The problem of expansive clay soil with regard to structural damage of buildings and roads was not recognized until the latter part of 1930. Up to now, some engineers are not familiar with certain characteristics of this soil. Many clay soils may be mistaken for expansive ones and costly structural designs be prepared for structures to be founded on them. Therefore, there is a need to characterize the soil for ease of identification. In this regard, Dr. M?Ndegwa points out that expansive soil can be easily identified through local climate, vegetation, ground topography, physical features of soil and simple laboratory tests. This book defines expansive soil, its occurrence, formation, mineralogical and chemical structure. The author explains the swelling behaviour of clay soil and discusses factors that influence actual amount of swell or shrinkage, concepts of swelling, modes of swelling and mechanisms of swelling. The classification and identification of this soil type including its compaction characteristics are also described. Finally, evaluation of swelling potential is discussed. Students of Civil Engineering and Practising Engineers will find this book very resourceful.