Design of Flexible Pavements on Expansive Soils

“American roads are good not because America is rich, but America is rich because American roads are good.” — John F. Kennedy. India has a road network of over 5, 472, 144 kilometres (3, 400, 233 mi) as on 31 March 2015, the second largest road network in the world. Expansive soils are typically clays that demonstrate extensive volume and strength changes at varying moisture content due to their chemical composition. The main causes of premature failures of road pavements is attributed to expansive subgrade soils and poor drainage, leading to severe cracking and heave on road surface. The amount of certain clay minerals that are present, such as montmorillonite and smectite, directly affect the shrink-swell capacity of soil. This ability to drastically change volume can cause damage to existing structures. The aim of this paper is to highlight issues of expansive subgrades & suggest some workable solutions so that highway engineers can improve design and construction methodology of pavement on expansive soils. As per a report, “Expansive clay soil causes more damage to U.S. commercial and residential property each year than all hurricanes, tornados, earthquakes and floods combined”.