Better Buildings with VINNAPAS ® - Wacker Chemie AG


Better Buildings with VINNAPAS®

WACKER dispersible polymer powders make dry-mix mortar more flexible and improve its adhesion and processing properties. For example, modified mortars can be used to lay autoclaved aerated concrete (AAC) blocks by the thin-bed method – an advantage greatly appreciated by construction experts in emerging markets such as India.

A view over suburban Mumbai: the metropolitan region on India’s west coast has more than 18 million inhabitants and is the country’s economic powerhouse.

India is a country of young people – half of its 1.3 billion inhabitants are under 25, and sooner or later they will need somewhere to live. At the same time, ever more Indians are benefiting from the economic boom and want to acquire their own home – in many cases near their place of work as well as in their native city. As a result, the construction market is booming – according to auditors at PwC, it is set to grow by seven to eight percent in the coming years – the second highest growth rate in the whole of Asia.

“To realize all the projects that have been planned and are necessary, we must slash the conventional construction time,” says Dr. Priti Pillay, a trained chemist and head of WACKER’s Technical Service Center in Mumbai. That was why contractors temporarily replaced traditional bricks with concrete blocks, which are easier to lay, since they are perfectly uniform, continues Dr. Pillay. “Though in the long run, they are not really suitable for use in residential buildings, since they are too heavy.”

Porous Materials Insulate Well

VINNAPAS®-modified dry-mix mortar – shown here in a lab test – is easier to spread and process.

Contractors, therefore, are now turning to aerated concrete, which is familiar in Europe under the trade name Ytong. The blocks are lightweight, fit together accurately, can be cut to size by hand, and, because of their porous structure, they also have very good thermal insulation properties. When used with the right mortar, they can be even further optimized. “Conventional thick-bed mortar is applied in layers of one to two centimeters, which poses several problems,” she says. “Poor bonding is one of the drawbacks.”

Dr. Pillay therefore advises her customers to use thin-bed mortar, which is modified with VINNAPAS® dispersible polymer powder from WACKER. If the dispersible polymer powder is added to conventional dry-mix mortar in advance, the bricklayer on site only needs to add water – no precise dosing instructions are required. “That makes factory-manufactured dry-mix mortar inherently less error-prone, since optimizing the properties is simply a matter of adding the right amount of water,” she adds.

If the mortar is modified with VINNAPAS® dispersible polymer powder, it can also be used in the thin-bed method – ideal for state-of-the-art construction materials.

As the mortar hardens, elastic polymer bridges form between the brittle mineral components. This greatly improves the mortar’s adhesion to a wide range of substrates. And since an ideal bond can now be achieved with a layer merely three millimeters thick, the mortar costs are also reduced. “The customer can do the same job with 60 to 70 percent less material,” Dr. Pillay explains.

To advise customers locally and tailor its products to particular market needs and applications, WACKER has built up application service centers around the globe – including in Greater Mumbai. At the technical center there, Dr. Pillay and her team deal with all the issues surrounding mortar applications.

“Factory-made dry-mix mortars are inherently less error-prone. They only have to be mixed with water.”

Dr. Priti Pillay Senior Technical Manager, WACKER Mumbai

Flexible Rather than Brittle

Dr. Priti Pillay during a product test at the Mumbai technical center: together with her team, the chemist tackles all manner of issues relating to mortar applications.

Up to two percent VINNAPAS® in the mortar is usually enough to form a stable bond between the AAC blocks. The polymers impart flexibility to the rather brittle mortar, enabling the hardened construction material to more readily accommodate stresses. That prevents cracks in the masonry and makes the building fabric more stable overall. Modified dry-mix mortars also exhibit better water retention. This makes them easier to process and they do not dry out so quickly. “On site, the bricklayers have five to ten minutes in which to position the blocks correctly. If they make a mistake, they can easily correct it,” she says. The slow hardening process also improves the mechanical properties – the material can thus withstand loads better and is more abrasion resistant.

The shell of an apartment block, the interior and exterior walls of which are made of aerated concrete: blocks of this type of concrete are lightweight, easy to process and yet capable of bearing loads – which is precisely why they are popular in developing countries.

Through the combination of AAC blocks and polymer-modified dry-mix mortar, much less water is required on site – that makes construction work more environmentally friendly. Another ecological advantage is that since there is only a thin bed of mortar between the blocks, there are no major thermal bridges. “The building is well insulated against low temperatures by design,” says Dr. Pillay. Planners welcome the versatility of the material for indoor and outdoor walls and facades, not to mention for tiling and plastering.

Rising Demand

VINNAPAS®

VINNAPAS® dispersible polymer powders and dispersions are continually optimized to improve the properties of dry-mix mortar:

Standard Features
VINNAPAS® standard products principally feature the following improved properties:

  • Adhesion to different kinds of substrates
  • Flexibility
  • Abrasion resistance
  • Neutral effect on rheology
  • Processability (e.g. long open time)

Special Features
VINNAPAS® specialty products go even further than our standard grades and optimize particular characteristics. They are divided into five product classes:

  • E for enhanced basic properties, such as adhesion and water resistance
  • H for improved water repellency
  • T for improved thixotropy
  • L for improved flow characteristics
  • F for improved liquefaction

Dispersible polymer powders from WACKER, as modifiers for dry-mix mortars, are popular in India: in 2015, WACKER POLYMERS’ sales there rose substantially. The Indian dry-mix-mortar market is growing by some 15 percent every year – the main reasons for this growth being skim-coat applications based on white cement. “Through applications such as block jointing mortar, WACKER is trying to increase the use of dispersible polymer powder by diversifying from white-cement applications to those involving gray cement,” explains Dr. Pillay from WACKER’s Mumbai technical center.

To meet rising demand, WACKER has therefore been continuously expanding VINNAPAS® capacity at all three of its production sites in Europe, Asia and the USA. In Nanjing, China, the production volume has more than doubled within three years. And in 2015, another spray dryer was installed at Burghausen; the new dryer can produce about a further 50,000 metric tons of dispersible polymer powder per year.

China as a Growth Engine

The Mumbai technical center adapts WACKER products to the needs of the Indian market and customers there.

These capacities will allow WACKER to continue to satisfy global demand into the future. One of the most interesting markets for construction chemicals beside India is China, where there is now more construction activity than anywhere else in the world. According to a study by the Centre for European Union Small and Medium Enterprises, about a third of all the world’s new buildings are constructed in China. To achieve this, the country consumes about 55 percent of the cement produced globally – as a result, a residential area of some 1.8 billion square meters is being created per year.

“Despite the boom in demand around the globe, most countries are still working with traditional mortar systems. That means further growth potential for us, which we are exploiting as part of our global transformation strategy,” says Dr. Benjamin Rossbach, senior technical service manager at WACKER in Burghausen.

Locally-based WACKER chemists like Dr. Priti Pillay therefore make full use of their applications expertise and consultancy skills: “We maintain close contacts with local mortar manufacturers, and explain the systems and their advantages at regular workshops. We are beginning to notice that the product is winning over ever more customers.” WACKER also makes a point of letting its customers try out products for themselves: in cooperation with the “WACKER on Wheels” mobile lab, which currently is chiefly deployed in the Mumbai region, skilled manual workers can experience first-hand the qualities of modified dry mortar applications directly on site.

After all, whatever regional differences there may be, the construction industry is unanimous about one thing: a solution adapted to local needs, with an attractive price/performance and many obvious advantages, is now indispensable on modern mega construction sites.