Predictive map of clay expansivity risks in Spain at a scale of 1:1,000,000

The Predictive Map of Expansivity Risks of Spanish Clays at a scale of 1:1,000. 000 delimits the clay formations, classifying them into 4 grades according to their expansivity potential: Non-expansive clays or clays dispersed in a non-clay matrix: No or low risk of expansivity; Subordinate expansive clays or clays located in climatic zones without an annual humidity deficit: Low to moderate expansivity risk; Locally predominant expansive clays located in climatic zones with annual moisture deficit: Moderate to high expansivity risk; Predominant expansive clays in areas where expansivity problems have occurred. High to very high expansivity risk. The term expansivity defines the capacity of the soil to undergo volume changes when its moisture conditions are modified, or to generate pressures if expansion is prevented. This map was made by the Geological Survey of Spain (IGME) with the collaboration of the Centro de Estudios y Experimentación de Obras Públicas (CEDEX) in 1986.