The contractor hired by DAER (Highway Department) to repair the stretch of RS-471 with heavy traffic (BR-290/Pantano Grande until the bridge that crosses the Camaquã River) worked out with these authorities a program to improve the cost/benefit of the final surfacing on the stretch from Pantano Grande to Encruzilhada do Sul.

Beginning studies with CAPFLEX-B from Petrobras in June/2003 and later on working with Ecoflex-B from Greca Asfaltos, Brasília Guaíba over the years put together an entire specialized structure for binding agent with an average viscosity of 1,700 centistokes, which is five times greater than the conventional HMAC, working with average temperatures of 175ºC.

All these special characteristics that require a specific treatment, both for the mixing process as well as for the road surfacing, are demonstrating today not only their validity but also their need. The variables to be considered along the stretch stated above are as follows:
• 90% of the traffic is trucks. The internal transportation is of Lime and Kaolin and of weighing, all semi-trucks, and is in the direction of the port of Rio Grande.
• The quarries in the region are made up of a granite composition and all of them of rocks at the limit of the abrasion, which makes it possible to obtain a healthy asphalt mix.
• We could say, then, that this aggregate requires a coating film that is as thick as possible.
• Since it is a region with great temperature changes within short time intervals, the phenomenon of thermal susceptibility is critical in comparison with the conventional asphalt concrete.
• And finally, it contains a stretch of 30 km along its extension of greater traffic that is undergoing a repair project. A bet on an existing base layer already classified as heterogeneous.

From all the aspects of differentiated characteristics, the Asphalt-Rubber is the best solution for the Hot Mix Asphalt in question.

With experimental stretches that have been in use for three years, the supervision of the project that is being carried out by STE – Technical Engineering Services has presented results that are consistent with everything that is expected from a binding agent:
• Because of its high viscosity, a greater thickness is possible on the asphalt film that covers the aggregate.
• With a percentage of rubber of around 15% incorporated into the binding agent, it allows to reach ratios up to 20% higher, which strengthens the asphalt mixture from the point of view of its life cycle (oxidation) without suffering from the problem of exudation.
• With a temperature of up to 180º, it provides a fantastic homogeneity in terms of density on the road, which allows higher aggregate temperatures without the risk of the infamous problem of "burnt mixture".
• Using 1000 unusable tires per kilometer of highway will certainly sidestep part of an unrecoverable environmental liability.
• Part of the damages caused on our traditional surfaces with plastic deformation, such as the common wheel-track rutting, will be minimized because of the lowering of the thermal sensitiveness.
• Lastly, we worked with a binding agent that presents an average elastic recuperation of 60% while the conventional type is no more than 10%.

All the paths that end up in a full utilization of a technology that requires greater investment and complexity in the primary production (asphalt production process) as well as greater training and specialization in the execution of road surfacing are beyond doubt arduous. Brasília Guaíba can say this because it has been through these paths.