An Achievement Of Olympic Proportions - Wacker Chemie AG


An Achievement Of Olympic Proportions

A revolution on the construction site

Polymer-modified cement mortar under a scanning electron microscope: The VAE polymers in the image have a smooth surface. They act as binders and increase the flexibility of the set mortar.

But the site management representative was not fooled. The man turned and called out to his colleagues, “They’ve been patching this up. But just take a look at how good it is – it’s almost better than the concrete itself.” Kranz sees the episode as a breakthrough for Ardex concrete filler at the Olympic building site.

Another Ardex product used was Ardurit X7G, a tile adhesive Kranz also had a major role in developing. “The product – today we’d call it a flexible adhesive – had been considerably enriched with VAE copolymer,” says Kranz.

Lean layers

VAE

VINNAPAS® vinyl acetate-ethylene (VAE) dispersions and dispersible polymer powders are copolymers produced by emulsion polymerization of vinyl acetate (a hard polar monomer) and ethylene (a soft hydrophobic monomer). Vinyl acetate and ethylene are polymerized at high pressure in water using colloidal stabilization. Ethylene is an ideal plasticizer for vinyl acetate, which imparts long-lasting durability to VAE polymers. As a result, vinyl acetate-ethylene doesn’t need an external plasticizer.

VAE polymers have outstanding film-formation properties – no solvents are needed. This means formulators can develop and manufacture water-based products with a very low VOC content that adhere well to non-polar substances. The glass transition temperature varies from +25 to –25 °C as a function of the ethylene content.

Up to that point, the thick-bed technique was used for tiling all over the world: tiles were placed in a layer of mortar at least 1.5 centimeters thick, consisting almost exclusively of cement, sand and water. “That kind of slightly moist material is difficult to process and almost impossible to apply with a spatula,” says Dr. Fritze from WACKER’s Technical Service. Also, he notes, the mortar tends to bleed. In other words, the water content migrates to the surface of the mortar and/or is absorbed by the substrate. “That could prevent the cement from setting sufficiently, especially if the mortar layer is thin,” says Fritze, adding that the adhesive mortar has to be a few centimeters thick in order to have enough water to harden sufficiently.

The thick-bed technique was both prone to error and time-consuming. “It wasn’t until we had VAE polymers that we could process cementitious materials into layers less than a half centimeter thick,” observes Kranz. These polymers improved tile adhesion on the substrate and helped dissipate any stress that might arise. Thin-bed technology – the standard of today – was born. “The technology meant that tilers could cover larger areas in the same amount of time – a huge advantage, given rising labor costs,” Fritze adds.

  • The thin-bed method for laying tiles with mortar layers of less than half a centimeter has become an established standard worldwide. VAE polymers improve the adhesion of the tiles on the substrate and help dissipate any stress that might arise.

  • The thin-bed method for laying tiles with mortar layers of less than half a centimeter has become an established standard worldwide. VAE polymers improve the adhesion of the tiles on the substrate and help dissipate any stress that might arise.

  • The thin-bed method for laying tiles with mortar layers of less than half a centimeter has become an established standard worldwide. VAE polymers improve the adhesion of the tiles on the substrate and help dissipate any stress that might arise.

  • The thin-bed method for laying tiles with mortar layers of less than half a centimeter has become an established standard worldwide. VAE polymers improve the adhesion of the tiles on the substrate and help dissipate any stress that might arise.