Investigation causes of pavement structure destruction using new AASHTO mechanistic-empirical procedures for improving roads function in different climatic condition of Iran

In recent years, procedure of AASHTO (American Association State Highway and Transportation Officials) Guide for Design of Pavement Structures distanced from first empirical procedure and advanced toward mechanistic-empirical procedures. “Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures” in 2004 and its attached software M-EPDG is the result of this new procedure that AASHTO presented it through projects NCHRP 1-37 A and NCHRP 1-40 B with cooperation of NCHRP (National Cooperative Highway Research Program) and FHWA (Federal Highway Administration) institutions. In this paper, required data for software analyzing of three real pavement structures pieces collected from three different climatic areas and pavement structures modeled in software by entering data into software. Modeled sections by this software were analyzed destructions, and, regarding to obtained results, common designing pavement structures procedures compared with the new way of AASHTO, and efficiency rate of related software investigated in three different climatic areas of Iran. Toward this process, Save, Hamadan and Qazvin, Boin Zahra cities selected as a case study and then studied. Results of software analyzing showed that the designs of old AASHTO method in tempered climate of country met all criteria of designing but in both of cold and warm areas, some destructions at designed pavement structures via this method exceeded from allowed rate and according to presented destructions, will be excessed more in future. This destruction in case project of cold area was longitude crack and was furrowing of pavement structures bed in warm area. Then, probable causes of mentioned destructions studied in pavement structures projects and procedures designed for rehabilitating pavement structures for met all of the designated criteria. Also, in Iran some suggestions indicated about required conductions for application of new method of AASHTO.