Can roads be made with crumb rubber from tyres at lower temperatures than normal? It is feasible but there is still insufficient experience in the field of this technology. For this reason, SIGNUS published a new technical document in May of this year. The objective was to provide the sector with technical information in order to encourage the manufacture of asphalt mixtures with tyre rubber using what are known as warm mix asphalt technologies.
Asphalt mixtures are the most commonly used material for the construction of paved surfaces worldwide. During the manufacture and onsite laying of these mixes, it is necessary to heat aggregates and binders to temperatures of around 160- 170 °C, in order to ensure adequate workability. Because of this, in recent years, the sector has been leaning towards the use of what are known as Warm Mix Asphalt (WMA) which can be manufactured at temperatures of around 20-40 °C less, thereby enabling minimisation of the negative effects associated with their production and laying, whilst maintaining mechanical properties.
To date, little information has been available on the use of crumb rubber from end-of-life tyres (ELT) in warm mix asphalts. For this reason, a few years ago, SIGNUS began a project to study the behaviour and feasibility of these mixtures, which gave rise to the document entitled “Warm mix asphalt with crumb rubber from end-of-life tyres”, published last May. The work was carried out in collaboration with the Roads Laboratory of the Madrid Polytechnic University (UPM), and the Laboratory of Engineering and Construction of the University of Granada.
This article presents an extract from the study reviewing the state of knowledge of warm mix asphalt in general, the most appropriate technologies in the case of mixes with rubber, laboratory working protocols and specific case studies at laboratory level.