Expansive Soils Characterizations and Their Destructive Effects on Tabriz Northern Highway, Iran

Nowadays, expansive or swelling soils considered as a worldwide issue which poses several challenges to geotechnical engineers. Expansive soils are classified as a high-plasticity fine grained soils which mainly consists of clay minerals. This paper is intended to investigate the expansive soils characterizations along Tabriz Northern Highway (TNH) and their destructive effects. TNH with length of 17 km is constructed about 10 years ago. Geology formation of TNH and its around is consisted of different layers of mudstone, marlstone, and sandstone. The expansive soils formation is result of weathering of these rock layers. There are some challenges for TNH pavement such as: longitudinal and transverse fractures and cracks, the distortion and settlement of surface which is cause many accidents. Field studies are shown that the main reasons of TNH pavement problems are soil swelling and settlement of fill soils below pavement. For investigation of swelling characterization of soils, some samples were obtained and tested in laboratory. The test results indicate that the unified classifications of soils are mostly CL and clay material of soils is about 30%. Plasticity index of soils is placed between 7 and 23%. Swelling potential of soils along TNH is evaluated low to medium. In order to ground treatment, soil-cement is placed under road using the local soil material.