Evaluation of structural properties of Baghdad-Baquba road pavements

Abstract

Structural evaluation of the road pavements is an essential concept to ensure their efficiency to carry traffic loads and to archive the data for future usage especially in major highways. Baghdad-Baquba is an important interstate highway as it connects the capital of Iraq with Diyala governorate which is one of the biggest governorates in Iraq. In addition, this highway connects Baghdad city with several governorates in the north of Iraq. However, this highway exhibits low serviceability due to poor condition of its pavements. Therefore, the structure of the pavements must be evaluated to specify the causes those lead to the decrease in its serviceability and to propose the suitable rehabilitation methods. This study aims to adopt a field survey to extract a number of samples from selected section in this highway to evaluate the structural properties of the pavements based on laboratory testing. Four cores and one pit with 1×1 m dimensions were extracted from the pavements in the field. Several tests were implemented on these tests based on standard methods. The results of the tests were adopted to evaluate the capacity of the pavement based on AASHTO 1993 method. The results exhibited that the estimated applied traffic load exceeded the calculated allowable traffic load by more than 12 times which reflect the disastrous situation. Therefore, the study proposed to rehabilitate the pavements by reconstruction. The study proposed to construct three layers: asphaltic layer with thickness of 240 mm, granular base with thickness of 250 mm, and granular subbase with a thickness of 250 mm. The study stated that all layers must have superior quality with high elastic modulus to resist the predicated traffic load.