkaline stable rheology modifiers which enhances low shear viscosity in order to improve storage stability and anti-settling properties of aqueous building material formulations.

We make cement grinding aids. The system consists of various inorganic sands, glycols, water and Limestone. We need defoamers to quell the foam creation of glycols in water.

For such system we recommend a polymeric defoamer like BYK-014 or BYK-1710.

We are looking for a thixotropic enhancer to allow mortar and concrete mixtures to hold their form while curing submerged within water.

We recommend OPTIGEL-WX, an organo-modified rheology modifier with excellent pH-stability.