Use of local available material for inverted pavement technique

This research has the purpose to build infrastructures by using new techniques, new materials and to start a sustainable design with the utilization of local resources. The project also aims to minimize the use of non-renewable sources as hot mix asphalt. Concerning the materials, it is particularly highlighted the use of stone materials available in the Region of Sardinia, currently extracted to create infrastructures and bitumen layers. New techniques have been studied to build up infrastructures such as the Inverted Pavement Technique used in South Africa for more than 30 years. In particular we focused on the realization of the G1 Layer for this paving. Through this work, we are willing to determine the possible use of the materials present in Sardinia to build Inverted Pavement infrastructure. The target is to better use the local obtainable resources in terms of aggregates, trying to make the most of their mechanical and physical features. During the research, a great attention was focused on the illustration of different typologies of paving currently used in Europe and in South Africa, specially those realized through base layers with granular material, examining in depth the anisotropic property of granular bases too. A panoramic of the property of road construction material used in South Africa is presented, by analyzing the issues linked to the type of minerals that are in the rocks and the way through which they affect the resistance and durability of one layer of the paving. In the first phase of the study, we concentrated on the specification of the kinds of materials mined in Sardinia and their location. Then, we chose to investigate about the following materials: andesite, basalt, quartzite, trachite, dolomite and ignimbrite. All these are materials with good features such as mechanical endurance and durability. An in-depth bibliographic research was done about the 'Inverted Pavement’ technique for understanding the behavior of this type of paving during the useful life, compared to a traditional paving. The building technique of the G1 layer was mainly examined, because some phases, such as that called "slushing", are considered complex and the main point for the good result of layer and the whole superstructure. To make sure the material is suitable, we referred to South-African regulations and we carried all the mechanical tests foreseen to categorize it as G1. Chemical analyses and thin sections were analyzed, because they are considered preliminary characterizations on the study of materials. Some triaxial tests were performed with several confining pressures to define the elastic modulus and other strength parameters.Anyway it is not enough to comparison chemistry and petrography to establish that a material is suitable. For this reason, were done other physical-mechanical laboratory tests. Two test sections of Inverted Pavements realized in Atlanta, using granite, were examined and were done some laboratory tests on material. From the monitoring of these two test sections and from the result of tests, it emerged that Inverted pavement has performances greater than conventional paving and that other kinds of materials can be used for realization.