Performance-based mix design method for bituminous hot-mix recycling in plant

Abstract

In the last years, bituminous hot-mix recycling in plant has been used in several road pavement rehabilitation cases in Portugal. From the environmental and economical point of view, this practice is generally recognized as an efficient technique. Therefore, an increase in the production and application of reclaimed bituminous mixtures in hot plant is expected in Portugal, in the next years. Generally, the mix design procedures in use for usual bituminous mixtures may be adapted for hot-mix recycled in plant (HMR). However, the revision of the existing methods needs some additional procedures to carry out throughout the mix design process. These adaptations must take into account the influence of milled bituminous material and its components on the final recycled bituminous mixture properties. This paper describes a mix design procedure for hot-mix recycled in plant based on mechanical performance of several compositions, which is applicable to the Portuguese common practice. Furthermore, the paper includes a description of a case study regarding a typical 0/25 bituminous mixture (it represents two thirds of the bituminous mixtures consumption in Portugal for the last five years) for base layer, which incorporates 40% of milled bituminous material.