The Mechanical Aging of Soils

Soils age. Their engineering properties often improve significantly during aging times of practical interest to engineers. This paper provides examples from research and practice. It includes a review of the triaxial IDS test, followed by examples of its use to investigate the question of whether the aging improvements result from frictional or cohesive effects. Contrary to most current thinking, the soil stiffening and strengthening appears entirely frictional in effect. The aging effects described appear mechanical, resulting from dispersive particle movements and internal stress arching under drained conditions. The paper concludes with suggestions for using these mechanical aging effects in practice.