Lightweight Geomaterials for Bridge Approach Utilization on Soft Ground Area

Abstract

Construction of bridge approach highway embankment using strong but lightweight geomaterials over soft ground will alleviated problems of instability and long-term settlement. Backfills of retaining structure can also be constructed using lightweight materials resulting in lower earth pressure and improved economics. There is a variety of lightweight geomaterials available. However, large volume needed in embankment and backfill construction often places limits on the use of costlier manufactured lightweight materials. This study is aimed on used rubber tire-sand mixtures reinforced with geogrid for embankment on soft ground. The test embankment is constructed in the campus of Asian Institute of
Technology (AIT). The geogrid reinforced embankment system is extensively instrumented in the subsoil and within the embankment itself in order to monitor the behavior of the wall both during construction and in the post-construction phases, and thereby to evaluate its performance. The unit weight of rubber tire sand mixture 30:70 by weight is 13.6 kN/m³ compare to conventional backfill sand of 18.0 kN/m³, it is lighter by about 75 %. The settlement magnitude of 122 mm at original ground is less when compare to conventional backfill. Differential settlements are small, so this type of lightweight material is appropriate for highway bridge approach utilization.