Showing 2 results for Geosynthetics
A. Khodaii, Sh. Fallah,
Volume 7, Issue 2 (6-2009)
Abstract
An experimental program was conducted to determine the effects of geosynthetic reinforcement on mitigating
reflection cracking in asphalt overlays. The objectives of this study were to asses the effects of geosynthetics inclusion
and its placement location on the accumulation of permanent deformation. To simulate an asphalt pavement overlaid
on top of a crack in a concrete or asphalt pavement, an asphalt mixture specimen was placed on top of two
discontinuous concrete or asphalt concrete blocks with 100 mm height. Four types of specimens were prepared with
respect to the location of geogrid: (I) Unreinforced samples, which served as control specimen, (II) Samples with
geogrid embedded on the concrete or asphalt concrete block, (III) Samples with geogrid embeded one-thired depth of
asphalt concrete from bottom, (IV) Samples with geogrid embedded in the middle of the asphalt beam. Each specimen
was then placed on the rubber foundation in order to be tested. Simulated- repeated loading was applied to the asphalt
mixture specimens using a hydraulic dynamic loading frame. Each experiment was recorded in its entirety by a video
camera to allow the physical observation of reflection crack formation and propagation. This study revealed that
geosynthetic reinforced specimens exhibited resistance to reflection cracking. Placing the geogrid at the one- third
depth of overlay thickness had the maximum predicted service life. Results indicate a significant reduction in the rate
of crack propagation and rutting in reinforced samples compared to unreinforced samples.
M. Ameri, J. Shahi, H. Khani Sanij,
Volume 11, Issue 1 (3-2013)
Abstract
The use of geotextiles to postpone reflective cracks in asphalt overlay is a popular practice, so researchers are eager to calculate
its structural value. This research study has focused on this issue for geotextiles used in the roads of Iran. Twelve sections from
the Tehran-Qom road were tested each examined before and after construction of the overlay. The tests were of the Falling
Weight Deflectometer type, and at least twelve tests were conducted each time. The data from five sections (four for developing
the model and one for evaluating the output) allowed a new mathematical model to be developed. For the seven remaining
sections, some foreign and Iranian geotextiles were used as interlayers. The mean structural value for all of the geotextiles was
equivalent to that of a 2.92 cm-thick Hot Mix Asphalt overlay, while that for only the Iranian sections was equivalent to 2.28 cm.
Economic evaluations, based on construction costs, showed that in 2011 the use of geotextiles was economical in Iran, because
fuel and bitumen subsidies had been eliminated and different geotextile brands had been brought to market in the country.
