The Materials division of the Sorigué group was selected to carry out the road surface improvements on a section of the TP-7013 between Alforja and La Selva de Camp (Tarragona) with a warm bituminous mixture, within the scope of the first Public Innovation Procurement programme RIS3CAT.

The aim of this initiative, developed by the Directorate-General of Mobility Infrastructures of the Ministry of Territory and Sustainability of the Government of Catalonia, is to enhance the competitiveness the sectors involved in the design, manufacture and maintenance of road surfaces in Catalonia.

The road surface improvement, carried out between September and November 2019, introduced various innovations with respect to conventional road surface repair works, chiefly in terms of the materials and techniques used. Specifically, the innovative road resurfacing technique used was based on the application of methods for the manufacture and use of bituminous mixtures at a temperature below 100 degrees, in comparison with conventional bituminous mixtures that are applied at between 160 and 180 degrees.

Different techniques and temperatures
The work was divided into different sections where the lower temperature techniques of cold recycling and/or warm bituminous mixtures and/or ultra-fine warm mixtures were applied. A conventional mixture was also applied, which served as a benchmark for comparing the different techniques with each other and with the conventional process.

From among all the combinations used, the one corresponding to section 6 stood out as the most innovative, as it employed warm mixtures both on the intermediate layer and on the wearing course. In this case, the work consisted of 6 cm of cold recycling of the existing surface, with the addition of a special modified emulsion, Emultem, followed by laying 5 cm of warm AC22, and finally laying 1.5 cm of an ultra-fine mixture AUTL11, also warm.

The execution of the work resulted in other innovative and distinctive tasks with respect to the usual manufacture and laying. For example: the 6-year monitoring of the surface and structural characteristics of the road surface to assess the evaluation of the functionality and structural capacity, as well as the measurement and control of the emissions associated with the manufacture, transportation and completion of the section to estimate its life cycle.

As a result, the team that carried out the work concluded that the functionality values achieved were fully equivalent to those for conventional techniques, and they were also able to see energy savings in the manufacture of mixtures with emulsion: Warm AC22 KAI and Rugofir Eco were 47% and 44% respectively, compared to the benchmark mixture AC16 SURF 35/50 S.

Sustainable road surface management
The Public Innovation Procurement programme from RIS3CAT is co-financed by the Catalonia ERDF operational programme 2014–2020.

The Public Innovation Procurement programme consisted of a preliminary phase of open market consultation with the aim of providing information on the tender process, the technical characteristics and the quality of the proposed solutions. A total of 23 organisations took part in the prior market consultation process and submitted more than 40 proposals for innovative techniques to incorporate sustainable technologies into the surfacing of Catalan roads.

Sorigué was awarded one of the two tenders resulting from this process for the resurfacing of roads with sustainable techniques. The proposal seeks to develop new methods and procedures that are more sustainable in technical, economic and environmental terms, providing new added value to their basic road safety functionality.