Fractions 0/6 and 6/22 were used in the AC22S mixture and the fraction 0/12 in the BBTM11B mix. The demolished material was added to the manufacture of the mixture directly in the dryer drum, behind the flow of the lighter flame to prevent the binder from becoming overheated, and mixed with the hot virgin aggregate, thereby allowing the drying of the demolished material and the homogenization of the temperature of all the granular material.
The working formula was prepared with the collaboration with the Asphalts laboratory of the Repsol Technology Center which, based on the samples supplied by the customer, defined the most adequate dose and assessed the characteristics of the mixtures manufactured.
In order to verify the behavior of the two mixtures manufactured using demolished material, a comparison was made with mixtures without addition of recycled product, obtaining similar characteristics in both cases and fulfilling the requirements for the two types of mixtures in all cases.
The work was not only limited to the design of the mixture, but also to control the executed sections in order to validate, on a real scale, the production and installation process on the basis on samples taken at the plant.
Such actions, in which it is verified that the addition of demolished material from bituminous mixtures for different percentages and types of mixtures produce results that fulfill the characteristics required for a bituminous mixture, make it possible to validate and demonstrate the use of demolished material, where applicable.