Sand that floats on water?

The development team at Dorfner has made a major breakthrough. Water-repellant quartz sand and quartz powder are now available for a broad range of applications. The team has succeeded in transferring the same functional design, which has been used so successfully with DORVALIT® SHO in paints and lacquers, to quartz sand.

Most silicate minerals have a high natural affinity for water. Water wets the surface of these minerals which sink in water because of their higher density. That is a world we know from our childhood. When we played with water and sand, the heavy sand always sank and never floated on the surface.

Dorfner however continually finds highly inventive ways of treating the surface chemistry of minerals as we open up new fields of application and support ongoing customer innovation. Anyone who is involved in construction knows that water is a building’s worst enemy. Through architectural design features and selection of the right materials, attempts are always made to keep water out of buildings and prevent water damage. Dorfner is a major supplier to the construction materials industry, and it has taken on the challenge of “water protection” by making its quartz sand and powder water-repellant. Dorfner’s modified quartz sand and powder are so water repellant that they swim on the surface of water. The list of possible applications includes building materials with built-in water barrier for backfilling at foundations or basements when it is absolutely essential to keep water away from the building. The flood disaster in 2013 is another example. Similar to the effect you see on oilskins, water beads off the surface of Dorfner’s hydrophobic quartz sand. The river embankments would not have become so thoroughly soaked if the sandbags had been filled with this sand rather than normal sand.   The products can also offer advantages in applications such as polymer-bonded and hydraulic mortar for grouting, sealants and plaster. Expensive hydrophobic agents are often used in these applications in order to make products water-repellant. There is however always the risk that these agents are not distributed finely enough and form islands instead. With Dorfner’s hydrophobic quartz sand, the user can be sure that the water-repellant function present on the surface of every grain is distributed uniformly with maximum dispersion throughout the entire compound. The result is outstanding water repellency at every point. In contrast to well-known hydrophobic additives, the active ingredients of DORVALIT® products are firmly bonded to the substrate and immobilized in the matrix. Water repellency is not washed out even over long periods of time.

When developing the water-repellant quartz sand and powder, Dorfner is able to apply its key core expertise and technology platform for “modifying inorganic solids”. The company uses two chemical tricks to apply the coating. One is silanization, in which a water-repellant layer reacts with the –OH groups on the surface of the sand. The other is a new coating technique for encasing the quartz particles in a special polymer.

 A tip for developers: very economical product solutions for applications with permanent hydrophobic functionality can be formulated with quartz-based DORVALIT®.

Would you like to know more?  We have the right solution for your products as well. Call us at Tel. +49 (0) 96 22 82-115 to find out more or send us an e-mail at ulrike.heidingsfelder (at) dorfner [punkt] com.