Modern Concepts of Clay Materials

Abstract

Clay materials are composed essentially of minute crystalline particles of any one or more members of a few groups of minerals known as the "clay minerals." Using this clay-mineral concept as a point of departure, researches starting from the many fields in which clay materials are important-from agriculture, engineering, geology, and the ceramic, rubber, paper, petroleum, and many other industries-have in the last fifteen years made outstanding progress toward a more satisfactory and complete understanding of the precise composition of clay materials, their structure, and the factors that determine their properties. The occurrence of the various clay minerals in soils, contemporaneous sediments, and ancient clays and shales is summarized briefly, and general conclusions are drawn that seem warranted. Pertinent information on the composition, structure, and certain properties of the individual clay minerals is assembled. Finally, the structural relationships of clay-mineral particles and water are analyzed for clay materials in the plastic state, and some new interpretations are suggested.