Calcareous sands are accumulations of pieces of carbonate materials, usually derived from reworked shell fragments and skeletal debris of minute life. Several factors affect the qualities of calcareous sediments, such as: grain type and size, cementation, pore spaces, environmental conditions, etc. Although, geotechnical engineers have been conducting extensive research on calcareous materials lately, however, they don’t agree on the appropriate field and laboratory investigation procedures and important parameters necessary to characterize them. The traditional practice successfully used for other types of materials will be ineffective for these deposits. This results in a bad understanding of these materials, leading to many problems in practice. The mechanical behavior of calcareous and carbonaceous soils and sediments mainly differ from those of terrigenous deposits or other types such as quartz sands or siliceous sediments. Experiences show that the application of engineering loads within the normal range causes calcareous soil structures to collapse and grains to crush, when for example, conventional pile design theory and experience rely on data developed from terrestrial sediments where particles are not crushed. The crushing characteristics of calcareous soils
are very important in defining foundation resistance. In Addition, overburden has very little influence on offshore calcareous sands in different manner with quartz sands. Therefore, conventional soil mechanics theories should not be directly applied to such cases.The aim of this paper is to illustrate key recommendations for predictions of the behavior of calcareous and carbonaceous soils and sediments when encountered, especially in coastal and offshore areas. This has been achieved by collecting and using valuable results of different tests.