Paving the way to the future, AkzoNobel Surface Chemistry has launched Rediset™ warm-mix additives on a commercial basis. The multifunctional technology reduces the mixing and paving temperatures of hot-mix asphalt and at the same time increases resistance to moisture damage. The breakthrough additive technology combines special surfactants and rheology modifiers that – together – serve to lower the temperature of hot-mix paving methods. The technology is significant in that it allows asphalt to be compacted very efficiently during the paving process at temperatures 40-70°F (22-39 C°) lower than traditional paving methods, effectively saving on energy costs and operational costs while minimizing worker exposure to fumes. Patents have been filed for this new technology in the United States and in other major countries.

A Year of Testing
Sundaram Logaraj, market development manager “We planned for 2008 as a year of validation. We wanted to see how the Rediset WMX products perform in a variety of asphalt mixes, and to understand better the production, storage handling and dosage of the products. We could not have wished for a more successful year in terms of the product performance. The trials have demonstrated some of the key advantages of our products over the several other warm mix technologies currently on offer and also allowed us to improve our manufacturing and product support functions. Now we are in full scale production and I expect 2009 will see significant interest from the market.”

The Rediset Concept
There are maybe 15-20 competing warm mix systems in the market, ranging from simple water injection, to complicated systems involving expensive changes to the mix plant. Rediset falls in the group of so-called “chemical” asphalt modifiers which do not involve the addition of water to the system. The product is simply blended into the asphalt before mixing and can even be added just as the asphalt enters the mixer. The treated asphalt can be stored before use. No changes in the mixer itself are required.

The convenient pastillated form of the product means it may be stored without the need for new tankage or heating. The big advantage of the Rediset which sets it apart from other “dry” chemical modifiers, is that it provides excellent adhesion promoting properties – eliminating the need for separate additions of antistrips or lime. In a side-by-side comparison in Lufkin Texas in April 2008, Rediset WMX treated binder was compared to other warm mix systems. Only Rediset WMX treated asphalt reached compacted densities comparable to the untreated control at normal temperatures.

PG grading
Another important advantage of Rediset WMX treatment is that, unlike many of the competing warm mix systems, the modified warm mix binder – exactly as used in the mixture – can be sampled and PG graded, and retained for Quality Assurance purposes. In particular, the bottom PG grade is unaffected or affected in a positive way, even when the binder is tested by the standard protocol.

Cold weather paving
In February 2008 a trial by APAC, Texas showed the benefits of the product in cold weather paving. Working with a dense mix using a polymer modified PG 76-22 binder, APAC would normally expect paving to stop when the air temperature fell below 60°F, (15°C) but on a decidedly chilly 50°F (10°C) February day in Dallas, the mixes (regular and one containing RAP) were successfully paved when Rediset WMX 7002 was used in the asphalt. And all at a 30°F lower mixing and paving temperature than normally used. Even handwork was possible, and the densities achieved were as good if not better than usual. The ability to extend the paving season gives a significant advantage to the contractor and the end user alike.

Like the idea of paving in cooler weather? How about an October night in Norway with the temperatures close to freezing. Contractor Kolo Viedekke was pleased to discover that Rediset WMX 8017 additive enabled them to complete a dense mix overlay in these less than perfect conditions.

Improved worker safety, effective asphalt compaction with increased resistance to moisture damage, lower energy and operational costs combine with the ability to extend the paving season for our customers. For more information, please contact Sundaram Logaraj.