A study of the mechanical characteristics of cold recycled bituminous concretes

摘要

Nowadays recycling rejects is one of the main objectives, both for economical reasons and for the protection of the environment. In this general frame the field of road constructions offers a wide range of techniques, among which the recycling of bituminous concrete pavements (Reclaimed Asphalt Pavement). So far in Italy Reclaimed Asphalt Pavement (RAP) ― both hot and cold ― has been carried out in a minimum percentage. Therefore, many are still the problems connected to the storage and management in waste disposal sites of debris obtained from bituminous concrete milling. In particular, hot recycling is seldom used due to several operational difficulties encountered, which are both technical ― the differentiated heating of the material to be recycled ― and environmental ― the release of toxic smokes. On the contrary, in recent years cold recycling is gaining an increasing importance, thanks also to the improvements achieved in the field of bituminous binders. New emulsions of modified bitumen at slow rupture allow to use more effective production methodologies (both in mobile plants and in fixed plants) and to obtain performances similar to those of traditional, hot bituminous concretes, with unquestionable environmental advantages. The purpose of this research is to study the many factors which influence the performances of cold recycled bituminous mixtures. In particular, the following aspects are emphasized: the particle-size distribution of the bituminous concrete to be recycled, the curing time and curing temperature of the mixtures. Such aspects are investigated carrying out mechanical tests (Duriez test), and rheological tests (compres-sive static creep and compressive and tensile dynamic creep tests). The results obtained should allow to define the influence of the various parameters so as to set the optimal conditions for cold recycling of bituminous concrete.