Due to the limited availability of earth materials for embankments of high speed lines, the lime-stabilized soils system is being become interesting. The cohesive or plastic soils, that contain high clay and limes quantity, present grave problems due their plasticity, low bearing rate and instability (expansion or contraction). The use of the site materials is recommended from the economical and environmental point of view. For this reason, Adif and CEDEX had work together redacting the new prescriptions on lime-stabilized soils for High Speed Railways core embankments.