Engineering geological characterization of Neogene marls in the Southeastern Granada Basin, Spain

Analysis of 171 samples taken from the Neogene cohesive soils of the Southeastern edge of the Granada basin shows inverse correlation between carbonate content and dispersion index and swelling behaviour and direct correlations between carbonate content and shear strength. This paper shows that carbonate content and clay fraction activity have a great influence on the compaction characteristics of soils. Marls of the middle and upper Tortonian age (lower marls) are inadequate for use as subgrade because of their high plasticity. In addition, marls of lower and upper Messinian age (upper marls) are inadequate for use as subgrade because of their high carbonate content. The relationship between carbonate content and geotechnical properties is particularly important because the changes caused by pedogenic dissolution and precipitation processes lead to changes in mechanical behaviour.