DNIT authorizes the use of the steel aggregate in federal highways
An alternative for reducing costs in road construction, the material is environmentally friendly and has quality and safety guaranteed
The National Department of Transport Infrastructure (DNIT) has issued a National Technical Specification which establishes technical conditions for the supply of steel aggregate, known as “Açobrita” (Gravel-Steel), to be used on federal highways. The material, originated from the productive process of Steel industry, represents a more economical paving alternative with the use of steel aggregate, without any risk to the environment. Usiminas had a significant participation in initiatives that led to the approval of “Açobrita”(Gravel-Steel) Project, a partnership between DNIT and Brasil Steel Institute, which has also involved “ArcelorMittal”, “Gerdau” and the University of Brasília (UnB).
With the Technical Specification, Brazilian steelmakers will be able to sell steel aggregate to be used in federal road paving. This is the case, of BR Highway 381, which has the potential to consume about 2 million tons of the product and is one of the main federal highways near Ipatinga Power Plant (MG). Usiminas also expects that this process will contribute to the release of the use of the co-product available at Cubatão Plant (SP) by “São Paulo Environment State Company” (Cetesb). To meet the new demand, Usiminas has developed a better product, called “Siderbrita TOP”, which follows technical, environmental and application conditions established by ABNT Standard.
According to Henrique Hélcio Eleto dos Santos, coordinator of “Açobrita” (Gravel-Steel), Project and Usiminas Coproducts Working Group, “Açobrita” project brings gains Brazil in service flexibility, since road works have high economic and environmental costs due to great demand of Non-renewable natural raw materials. “In addition, there is a significant environmental benefit, both because of the recycling process and reuse of steel aggregate as for the reduction of withdraw resources such as gravel and sand from nature”, he says.
For the project to be made feasible, teamwork was developed during the last 39 months involving trips, meetings for analysis and definition of technical and environmental parameters, laboratory studies, field experiments, preparation and dissemination of a national Standard – ABNT NBR 16364 , published on 05/10/2015, and lastly, the preparation and approval of 02 Technical Specifications, DNIT 406/2017 – ES – granulometrically stabilized Base with Açobrita® – Service Specification and DNIT 407/2017 sub-base granulometrically stabilized with Açobrita®.
Brazilian road network composed of federal, state and municipal highways is one of the largest in the world, with a total extension of 1,720,755.7 km. However, only 12.3% of this total is paved, that is, 211,653.0 km (DNIT, 2015). This is a worrying scenario, because although roads are widely distributed, they do not have the desired quality, increasing operational costs, pollution and unreliability in transportation.
In this scenario, “Açobrita” has great applicability in Brazil and a large supply capacity, since the country is the largest Latin American producer of steel and one of the largest producers in the world.
It is a product derived from Melt Shop production process, composed of oxides and silicates, with abrasion high resistance. After separated and benefited, it can be used in paving works, concrete artifacts, slope restraint, agriculture and rail ballast, among other uses. “Açobrita” replaces non-renewable natural raw materials such as gravel and sand.