A Mathematical Model for Determination of Structural Value of Geotextile used in Iran

During the last few decades, application of geotextile in asphalt concrete before laying it for the purpose of reducing the overlay thickness has drawn the attention of many researchers, therefore determination of its structural value is considered as an important issue.Falling Wight Deflectometer (FWD) is the most popular non - destructive test for thedetermination of asphalt overlay structural value. In this paper, to determine this value, twelve sections, 150 meters each, were studied on Tehran–Qom old road. Each section was tested twice (once before and once after the overlay implementation) and each time, at least 12 FWD tests were carried out. Overlay thickness was determined using the tests results. For the first time, a model has been developed to evaluate the asphalt overlay structural value using FWD test data of 5 sections with pure asphalt overlay (4 sections to develop the model and one to verify the output). The seven remaining sections were implemented using various popular, Iranian or foreign geotextiles as interlayers, and their structural values were determined by help of a developed model. Based on the outcome of the present research, the average structural value of overall geotextiles is equivalent to a 2.67 cm thick Hot Mix Asphalt (HMA) overlay while that of the Iranian ones equals 2.29 cm.