Experimental research on the performances of cement bound granular materials containing recycled aggregate

Among the techniques adopted to stabilise road foundations, the use of cement bound granular materials is worth mentioning: although this technique isn’t properly innovative, it represents a satisfying solution in case a layer with rather contained deformations (produced by heavy vehicular traffic, to which pavement fatigue failure is often associated) is needed. Up to now, the research has been mainly carried on cement-bound granular mixtures containing natural aggregate. On the contrary, in Italy, researches evaluating the characteristics of cement-bound granular aggregate made by recycled material are still at an early stage. More precisely, it can be stated that, despite the common re-utilisation of recycled material in the building sector (this re-use, especially in the last few years, has aroused growing interest thanks to strong economic reasons and environmental awareness), it is not yet adequately supported by extended scientific knowledge. Furthermore, there is an ever growing need to identify techniques not only to reduce the quantity of milled road material to be conveyed to waste dumps, but also to seek alternative material to be used in road construction, in order to take into account the reduced availability of non-renewable natural resources. Under these circumstances, the performances of a cement-bound granular mixture containing milled aggregate (from road pavements) have been compared with those of a cement-bound mix containing natural aggregate; for both types of materials the grading curve, dosage of cement, water content and mechanical properties of the mixtures (compressive strength and indirect tensile strength) have been evaluated. The results have been compared with those required in the Specifications and Regulations in force in Italy. The experimental study has demonstrated that the performances of both mixtures are equivalent and the milled aggregate from road pavements can be used as material for road foundations.